fix readme

fix

.gitignore

@@ -1,4 +1,6 @@
 /target
 *.uf2
-abi_sys.h
+userlib_sys.h
 assets/gif/bad_apple.gif
+picolibc
+user-apps/gboy/Peanut-GB

.gitmodules

@@ -0,0 +1,6 @@
+[submodule "picolibc"]
+	path = picolibc
+	url = https://github.com/picolibc/picolibc
+[submodule "user-apps/gboy/Peanut-GB"]
+	path = user-apps/gboy/Peanut-GB
+	url = https://github.com/deltabeard/Peanut-GB

Cargo.toml

@@ -2,12 +2,14 @@
 resolver = "3"
 members = [
   "kernel",
-  "abi_sys",
+  "userlib_sys",
-  "abi",
+  "userlib",
-  "user-apps/calculator",
+  "selection_ui",
-  "user-apps/snake",
+  "user_apps/calculator",
-  "user-apps/gallery",
+  "user_apps/snake",
-  "user-apps/gif",
+  "user_apps/gallery",
+  "user_apps/gif",
+  "user_apps/wav_player",
 ]
 
 [profile.release]
@@ -22,8 +24,8 @@ codegen-units = 1
 lto = true
 debug = false
 opt-level = "z"
-panic = "abort"
+panic = "unwind"
 
 [profile.dev]
 lto = true
-opt-level = "z"
+opt-level = "s"

README.md

@@ -1,26 +1,27 @@
 # PicoCalc OS (Rust)
 
-A simple operating system for the **Clockwork PicoCalc**, written in Rust.  
+A simple kernel and applications for the **Clockwork PicoCalc**, written in Rust.  
-This project provides a minimal kernel, ABI, and user-space applications to experiment with OS development on constrained hardware.
+This project provides a minimal kernel, syscall table, and user-space applications to experiment with kernel development on constrained hardware.
 
 ## Status
 
 Basic synchronous applications are working great.  
-Current focus is on **expanding the ABI syscalls** and **fixing the MSC/USB-SCSI driver** to make application development easier and smoother.
+Current focus is on exanding applications and porting software, finding bugs in ffi, and making sure the kernel is as stable as possible.
 
 ## Project Structure
 
-- **`kernel/`** – The core OS kernel (task scheduling, drivers, memory, etc.)
+- **`kernel/`** – The core OS kernel
-- **`abi_sys/`** – Shared application binary interface definitions for kernel ↔ userspace (Repr "C")
+- **`userlib_sys/`** – C FFI bindings for kernel syscall
-- **`abi/`** – Rust focused ABI helpers and abstractions for easier development
+- **`userlib/`** – Rust wrapper on top of `userlib_sys` 
-- **`user-apps/`** – Collection of userspace programs (calculator, snake, etc.)
+- **`picolib/`** – Built with ```just newlib```, and provides libc symbols when linking with C libraries 
+- **`user_apps/`** – Collection of userspace programs (gif player, wav player, calculator, snake, etc.)
 
 ## Features
 
 - Minimal Rust-based kernel targeting the PicoCalc
-- Custom ABI for safe communication between kernel and applications
+- Custom ABI for *Mostly* safe communication between kernel and applications
 - Support for multiple user-space applications
-- Hardware drivers tailored for the PicoCalc
+- Hardware drivers tailored for the PicoCalc( Audio, Display, Keyboard, ans Storage )
 
 ## Getting Started
 

abi/src/lib.rs

@@ -1,162 +0,0 @@
-#![no_std]
-#![allow(static_mut_refs)]
-
-extern crate alloc;
-
-pub use abi_sys::{self, keyboard};
-use abi_sys::{RngRequest, alloc, dealloc, keyboard::KeyEvent};
-pub use alloc::format;
-use core::alloc::{GlobalAlloc, Layout};
-use rand_core::RngCore;
-
-#[global_allocator]
-static ALLOC: Alloc = Alloc;
-
-struct Alloc;
-
-unsafe impl GlobalAlloc for Alloc {
-    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
-        alloc(layout.into())
-    }
-
-    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
-        dealloc(ptr, layout.into());
-    }
-}
-
-#[macro_export]
-macro_rules! print {
-    ($($arg:tt)*) => {{
-        let s = $crate::format!($($arg)*);
-        $crate::abi_sys::print(s.as_ptr(), s.len());
-    }};
-}
-
-pub fn sleep(ms: u64) {
-    abi_sys::sleep(ms);
-}
-
-pub fn get_ms() -> u64 {
-    abi_sys::get_ms()
-}
-
-pub fn get_key() -> KeyEvent {
-    abi_sys::keyboard::get_key().into()
-}
-
-pub mod display {
-    use abi_sys::CPixel;
-    use embedded_graphics::{
-        Pixel,
-        geometry::{Dimensions, Point},
-        pixelcolor::Rgb565,
-        prelude::{DrawTarget, Size},
-        primitives::Rectangle,
-    };
-
-    pub const SCREEN_WIDTH: usize = 320;
-    pub const SCREEN_HEIGHT: usize = 320;
-
-    pub type Pixel565 = Pixel<Rgb565>;
-
-    const BUF_SIZE: usize = 15 * 1024; // tune this for performance
-    static mut BUF: [CPixel; BUF_SIZE] = [CPixel::new(); BUF_SIZE];
-    // const BUF_SIZE: usize = 250 * 1024; // tune this for performance
-    // static mut BUF: Lazy<Vec<CPixel>> = Lazy::new(|| vec![const { CPixel::new() }; BUF_SIZE]);
-
-    pub struct Display;
-
-    impl Dimensions for Display {
-        fn bounding_box(&self) -> Rectangle {
-            Rectangle {
-                top_left: Point { x: 0, y: 0 },
-                size: Size {
-                    width: SCREEN_WIDTH as u32,
-                    height: SCREEN_HEIGHT as u32,
-                },
-            }
-        }
-    }
-
-    impl DrawTarget for Display {
-        type Color = Rgb565;
-        type Error = ();
-
-        fn draw_iter<I>(&mut self, pixels: I) -> Result<(), Self::Error>
-        where
-            I: IntoIterator<Item = Pixel<Self::Color>>,
-        {
-            let mut count = 0;
-            for p in pixels {
-                unsafe { BUF[count] = p.into() };
-                count += 1;
-
-                if count == BUF_SIZE - 1 {
-                    abi_sys::draw_iter(unsafe { BUF.as_ptr() }, count);
-                    count = 0;
-                }
-            }
-
-            if count > 0 {
-                abi_sys::draw_iter(unsafe { BUF.as_ptr() }, count);
-            }
-
-            Ok(())
-        }
-    }
-}
-
-fn gen_rand(req: &mut RngRequest) {
-    abi_sys::gen_rand(req);
-}
-
-pub struct Rng;
-
-impl RngCore for Rng {
-    fn next_u32(&mut self) -> u32 {
-        let mut req = RngRequest::U32(0);
-        gen_rand(&mut req);
-        if let RngRequest::U32(i) = req {
-            return i;
-        };
-        0
-    }
-
-    fn next_u64(&mut self) -> u64 {
-        let mut req = RngRequest::U64(0);
-        gen_rand(&mut req);
-        if let RngRequest::U64(i) = req {
-            return i;
-        };
-        0
-    }
-    fn fill_bytes(&mut self, dst: &mut [u8]) {
-        let mut req = RngRequest::Bytes {
-            ptr: dst.as_mut_ptr(),
-            len: dst.len(),
-        };
-        gen_rand(&mut req);
-    }
-}
-
-pub mod fs {
-    use embedded_sdmmc::DirEntry;
-
-    pub fn read_file(file: &str, read_from: usize, buf: &mut [u8]) -> usize {
-        abi_sys::read_file(
-            file.as_ptr(),
-            file.len(),
-            read_from,
-            buf.as_mut_ptr(),
-            buf.len(),
-        )
-    }
-
-    pub fn list_dir(path: &str, files: &mut [Option<DirEntry>]) -> usize {
-        abi_sys::list_dir(path.as_ptr(), path.len(), files.as_mut_ptr(), files.len())
-    }
-
-    pub fn file_len(str: &str) -> usize {
-        abi_sys::file_len(str.as_ptr(), str.len())
-    }
-}

justfile

@@ -1,13 +1,37 @@
+target := "thumbv8m.main-none-eabihf"
+
 kernel-dev board:
-    cargo run --bin kernel --features {{board}}
+    cargo run --bin kernel --features {{board}}  --features fps --features defmt
+kernel-release-probe board:
+    cargo run --bin kernel --profile release --features {{board}} --features fps
 kernel-release board:
     cargo build --bin kernel --release --no-default-features --features {{board}}
-    elf2uf2-rs -d target/thumbv8m.main-none-eabihf/release/kernel
+    elf2uf2-rs -d target/{{target}}/release/kernel
 
 binary-args := "RUSTFLAGS=\"-C link-arg=-pie -C relocation-model=pic\""
 
 cbindgen:
-    cbindgen abi_sys --output abi_sys.h -q
+    cbindgen userlib_sys --output userlib_sys.h -q
+
+newlib:
+    #!/bin/bash
+    cd picolibc
+    mkdir build
+    cd build
+    CONFIG_PICOLIBC=true ../scripts/do-configure thumbv8m_main_fp-none-eabi \
+        --buildtype=minsize \
+        -Dtests=true \
+        -Dtinystdio=false \
+        -Dsingle-thread=true \
+        -Db_pie=true \
+        -Ddefault_library=static \
+        -Dtinystdio=false \
+        -Dnewlib-nano-malloc=true \
+        -Dmultilib=false \
+        -Dpicolib=true \
+        "$@" 
+    DESTDIR=./install meson install
+    ninja
 
 userapp app:
      {{binary-args}} cargo build --bin {{app}} --profile release-binary
@@ -17,3 +41,20 @@ userapps: cbindgen
     just userapp snake
     just userapp gallery
     just userapp gif
+    just userapp wav_player
+
+copy-userapp app:
+    cp ./target/{{target}}/release-binary/{{app}} /run/media/$(whoami)/PICOCALC/{{app}}.bin
+
+copy-userapps:
+    #!/bin/bash
+    just userapps
+    just copy-userapp calculator
+    just copy-userapp snake
+    just copy-userapp gallery
+    just copy-userapp gif
+    just copy-userapp wav_player
+
+    DEV=$(lsblk -o LABEL,NAME -nr | awk -v L="PICOCALC" '$1==L {print "/dev/" $2}')
+    udisksctl unmount -b "$DEV"
+    udisksctl power-off -b "$DEV"    

kernel/Cargo.toml

@@ -11,11 +11,14 @@ doctest = false
 bench = false
 
 [features]
-default = ["rp235x", "defmt"]
+default = ["rp235x"]
-pimoroni2w = ["rp235x"]
+pimoroni2w = ["rp235x", "psram"]
-rp2040 = ["embassy-rp/rp2040"]
+# rp2040 = ["embassy-rp/rp2040"] # unsupported, ram too small for fb
 rp235x = ["embassy-rp/rp235xb"]
 trouble = ["dep:bt-hci", "dep:cyw43", "dep:cyw43-pio", "dep:trouble-host"]
+psram = ["dep:embedded-alloc"]
+overclock = []
+fps = []
 defmt = [
   "dep:defmt",
   "panic-probe/print-defmt",
@@ -70,16 +73,17 @@ panic-probe = "0.3"
 portable-atomic = { version = "1.11", features = ["critical-section"] }
 assign-resources = "0.5.0"
 
-defmt = { version = "0.3", optional = true }
+defmt = { version = "1.0.1", optional = true }
-defmt-rtt = "0.4.2"
+defmt-rtt = "1.1.0"
 
 embedded-sdmmc = { version = "0.9", default-features = false }
 st7365p-lcd = { git = "https://github.com/legitcamper/st7365p-lcd-rs", rev = "a784b9e6df0769371dfc522528e770cf8fc6403a" } # async branch
 embedded-graphics = { version = "0.8.1" }
 embedded-text = "0.7.2"
 embedded-layout = "0.4.2"
-kolibri-embedded-gui = "0.1.0"
 
+micromath = "2.1.0"
+fixed = "1.29.0"
 strum = { version = "0.27.2", default-features = false }
 rand = { version = "0.9.0", default-features = false }
 once_cell = { version = "1.21.3", default-features = false }
@@ -90,7 +94,9 @@ spin = "0.10.0"
 num_enum = { version = "0.7.4", default-features = false }
 goblin = { version = "0.10.1", default-features = false, features = ["elf32"] }
 talc = "4.4.3"
-embedded-alloc = { version = "0.6.0", features = ["allocator_api"] }
+embedded-alloc = { version = "0.6.0", features = [
+  "allocator_api",
+], optional = true }
 bumpalo = "3.19.0"
 
-abi_sys = { path = "../abi_sys" }
+userlib_sys = { path = "../userlib_sys" }

kernel/build.rs

@@ -14,7 +14,7 @@ use std::io::Write;
 use std::path::PathBuf;
 
 #[cfg(all(feature = "rp235x", not(feature = "pimoroni2w")))]
-const MEMORY: &'static [u8] = include_bytes!("rp2350.x");
+const MEMORY: &[u8] = include_bytes!("rp2350.x");
 #[cfg(feature = "pimoroni2w")]
 const MEMORY: &'static [u8] = include_bytes!("rp2350.x");
 

