WIP

kernel/src/elf.rs

@@ -16,7 +16,7 @@ use goblin::{
     elf32::{reloc::Rel, section_header::SectionHeader, sym::Sym},
 };
 use strum::IntoEnumIterator;
-use userlib_sys::{EntryFn, SyscallTable};
+use userlib_sys::{EntryFn, SYS_CALL_TABLE_COUNT, SyscallTable};
 
 const ELF32_HDR_SIZE: usize = 52;
 
@@ -28,6 +28,7 @@ pub enum LoadError {
     ElfIsNotPie,
     UnknownRelocationType,
     SyscallTableNotFound,
+    SyscallTableSizeMismatch,
 }
 
 pub async unsafe fn load_binary(name: &ShortFileName) -> Result<(EntryFn, Bump), LoadError> {
@@ -212,6 +213,15 @@ fn patch_syscalls(
 
                 let symbol_name = core::str::from_utf8(&name).expect("symbol was not utf8");
                 if symbol_name == stringify!(SYS_CALL_TABLE) {
+                    // The binary was linked against a different SyscallTable
+                    // than this kernel (e.g. built before a syscall was
+                    // added) -- writing the full table would overrun its
+                    // `.syscall_table` array and corrupt whatever follows it.
+                    let expected_size = SYS_CALL_TABLE_COUNT * size_of::<usize>();
+                    if sym.st_size as usize != expected_size {
+                        return Err(LoadError::SyscallTableSizeMismatch);
+                    }
+
                     let table_base =
                         unsafe { base.add((sym.st_value as usize) - min_vaddr as usize) }
                             as *mut usize;
@@ -235,6 +245,8 @@ fn patch_syscalls(
                             }
                             SyscallTable::AudioBufferReady => syscalls::audio_buffer_ready as usize,
                             SyscallTable::SendAudioBuffer => syscalls::send_audio_buffer as usize,
+                            SyscallTable::FillRect => syscalls::fill_rect as usize,
+                            SyscallTable::Blit => syscalls::blit as usize,
                         };
                         unsafe {
                             table_base.add(idx).write(ptr);

kernel/src/framebuffer.rs

@@ -329,7 +329,10 @@ impl<'a> DrawTarget for AtomicFrameBuffer<'a> {
 
                 if (x as usize) < SCREEN_WIDTH && (y as usize) < SCREEN_HEIGHT {
                     let idx = (y as usize) * SCREEN_WIDTH + (x as usize);
-                    let raw_color = RawU16::from(color).into_inner();
+                    // Stored pre-swapped so a full/partial draw can hand the
+                    // buffer straight to the display as raw bytes, see
+                    // `ST7365P::write_words_buffered`.
+                    let raw_color = RawU16::from(color).into_inner().swap_bytes();
                     if self.fb[idx] != raw_color {
                         self.fb[idx] = raw_color;
                         changed = true;
@@ -377,7 +380,7 @@ impl<'a> DrawTarget for AtomicFrameBuffer<'a> {
                     if drawable_area.contains(p) {
                         if let Some(color) = colors.next() {
                             let idx = (p.y as usize * SCREEN_WIDTH) + (p.x as usize);
-                            let raw_color = RawU16::from(color).into_inner();
+                            let raw_color = RawU16::from(color).into_inner().swap_bytes();
                             if self.fb[idx] != raw_color {
                                 self.fb[idx] = raw_color;
                                 changed = true;
@@ -414,7 +417,7 @@ impl<'a> DrawTarget for AtomicFrameBuffer<'a> {
             self.size().width as u16 - 1,
             self.size().height as u16 - 1,
             core::iter::repeat_n(
-                RawU16::from(color).into_inner(),
+                RawU16::from(color).into_inner().swap_bytes(),
                 (self.size().width * self.size().height) as usize,
             ),
         )?;
@@ -517,7 +520,9 @@ pub mod fps {
                 }
 
                 let index = (point.y as usize) * FPS_CANVAS_WIDTH + point.x as usize;
-                self.canvas[index] = color.into_storage();
+                // Pre-swapped to match the main framebuffer's storage, since
+                // this canvas is copied directly into it (see draw_fps_into_fb).
+                self.canvas[index] = color.into_storage().swap_bytes();
             }
             Ok(())
         }

kernel/src/syscalls.rs

@@ -2,13 +2,19 @@ use alloc::{string::ToString, vec::Vec};
 use core::{ffi::c_char, ptr, slice, sync::atomic::Ordering};
 use embassy_rp::clocks::{RoscRng, clk_sys_freq};
 use embassy_time::Instant;
-use embedded_graphics::{Pixel, draw_target::DrawTarget, pixelcolor::Rgb565};
+use embedded_graphics::{
+    Pixel,
+    draw_target::DrawTarget,
+    geometry::{Point, Size},
+    pixelcolor::{Rgb565, raw::RawU16},
+    primitives::Rectangle,
+};
 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::*,
+    AUDIO_BUFFER_SAMPLES, Alloc, AudioBufferReady, Blit, CLayout, CPixel, Dealloc, DrawIter,
+    FileLen, FillRect, GenRand, GetMs, ListDir, Print, ReadFile, ReconfigureAudioSampleRate,
+    RngRequest, SendAudioBuffer, SleepMs, WriteFile, keyboard::*,
 };
 
 #[cfg(feature = "psram")]
@@ -102,6 +108,44 @@ pub extern "C" fn draw_iter(cpixels: *const CPixel, len: usize) {
     FB_PAUSED.store(false, Ordering::Release);
 }
 