kernel/src/audio.rs

@@ -0,0 +1,204 @@
+use crate::Audio;
+use core::sync::atomic::{AtomicBool, AtomicU32, Ordering};
+use embassy_futures::{join::join, yield_now};
+use embassy_rp::{
+    Peri,
+    clocks::clk_sys_freq,
+    dma::{AnyChannel, Channel},
+    gpio::Level,
+    pio::{
+        Common, Config, Direction, FifoJoin, Instance, LoadedProgram, PioPin, ShiftConfig,
+        StateMachine, program::pio_asm,
+    },
+};
+use fixed::traits::ToFixed;
+
+pub const SAMPLE_RATE_HZ: u32 = 22_050;
+const AUDIO_BUFFER_SAMPLES: usize = 1024;
+const _: () = assert!(AUDIO_BUFFER_SAMPLES == userlib_sys::AUDIO_BUFFER_SAMPLES);
+
+const SILENCE: u8 = u8::MAX / 2;
+
+// 8bit stereo interleaved PCM audio buffers
+pub static mut AUDIO_BUFFER: [u8; AUDIO_BUFFER_SAMPLES * 2] = [SILENCE; AUDIO_BUFFER_SAMPLES * 2];
+static mut AUDIO_BUFFER_1: [u8; AUDIO_BUFFER_SAMPLES * 2] = [SILENCE; AUDIO_BUFFER_SAMPLES * 2];
+
+// atomics for user applications to signal changes to audio buffers
+pub static AUDIO_BUFFER_READY: AtomicBool = AtomicBool::new(true);
+pub static AUDIO_BUFFER_WRITTEN: AtomicBool = AtomicBool::new(false);
+pub static AUDIO_BUFFER_SAMPLE_RATE: AtomicU32 = AtomicU32::new(SAMPLE_RATE_HZ);
+
+/// resets audio buffers after user applications are unloaded
+pub fn clear_audio_buffers() {
+    unsafe {
+        AUDIO_BUFFER.fill(SILENCE);
+        AUDIO_BUFFER_1.fill(SILENCE);
+    }
+}
+
+#[embassy_executor::task]
+pub async fn audio_handler(mut audio: Audio) {
+    let prg = PioPwmAudioProgram8Bit::new(&mut audio.pio);
+    let mut pwm_pio_left =
+        PioPwmAudio::new(audio.dma0, &mut audio.pio, audio.sm0, audio.left, &prg);
+    let mut pwm_pio_right =
+        PioPwmAudio::new(audio.dma1, &mut audio.pio, audio.sm1, audio.right, &prg);
+
+    // enable sms at the same time to ensure they are synced
+    audio.pio.apply_sm_batch(|pio| {
+        pio.set_enable(&mut pwm_pio_right.sm, true);
+        pio.set_enable(&mut pwm_pio_left.sm, true);
+    });
+
+    let mut sample_rate = SAMPLE_RATE_HZ;
+
+    loop {
+        unsafe {
+            let new_sample_rate = AUDIO_BUFFER_SAMPLE_RATE.load(Ordering::Acquire);
+            if new_sample_rate != sample_rate {
+                sample_rate = new_sample_rate;
+                pwm_pio_left.reconfigure(sample_rate);
+                pwm_pio_right.reconfigure(sample_rate);
+
+                // restart sms at the same time to ensure they are synced
+                audio.pio.apply_sm_batch(|pio| {
+                    pio.restart(&mut pwm_pio_right.sm);
+                    pio.restart(&mut pwm_pio_left.sm);
+                });
+            }
+
+            if AUDIO_BUFFER_WRITTEN.load(Ordering::Acquire) {
+                write_samples(&mut pwm_pio_left, &mut pwm_pio_right, &AUDIO_BUFFER_1).await;
+                AUDIO_BUFFER_1.fill(SILENCE);
+                core::mem::swap(&mut AUDIO_BUFFER, &mut AUDIO_BUFFER_1);
+                AUDIO_BUFFER_READY.store(true, Ordering::Release)
+            } else {
+                yield_now().await;
+            }
+        }
+    }
+}
+
+async fn write_samples<PIO: Instance>(
+    left: &mut PioPwmAudio<'static, PIO, 0>,
+    right: &mut PioPwmAudio<'static, PIO, 1>,
+    buf: &[u8],
+) {
+    // pack two samples per word
+    static mut PACKED_BUF_L: [u32; AUDIO_BUFFER_SAMPLES / 2] = [0; AUDIO_BUFFER_SAMPLES / 2];
+    static mut PACKED_BUF_R: [u32; AUDIO_BUFFER_SAMPLES / 2] = [0; AUDIO_BUFFER_SAMPLES / 2];
+
+    unsafe {
+        for ((pl, pr), sample) in PACKED_BUF_L
+            .iter_mut()
+            .zip(PACKED_BUF_R.iter_mut())
+            .zip(buf.chunks(4))
+        {
+            *pl = pack_u8_samples(sample[0], sample[2]);
+            *pr = pack_u8_samples(sample[1], sample[3]);
+        }
+
+        let left_fut = left
+            .sm
+            .tx()
+            .dma_push(left.dma.reborrow(), &PACKED_BUF_L, false);
+
+        let right_fut = right
+            .sm
+            .tx()
+            .dma_push(right.dma.reborrow(), &PACKED_BUF_R, false);
+
+        join(left_fut, right_fut).await;
+    }
+}
+
+struct PioPwmAudioProgram8Bit<'d, PIO: Instance>(LoadedProgram<'d, PIO>);
+
+/// Writes one sample to pwm as high and low time
+impl<'d, PIO: Instance> PioPwmAudioProgram8Bit<'d, PIO> {
+    fn new(common: &mut Common<'d, PIO>) -> Self {
+        // only uses 16 bits top for pwm high, bottom for pwm low
+        // allows storing two samples per word
+        let prg = pio_asm!(
+            ".side_set 1",
+
+            "set x, 0 side 1",
+            "set y, 0 side 0",
+            ".wrap_target",
+
+            "check:",
+            "pull ifempty noblock side 1", // gets new osr or loads 0 into x, gets second sample if osr not empty
+            "out x, 8 side 0", // pwm high time
+            "out y, 8 side 1", // pwm low time
+            "jmp x!=y play_sample side 0", // x & y are never equal unless osr was empty
+            "set x, 1 side 1",
+            "set y, 1 side 0",
+
+            "play_sample:"
+            "loop_high:",
+            "jmp x-- loop_high side 1", // keep pwm high, decrement X until 0
+            "loop_low:",
+            "jmp y-- loop_low side 0", // keep pwm low, decrement Y until 0
+            ".wrap"
+        );
+
+        let prg = common.load_program(&prg.program);
+
+        Self(prg)
+    }
+}
+
+struct PioPwmAudio<'d, PIO: Instance, const SM: usize> {
+    dma: Peri<'d, AnyChannel>,
+    sm: StateMachine<'d, PIO, SM>,
+}
+
+impl<'d, PIO: Instance, const SM: usize> PioPwmAudio<'d, PIO, SM> {
+    fn get_sm_divider(sample_rate: u32) -> u32 {
+        let target_clock = (u8::MAX as u32 + 1) * sample_rate;
+        clk_sys_freq() / target_clock
+    }
+
+    fn new(
+        dma: Peri<'d, impl Channel>,
+        pio: &mut Common<'d, PIO>,
+        mut sm: StateMachine<'d, PIO, SM>,
+        pin: Peri<'d, impl PioPin>,
+        prg: &PioPwmAudioProgram8Bit<'d, PIO>,
+    ) -> Self {
+        let pin = pio.make_pio_pin(pin);
+        sm.set_pins(Level::High, &[&pin]);
+        sm.set_pin_dirs(Direction::Out, &[&pin]);
+
+        let mut cfg = Config::default();
+        cfg.fifo_join = FifoJoin::TxOnly;
+        let shift_cfg = ShiftConfig {
+            auto_fill: false,
+            ..Default::default()
+        };
+        cfg.shift_out = shift_cfg;
+        cfg.use_program(&prg.0, &[&pin]);
+        sm.set_config(&cfg);
+
+        sm.set_clock_divider(Self::get_sm_divider(SAMPLE_RATE_HZ).to_fixed());
+
+        Self {
+            dma: dma.into(),
+            sm,
+        }
+    }
+
+    fn reconfigure(&mut self, sample_rate: u32) {
+        self.sm
+            .set_clock_divider(Self::get_sm_divider(sample_rate).to_fixed());
+    }
+}
+
+/// packs two u8 samples into 32bit word
+fn pack_u8_samples(sample1: u8, sample2: u8) -> u32 {
+    (u8_pcm_to_pwm(sample1) as u32) << 16 | u8_pcm_to_pwm(sample2) as u32
+}
+
+fn u8_pcm_to_pwm(sample: u8) -> u16 {
+    ((sample as u16) << 8) | ((u8::MAX - sample) as u16)
+}

kernel/src/display.rs

@@ -1,21 +1,27 @@
 use crate::framebuffer::{self, AtomicFrameBuffer, FB_PAUSED};
-use core::alloc::{GlobalAlloc, Layout};
 use core::sync::atomic::Ordering;
+use embassy_futures::yield_now;
 use embassy_rp::{
     Peri,
     gpio::{Level, Output},
     peripherals::{PIN_13, PIN_14, PIN_15, SPI1},
     spi::{Async, Spi},
 };
-use embassy_time::{Delay, Timer};
+use embassy_time::Delay;
-use embedded_graphics::{
-    pixelcolor::Rgb565,
-    prelude::{DrawTarget, RgbColor},
-};
 use embedded_hal_bus::spi::ExclusiveDevice;
 use st7365p_lcd::ST7365P;
 
-type DISPLAY = ST7365P<
+#[cfg(feature = "psram")]
+use crate::heap::HEAP;
+#[cfg(feature = "psram")]
+use core::alloc::{GlobalAlloc, Layout};
+#[cfg(feature = "psram")]
+use embedded_graphics::{draw_target::DrawTarget, pixelcolor::Rgb565, prelude::RgbColor};
+
+#[cfg(feature = "fps")]
+pub use framebuffer::fps::{FPS_CANVAS, FPS_COUNTER};
+
+type Display = ST7365P<
     ExclusiveDevice<Spi<'static, SPI1, Async>, Output<'static>, Delay>,
     Output<'static>,
     Output<'static>,
@@ -29,18 +35,21 @@ pub static mut FRAMEBUFFER: Option<AtomicFrameBuffer> = None;
 
 fn init_fb() {
     unsafe {
-        FRAMEBUFFER = Some(if cfg!(not(feature = "pimoroni2w")) {
+        #[cfg(feature = "psram")]
-            static mut BUF: [u16; framebuffer::SIZE] = [0; framebuffer::SIZE];
+        {
-            AtomicFrameBuffer::new(&mut BUF)
+            let slab = HEAP.alloc(Layout::array::<u16>(framebuffer::SIZE).unwrap()) as *mut u16;
-        } else {
-            let slab = crate::heap::HEAP.alloc(Layout::array::<u16>(framebuffer::SIZE).unwrap())
-                as *mut u16;
             let buf = core::slice::from_raw_parts_mut(slab, framebuffer::SIZE);
 
             let mut fb = AtomicFrameBuffer::new(buf);
             fb.clear(Rgb565::BLACK).unwrap();
-            fb
+            FRAMEBUFFER = Some(fb);
-        });
+        }
+
+        #[cfg(not(feature = "psram"))]
+        {
+            static mut BUF: [u16; framebuffer::SIZE] = [0; framebuffer::SIZE];
+            FRAMEBUFFER = Some(AtomicFrameBuffer::new(&mut BUF));
+        }
     }
 }
 
@@ -49,7 +58,7 @@ pub async fn init_display(
     cs: Peri<'static, PIN_13>,
     data: Peri<'static, PIN_14>,
     reset: Peri<'static, PIN_15>,
-) -> DISPLAY {
+) -> Display {
     init_fb();
 
     let spi_device = ExclusiveDevice::new(spi, Output::new(cs, Level::Low), Delay).unwrap();
@@ -77,8 +86,22 @@ pub async fn init_display(
 }
 
 #[embassy_executor::task]
-pub async fn display_handler(mut display: DISPLAY) {
+pub async fn display_handler(mut display: Display) {
+    use embassy_time::{Instant, Timer};
+
+    // Target ~60 Hz refresh (≈16.67 ms per frame)
+    const FRAME_TIME_MS: u64 = 1000 / 60;
+
     loop {
+        let start = Instant::now();
+
+        #[cfg(feature = "fps")]
+        unsafe {
+            if FPS_COUNTER.should_draw() {
+                FPS_CANVAS.draw_fps().await;
+            }
+        }
+
         if !FB_PAUSED.load(Ordering::Acquire) {
             unsafe {
                 FRAMEBUFFER
@@ -86,11 +109,15 @@ pub async fn display_handler(mut display: DISPLAY) {
                     .unwrap()
                     .partial_draw(&mut display)
                     .await
-                    .unwrap()
+                    .unwrap();
-            };
+            }
         }
 
-        // small yield to allow other tasks to run
+        let elapsed = start.elapsed().as_millis();
-        Timer::after_nanos(500).await;
+        if elapsed < FRAME_TIME_MS {
+            Timer::after_millis(FRAME_TIME_MS - elapsed).await;
+        } else {
+            yield_now().await;
+        }
     }
 }

kernel/src/elf.rs

@@ -1,9 +1,7 @@
 use crate::{
-    abi,
     storage::{File, SDCARD},
+    syscalls,
 };
-use abi_sys::CallTable;
-use abi_sys::EntryFn;
 use alloc::{vec, vec::Vec};
 use bumpalo::Bump;
 use core::ptr;
@@ -18,6 +16,7 @@ use goblin::{
     elf32::{header, reloc::Rel, section_header::SectionHeader, sym::Sym},
 };
 use strum::IntoEnumIterator;
+use userlib_sys::{EntryFn, SyscallTable};
 
 const ELF32_HDR_SIZE: usize = 52;
 
@@ -40,7 +39,7 @@ pub async unsafe fn load_binary(name: &ShortFileName) -> Option<(EntryFn, Bump)>
             let mut ph_buf = vec![0_u8; elf_header.e_phentsize as usize];
 
             let (total_size, min_vaddr, _max_vaddr) =
-                total_loadable_size(&mut file, &elf_header, &mut ph_buf);
+                total_loadable_size(&mut file, elf_header, &mut ph_buf);
 
             let bump = Bump::with_capacity(total_size);
             let base = bump.alloc_slice_fill_default::<u8>(total_size);
@@ -53,25 +52,22 @@ pub async unsafe fn load_binary(name: &ShortFileName) -> Option<(EntryFn, Bump)>
                 let ph = cast_phdr(&ph_buf);
 
                 let seg_offset = (ph.p_vaddr - min_vaddr) as usize;
-                let mut segment = &mut base[seg_offset..seg_offset + ph.p_memsz as usize];
+                let segment = &mut base[seg_offset..seg_offset + ph.p_memsz as usize];
 
                 if ph.p_type == PT_LOAD {
-                    load_segment(&mut file, &ph, &mut segment).unwrap();
+                    load_segment(&mut file, &ph, segment).unwrap();
                 }
             }
 
             for i in 0..elf_header.e_shnum {
                 let sh = read_section(&mut file, elf_header, i.into());
 
-                match sh.sh_type {
+                if sh.sh_type == SHT_REL {
-                    SHT_REL => {
                     apply_relocations(&sh, min_vaddr, base.as_mut_ptr(), &mut file).unwrap();
                 }
-                    _ => {}
-                }
             }
 
-            patch_abi(&elf_header, base.as_mut_ptr(), min_vaddr, &mut file).unwrap();
+            patch_syscalls(elf_header, base.as_mut_ptr(), min_vaddr, &mut file).unwrap();
 
             // entry pointer is base_ptr + (entry - min_vaddr)
             let entry_ptr: EntryFn = unsafe {
@@ -151,14 +147,14 @@ fn apply_relocations(
     Ok(())
 }
 
-fn patch_abi(
+fn patch_syscalls(
     elf_header: &Header,
     base: *mut u8,
     min_vaddr: u32,
     file: &mut File,
 ) -> Result<(), ()> {
     for i in 1..=elf_header.e_shnum {
-        let sh = read_section(file, &elf_header, i.into());
+        let sh = read_section(file, elf_header, i.into());
 
         // find the symbol table
         if sh.sh_type == SHT_SYMTAB {
@@ -173,7 +169,7 @@ fn patch_abi(
                     &symtab_buf[i * sh.sh_entsize as usize..(i + 1) * sh.sh_entsize as usize];
                 let sym = cast_sym(sym_bytes);
 
-                let str_sh = read_section(file, &elf_header, sh.sh_link);
+                let str_sh = read_section(file, elf_header, sh.sh_link);
 
                 let mut name = Vec::new();
                 file.seek_from_start(str_sh.sh_offset + sym.st_name)
@@ -189,27 +185,33 @@ fn patch_abi(
                 }
 
                 let symbol_name = core::str::from_utf8(&name).unwrap();
-                if symbol_name == "CALL_ABI_TABLE" {
+                if symbol_name == stringify!(SYS_CALL_TABLE) {
                     let table_base =
                         unsafe { base.add((sym.st_value as usize) - min_vaddr as usize) }
                             as *mut usize;
 
-                    for (idx, call) in CallTable::iter().enumerate() {
+                    for (idx, call) in SyscallTable::iter().enumerate() {
                         let ptr = match call {
-                            CallTable::Alloc => abi::alloc as usize,
+                            SyscallTable::Alloc => syscalls::alloc as usize,
-                            CallTable::Dealloc => abi::dealloc as usize,
+                            SyscallTable::Dealloc => syscalls::dealloc as usize,
-                            CallTable::PrintString => abi::print as usize,
+                            SyscallTable::PrintString => syscalls::print as usize,
-                            CallTable::SleepMs => abi::sleep as usize,
+                            SyscallTable::SleepMs => syscalls::sleep as usize,
-                            CallTable::GetMs => abi::get_ms as usize,
+                            SyscallTable::GetMs => syscalls::get_ms as usize,
-                            CallTable::DrawIter => abi::draw_iter as usize,
+                            SyscallTable::DrawIter => syscalls::draw_iter as usize,
-                            CallTable::GetKey => abi::get_key as usize,
+                            SyscallTable::GetKey => syscalls::get_key as usize,
-                            CallTable::GenRand => abi::gen_rand as usize,
+                            SyscallTable::GenRand => syscalls::gen_rand as usize,
-                            CallTable::ListDir => abi::list_dir as usize,
+                            SyscallTable::ListDir => syscalls::list_dir as usize,
-                            CallTable::ReadFile => abi::read_file as usize,
+                            SyscallTable::ReadFile => syscalls::read_file as usize,
-                            CallTable::FileLen => abi::file_len as usize,
+                            SyscallTable::WriteFile => syscalls::write_file as usize,
+                            SyscallTable::FileLen => syscalls::file_len as usize,
+                            SyscallTable::ReconfigureAudioSampleRate => {
+                                syscalls::reconfigure_audio_sample_rate as usize
+                            }
+                            SyscallTable::AudioBufferReady => syscalls::audio_buffer_ready as usize,
+                            SyscallTable::SendAudioBuffer => syscalls::send_audio_buffer as usize,
                         };
                         unsafe {
-                            table_base.add(idx as usize).write(ptr);
+                            table_base.add(idx).write(ptr);
                         }
                     }
                     return Ok(());
@@ -231,7 +233,7 @@ fn total_loadable_size(
         file.seek_from_start(elf_header.e_phoff + (elf_header.e_phentsize * i) as u32)
             .unwrap();
         file.read(ph_buf).unwrap();
-        let ph = cast_phdr(&ph_buf);
+        let ph = cast_phdr(ph_buf);
 
         if ph.p_type == PT_LOAD {
             if ph.p_vaddr < min_vaddr {

kernel/src/framebuffer.rs

@@ -13,6 +13,9 @@ use embedded_hal_2::digital::OutputPin;
 use embedded_hal_async::{delay::DelayNs, spi::SpiDevice};
 use st7365p_lcd::ST7365P;
 
+#[cfg(feature = "fps")]
+use fps::{FPS_CANVAS, FPS_CANVAS_HEIGHT, FPS_CANVAS_WIDTH, FPS_CANVAS_X, FPS_CANVAS_Y};
+
 const TILE_SIZE: usize = 16; // 16x16 tile
 const TILE_COUNT: usize = (SCREEN_WIDTH / TILE_SIZE) * (SCREEN_HEIGHT / TILE_SIZE); // 400 tiles
 const NUM_TILE_ROWS: usize = SCREEN_WIDTH / TILE_SIZE;
@@ -43,7 +46,7 @@ impl<'a> AtomicFrameBuffer<'a> {
     }
 
     fn mark_tiles_dirty(&mut self, rect: Rectangle) {
-        let tiles_x = (SCREEN_WIDTH + TILE_SIZE - 1) / TILE_SIZE;
+        let tiles_x = SCREEN_WIDTH.div_ceil(TILE_SIZE);
         let start_tx = (rect.top_left.x as usize) / TILE_SIZE;
         let end_tx = ((rect.top_left.x + rect.size.width as i32 - 1) as usize) / TILE_SIZE;
         let start_ty = (rect.top_left.y as usize) / TILE_SIZE;
@@ -130,9 +133,34 @@ impl<'a> AtomicFrameBuffer<'a> {
             tile.store(false, Ordering::Release);
         }
 
+        #[cfg(feature = "fps")]
+        unsafe {
+            crate::display::FPS_COUNTER.measure()
+        }
+
         Ok(())
     }
 
+    // used when doing a full screen refresh fps must be drawn into fb
+    // unfortunately it is not garenteed to not be drawn over before
+    // being pushed to the display
+    #[cfg(feature = "fps")]
+    pub fn draw_fps_into_fb(&mut self) {
+        unsafe {
+            let canvas = &FPS_CANVAS.canvas;
+
+            for y in 0..FPS_CANVAS_HEIGHT {
+                let fb_y = FPS_CANVAS_Y + y;
+                let fb_row_start = fb_y * SCREEN_WIDTH + FPS_CANVAS_X;
+                let canvas_row_start = y * FPS_CANVAS_WIDTH;
+
+                self.fb[fb_row_start..fb_row_start + FPS_CANVAS_WIDTH].copy_from_slice(
+                    &canvas[canvas_row_start..canvas_row_start + FPS_CANVAS_WIDTH],
+                );
+            }
+        }
+    }
+
     // copy N tiles horizontally to the right into batch tile buf
     fn append_tiles_to_batch(
         &mut self,
@@ -152,6 +180,45 @@ impl<'a> AtomicFrameBuffer<'a> {
                 &self.fb[fb_row_offset..fb_row_offset + (total_tiles as usize * TILE_SIZE)];
 
             batch_row.copy_from_slice(fb_row);
+
+            // override fps pixel region with fps
+            // avoids writing to fps, and having it overridden before draw
+            #[cfg(feature = "fps")]
+            {
+                let global_y = tile_y as usize * TILE_SIZE + batch_row_num;
+
+                if global_y >= FPS_CANVAS_Y && global_y < FPS_CANVAS_Y + FPS_CANVAS_HEIGHT {
+                    let start_x = tile_x as usize * TILE_SIZE;
+                    let end_x = start_x + (total_tiles as usize * TILE_SIZE);
+
+                    // horizontal overlap check
+                    let fps_x0 = FPS_CANVAS_X;
+                    let fps_x1 = FPS_CANVAS_X + FPS_CANVAS_WIDTH;
+
+                    let x0 = start_x.max(fps_x0);
+                    let x1 = end_x.min(fps_x1);
+
+                    if x1 > x0 {
+                        let row_in_fps = global_y - FPS_CANVAS_Y;
+                        let fps_off = row_in_fps
+                            .checked_mul(FPS_CANVAS_WIDTH)
+                            .and_then(|v| v.checked_add(x0 - fps_x0));
+                        let batch_off = x0 - start_x;
+                        let len = x1 - x0;
+
+                        if let Some(fps_off) = fps_off {
+                            let fps_len_ok = fps_off + len <= unsafe { FPS_CANVAS.canvas.len() };
+                            let batch_len_ok = batch_off + len <= batch_row.len();
+
+                            if fps_len_ok && batch_len_ok {
+                                batch_row[batch_off..batch_off + len].copy_from_slice(unsafe {
+                                    &FPS_CANVAS.canvas[fps_off..fps_off + len]
+                                });
+                            }
+                        }
+                    }
+                }
+            }
         }
     }
 
@@ -167,9 +234,25 @@ impl<'a> AtomicFrameBuffer<'a> {
         DELAY: DelayNs,
     {
         if self.should_full_draw() {
+            #[cfg(feature = "fps")]
+            self.draw_fps_into_fb();
             return self.draw(display).await;
         }
 
+        #[cfg(feature = "fps")]
+        {
+            let fps_tile_x = FPS_CANVAS_X / TILE_SIZE;
+            let fps_tile_y = FPS_CANVAS_Y / TILE_SIZE;
+            let fps_tile_w = (FPS_CANVAS_WIDTH + TILE_SIZE - 1) / TILE_SIZE;
+            let fps_tile_h = (FPS_CANVAS_HEIGHT + TILE_SIZE - 1) / TILE_SIZE;
+
+            for ty in fps_tile_y..fps_tile_y + fps_tile_h {
+                for tx in fps_tile_x..fps_tile_x + fps_tile_w {
+                    self.dirty_tiles[ty * NUM_TILE_COLS + tx].store(true, Ordering::Release);
+                }
+            }
+        }
+
         for tile_row in 0..NUM_TILE_ROWS {
             let row_start_idx = tile_row * NUM_TILE_COLS;
             let mut col = 0;
@@ -178,14 +261,15 @@ impl<'a> AtomicFrameBuffer<'a> {
                 // Check for dirty tile
                 if self.dirty_tiles[row_start_idx + col].swap(false, Ordering::Acquire) {
                     let run_start = col;
+                    let mut scan_col = col;
                     let mut run_len = 1;
 
                     // Extend run while contiguous dirty tiles and within MAX_BATCH_TILES
-                    while col + 1 < NUM_TILE_COLS
+                    while scan_col + 1 < NUM_TILE_COLS
                         && self.dirty_tiles[row_start_idx + col + 1].load(Ordering::Acquire)
                         && run_len < MAX_BATCH_TILES
                     {
-                        col += 1;
+                        scan_col += 1;
                         run_len += 1;
                     }
 
@@ -210,12 +294,19 @@ impl<'a> AtomicFrameBuffer<'a> {
                             &self.batch_tile_buf[..run_len * TILE_SIZE * TILE_SIZE],
                         )
                         .await?;
+
+                    col = scan_col;
                 }
 
                 col += 1;
             }
         }
 
+        #[cfg(feature = "fps")]
+        unsafe {
+            crate::display::FPS_COUNTER.measure()
+        }
+
         Ok(())
     }
 }
@@ -258,11 +349,9 @@ impl<'a> DrawTarget for AtomicFrameBuffer<'a> {
             }
         }
 
-        if changed {
+        if changed && let Some(rect) = dirty_rect {
-            if let Some(rect) = dirty_rect {
             self.mark_tiles_dirty(rect);
         }
-        }
 
         Ok(())
     }
@@ -314,7 +403,7 @@ impl<'a> DrawTarget for AtomicFrameBuffer<'a> {
     fn fill_solid(&mut self, area: &Rectangle, color: Self::Color) -> Result<(), Self::Error> {
         self.fill_contiguous(
             area,
-            core::iter::repeat(color).take((self.size().width * self.size().height) as usize),
+            core::iter::repeat_n(color, (self.size().width * self.size().height) as usize),
         )
     }
 
@@ -324,8 +413,10 @@ impl<'a> DrawTarget for AtomicFrameBuffer<'a> {
             0,
             self.size().width as u16 - 1,
             self.size().height as u16 - 1,
-            core::iter::repeat(RawU16::from(color).into_inner())
+            core::iter::repeat_n(
-                .take((self.size().width * self.size().height) as usize),
+                RawU16::from(color).into_inner(),
+                (self.size().width * self.size().height) as usize,
+            ),
         )?;
 
         for tile in self.dirty_tiles.iter() {
@@ -341,3 +432,146 @@ impl<'a> OriginDimensions for AtomicFrameBuffer<'a> {
         Size::new(SCREEN_WIDTH as u32, SCREEN_HEIGHT as u32)
     }
 }
+
+#[cfg(feature = "fps")]
+pub mod fps {
+    use crate::display::SCREEN_WIDTH;
+    use core::fmt::Write;
+    use embassy_time::{Duration, Instant};
+    use embedded_graphics::{
+        Drawable, Pixel,
+        draw_target::DrawTarget,
+        geometry::Point,
+        mono_font::{MonoTextStyle, ascii::FONT_8X13},
+        pixelcolor::Rgb565,
+        prelude::{IntoStorage, OriginDimensions, RgbColor, Size},
+        text::{Alignment, Text},
+    };
+
+    pub static mut FPS_COUNTER: FpsCounter = FpsCounter::new();
+    pub static mut FPS_CANVAS: FpsCanvas = FpsCanvas::new();
+
+    // "FPS: 120" = 8 len
+    const FPS_LEN: usize = 8;
+    pub const FPS_CANVAS_WIDTH: usize = (FONT_8X13.character_size.width + 4) as usize * FPS_LEN;
+    pub const FPS_CANVAS_HEIGHT: usize = FONT_8X13.character_size.height as usize;
+
+    // puts canvas in the top right of the display
+    // top left point of canvas
+    pub const FPS_CANVAS_X: usize = SCREEN_WIDTH - FPS_CANVAS_WIDTH;
+    pub const FPS_CANVAS_Y: usize = 0;
+
+    pub struct FpsCanvas {
+        pub canvas: [u16; FPS_CANVAS_HEIGHT * FPS_CANVAS_WIDTH],
+    }
+
+    impl FpsCanvas {
+        const fn new() -> Self {
+            Self {
+                canvas: [0; FPS_CANVAS_HEIGHT * FPS_CANVAS_WIDTH],
+            }
+        }
+
+        fn clear(&mut self) {
+            for p in &mut self.canvas {
+                *p = 0;
+            }
+        }
+
+        pub async fn draw_fps(&mut self) {
+            let mut buf: heapless::String<FPS_LEN> = heapless::String::new();
+            let fps = unsafe { FPS_COUNTER.smoothed };
+            let _ = write!(buf, "FPS: {}", fps as u8);
+
+            self.clear();
+            let text_style = MonoTextStyle::new(&FONT_8X13, Rgb565::WHITE);
+            Text::with_alignment(
+                buf.as_str(),
+                Point::new(
+                    FPS_CANVAS_WIDTH as i32 / 2,
+                    (FPS_CANVAS_HEIGHT as i32 + 8) / 2,
+                ),
+                text_style,
+                Alignment::Center,
+            )
+            .draw(self)
+            .unwrap();
+        }
+    }
+
+    impl DrawTarget for FpsCanvas {
+        type Error = ();
+        type Color = Rgb565;
+
+        fn draw_iter<I>(&mut self, pixels: I) -> Result<(), Self::Error>
+        where
+            I: IntoIterator<Item = Pixel<Self::Color>>,
+        {
+            for Pixel(point, color) in pixels {
+                if point.x < 0
+                    || point.x >= FPS_CANVAS_WIDTH as i32
+                    || point.y < 0
+                    || point.y >= FPS_CANVAS_HEIGHT as i32
+                {
+                    continue;
+                }
+
+                let index = (point.y as usize) * FPS_CANVAS_WIDTH + point.x as usize;
+                self.canvas[index] = color.into_storage();
+            }
+            Ok(())
+        }
+    }
+
+    impl OriginDimensions for FpsCanvas {
+        fn size(&self) -> Size {
+            Size::new(FPS_CANVAS_WIDTH as u32, FPS_CANVAS_HEIGHT as u32)
+        }
+    }
+
+    pub struct FpsCounter {
+        last_frame: Option<Instant>,
+        smoothed: f32,
+        last_draw: Option<Instant>,
+    }
+
+    impl FpsCounter {
+        pub const fn new() -> Self {
+            Self {
+                last_frame: None,
+                smoothed: 0.0,
+                last_draw: None,
+            }
+        }
+
+        // Is called once per frame or partial frame to update FPS
+        pub fn measure(&mut self) {
+            let now = Instant::now();
+
+            if let Some(last) = self.last_frame {
+                let dt_us = (now - last).as_micros() as f32;
+                if dt_us > 0.0 {
+                    let current = 1_000_000.0 / dt_us;
+                    self.smoothed = if self.smoothed == 0.0 {
+                        current
+                    } else {
+                        0.9 * self.smoothed + 0.1 * current
+                    };
+                }
+            }
+
+            self.last_frame = Some(now);
+        }
+
+        pub fn should_draw(&mut self) -> bool {
+            let now = Instant::now();
+            match self.last_draw {
+                Some(last) if now - last < Duration::from_millis(200) => false,
+                _ => {
+                    self.last_draw = Some(now);
+                    true
+                }
+            }
+        }
+    }
+}

kernel/src/heap.rs

@@ -22,8 +22,8 @@ impl Region {
 
     fn contains(&self, address: usize) -> bool {
         let start = self.start.load(Ordering::Relaxed);
-        let end = self.start.load(Ordering::Relaxed);
+        let end = start + self.size.load(Ordering::Relaxed);
-        (start..start + end).contains(&address)
+        (start..end).contains(&address)
     }
 
     fn new(start: usize, size: usize) -> Self {

kernel/src/main.rs

@@ -8,53 +8,58 @@
 
 extern crate alloc;
 
-mod abi;
+mod audio;
 mod display;
 mod elf;
 mod framebuffer;
+// TODO: NEED TO UPDATE MCU TO TEST BATTERY READS
 #[allow(unused)]
-mod heap;
 mod peripherals;
 #[allow(unused)]
-mod psram;
 mod scsi;
 mod storage;
+mod syscalls;
 mod ui;
+#[allow(unused)]
 mod usb;
 mod utils;
 
-#[cfg(feature = "pimoroni2w")]
+#[cfg(feature = "psram")]
+#[allow(unused)]
+mod heap;
+#[cfg(feature = "psram")]
+#[allow(unused)]
+mod psram;
+
+#[cfg(feature = "psram")]
 use crate::{heap::init_qmi_psram_heap, psram::init_psram_qmi};
 
 use crate::{
-    abi::{KEY_CACHE, MS_SINCE_LAUNCH},
+    audio::{AUDIO_BUFFER_WRITTEN, audio_handler, clear_audio_buffers},
     display::{FRAMEBUFFER, display_handler, init_display},
-    heap::HEAP,
+    peripherals::{conf_peripherals, keyboard::read_keyboard_fifo},
-    peripherals::{
-        conf_peripherals,
-        keyboard::{KeyState, read_keyboard_fifo},
-    },
-    psram::init_psram,
     scsi::MSC_SHUTDOWN,
     storage::{SDCARD, SdCard},
+    syscalls::{KEY_CACHE, MS_SINCE_LAUNCH},
     ui::{SELECTIONS, clear_selection, ui_handler},
 };
-use abi_sys::EntryFn;
 use bumpalo::Bump;
 use core::sync::atomic::{AtomicBool, Ordering};
 use embassy_executor::{Executor, Spawner};
 use embassy_futures::{join::join, select::select};
 use embassy_rp::{
     Peri,
+    clocks::ClockConfig,
+    config::Config,
     gpio::{Input, Level, Output, Pull},
     i2c::{self, I2c},
     multicore::{Stack, spawn_core1},
     peripherals::{
         DMA_CH0, DMA_CH1, DMA_CH3, DMA_CH4, I2C1, PIN_2, PIN_3, PIN_6, PIN_7, PIN_10, PIN_11,
         PIN_12, PIN_13, PIN_14, PIN_15, PIN_16, PIN_17, PIN_18, PIN_19, PIN_20, PIN_21, PIN_22,
-        PIO0, SPI0, SPI1, USB, WATCHDOG,
+        PIN_26, PIN_27, PIO0, SPI0, SPI1, USB, WATCHDOG,
     },
-    pio,
+    pio::{self, Common, Pio, StateMachine},
     spi::{self, Spi},
     usb as embassy_rp_usb,
     watchdog::{ResetReason, Watchdog},
@@ -71,6 +76,7 @@ use embedded_hal_bus::spi::ExclusiveDevice;
 use embedded_sdmmc::SdCard as SdmmcSdCard;
 use static_cell::StaticCell;
 use talc::*;
+use userlib_sys::EntryFn;
 use {defmt_rtt as _, panic_probe as _};
 
 embassy_rp::bind_interrupts!(struct Irqs {
@@ -100,7 +106,7 @@ async fn watchdog_task(mut watchdog: Watchdog) {
             ResetReason::Forced => "forced",
             ResetReason::TimedOut => "timed out",
         };
-        #[cfg(feature = "debug")]
+        #[cfg(feature = "defmt")]
         defmt::error!("Watchdog reset reason: {}", _reason);
     }
 
@@ -116,9 +122,17 @@ async fn watchdog_task(mut watchdog: Watchdog) {
 static ENABLE_UI: AtomicBool = AtomicBool::new(true);
 static UI_CHANGE: Signal<CriticalSectionRawMutex, ()> = Signal::new();
 
+const OVERCLOCK: u32 = 300_000_000;
+
 #[embassy_executor::main]
 async fn main(_spawner: Spawner) {
-    let p = embassy_rp::init(Default::default());
+    let p = if cfg!(feature = "overclock") {
+        let clocks = ClockConfig::system_freq(OVERCLOCK).unwrap();
+        let config = Config::new(clocks);
+        embassy_rp::init(config)
+    } else {
+        embassy_rp::init(Default::default())
+    };
 
     spawn_core1(
         p.CORE1,
@@ -140,6 +154,19 @@ async fn main(_spawner: Spawner) {
         data: p.PIN_14,
         reset: p.PIN_15,
     };
+    let Pio {
+        common, sm0, sm1, ..
+    } = Pio::new(p.PIO0, Irqs);
+
+    let audio = Audio {
+        pio: common,
+        sm0,
+        dma0: p.DMA_CH3,
+        left: p.PIN_26,
+        sm1,
+        dma1: p.DMA_CH4,
+        right: p.PIN_27,
+    };
     let sd = Sd {
         spi: p.SPI0,
         clk: p.PIN_18,
@@ -148,15 +175,15 @@ async fn main(_spawner: Spawner) {
         cs: p.PIN_17,
         det: p.PIN_22,
     };
-    let psram = Psram {
+    // let psram = Psram {
-        pio: p.PIO0,
+    //     pio: p.PIO0,
-        sclk: p.PIN_21,
+    //     sclk: p.PIN_21,
-        mosi: p.PIN_2,
+    //     mosi: p.PIN_2,
-        miso: p.PIN_3,
+    //     miso: p.PIN_3,
-        cs: p.PIN_20,
+    //     cs: p.PIN_20,
-        dma1: p.DMA_CH3,
+    //     dma1: p.DMA_CH3,
-        dma2: p.DMA_CH4,
+    //     dma2: p.DMA_CH4,
-    };
+    // };
     let mcu = Mcu {
         i2c: p.I2C1,
         clk: p.PIN_7,
@@ -166,7 +193,7 @@ async fn main(_spawner: Spawner) {
     executor0.run(|spawner| {
         spawner
             .spawn(kernel_task(
-                spawner, p.WATCHDOG, display, sd, psram, mcu, p.USB,
+                spawner, p.WATCHDOG, display, audio, sd, mcu, p.USB,
             ))
             .unwrap()
     });
@@ -199,6 +226,9 @@ async fn userland_task() {
 
         // enable kernel ui
         {
+            AUDIO_BUFFER_WRITTEN.store(false, Ordering::Release);
+            clear_audio_buffers();
+
             ENABLE_UI.store(true, Ordering::Release);
             UI_CHANGE.signal(());
             unsafe { FRAMEBUFFER.as_mut().unwrap().clear(Rgb565::BLACK).unwrap() };
@@ -220,6 +250,15 @@ struct Display {
     data: Peri<'static, PIN_14>,
     reset: Peri<'static, PIN_15>,
 }
+struct Audio {
+    pio: Common<'static, PIO0>,
+    dma0: Peri<'static, DMA_CH3>,
+    sm0: StateMachine<'static, PIO0, 0>,
+    left: Peri<'static, PIN_26>,
+    dma1: Peri<'static, DMA_CH4>,
+    sm1: StateMachine<'static, PIO0, 1>,
+    right: Peri<'static, PIN_27>,
+}
 struct Sd {
     spi: Peri<'static, SPI0>,
     clk: Peri<'static, PIN_18>,
@@ -254,7 +293,7 @@ async fn setup_mcu(mcu: Mcu) {
 
 async fn setup_display(display: Display, spawner: Spawner) {
     let mut config = spi::Config::default();
-    config.frequency = 64_000_000;
+    config.frequency = 192_000_000;
     let spi = Spi::new(
         display.spi,
         display.clk,
@@ -270,26 +309,26 @@ async fn setup_display(display: Display, spawner: Spawner) {
 
 // psram is kind of useless on the pico calc
 // ive opted to use the pimoroni with on onboard xip psram instead
-async fn setup_psram(psram: Psram) {
+// async fn setup_psram(psram: Psram) {
-    let psram = init_psram(
+//     let psram = init_psram(
-        psram.pio, psram.sclk, psram.mosi, psram.miso, psram.cs, psram.dma1, psram.dma2,
+//         psram.pio, psram.sclk, psram.mosi, psram.miso, psram.cs, psram.dma1, psram.dma2,
-    )
+//     )
-    .await;
+//     .await;
 
-    #[cfg(feature = "defmt")]
+//     #[cfg(feature = "defmt")]
-    defmt::info!("psram size: {}", psram.size);
+//     defmt::info!("psram size: {}", psram.size);
 
-    if psram.size == 0 {
+//     if psram.size == 0 {
-        #[cfg(feature = "defmt")]
+//         #[cfg(feature = "defmt")]
-        defmt::info!("\u{1b}[1mExternal PSRAM was NOT found!\u{1b}[0m");
+//         defmt::info!("\u{1b}[1mExternal PSRAM was NOT found!\u{1b}[0m");
-    }
+//     }
-}
+// }
 
-#[cfg(feature = "pimoroni2w")]
+#[cfg(feature = "psram")]
 async fn setup_qmi_psram() {
     Timer::after_millis(250).await;
     let psram_qmi_size = init_psram_qmi(&embassy_rp::pac::QMI, &embassy_rp::pac::XIP_CTRL);
-    #[cfg(feature = "debug")]
+    #[cfg(feature = "defmt")]
     defmt::info!("size:  {}", psram_qmi_size);
     Timer::after_millis(100).await;
 
@@ -321,8 +360,9 @@ async fn kernel_task(
     spawner: Spawner,
     watchdog: Peri<'static, WATCHDOG>,
     display: Display,
+    audio: Audio,
     sd: Sd,
-    psram: Psram,
+    // _psram: Psram,
     mcu: Mcu,
     usb: Peri<'static, USB>,
 ) {
@@ -330,19 +370,25 @@ async fn kernel_task(
         .spawn(watchdog_task(Watchdog::new(watchdog)))
         .unwrap();
 
+    #[cfg(feature = "defmt")]
+    defmt::info!("Clock: {}", embassy_rp::clocks::clk_sys_freq());
+
     setup_mcu(mcu).await;
 
+    #[cfg(feature = "defmt")]
     defmt::info!("setting up psram");
     Timer::after_millis(100).await;
 
     // setup_psram(psram).await;
-    #[cfg(feature = "pimoroni2w")]
+    #[cfg(feature = "psram")]
     setup_qmi_psram().await;
 
     Timer::after_millis(100).await;
     setup_display(display, spawner).await;
     setup_sd(sd).await;
 
+    spawner.spawn(audio_handler(audio)).unwrap();
+
     let _usb = embassy_rp_usb::Driver::new(usb, Irqs);
     // spawner.spawn(usb_handler(usb)).unwrap();
 
@@ -362,7 +408,8 @@ async fn prog_search_handler() {
             let mut guard = SDCARD.get().lock().await;
             let sd = guard.as_mut().unwrap();
 
-            let files = sd.list_files_by_extension(".bin").unwrap();
+            let mut files = sd.list_files_by_extension(".bin").unwrap();
+            files.sort();
             let mut select = SELECTIONS.lock().await;
 
             if *select.selections() != files {
@@ -377,12 +424,10 @@ async fn prog_search_handler() {
 async fn key_handler() {
     loop {
         if let Some(event) = read_keyboard_fifo().await {
-            if let KeyState::Pressed = event.state {
             unsafe {
                 let _ = KEY_CACHE.enqueue(event);
             }
         }
-        }
         Timer::after_millis(50).await;
     }
 }

kernel/src/peripherals/keyboard.rs

@@ -1,5 +1,5 @@
 use crate::peripherals::PERIPHERAL_BUS;
-pub use abi_sys::keyboard::{KeyCode, KeyEvent, KeyState, Modifiers};
+pub use userlib_sys::keyboard::{KeyCode, KeyEvent, KeyState, Modifiers};
 
 const REG_ID_KEY: u8 = 0x04;
 const REG_ID_FIF: u8 = 0x09;

kernel/src/psram.rs

@@ -526,7 +526,7 @@ pub fn init_psram_qmi(
     let psram_size = detect_psram_qmi(qmi);
 
     if psram_size == 0 {
-        #[cfg(feature = "debug")]
+        #[cfg(feature = "defmt")]
         defmt::error!("qmi psram size 0");
         return 0;
     }

kernel/src/scsi/mod.rs

@@ -30,7 +30,7 @@ pub struct MassStorageClass<'d, D: Driver<'d>> {
     bulk_in: D::EndpointIn,
 }
 
-impl<'d, 's, D: Driver<'d>> MassStorageClass<'d, D> {
+impl<'d, D: Driver<'d>> MassStorageClass<'d, D> {
     pub fn new(builder: &mut Builder<'d, D>, temp_sd: Option<SdCard>) -> Self {
         let mut function = builder.function(0x08, SUBCLASS_SCSI, 0x50); // Mass Storage class
         let mut interface = function.interface();
@@ -72,9 +72,10 @@ impl<'d, 's, D: Driver<'d>> MassStorageClass<'d, D> {
 
     async fn handle_cbw(&mut self) {
         let mut cbw_buf = [0u8; 31];
-        if let Ok(n) = self.bulk_out.read(&mut cbw_buf).await {
+        if let Ok(n) = self.bulk_out.read(&mut cbw_buf).await
-            if n == 31 {
+            && n == 31
-                if let Some(cbw) = CommandBlockWrapper::parse(&cbw_buf[..n]) {
+            && let Some(cbw) = CommandBlockWrapper::parse(&cbw_buf[..n])
+        {
             // Take sdcard to increase speed
             if self.temp_sd.is_none() {
                 let mut guard = SDCARD.get().lock().await;
@@ -94,15 +95,13 @@ impl<'d, 's, D: Driver<'d>> MassStorageClass<'d, D> {
                 self.send_csw_fail(cbw.dCBWTag).await
             }
 
-                    if self.pending_eject {
+            if self.pending_eject
-                        if let ScsiCommand::Write { lba: _, len: _ } = command {
+                && let ScsiCommand::Write { lba: _, len: _ } = command
+            {
                 MSC_SHUTDOWN.signal(());
             }
         }
     }
-            }
-        }
-    }
 
     async fn handle_command(&mut self, command: ScsiCommand) -> Result<(), ()> {
         let mut response: Vec<u8, BULK_ENDPOINT_PACKET_SIZE> = Vec::new();
@@ -238,7 +237,7 @@ impl<'d, 's, D: Driver<'d>> MassStorageClass<'d, D> {
                 let block_size = SdCard::BLOCK_SIZE as u64;
                 let total_blocks = self.temp_sd.as_ref().unwrap().size() / block_size;
 
-                let last_lba = total_blocks.checked_sub(1).unwrap_or(0);
+                let last_lba = total_blocks.saturating_sub(1);
 
                 response.extend_from_slice(&(last_lba as u32).to_be_bytes())?;
                 response.extend_from_slice(&(block_size as u32).to_be_bytes())?;
@@ -249,7 +248,7 @@ impl<'d, 's, D: Driver<'d>> MassStorageClass<'d, D> {
                 let block_size = SdCard::BLOCK_SIZE as u64;
                 let total_blocks = self.temp_sd.as_ref().unwrap().size() / block_size;
 
-                let last_lba = total_blocks.checked_sub(1).unwrap_or(0);
+                let last_lba = total_blocks.saturating_sub(1);
 
                 response.extend_from_slice(&last_lba.to_be_bytes())?; // 8 bytes last LBA
                 response.extend_from_slice(&(block_size as u32).to_be_bytes())?; // 4 bytes block length
@@ -269,7 +268,7 @@ impl<'d, 's, D: Driver<'d>> MassStorageClass<'d, D> {
                         sdcard.read_blocks(block_buf, BlockIdx(idx as u32))?;
 
                         for block in &mut *block_buf {
-                            for chunk in block.contents.chunks(BULK_ENDPOINT_PACKET_SIZE.into()) {
+                            for chunk in block.contents.chunks(BULK_ENDPOINT_PACKET_SIZE) {
                                 self.bulk_in.write(chunk).await.map_err(|_| ())?;
                             }
                         }
@@ -281,7 +280,7 @@ impl<'d, 's, D: Driver<'d>> MassStorageClass<'d, D> {
                             .read_blocks(&mut block_buf[..blocks as usize], BlockIdx(idx as u32))?;
 
                         for block in &block_buf[..blocks as usize] {
-                            for chunk in block.contents.chunks(BULK_ENDPOINT_PACKET_SIZE.into()) {
+                            for chunk in block.contents.chunks(BULK_ENDPOINT_PACKET_SIZE) {
                                 self.bulk_in.write(chunk).await.map_err(|_| ())?;
                             }
                         }
@@ -301,8 +300,7 @@ impl<'d, 's, D: Driver<'d>> MassStorageClass<'d, D> {
                 while blocks > 0 {
                     if blocks >= block_buf.len() as u64 {
                         for block in block_buf.as_mut() {
-                            for chunk in block.contents.chunks_mut(BULK_ENDPOINT_PACKET_SIZE.into())
+                            for chunk in block.contents.chunks_mut(BULK_ENDPOINT_PACKET_SIZE) {
-                            {
                                 self.bulk_out.read(chunk).await.map_err(|_| ())?;
                             }
                         }
@@ -313,8 +311,7 @@ impl<'d, 's, D: Driver<'d>> MassStorageClass<'d, D> {
                         idx += block_buf.len() as u64;
                     } else {
                         for block in block_buf[..blocks as usize].as_mut() {
-                            for chunk in block.contents.chunks_mut(BULK_ENDPOINT_PACKET_SIZE.into())
+                            for chunk in block.contents.chunks_mut(BULK_ENDPOINT_PACKET_SIZE) {
-                            {
                                 self.bulk_out.read(chunk).await.map_err(|_| ())?;
                             }
                         }

kernel/src/scsi/scsi_types.rs

@@ -1,7 +1,7 @@
 use num_enum::TryFromPrimitive;
 
 /// THE CODE BELOW ORIGINATES FROM: https://github.com/apohrebniak/usbd-storage/blob/master/usbd-storage/src/subclass/scsi.rs
-
+///
 /// SCSI device subclass code
 pub const SUBCLASS_SCSI: u8 = 0x06; // SCSI Transparent command set
 
@@ -91,6 +91,7 @@ pub enum ScsiCommand {
     },
 }
 
+#[allow(clippy::enum_variant_names)]
 #[repr(u8)]
 #[derive(Copy, Clone, Debug, TryFromPrimitive)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]

kernel/src/storage.rs

@@ -9,8 +9,8 @@ use embassy_sync::mutex::Mutex;
 use embassy_time::Delay;
 use embedded_hal_bus::spi::ExclusiveDevice;
 use embedded_sdmmc::{
-    Block, BlockCount, BlockDevice, BlockIdx, Directory, SdCard as SdmmcSdCard, TimeSource,
+    Block, BlockDevice, BlockIdx, Directory, SdCard as SdmmcSdCard, TimeSource, Timestamp,
-    Timestamp, Volume, VolumeIdx, VolumeManager, sdcard::Error,
+    VolumeIdx, VolumeManager, sdcard::Error,
 };
 use embedded_sdmmc::{File as SdFile, LfnBuffer, Mode, ShortFileName};
 
@@ -21,7 +21,6 @@ pub const MAX_VOLUMES: usize = 1;
 type Device = ExclusiveDevice<Spi<'static, SPI0, Blocking>, Output<'static>, embassy_time::Delay>;
 type SD = SdmmcSdCard<Device, Delay>;
 type VolMgr = VolumeManager<SD, DummyTimeSource, MAX_DIRS, MAX_FILES, MAX_VOLUMES>;
-type Vol<'a> = Volume<'a, SD, DummyTimeSource, MAX_DIRS, MAX_FILES, MAX_VOLUMES>;
 pub type Dir<'a> = Directory<'a, SD, DummyTimeSource, MAX_DIRS, MAX_FILES, MAX_VOLUMES>;
 pub type File<'a> = SdFile<'a, SD, DummyTimeSource, MAX_DIRS, MAX_FILES, MAX_VOLUMES>;
 
@@ -35,12 +34,24 @@ impl TimeSource for DummyTimeSource {
     }
 }
 
-#[derive(Clone, PartialEq)]
+#[derive(Clone, PartialEq, Eq)]
 pub struct FileName {
     pub long_name: String,
     pub short_name: ShortFileName,
 }
 
+impl PartialOrd for FileName {
+    fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for FileName {
+    fn cmp(&self, other: &Self) -> core::cmp::Ordering {
+        self.long_name.cmp(&other.long_name)
+    }
+}
+
 pub struct SdCard {
     det: Input<'static>,
     volume_mgr: VolMgr,
@@ -55,10 +66,7 @@ impl SdCard {
             DummyTimeSource {},
             5000,
         );
-        Self {
+        Self { det, volume_mgr }
-            det: det,
-            volume_mgr,
-        }
     }
 
     /// Returns true if an SD card is inserted.
@@ -78,17 +86,6 @@ impl SdCard {
         result
     }
 
-    pub fn num_blocks(&self) -> u32 {
-        let mut result = 0;
-
-        self.volume_mgr.device(|sd| {
-            result = sd.num_blocks().unwrap_or(BlockCount(0)).0;
-            DummyTimeSource {}
-        });
-
-        result
-    }
-
     pub fn read_blocks(&self, blocks: &mut [Block], start_block_idx: BlockIdx) -> Result<(), ()> {
         let mut res: Result<(), Error> = Ok(());
         self.volume_mgr.device(|sd| {

kernel/src/syscalls.rs

@@ -1,46 +1,60 @@
-use abi_sys::{
-    AllocAbi, CLayout, CPixel, DeallocAbi, DrawIterAbi, FileLen, GenRand, GetMsAbi, ListDir,
-    PrintAbi, ReadFile, RngRequest, SleepMsAbi, keyboard::*,
-};
 use alloc::{string::ToString, vec::Vec};
-use core::{alloc::GlobalAlloc, sync::atomic::Ordering};
+use core::{ffi::c_char, ptr, sync::atomic::Ordering};
 use embassy_rp::clocks::{RoscRng, clk_sys_freq};
 use embassy_time::Instant;
 use embedded_graphics::draw_target::DrawTarget;
-use embedded_sdmmc::{DirEntry, LfnBuffer};
+use embedded_sdmmc::LfnBuffer;
 use heapless::spsc::Queue;
+use userlib_sys::{
+    AUDIO_BUFFER_SAMPLES, Alloc, AudioBufferReady, CLayout, CPixel, Dealloc, DrawIter, FileLen,
+    GenRand, GetMs, ListDir, Print, ReadFile, ReconfigureAudioSampleRate, RngRequest,
+    SendAudioBuffer, SleepMs, WriteFile, keyboard::*,
+};
+
+#[cfg(feature = "psram")]
+use crate::heap::HEAP;
+
+#[cfg(feature = "psram")]
+use core::alloc::GlobalAlloc;
 
 use crate::{
+    audio::{AUDIO_BUFFER, AUDIO_BUFFER_READY, AUDIO_BUFFER_SAMPLE_RATE, AUDIO_BUFFER_WRITTEN},
     display::FRAMEBUFFER,
     framebuffer::FB_PAUSED,
     storage::{Dir, File, SDCARD},
 };
 
-const _: AllocAbi = alloc;
+const _: Alloc = alloc;
 pub extern "C" fn alloc(layout: CLayout) -> *mut u8 {
     // SAFETY: caller guarantees layout is valid
     unsafe {
-        if cfg!(feature = "pimoroni2w") {
+        #[cfg(feature = "psram")]
-            crate::heap::HEAP.alloc(layout.into())
+        {
-        } else {
+            return HEAP.alloc(layout.into());
+        }
+
+        #[cfg(not(feature = "psram"))]
+        {
             alloc::alloc::alloc(layout.into())
         }
     }
 }
 
-const _: DeallocAbi = dealloc;
+const _: Dealloc = dealloc;
 pub extern "C" fn dealloc(ptr: *mut u8, layout: CLayout) {
     // SAFETY: caller guarantees ptr and layout are valid
-    unsafe {
+    #[cfg(feature = "psram")]
-        if cfg!(feature = "pimoroni2w") {
+    {
-            crate::heap::HEAP.dealloc(ptr, layout.into())
+        unsafe { HEAP.dealloc(ptr, layout.into()) }
-        } else {
-            alloc::alloc::dealloc(ptr, layout.into())
     }
+
+    #[cfg(not(feature = "psram"))]
+    {
+        unsafe { alloc::alloc::dealloc(ptr, layout.into()) }
     }
 }
 
-const _: PrintAbi = print;
+const _: Print = print;
 pub extern "C" fn print(ptr: *const u8, len: usize) {
     // SAFETY: caller guarantees `ptr` is valid for `len` bytes
     let slice = unsafe { core::slice::from_raw_parts(ptr, len) };
@@ -54,7 +68,7 @@ pub extern "C" fn print(ptr: *const u8, len: usize) {
     }
 }
 
-const _: SleepMsAbi = sleep;
+const _: SleepMs = sleep;
 pub extern "C" fn sleep(ms: u64) {
     let cycles_per_ms = clk_sys_freq() / 1000;
     let total_cycles = ms * cycles_per_ms as u64;
@@ -66,14 +80,14 @@ pub extern "C" fn sleep(ms: u64) {
 
 pub static mut MS_SINCE_LAUNCH: Option<Instant> = None;
 
-const _: GetMsAbi = get_ms;
+const _: GetMs = get_ms;
 pub extern "C" fn get_ms() -> u64 {
     Instant::now()
         .duration_since(unsafe { MS_SINCE_LAUNCH.unwrap() })
         .as_millis()
 }
 
-const _: DrawIterAbi = draw_iter;
+const _: DrawIter = draw_iter;
 pub extern "C" fn draw_iter(cpixels: *const CPixel, len: usize) {
     // SAFETY: caller guarantees `ptr` is valid for `len` bytes
     let cpixels = unsafe { core::slice::from_raw_parts(cpixels, len) };
@@ -87,7 +101,7 @@ pub extern "C" fn draw_iter(cpixels: *const CPixel, len: usize) {
 
 pub static mut KEY_CACHE: Queue<KeyEvent, 32> = Queue::new();
 
-const _: GetKeyAbi = get_key;
+const _: GetKey = get_key;
 pub extern "C" fn get_key() -> KeyEventC {
     if let Some(event) = unsafe { KEY_CACHE.dequeue() } {
         event.into()
@@ -116,11 +130,27 @@ pub extern "C" fn gen_rand(req: &mut RngRequest) {
     }
 }
 
-fn get_dir_entries(dir: &Dir, files: &mut [Option<DirEntry>]) -> usize {
+unsafe fn copy_entry_to_user_buf(name: &[u8], dest: *mut c_char, max_str_len: usize) {
+    if !dest.is_null() {
+        let len = name.len().min(max_str_len - 1);
+        unsafe {
+            ptr::copy_nonoverlapping(name.as_ptr(), dest, len);
+            *dest.add(len) = 0; // nul terminator
+        }
+    }
+}
+
+unsafe fn get_dir_entries(dir: &Dir, entries: &mut [*mut c_char], max_str_len: usize) -> usize {
+    let mut b = [0; 25];
+    let mut buf = LfnBuffer::new(&mut b);
     let mut i = 0;
-    dir.iterate_dir(|entry| {
+    dir.iterate_dir_lfn(&mut buf, |entry, lfn_name| {
-        if i < files.len() {
+        if i < entries.len() {
-            files[i] = Some(entry.clone());
+            if let Some(name) = lfn_name {
+                unsafe { copy_entry_to_user_buf(name.as_bytes(), entries[i], max_str_len) };
+            } else {
+                unsafe { copy_entry_to_user_buf(entry.name.base_name(), entries[i], max_str_len) };
+            }
             i += 1;
         }
     })
@@ -128,24 +158,30 @@ fn get_dir_entries(dir: &Dir, files: &mut [Option<DirEntry>]) -> usize {
     i
 }
 
-fn recurse_dir(dir: &Dir, dirs: &[&str], files: &mut [Option<DirEntry>]) -> usize {
+unsafe fn recurse_dir(
+    dir: &Dir,
+    dirs: &[&str],
+    entries: &mut [*mut c_char],
+    max_str_len: usize,
+) -> usize {
     if dirs.is_empty() {
-        return get_dir_entries(dir, files);
+        return unsafe { get_dir_entries(dir, entries, max_str_len) };
     }
 
     let dir = dir.open_dir(dirs[0]).unwrap();
-    recurse_dir(&dir, &dirs[1..], files)
+    unsafe { recurse_dir(&dir, &dirs[1..], entries, max_str_len) }
 }
 
 const _: ListDir = list_dir;
 pub extern "C" fn list_dir(
     dir: *const u8,
     len: usize,
-    files: *mut Option<DirEntry>,
+    entries: *mut *mut c_char,
     files_len: usize,
+    max_entry_str_len: usize,
 ) -> usize {
     // SAFETY: caller guarantees `ptr` is valid for `len` bytes
-    let files = unsafe { core::slice::from_raw_parts_mut(files, files_len) };
+    let files = unsafe { core::slice::from_raw_parts_mut(entries, files_len) };
     // SAFETY: caller guarantees `ptr` is valid for `len` bytes
     let dir = unsafe { core::str::from_raw_parts(dir, len) };
     let dirs: Vec<&str> = dir.split('/').collect();
@@ -155,11 +191,13 @@ pub extern "C" fn list_dir(
 
     let mut wrote = 0;
     sd.access_root_dir(|root| {
-        if dirs[0] == "" && dirs.len() >= 2 {
+        if dirs[0].is_empty() && dirs.len() >= 2 {
+            unsafe {
                 if dir == "/" {
-                wrote = get_dir_entries(&root, files);
+                    wrote = get_dir_entries(&root, files, max_entry_str_len);
                 } else {
-                wrote = recurse_dir(&root, &dirs[1..], files);
+                    wrote = recurse_dir(&root, &dirs[1..], files, max_entry_str_len);
+                }
             }
         }
     });
@@ -176,13 +214,14 @@ fn recurse_file<T>(
         let mut buf = LfnBuffer::new(&mut b);
         let mut short_name = None;
         dir.iterate_dir_lfn(&mut buf, |entry, name| {
-            if let Some(name) = name {
+            if let Some(name) = name
-                if name == dirs[0] || entry.name.to_string().as_str() == dirs[0] {
+                && (name == dirs[0] || entry.name.to_string().as_str() == dirs[0])
+            {
                 short_name = Some(entry.name.clone());
             }
-            }
         })
-        .unwrap();
+        .expect("Failed to iterate dir");
+
         if let Some(name) = short_name {
             let mut file = dir
                 .open_file_in_dir(name, embedded_sdmmc::Mode::ReadWriteAppend)
@@ -206,9 +245,19 @@ pub extern "C" fn read_file(
 ) -> usize {
     // SAFETY: caller guarantees `ptr` is valid for `len` bytes
     let file = unsafe { core::str::from_raw_parts(str, len) };
-    let file: Vec<&str> = file.split('/').collect();
+
+    let mut components: [&str; 8] = [""; 8];
+    let mut count = 0;
+    for part in file.split('/') {
+        if count >= components.len() {
+            break;
+        }
+        components[count] = part;
+        count += 1;
+    }
+
     // SAFETY: caller guarantees `ptr` is valid for `len` bytes
-    let mut buf = unsafe { core::slice::from_raw_parts_mut(buf, buf_len) };
+    let buf = unsafe { core::slice::from_raw_parts_mut(buf, buf_len) };
 
     let mut read = 0;
 
@@ -216,9 +265,9 @@ pub extern "C" fn read_file(
     let sd = guard.as_mut().unwrap();
     if !file.is_empty() {
         sd.access_root_dir(|root| {
-            if let Ok(result) = recurse_file(&root, &file[1..], |file| {
+            if let Ok(result) = recurse_file(&root, &components[1..count], |file| {
-                file.seek_from_start(start_from as u32).unwrap();
+                file.seek_from_start(start_from as u32).unwrap_or(());
-                file.read(&mut buf).unwrap()
+                file.read(buf).unwrap()
             }) {
                 read = result
             };
@@ -227,9 +276,46 @@ pub extern "C" fn read_file(
     read
 }
 
+const _: WriteFile = write_file;
+pub extern "C" fn write_file(
+    str: *const u8,
+    len: usize,
+    start_from: usize,
+    buf: *const u8,
+    buf_len: usize,
+) {
+    // SAFETY: caller guarantees str ptr is valid for `len` bytes
+    let file = unsafe { core::str::from_raw_parts(str, len) };
+
+    let mut components: [&str; 8] = [""; 8];
+    let mut count = 0;
+    for part in file.split('/') {
+        if count >= components.len() {
+            break;
+        }
+        components[count] = part;
+        count += 1;
+    }
+
+    // SAFETY: caller guarantees buf ptr is valid for `buf_len` bytes
+    let buf = unsafe { core::slice::from_raw_parts(buf, buf_len) };
+
+    let mut guard = SDCARD.get().try_lock().expect("Failed to get sdcard");
+    let sd = guard.as_mut().unwrap();
+    if !file.is_empty() {
+        sd.access_root_dir(|root| {
+            recurse_file(&root, &components[1..count], |file| {
+                file.seek_from_start(start_from as u32).unwrap();
+                file.write(buf).unwrap()
+            })
+            .unwrap_or(())
+        });
+    };
+}
+
 const _: FileLen = file_len;
 pub extern "C" fn file_len(str: *const u8, len: usize) -> usize {
-    // SAFETY: caller guarantees `ptr` is valid for `len` bytes
+    // SAFETY: caller guarantees str ptr is valid for `len` bytes
     let file = unsafe { core::str::from_raw_parts(str, len) };
     let file: Vec<&str> = file.split('/').collect();
 
@@ -246,3 +332,36 @@ pub extern "C" fn file_len(str: *const u8, len: usize) -> usize {
     }
     len as usize
 }
+
+const _: ReconfigureAudioSampleRate = reconfigure_audio_sample_rate;
+pub extern "C" fn reconfigure_audio_sample_rate(sample_rate: u32) {
+    AUDIO_BUFFER_SAMPLE_RATE.store(sample_rate, Ordering::Release);
+}
+
+const _: AudioBufferReady = audio_buffer_ready;
+pub extern "C" fn audio_buffer_ready() -> bool {
+    AUDIO_BUFFER_READY.load(Ordering::Acquire)
+}
+
+const _: SendAudioBuffer = send_audio_buffer;
+pub extern "C" fn send_audio_buffer(ptr: *const u8, len: usize) {
+    // SAFETY: caller guarantees `ptr` is valid for `len` bytes
+    let buf = unsafe { core::slice::from_raw_parts(ptr, len) };
+
+    while !AUDIO_BUFFER_READY.load(Ordering::Acquire) {
+        core::hint::spin_loop();
+    }
+
+    if buf.len() == AUDIO_BUFFER_SAMPLES * 2 {
+        AUDIO_BUFFER_READY.store(false, Ordering::Release);
+        unsafe { AUDIO_BUFFER.copy_from_slice(buf) };
+        AUDIO_BUFFER_WRITTEN.store(true, Ordering::Release);
+    } else {
+        #[cfg(feature = "defmt")]
+        defmt::warn!(
+            "user audio stream was wrong size: {} should be {}",
+            buf.len(),
+            AUDIO_BUFFER_SAMPLES * 2
+        )
+    }
+}

kernel/src/ui.rs

@@ -2,7 +2,6 @@ use crate::{
     BINARY_CH, display::FRAMEBUFFER, elf::load_binary, framebuffer::FB_PAUSED,
     peripherals::keyboard, storage::FileName,
 };
-use abi_sys::keyboard::{KeyCode, KeyState};
 use alloc::{str::FromStr, string::String, vec::Vec};
 use core::sync::atomic::Ordering;
 use embassy_sync::{blocking_mutex::raw::CriticalSectionRawMutex, mutex::Mutex};
@@ -20,14 +19,16 @@ use embedded_layout::{
     prelude::*,
 };
 use embedded_text::TextBox;
+use userlib_sys::keyboard::{KeyCode, KeyState};
 
 pub static SELECTIONS: Mutex<CriticalSectionRawMutex, SelectionList> =
     Mutex::new(SelectionList::new());
 
 pub async fn ui_handler() {
     loop {
-        if let Some(event) = keyboard::read_keyboard_fifo().await {
+        if let Some(event) = keyboard::read_keyboard_fifo().await
-            if let KeyState::Pressed = event.state {
+            && let KeyState::Pressed = event.state
+        {
             match event.key {
                 KeyCode::Up => {
                     let mut selections = SELECTIONS.lock().await;
@@ -52,7 +53,6 @@ pub async fn ui_handler() {
                 _ => (),
             }
         }
-        }
 
         let changed = SELECTIONS.lock().await.changed;
         if changed {
@@ -75,7 +75,7 @@ pub async fn clear_selection() {
 
 async fn draw_selection() {
     let mut guard = SELECTIONS.lock().await;
-    let file_names = &guard.selections.clone();
+    let file_names = guard.selections.clone();
 
     let text_style = MonoTextStyle::new(&FONT_10X20, Rgb565::WHITE);
     let display_area = unsafe { FRAMEBUFFER.as_mut().unwrap().bounding_box() };
@@ -99,7 +99,7 @@ async fn draw_selection() {
     } else {
         let mut views: alloc::vec::Vec<Text<MonoTextStyle<Rgb565>>> = Vec::new();
 
-        for i in file_names {
+        for i in &file_names {
             views.push(Text::new(&i.long_name, Point::zero(), text_style));
         }
 

selection_ui/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "selection_ui"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+userlib = { path = "../userlib" }
+embedded-graphics = "0.8.1"
+embedded-layout = "0.4.2"
+embedded-text = "0.7.3"

selection_ui/src/lib.rs

@@ -0,0 +1,153 @@
+#![no_std]
+
+extern crate alloc;
+
+use alloc::vec::Vec;
+use embedded_graphics::{
+    mono_font::{ascii::FONT_10X20, MonoTextStyle},
+    pixelcolor::Rgb565,
+    prelude::{Dimensions, DrawTarget, Point, Primitive, RgbColor},
+    primitives::{PrimitiveStyle, Rectangle},
+    text::{renderer::TextRenderer, Alignment, Text},
+    Drawable,
+};
+use embedded_layout::{
+    align::{horizontal, vertical},
+    layout::linear::{FixedMargin, LinearLayout},
+    prelude::*,
+};
+use userlib::{
+    display::Display,
+    get_key,
+    keyboard::{KeyCode, KeyState},
+};
+
+#[derive(Debug)]
+pub enum SelectionUiError<DisplayError> {
+    SelectionListEmpty,
+    DisplayError(DisplayError),
+}
+
+pub struct SelectionUi<'a> {
+    selection: usize,
+    items: &'a [&'a str],
+    last_bounds: Option<Rectangle>,
+}
+
+impl<'a> SelectionUi<'a> {
+    pub fn new(items: &'a [&'a str]) -> Self {
+        Self {
+            selection: 0,
+            items,
+            last_bounds: None,
+        }
+    }
+
+    pub fn run_selection_ui(
+        &mut self,
+        display: &mut Display,
+    ) -> Result<Option<usize>, SelectionUiError<<Display as DrawTarget>::Error>> {
+        self.draw(display)?;
+        let selection;
+        loop {
+            let key = get_key();
+            if key.state == KeyState::Pressed
+                && let Some(s) = self.update(display, key.key)? {
+                    selection = Some(s);
+                    display
+                        .clear(Rgb565::BLACK)
+                        .map_err(SelectionUiError::DisplayError)?;
+                    break;
+                }
+        }
+        Ok(selection)
+    }
+
+    /// updates the display with a new keypress.
+    /// returns selection idx if selected
+    pub fn update(
+        &mut self,
+        display: &mut Display,
+        key: KeyCode,
+    ) -> Result<Option<usize>, SelectionUiError<<Display as DrawTarget>::Error>> {
+        match key {
+            KeyCode::Down => {
+                self.selection = (self.selection + 1).min(self.items.len() - 1);
+            }
+            KeyCode::Up => {
+                self.selection = self.selection.saturating_sub(1);
+            }
+            KeyCode::Enter | KeyCode::Right => return Ok(Some(self.selection)),
+            _ => return Ok(None),
+        };
+        self.draw(display)?;
+        Ok(None)
+    }
+
+    fn draw(
+        &mut self,
+        display: &mut Display,
+    ) -> Result<(), SelectionUiError<<Display as DrawTarget>::Error>> {
+        let text_style = MonoTextStyle::new(&FONT_10X20, Rgb565::WHITE);
+        let display_area = display.bounding_box();
+
+        if self.items.is_empty() {
+            return Err(SelectionUiError::SelectionListEmpty);
+        }
+
+        if let Some(bounds) = self.last_bounds {
+            Rectangle::new(bounds.top_left, bounds.size)
+                .into_styled(PrimitiveStyle::with_fill(Rgb565::BLACK))
+                .draw(display)
+                .map_err(SelectionUiError::DisplayError)?;
+        }
+
+        let mut views: Vec<Text<MonoTextStyle<Rgb565>>> = Vec::new();
+
+        for i in self.items {
+            views.push(Text::new(i, Point::zero(), text_style));
+        }
+
+        let views_group = Views::new(views.as_mut_slice());
+
+        let layout = LinearLayout::vertical(views_group)
+            .with_alignment(horizontal::Center)
+            .with_spacing(FixedMargin(5))
+            .arrange()
+            .align_to(&display_area, horizontal::Center, vertical::Center);
+
+        layout
+            .draw(display)
+            .map_err(SelectionUiError::DisplayError)?;
+
+        // draw selected box
+        if let Some(selected_bounds) = layout.inner().get(self.selection) {
+            let selected_bounds = selected_bounds.bounding_box();
+            Rectangle::new(selected_bounds.top_left, selected_bounds.size)
+                .into_styled(PrimitiveStyle::with_stroke(Rgb565::WHITE, 1))
+                .draw(display)
+                .map_err(SelectionUiError::DisplayError)?;
+
+            self.last_bounds = Some(selected_bounds);
+        }
+
+        Ok(())
+    }
+}
+
+pub fn draw_text_center<S>(
+    display: &mut Display,
+    text: &str,
+    style: S,
+) -> Result<Point, <Display as DrawTarget>::Error>
+where
+    S: TextRenderer<Color = <Display as DrawTarget>::Color>,
+{
+    Text::with_alignment(
+        text,
+        display.bounding_box().center(),
+        style,
+        Alignment::Center,
+    )
+    .draw(display)
+}

user-apps/gallery/src/main.rs

@@ -1,102 +0,0 @@
-#![no_std]
-#![no_main]
-#![allow(static_mut_refs)]
-
-extern crate alloc;
-use abi::{
-    display::{Display, SCREEN_HEIGHT, SCREEN_WIDTH},
-    fs::{list_dir, read_file},
-    get_key,
-    keyboard::{KeyCode, KeyState},
-    print,
-};
-use alloc::{format, string::ToString, vec};
-use core::panic::PanicInfo;
-use embedded_graphics::{
-    Drawable, image::Image, mono_font::MonoTextStyle, mono_font::ascii::FONT_6X10,
-    pixelcolor::Rgb565, prelude::*, text::Text,
-};
-use tinybmp::Bmp;
-
-#[panic_handler]
-fn panic(info: &PanicInfo) -> ! {
-    print!("user panic: {} @ {:?}", info.message(), info.location());
-    loop {}
-}
-
-#[unsafe(no_mangle)]
-pub extern "Rust" fn _start() {
-    main()
-}
-
-pub fn main() {
-    print!("Starting Gallery app");
-    let mut bmp_buf = vec![0_u8; 100_000];
-    let mut display = Display;
-
-    // Grid parameters
-    let grid_cols = 3;
-    let grid_rows = 3;
-    let cell_width = SCREEN_WIDTH as i32 / grid_cols;
-    let cell_height = SCREEN_HEIGHT as i32 / grid_rows;
-
-    let mut images_drawn = 0;
-
-    let mut files = [const { None }; 18];
-    let files_num = list_dir("/images", &mut files);
-
-    for file in &files[2..files_num] {
-        if images_drawn >= grid_cols * grid_rows {
-            break; // only draw 3x3
-        }
-
-        if let Some(f) = file {
-            print!("file: {}", f.name);
-            if f.name.extension() == b"bmp" || f.name.extension() == b"BMP" {
-                let file = format!("/images/{}", f.name);
-
-                let read = read_file(&file, 0, &mut &mut bmp_buf[..]);
-                if read > 0 {
-                    let bmp = Bmp::from_slice(&bmp_buf).expect("failed to parse bmp");
-
-                    let row = images_drawn / grid_cols;
-                    let col = images_drawn % grid_cols;
-                    let cell_x = col * cell_width;
-                    let cell_y = row * cell_height;
-
-                    // Center image inside cell
-                    let bmp_w = bmp.size().width as i32;
-                    let bmp_h = bmp.size().height as i32;
-                    let x = cell_x + (cell_width - bmp_w) / 2;
-                    let y = cell_y + 5; // 5px top margin
-
-                    Image::new(&bmp, Point::new(x, y))
-                        .draw(&mut display)
-                        .unwrap();
-
-                    let text_style = MonoTextStyle::new(&FONT_6X10, Rgb565::WHITE);
-                    let text_y = y + bmp_h + 2; // 2px gap under image
-                    Text::new(
-                        f.name.to_string().as_str(),
-                        Point::new(cell_x + 2, text_y),
-                        text_style,
-                    )
-                    .draw(&mut display)
-                    .unwrap();
-
-                    images_drawn += 1;
-                }
-            }
-        }
-    }
-
-    loop {
-        let event = get_key();
-        if event.state != KeyState::Idle {
-            match event.key {
-                KeyCode::Esc => return,
-                _ => (),
-            }
-        };
-    }
-}

user-apps/gif/src/main.rs

@@ -1,69 +0,0 @@
-#![no_std]
-#![no_main]
-
-extern crate alloc;
-use abi::{
-    display::Display,
-    fs::{file_len, read_file},
-    get_key, get_ms,
-    keyboard::{KeyCode, KeyState},
-    print, sleep,
-};
-use alloc::vec;
-use core::panic::PanicInfo;
-use embedded_graphics::{
-    image::ImageDrawable, pixelcolor::Rgb565, prelude::Point, transform::Transform,
-};
-use tinygif::Gif;
-
-#[panic_handler]
-fn panic(info: &PanicInfo) -> ! {
-    print!("user panic: {} @ {:?}", info.message(), info.location(),);
-    loop {}
-}
-
-#[unsafe(no_mangle)]
-pub extern "Rust" fn _start() {
-    main()
-}
-
-pub fn main() {
-    print!("Starting Gif app");
-    let mut display = Display;
-
-    let size = file_len("/gifs/bad_apple.gif");
-    let mut buf = vec![0_u8; size];
-    let read = read_file("/gifs/bad_apple.gif", 0, &mut buf);
-    print!("read: {}, file size: {}", read, size);
-    assert!(read == size);
-
-    let gif = Gif::<Rgb565>::from_slice(&buf).unwrap();
-    let height = gif.height();
-
-    let mut frame_num = 0;
-    loop {
-        for mut frame in gif.frames() {
-            let start = get_ms();
-
-            frame
-                .translate_mut(Point::new(0, (320 - height as i32) / 2))
-                .draw(&mut display)
-                .unwrap();
-            frame_num += 1;
-
-            if frame_num % 5 == 0 {
-                let event = get_key();
-                if event.state != KeyState::Idle {
-                    match event.key {
-                        KeyCode::Esc => {
-                            drop(buf);
-                            return;
-                        }
-                        _ => (),
-                    };
-                };
-            }
-            sleep(((frame.delay_centis as u64) * 10).saturating_sub(start));
-        }
-    }
-}

user_apps/calculator/Cargo.toml

@@ -4,6 +4,6 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-abi = { path = "../../abi" }
+userlib = { path = "../../userlib" }
 embedded-graphics = "0.8.1"
 embedded-layout = "0.4.2"

user_apps/calculator/src/main.rs

@@ -2,12 +2,6 @@
 #![no_main]
 
 extern crate alloc;
-use abi::{
-    display::Display,
-    get_key,
-    keyboard::{KeyCode, KeyState},
-    print,
-};
 use alloc::{format, string::String, vec, vec::Vec};
 use core::panic::PanicInfo;
 use embedded_graphics::{
@@ -25,10 +19,16 @@ use embedded_layout::{
     layout::linear::LinearLayout,
     prelude::Chain,
 };
+use userlib::{
+    display::Display,
+    get_key,
+    keyboard::{KeyCode, KeyState},
+    println,
+};
 
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
-    print!("user panic: {} @ {:?}", info.message(), info.location(),);
+    println!("user panic: {} @ {:?}", info.message(), info.location(),);
     loop {}
 }
 
@@ -38,8 +38,8 @@ pub extern "Rust" fn _start() {
 }
 
 pub fn main() {
-    print!("Starting Calculator app");
+    println!("Starting Calculator app");
-    let mut display = Display;
+    let mut display = Display::take().unwrap();
 
     let mut input = vec!['e', 'x', 'p', 'r', ':', ' '];
     let input_min = input.len();
@@ -83,7 +83,7 @@ pub fn main() {
             .align_to(&display.bounding_box(), horizontal::Left, vertical::Center);
 
             let result = if let Ok(result) = evaluate(&input[input_min..]) {
-                &format!(" = {}", result)
+                &format!(" = {result}")
             } else {
                 " = Error"
             };
@@ -104,7 +104,7 @@ pub fn main() {
         }
 
         let event = get_key();
-        if event.state != KeyState::Idle {
+        if event.state == KeyState::Released {
             match event.key {
                 KeyCode::Char(ch) => {
                     input.push(ch);

user_apps/gallery/Cargo.toml

@@ -4,6 +4,6 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-abi = { path = "../../abi" }
+userlib = { path = "../../userlib" }
 embedded-graphics = "0.8.1"
 tinybmp = "0.6.0"

user_apps/gallery/src/main.rs

@@ -0,0 +1,92 @@
+#![no_std]
+#![no_main]
+#![allow(static_mut_refs)]
+
+extern crate alloc;
+use alloc::{format, vec};
+use core::panic::PanicInfo;
+use embedded_graphics::{
+    Drawable, image::Image, mono_font::MonoTextStyle, mono_font::ascii::FONT_6X10,
+    pixelcolor::Rgb565, prelude::*, text::Text,
+};
+use tinybmp::Bmp;
+use userlib::{
+    display::{Display, SCREEN_HEIGHT, SCREEN_WIDTH},
+    fs::{Entries, list_dir, read_file},
+    get_key,
+    keyboard::{KeyCode, KeyState},
+    println,
+};
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    println!("user panic: {} @ {:?}", info.message(), info.location());
+    loop {}
+}
+
+#[unsafe(no_mangle)]
+pub extern "Rust" fn _start() {
+    main()
+}
+
+pub fn main() {
+    println!("Starting Gallery app");
+    let mut bmp_buf = vec![0_u8; 100_000];
+    let mut display = Display::take().unwrap();
+
+    let grid_cols = 3;
+    let grid_rows = 3;
+    let cell_width = SCREEN_WIDTH as i32 / grid_cols;
+    let cell_height = SCREEN_HEIGHT as i32 / grid_rows;
+
+    let mut images_drawn = 0;
+
+    let mut entries = Entries::new();
+    let files_num = list_dir("/images", &mut entries);
+
+    for file in &entries.entries()[2..files_num] {
+        if images_drawn >= grid_cols * grid_rows {
+            break; // only draw 3x3
+        }
+
+        println!("file: {}", file);
+        if file.extension().unwrap_or("") == "bmp" || file.extension().unwrap_or("") == "BMP" {
+            let file_path = format!("/images/{file}");
+
+            let read = read_file(&file_path, 0, &mut bmp_buf[..]);
+            if read > 0 {
+                let bmp = Bmp::from_slice(&bmp_buf).expect("failed to parse bmp");
+
+                let row = images_drawn / grid_cols;
+                let col = images_drawn % grid_cols;
+                let cell_x = col * cell_width;
+                let cell_y = row * cell_height;
+
+                // Center image inside cell
+                let bmp_w = bmp.size().width as i32;
+                let bmp_h = bmp.size().height as i32;
+                let x = cell_x + (cell_width - bmp_w) / 2;
+                let y = cell_y + 5; // 5px top margin
+
+                Image::new(&bmp, Point::new(x, y))
+                    .draw(&mut display)
+                    .unwrap();
+
+                let text_style = MonoTextStyle::new(&FONT_6X10, Rgb565::WHITE);
+                let text_y = y + bmp_h + 2; // 2px gap under image
+                Text::new(file.base(), Point::new(cell_x + 2, text_y), text_style)
+                    .draw(&mut display)
+                    .unwrap();
+
+                images_drawn += 1;
+            }
+        }
+    }
+
+    loop {
+        let event = get_key();
+        if event.state != KeyState::Idle && event.key == KeyCode::Esc {
+            return;
+        }
+    }
+}

user_apps/gif/Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-abi = { path = "../../abi" }
+userlib = { path = "../../userlib" }
+selection_ui = { path = "../../selection_ui" }
 embedded-graphics = "0.8.1"
 tinygif = { git = "https://github.com/LegitCamper/tinygif" }

user_apps/gif/src/main.rs

@@ -0,0 +1,98 @@
+#![no_std]
+#![no_main]
+
+extern crate alloc;
+use alloc::{format, vec, vec::Vec};
+use core::panic::PanicInfo;
+use embedded_graphics::{
+    image::ImageDrawable,
+    mono_font::{MonoTextStyle, ascii::FONT_6X10},
+    pixelcolor::Rgb565,
+    prelude::{Point, RgbColor},
+    transform::Transform,
+};
+use selection_ui::{SelectionUi, SelectionUiError, draw_text_center};
+use tinygif::Gif;
+use userlib::{
+    display::{Display, SCREEN_HEIGHT, SCREEN_WIDTH},
+    fs::{Entries, file_len, list_dir, read_file},
+    get_key, get_ms,
+    keyboard::{KeyCode, KeyState},
+    println, sleep,
+};
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    println!("user panic: {} @ {:?}", info.message(), info.location(),);
+    loop {}
+}
+
+#[unsafe(no_mangle)]
+pub extern "Rust" fn _start() {
+    main()
+}
+
+pub fn main() {
+    println!("Starting Gif app");
+    let mut display = Display::take().unwrap();
+
+    let mut entries = Entries::new();
+    list_dir("/gifs", &mut entries);
+
+    let mut files = entries.entries();
+    files.retain(|e| e.extension().unwrap_or("") == "gif");
+    let mut gifs = files.iter().map(|e| e.full_name()).collect::<Vec<&str>>();
+    gifs.sort();
+
+    let mut selection_ui = SelectionUi::new(&gifs);
+    let selection = match selection_ui.run_selection_ui(&mut display) {
+        Ok(maybe_sel) => maybe_sel,
+        Err(e) => match e {
+            SelectionUiError::SelectionListEmpty => {
+                draw_text_center(
+                    &mut display,
+                    "No Gifs were found in /gifs",
+                    MonoTextStyle::new(&FONT_6X10, Rgb565::RED),
+                )
+                .expect("Display Error");
+                None
+            }
+            SelectionUiError::DisplayError(_) => panic!("Display Error"),
+        },
+    };
+
+    assert!(selection.is_some());
+
+    let file_name = format!("/gifs/{}", gifs[selection.unwrap()]);
+    let size = file_len(&file_name);
+    let mut buf = vec![0_u8; size];
+    let read = read_file(&file_name, 0, &mut buf);
+    println!("read: {}, file size: {}", read, size);
+    assert!(read == size);
+
+    let gif = Gif::<Rgb565>::from_slice(&buf).expect("Failed to parse gif");
+
+    let translation = Point::new(
+        (SCREEN_WIDTH as i32 - gif.width() as i32) / 2,
+        (SCREEN_HEIGHT as i32 - gif.height() as i32) / 2,
+    );
+
+    let mut frame_num = 0;
+    loop {
+        for mut frame in gif.frames() {
+            let start = get_ms();
+
+            frame.translate_mut(translation).draw(&mut display).unwrap();
+            frame_num += 1;
+
+            if frame_num % 5 == 0 {
+                let event = get_key();
+                if event.state != KeyState::Idle && event.key == KeyCode::Esc {
+                    drop(buf);
+                    return;
+                };
+            }
+            sleep(((frame.delay_centis as u64) * 10).saturating_sub(start));
+        }
+    }
+}

user_apps/snake/Cargo.toml

@@ -4,7 +4,7 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-abi = { path = "../../abi" }
+userlib = { path = "../../userlib" }
 embedded-graphics = "0.8.1"
 embedded-snake = { git = "https://github.com/LegitCamper/embedded-snake-rs" }
 rand = { version = "0.9.0", default-features = false }

user_apps/snake/src/main.rs

@@ -2,20 +2,20 @@
 #![no_main]
 
 extern crate alloc;
-use abi::{
+use core::panic::PanicInfo;
+use embedded_graphics::{pixelcolor::Rgb565, prelude::RgbColor};
+use embedded_snake::{Direction, SnakeGame};
+use userlib::{
     Rng,
     display::{Display, SCREEN_HEIGHT, SCREEN_WIDTH},
     get_key,
     keyboard::{KeyCode, KeyState},
-    print, sleep,
+    println, sleep,
 };
-use core::panic::PanicInfo;
-use embedded_graphics::{pixelcolor::Rgb565, prelude::RgbColor};
-use embedded_snake::{Direction, SnakeGame};
 
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
-    print!("user panic: {} @ {:?}", info.message(), info.location(),);
+    println!("user panic: {} @ {:?}", info.message(), info.location(),);
     loop {}
 }
 
@@ -27,8 +27,8 @@ pub extern "Rust" fn _start() {
 const CELL_SIZE: usize = 8;
 
 pub fn main() {
-    print!("Starting Snake app");
+    println!("Starting Snake app");
-    let mut display = Display;
+    let mut display = Display::take().unwrap();
 
     let mut game = SnakeGame::<100, Rgb565, Rng>::new(
         SCREEN_WIDTH as u16,

user_apps/wav_player/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "wav_player"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+userlib = { path = "../../userlib" }
+selection_ui = { path = "../../selection_ui" }
+embedded-graphics = "0.8.1"
+rand = { version = "0.9.0", default-features = false }
+embedded-audio = { git = "https://github.com/LegitCamper/embedded-audio" }

user_apps/wav_player/build.rs

@@ -0,0 +1,28 @@
+//! This build script copies the `memory.x` file from the crate root into
+//! a directory where the linker can always find it at build time.
+//! For many projects this is optional, as the linker always searches the
+//! project root directory -- wherever `Cargo.toml` is. However, if you
+//! are using a workspace or have a more complicated build setup, this
+//! build script becomes required. Additionally, by requesting that
+//! Cargo re-run the build script whenever `memory.x` is changed,
+//! updating `memory.x` ensures a rebuild of the application with the
+//! new memory settings.
+
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put `memory.x` in our output directory and ensure it's
+    // on the linker search path.
+    let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    File::create(out.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("../memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+
+    println!("cargo:rerun-if-changed=memory.x");
+    println!("cargo:rustc-link-arg-bins=-Tmemory.x");
+}

user_apps/wav_player/src/main.rs

@@ -0,0 +1,143 @@
+#![no_std]
+#![no_main]
+
+extern crate alloc;
+use alloc::{string::String, vec::Vec};
+use core::panic::PanicInfo;
+use embedded_audio::{AudioFile, PlatformFile, PlatformFileError, wav::Wav};
+use embedded_graphics::{
+    mono_font::{MonoTextStyle, ascii::FONT_6X10},
+    pixelcolor::Rgb565,
+    prelude::RgbColor,
+};
+use selection_ui::{SelectionUi, SelectionUiError, draw_text_center};
+use userlib::{
+    audio::{AUDIO_BUFFER_LEN, audio_buffer_ready, send_audio_buffer},
+    display::Display,
+    format,
+    fs::{Entries, file_len, list_dir, read_file},
+    get_key,
+    keyboard::{KeyCode, KeyState},
+    println,
+};
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    println!("user panic: {} @ {:?}", info.message(), info.location(),);
+    loop {}
+}
+
+#[unsafe(no_mangle)]
+pub extern "Rust" fn _start() {
+    main()
+}
+
+pub fn main() {
+    println!("Starting Wav player app");
+    let mut display = Display::take().unwrap();
+
+    loop {
+        let mut entries = Entries::new();
+        list_dir("/music", &mut entries);
+
+        let mut files = entries.entries();
+        files.retain(|e| e.extension().unwrap_or("") == "wav");
+        let mut wavs = files.iter().map(|e| e.full_name()).collect::<Vec<&str>>();
+        wavs.sort();
+
+        let mut selection_ui = SelectionUi::new(&wavs);
+        let selection = match selection_ui.run_selection_ui(&mut display) {
+            Ok(maybe_sel) => maybe_sel,
+            Err(e) => match e {
+                SelectionUiError::SelectionListEmpty => {
+                    draw_text_center(
+                        &mut display,
+                        "No Wavs were found in /music",
+                        MonoTextStyle::new(&FONT_6X10, Rgb565::RED),
+                    )
+                    .expect("Display Error");
+                    None
+                }
+                SelectionUiError::DisplayError(_) => panic!("Display Error"),
+            },
+        };
+
+        assert!(selection.is_some());
+
+        draw_text_center(
+            &mut display,
+            &format!("Now playing {}", wavs[selection.unwrap()]),
+            MonoTextStyle::new(&FONT_6X10, Rgb565::WHITE),
+        )
+        .expect("Display Error");
+
+        let file_name = format!("/music/{}", wavs[selection.unwrap()]);
+        let file = File::new(file_name);
+        let mut wav = Wav::new(file).unwrap();
+        println!("sample rate: {}", wav.sample_rate());
+        println!("channels: {:?}", wav.channels() as u8);
+
+        let mut buf = [0_u8; AUDIO_BUFFER_LEN];
+
+        loop {
+            if audio_buffer_ready() {
+                if wav.is_eof() {
+                    break;
+                }
+
+                let _read = wav.read(&mut buf).unwrap();
+                send_audio_buffer(&buf);
+            }
+
+            let event = get_key();
+            if event.state == KeyState::Released && event.key == KeyCode::Esc {
+                return;
+            }
+        }
+    }
+}
+
+struct File {
+    current_pos: usize,
+    file: String,
+}
+
+impl File {
+    fn new(file: String) -> Self {
+        Self {
+            current_pos: 0,
+            file,
+        }
+    }
+}
+
+impl PlatformFile for File {
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize, PlatformFileError> {
+        let read = read_file(&self.file, self.current_pos, buf);
+        self.current_pos += read;
+        Ok(read)
+    }
+
+    fn seek_from_current(&mut self, offset: i64) -> Result<(), PlatformFileError> {
+        if offset.is_positive() {
+            self.current_pos += offset as usize;
+        } else {
+            self.current_pos -= offset as usize;
+        }
+        Ok(())
+    }
+
+    fn seek_from_start(&mut self, offset: usize) -> Result<(), PlatformFileError> {
+        self.current_pos = offset;
+        Ok(())
+    }
+
+    fn seek_from_end(&mut self, offset: usize) -> Result<(), PlatformFileError> {
+        self.current_pos = self.length() - offset;
+        Ok(())
+    }
+
+    fn length(&mut self) -> usize {
+        file_len(&self.file)
+    }
+}

userlib/Cargo.toml

@@ -1,11 +1,10 @@
 [package]
-name = "abi"
+name = "userlib"
 version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-embedded-sdmmc = { version = "0.9.0", default-features = false }
+userlib_sys = { path = "../userlib_sys" }
 embedded-graphics = "0.8.1"
-abi_sys = { path = "../abi_sys" }
 once_cell = { version = "1", default-features = false }
 rand_core = "0.9.3"

userlib/src/lib.rs

@@ -0,0 +1,283 @@
+#![no_std]
+#![allow(static_mut_refs)]
+
+extern crate alloc;
+
+pub use alloc::format;
+use core::alloc::{GlobalAlloc, Layout};
+use rand_core::RngCore;
+use userlib_sys::{RngRequest, keyboard::KeyEvent};
+pub use userlib_sys::{keyboard, print};
+
+#[global_allocator]
+static ALLOC: Alloc = Alloc;
+
+struct Alloc;
+
+unsafe impl GlobalAlloc for Alloc {
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        userlib_sys::alloc(layout.into())
+    }
+
+    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+        userlib_sys::dealloc(ptr, layout.into());
+    }
+}
+
+#[macro_export]
+macro_rules! println {
+    ($($arg:tt)*) => {{
+        let s = $crate::format!($($arg)*);
+        $crate::print(s.as_ptr(), s.len());
+    }};
+}
+
+pub fn sleep(ms: u64) {
+    userlib_sys::sleep(ms);
+}
+
+pub fn get_ms() -> u64 {
+    userlib_sys::get_ms()
+}
+
+pub fn get_key() -> KeyEvent {
+    userlib_sys::keyboard::get_key().into()
+}
+
+pub mod display {
+    use core::sync::atomic::{AtomicBool, Ordering};
+
+    use embedded_graphics::{
+        Pixel,
+        geometry::{Dimensions, Point},
+        pixelcolor::Rgb565,
+        prelude::{DrawTarget, Size},
+        primitives::Rectangle,
+    };
+    use userlib_sys::CPixel;
+
+    pub const SCREEN_WIDTH: usize = 320;
+    pub const SCREEN_HEIGHT: usize = 320;
+
+    pub type Pixel565 = Pixel<Rgb565>;
+
+    const BUF_SIZE: usize = 1024;
+    static mut BUF: [CPixel; BUF_SIZE] = [CPixel::new(); BUF_SIZE];
+
+    static DISPLAY_TAKEN: AtomicBool = AtomicBool::new(false);
+
+    pub struct Display {
+        _private: (),
+    }
+
+    impl Display {
+        /// Only one instance of Display can be taken
+        pub fn take() -> Option<Display> {
+            if DISPLAY_TAKEN
+                .compare_exchange(false, true, Ordering::Acquire, Ordering::Relaxed)
+                .is_ok()
+            {
+                Some(Self { _private: () })
+            } else {
+                None
+            }
+        }
+    }
+
+    impl Dimensions for Display {
+        fn bounding_box(&self) -> Rectangle {
+            Rectangle {
+                top_left: Point { x: 0, y: 0 },
+                size: Size {
+                    width: SCREEN_WIDTH as u32,
+                    height: SCREEN_HEIGHT as u32,
+                },
+            }
+        }
+    }
+
+    impl DrawTarget for Display {
+        type Color = Rgb565;
+        type Error = ();
+
+        fn draw_iter<I>(&mut self, pixels: I) -> Result<(), Self::Error>
+        where
+            I: IntoIterator<Item = Pixel<Self::Color>>,
+        {
+            let mut count = 0;
+            for p in pixels {
+                unsafe { BUF[count] = p.into() };
+                count += 1;
+
+                if count == BUF_SIZE - 1 {
+                    userlib_sys::draw_iter(unsafe { BUF.as_ptr() }, count);
+                    count = 0;
+                }
+            }
+
+            if count > 0 {
+                userlib_sys::draw_iter(unsafe { BUF.as_ptr() }, count);
+            }
+
+            Ok(())
+        }
+    }
+}
+
+fn gen_rand(req: &mut RngRequest) {
+    userlib_sys::gen_rand(req);
+}
+
+pub struct Rng;
+
+impl RngCore for Rng {
+    fn next_u32(&mut self) -> u32 {
+        let mut req = RngRequest::U32(0);
+        gen_rand(&mut req);
+        if let RngRequest::U32(i) = req {
+            return i;
+        };
+        0
+    }
+
+    fn next_u64(&mut self) -> u64 {
+        let mut req = RngRequest::U64(0);
+        gen_rand(&mut req);
+        if let RngRequest::U64(i) = req {
+            return i;
+        };
+        0
+    }
+    fn fill_bytes(&mut self, dst: &mut [u8]) {
+        let mut req = RngRequest::Bytes {
+            ptr: dst.as_mut_ptr(),
+            len: dst.len(),
+        };
+        gen_rand(&mut req);
+    }
+}
+
+pub mod fs {
+    use alloc::vec::Vec;
+    use core::fmt::Display;
+
+    pub fn read_file(file: &str, start_from: usize, buf: &mut [u8]) -> usize {
+        userlib_sys::read_file(
+            file.as_ptr(),
+            file.len(),
+            start_from,
+            buf.as_mut_ptr(),
+            buf.len(),
+        )
+    }
+
+    pub fn write_file(file: &str, start_from: usize, buf: &[u8]) {
+        userlib_sys::write_file(
+            file.as_ptr(),
+            file.len(),
+            start_from,
+            buf.as_ptr(),
+            buf.len(),
+        )
+    }
+
+    #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+    pub struct FileName<'a> {
+        full: &'a str,
+        base: &'a str,
+        ext: Option<&'a str>,
+    }
+
+    impl<'a> FileName<'a> {
+        pub fn full_name(&self) -> &str {
+            self.full
+        }
+
+        pub fn base(&self) -> &str {
+            self.base
+        }
+
+        pub fn extension(&self) -> Option<&str> {
+            self.ext
+        }
+    }
+
+    impl<'a> Display for FileName<'a> {
+        fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+            write!(f, "{}", self.full_name())
+        }
+    }
+
+    impl<'a> From<&'a str> for FileName<'a> {
+        fn from(s: &'a str) -> FileName<'a> {
+            let full = s;
+
+            // Split on last dot for extension
+            let (base, ext) = match s.rfind('.') {
+                Some(idx) => (&s[..idx], Some(&s[idx + 1..])),
+                None => (s, None),
+            };
+
+            FileName { full, base, ext }
+        }
+    }
+
+    const MAX_ENTRY_NAME_LEN: usize = 25;
+    const MAX_ENTRIES: usize = 25;
+
+    #[derive(Clone, Copy, Debug)]
+    pub struct Entries([[u8; MAX_ENTRY_NAME_LEN]; MAX_ENTRIES]);
+
+    impl Default for Entries {
+        fn default() -> Self {
+            Self::new()
+        }
+    }
+
+    impl Entries {
+        pub fn new() -> Self {
+            Self([[0; MAX_ENTRY_NAME_LEN]; MAX_ENTRIES])
+        }
+
+        /// Get list of file names after listing
+        pub fn entries<'a>(&'a self) -> Vec<FileName<'a>> {
+            self.0
+                .iter()
+                .filter_map(|buf| {
+                    let nul_pos = buf.iter().position(|&b| b == 0).unwrap_or(buf.len());
+                    Some(core::str::from_utf8(&buf[..nul_pos]).ok()?.into())
+                })
+                .collect()
+        }
+
+        fn as_ptrs(&mut self) -> [*mut u8; MAX_ENTRIES] {
+            let mut ptrs: [*mut u8; MAX_ENTRIES] = [core::ptr::null_mut(); MAX_ENTRIES];
+            for (i, buf) in self.0.iter_mut().enumerate() {
+                ptrs[i] = buf.as_mut_ptr();
+            }
+            ptrs
+        }
+    }
+
+    pub fn list_dir(path: &str, entries: &mut Entries) -> usize {
+        userlib_sys::list_dir(
+            path.as_ptr(),
+            path.len(),
+            entries.as_ptrs().as_mut_ptr(),
+            MAX_ENTRIES,
+            MAX_ENTRY_NAME_LEN,
+        )
+    }
+
+    pub fn file_len(str: &str) -> usize {
+        userlib_sys::file_len(str.as_ptr(), str.len())
+    }
+}
+
+pub mod audio {
+    pub use userlib_sys::{AUDIO_BUFFER_LEN, AUDIO_BUFFER_SAMPLES, audio_buffer_ready};
+
+    pub fn send_audio_buffer(buf: &[u8]) {
+        userlib_sys::send_audio_buffer(buf.as_ptr(), buf.len())
+    }
+}

userlib_sys/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "abi_sys"
+name = "userlib_sys"
 version = "0.1.0"
 edition = "2024"
 
@@ -12,7 +12,6 @@ defmt = ["dep:defmt"]
 strum = { version = "0.27.2", default-features = false, features = ["derive"] }
 bitflags = "2.9.4"
 embedded-graphics = "0.8.1"
-embedded-sdmmc = { version = "0.9.0", default-features = false }
 defmt = { version = "0.3", optional = true }
 
 [build-dependencies]

userlib_sys/src/lib.rs

@@ -1,24 +1,23 @@
 #![no_std]
-
 #[cfg(feature = "alloc")]
 use core::alloc::Layout;
 
+use core::ffi::c_char;
 use embedded_graphics::{
     Pixel,
     pixelcolor::{Rgb565, raw::RawU16},
     prelude::{IntoStorage, Point},
 };
-use embedded_sdmmc::DirEntry;
 use strum::{EnumCount, EnumIter};
 
 pub type EntryFn = fn();
 
-pub const ABI_CALL_TABLE_COUNT: usize = 11;
+pub const SYS_CALL_TABLE_COUNT: usize = 15;
-const _: () = assert!(ABI_CALL_TABLE_COUNT == CallTable::COUNT);
+const _: () = assert!(SYS_CALL_TABLE_COUNT == SyscallTable::COUNT);
 
 #[derive(Clone, Copy, EnumIter, EnumCount)]
 #[repr(u8)]
-pub enum CallTable {
+pub enum SyscallTable {
     Alloc = 0,
     Dealloc = 1,
     PrintString = 2,
@@ -29,12 +28,16 @@ pub enum CallTable {
     GenRand = 7,
     ListDir = 8,
     ReadFile = 9,
-    FileLen = 10,
+    WriteFile = 10,
+    FileLen = 11,
+    ReconfigureAudioSampleRate = 12,
+    AudioBufferReady = 13,
+    SendAudioBuffer = 14,
 }
 
 #[unsafe(no_mangle)]
 #[unsafe(link_section = ".syscall_table")]
-pub static mut CALL_ABI_TABLE: [usize; ABI_CALL_TABLE_COUNT] = [0; ABI_CALL_TABLE_COUNT];
+pub static mut SYS_CALL_TABLE: [usize; SYS_CALL_TABLE_COUNT] = [0; SYS_CALL_TABLE_COUNT];
 
 #[cfg(feature = "alloc")]
 #[repr(C)]
@@ -44,9 +47,9 @@ pub struct CLayout {
 }
 
 #[cfg(feature = "alloc")]
-impl Into<Layout> for CLayout {
+impl From<CLayout> for Layout {
-    fn into(self) -> Layout {
+    fn from(val: CLayout) -> Self {
-        unsafe { Layout::from_size_align_unchecked(self.size, self.alignment) }
+        unsafe { Layout::from_size_align_unchecked(val.size, val.alignment) }
     }
 }
 
@@ -60,51 +63,51 @@ impl From<Layout> for CLayout {
     }
 }
 
-pub type AllocAbi = extern "C" fn(layout: CLayout) -> *mut u8;
+pub type Alloc = extern "C" fn(layout: CLayout) -> *mut u8;
 
 #[unsafe(no_mangle)]
 pub extern "C" fn alloc(layout: CLayout) -> *mut u8 {
-    let f: AllocAbi = unsafe { core::mem::transmute(CALL_ABI_TABLE[CallTable::Alloc as usize]) };
+    let f: Alloc = unsafe { core::mem::transmute(SYS_CALL_TABLE[SyscallTable::Alloc as usize]) };
     f(layout)
 }
 
-pub type DeallocAbi = extern "C" fn(ptr: *mut u8, layout: CLayout);
+pub type Dealloc = extern "C" fn(ptr: *mut u8, layout: CLayout);
 
 #[unsafe(no_mangle)]
 pub extern "C" fn dealloc(ptr: *mut u8, layout: CLayout) {
-    let f: DeallocAbi =
+    let f: Dealloc =
-        unsafe { core::mem::transmute(CALL_ABI_TABLE[CallTable::Dealloc as usize]) };
+        unsafe { core::mem::transmute(SYS_CALL_TABLE[SyscallTable::Dealloc as usize]) };
     f(ptr, layout)
 }
 
-pub type PrintAbi = extern "C" fn(ptr: *const u8, len: usize);
+pub type Print = extern "C" fn(ptr: *const u8, len: usize);
 
 #[unsafe(no_mangle)]
 pub extern "C" fn print(ptr: *const u8, len: usize) {
-    let f: PrintAbi =
+    let f: Print =
-        unsafe { core::mem::transmute(CALL_ABI_TABLE[CallTable::PrintString as usize]) };
+        unsafe { core::mem::transmute(SYS_CALL_TABLE[SyscallTable::PrintString as usize]) };
     f(ptr, len);
 }
 
-pub type SleepMsAbi = extern "C" fn(ms: u64);
+pub type SleepMs = extern "C" fn(ms: u64);
 
 #[unsafe(no_mangle)]
 pub extern "C" fn sleep(ms: u64) {
-    let f: SleepMsAbi =
+    let f: SleepMs =
-        unsafe { core::mem::transmute(CALL_ABI_TABLE[CallTable::SleepMs as usize]) };
+        unsafe { core::mem::transmute(SYS_CALL_TABLE[SyscallTable::SleepMs as usize]) };
     f(ms);
 }
 
-pub type GetMsAbi = extern "C" fn() -> u64;
+pub type GetMs = extern "C" fn() -> u64;
 
 #[unsafe(no_mangle)]
 pub extern "C" fn get_ms() -> u64 {
-    let f: GetMsAbi = unsafe { core::mem::transmute(CALL_ABI_TABLE[CallTable::GetMs as usize]) };
+    let f: GetMs = unsafe { core::mem::transmute(SYS_CALL_TABLE[SyscallTable::GetMs as usize]) };
     f()
 }
 
 #[repr(C)]
-#[derive(Copy, Clone)]
+#[derive(Default, Copy, Clone)]
 pub struct CPixel {
     pub x: i32,
     pub y: i32,
@@ -121,33 +124,36 @@ impl CPixel {
     }
 }
 
-impl Into<CPixel> for Pixel<Rgb565> {
+impl From<CPixel> for Pixel<Rgb565> {
-    fn into(self) -> CPixel {
+    fn from(value: CPixel) -> Self {
+        Pixel(
+            Point::new(value.x, value.y),
+            RawU16::new(value.color).into(),
+        )
+    }
+}
+
+impl From<Pixel<Rgb565>> for CPixel {
+    fn from(value: Pixel<Rgb565>) -> Self {
         CPixel {
-            x: self.0.x,
+            x: value.0.x,
-            y: self.0.y,
+            y: value.0.y,
-            color: self.1.into_storage(),
+            color: value.1.into_storage(),
         }
     }
 }
 
-impl Into<Pixel<Rgb565>> for CPixel {
+pub type DrawIter = extern "C" fn(ptr: *const CPixel, len: usize);
-    fn into(self) -> Pixel<Rgb565> {
-        Pixel(Point::new(self.x, self.y), RawU16::new(self.color).into())
-    }
-}
-
-pub type DrawIterAbi = extern "C" fn(ptr: *const CPixel, len: usize);
 
 #[unsafe(no_mangle)]
 pub extern "C" fn draw_iter(ptr: *const CPixel, len: usize) {
-    let f: DrawIterAbi =
+    let f: DrawIter =
-        unsafe { core::mem::transmute(CALL_ABI_TABLE[CallTable::DrawIter as usize]) };
+        unsafe { core::mem::transmute(SYS_CALL_TABLE[SyscallTable::DrawIter as usize]) };
     f(ptr, len);
 }
 
 pub mod keyboard {
-    use crate::{CALL_ABI_TABLE, CallTable};
+    use crate::{SYS_CALL_TABLE, SyscallTable};
 
     bitflags::bitflags! {
         #[derive(Default, Debug, PartialEq, Eq, Clone, Copy)]
@@ -169,12 +175,12 @@ pub mod keyboard {
         pub mods: Modifiers,
     }
 
-    impl Into<KeyEvent> for KeyEventC {
+    impl From<KeyEventC> for KeyEvent {
-        fn into(self) -> KeyEvent {
+        fn from(val: KeyEventC) -> Self {
             KeyEvent {
-                key: self.key.into(),
+                key: val.key.into(),
-                state: self.state,
+                state: val.state,
-                mods: self.mods,
+                mods: val.mods,
             }
         }
     }
@@ -186,12 +192,12 @@ pub mod keyboard {
         pub mods: Modifiers,
     }
 
-    impl Into<KeyEventC> for KeyEvent {
+    impl From<KeyEvent> for KeyEventC {
-        fn into(self) -> KeyEventC {
+        fn from(val: KeyEvent) -> Self {
             KeyEventC {
-                key: self.key.into(),
+                key: val.key.into(),
-                state: self.state,
+                state: val.state,
-                mods: self.mods,
+                mods: val.mods,
             }
         }
     }
@@ -212,7 +218,7 @@ pub mod keyboard {
                 1 => KeyState::Pressed,
                 2 => KeyState::Hold,
                 3 => KeyState::Released,
-                0 | _ => KeyState::Idle,
+                _ => KeyState::Idle,
             }
         }
     }
@@ -265,9 +271,9 @@ pub mod keyboard {
         Unknown(u8),
     }
 
-    impl Into<u8> for KeyCode {
+    impl From<KeyCode> for u8 {
-        fn into(self) -> u8 {
+        fn from(val: KeyCode) -> Self {
-            match self {
+            match val {
                 KeyCode::JoyUp => 0x01,
                 KeyCode::JoyDown => 0x02,
                 KeyCode::JoyLeft => 0x03,
@@ -365,12 +371,12 @@ pub mod keyboard {
         }
     }
 
-    pub type GetKeyAbi = extern "C" fn() -> KeyEventC;
+    pub type GetKey = extern "C" fn() -> KeyEventC;
 
     #[unsafe(no_mangle)]
     pub extern "C" fn get_key() -> KeyEventC {
-        let f: GetKeyAbi =
+        let f: GetKey =
-            unsafe { core::mem::transmute(CALL_ABI_TABLE[CallTable::GetKey as usize]) };
+            unsafe { core::mem::transmute(SYS_CALL_TABLE[SyscallTable::GetKey as usize]) };
         f()
     }
 }
@@ -387,7 +393,7 @@ pub type GenRand = extern "C" fn(req: &mut RngRequest);
 #[unsafe(no_mangle)]
 pub extern "C" fn gen_rand(req: &mut RngRequest) {
     unsafe {
-        let ptr = CALL_ABI_TABLE[CallTable::GenRand as usize];
+        let ptr = SYS_CALL_TABLE[SyscallTable::GenRand as usize];
         let f: GenRand = core::mem::transmute(ptr);
         f(req)
     }
@@ -396,21 +402,23 @@ pub extern "C" fn gen_rand(req: &mut RngRequest) {
 pub type ListDir = extern "C" fn(
     str: *const u8,
     len: usize,
-    files: *mut Option<DirEntry>,
+    entries: *mut *mut c_char,
     file_len: usize,
+    max_entry_str_len: usize,
 ) -> usize;
 
 #[unsafe(no_mangle)]
 pub extern "C" fn list_dir(
     str: *const u8,
     len: usize,
-    files: *mut Option<DirEntry>,
+    entries: *mut *mut c_char,
-    file_len: usize,
+    entry_count: usize,
+    max_entry_str_len: usize,
 ) -> usize {
     unsafe {
-        let ptr = CALL_ABI_TABLE[CallTable::ListDir as usize];
+        let ptr = SYS_CALL_TABLE[SyscallTable::ListDir as usize];
         let f: ListDir = core::mem::transmute(ptr);
-        f(str, len, files, file_len)
+        f(str, len, entries, entry_count, max_entry_str_len)
     }
 }
 
@@ -431,19 +439,73 @@ pub extern "C" fn read_file(
     buf_len: usize,
 ) -> usize {
     unsafe {
-        let ptr = CALL_ABI_TABLE[CallTable::ReadFile as usize];
+        let ptr = SYS_CALL_TABLE[SyscallTable::ReadFile as usize];
         let f: ReadFile = core::mem::transmute(ptr);
         f(str, len, read_from, buf, buf_len)
     }
 }
 
+pub type WriteFile =
+    extern "C" fn(str: *const u8, len: usize, write_from: usize, buf: *const u8, buf_len: usize);
+
+#[unsafe(no_mangle)]
+pub extern "C" fn write_file(
+    str: *const u8,
+    len: usize,
+    write_from: usize,
+    buf: *const u8,
+    buf_len: usize,
+) {
+    unsafe {
+        let ptr = SYS_CALL_TABLE[SyscallTable::WriteFile as usize];
+        let f: WriteFile = core::mem::transmute(ptr);
+        f(str, len, write_from, buf, buf_len)
+    }
+}
+
 pub type FileLen = extern "C" fn(str: *const u8, len: usize) -> usize;
 
 #[unsafe(no_mangle)]
 pub extern "C" fn file_len(str: *const u8, len: usize) -> usize {
     unsafe {
-        let ptr = CALL_ABI_TABLE[CallTable::FileLen as usize];
+        let ptr = SYS_CALL_TABLE[SyscallTable::FileLen as usize];
         let f: FileLen = core::mem::transmute(ptr);
         f(str, len)
     }
 }
+
+pub type ReconfigureAudioSampleRate = extern "C" fn(sample_rate: u32);
+
+#[allow(unused)]
+pub fn reconfigure_audio_sample_rate(sample_rate: u32) {
+    unsafe {
+        let ptr = SYS_CALL_TABLE[SyscallTable::ReconfigureAudioSampleRate as usize];
+        let f: ReconfigureAudioSampleRate = core::mem::transmute(ptr);
+        f(sample_rate)
+    }
+}
+
+pub type AudioBufferReady = extern "C" fn() -> bool;
+
+#[allow(unused)]
+pub fn audio_buffer_ready() -> bool {
+    unsafe {
+        let ptr = SYS_CALL_TABLE[SyscallTable::AudioBufferReady as usize];
+        let f: AudioBufferReady = core::mem::transmute(ptr);
+        f()
+    }
+}
+
+pub const AUDIO_BUFFER_SAMPLES: usize = 1024;
+pub const AUDIO_BUFFER_LEN: usize = AUDIO_BUFFER_SAMPLES * 2;
+
+pub type SendAudioBuffer = extern "C" fn(ptr: *const u8, len: usize);
+
+#[allow(unused)]
+pub fn send_audio_buffer(buf: *const u8, len: usize) {
+    unsafe {
+        let ptr = SYS_CALL_TABLE[SyscallTable::SendAudioBuffer as usize];
+        let f: SendAudioBuffer = core::mem::transmute(ptr);
+        f(buf, len)
+    }
+}