+const _: FillRect = fill_rect;
+pub extern "C" fn fill_rect(x: u16, y: u16, w: u16, h: u16, color: u16) {
+    let area = Rectangle::new(
+        Point::new(x as i32, y as i32),
+        Size::new(w as u32, h as u32),
+    );
+    let color: Rgb565 = RawU16::new(color).into();
+
+    FB_PAUSED.store(true, Ordering::Release);
+    unsafe {
+        FRAMEBUFFER
+            .as_mut()
+            .unwrap()
+            .fill_solid(&area, color)
+            .unwrap()
+    }
+    FB_PAUSED.store(false, Ordering::Release);
+}
+
+const _: Blit = blit;
+pub extern "C" fn blit(x: u16, y: u16, w: u16, h: u16, colors: *const u16, len: usize) {
+    let area = Rectangle::new(
+        Point::new(x as i32, y as i32),
+        Size::new(w as u32, h as u32),
+    );
+    let raw: &[u16] = unsafe { slice::from_raw_parts(colors, len) };
+
+    FB_PAUSED.store(true, Ordering::Release);
+    unsafe {
+        FRAMEBUFFER
+            .as_mut()
+            .unwrap()
+            .fill_contiguous(&area, raw.iter().map(|&c| RawU16::new(c).into()))
+            .unwrap()
+    }
+    FB_PAUSED.store(false, Ordering::Release);
+}
+
 pub static mut KEY_CACHE: Queue<KeyEvent, 32> = Queue::new();
 
 const _: GetKey = get_key;

userlib/src/lib.rs

@@ -50,7 +50,10 @@ pub mod display {
     use embedded_graphics::{
         Pixel,
         geometry::{Dimensions, Point},
-        pixelcolor::Rgb565,
+        pixelcolor::{
+            Rgb565,
+            raw::{RawData, RawU16},
+        },
         prelude::{DrawTarget, Size},
         primitives::Rectangle,
     };
@@ -121,6 +124,111 @@ pub mod display {
 
             Ok(())
         }
+
+        // One `fill_rect` syscall instead of decomposing the area into
+        // individual pixels through `draw_iter` (the default impl this
+        // overrides), e.g. for game backgrounds and UI panels.
+        fn fill_solid(&mut self, area: &Rectangle, color: Self::Color) -> Result<(), Self::Error> {
+            let drawable = area.intersection(&self.bounding_box());
+            if drawable.size.width == 0 || drawable.size.height == 0 {
+                return Ok(());
+            }
+
+            userlib_sys::fill_rect(
+                drawable.top_left.x as u16,
+                drawable.top_left.y as u16,
+                drawable.size.width as u16,
+                drawable.size.height as u16,
+                RawU16::from(color).into_inner(),
+            );
+
+            Ok(())
+        }
+
+        // Batches contiguous rows into `blit` calls instead of decomposing
+        // the area into individual pixels through `draw_iter` (the default
+        // impl this overrides), e.g. for images and animation frames. Every
+        // row within the screen-clipped area shares the same horizontal
+        // clip, so runs of rows are batched into a single rectangular blit.
+        fn fill_contiguous<I>(&mut self, area: &Rectangle, colors: I) -> Result<(), Self::Error>
+        where
+            I: IntoIterator<Item = Self::Color>,
+        {
+            let drawable = area.intersection(&self.bounding_box());
+            if drawable.size.width == 0 || drawable.size.height == 0 {
+                return Ok(());
+            }
+
+            let area_width = area.size.width;
+            let area_height = area.size.height;
+            let clip_w = drawable.size.width as usize;
+            let clip_x0 = drawable.top_left.x;
+            let clip_y0 = drawable.top_left.y;
+            let clip_y1 = clip_y0 + drawable.size.height as i32;
+
+            const CHUNK_LEN: usize = 4096;
+            static mut CHUNK: [u16; CHUNK_LEN] = [0; CHUNK_LEN];
+            let rows_per_chunk = (CHUNK_LEN / clip_w).max(1);
+
+            let mut colors = colors.into_iter();
+            let mut chunk_count = 0usize;
+            let mut chunk_row0 = clip_y0;
+
+            for y in 0..area_height {
+                let py = area.top_left.y + y as i32;
+                let row_in_bounds = py >= clip_y0 && py < clip_y1;
+
+                for x in 0..area_width {
+                    let px = area.top_left.x + x as i32;
+                    let in_bounds = row_in_bounds && px >= clip_x0 && px < clip_x0 + clip_w as i32;
+
+                    let Some(color) = colors.next() else {
+                        break;
+                    };
+
+                    if in_bounds {
+                        if chunk_count == 0 {
+                            chunk_row0 = py;
+                        }
+                        unsafe { CHUNK[chunk_count] = RawU16::from(color).into_inner() };
+                        chunk_count += 1;
+                    }
+                }
+
+                if row_in_bounds {
+                    let rows_buffered = chunk_count / clip_w;
+                    if rows_buffered >= rows_per_chunk {
+                        unsafe {
+                            userlib_sys::blit(
+                                clip_x0 as u16,
+                                chunk_row0 as u16,
+                                clip_w as u16,
+                                rows_buffered as u16,
+                                CHUNK.as_ptr(),
+                                chunk_count,
+                            );
+                        }
+                        chunk_count = 0;
+                    }
+                }
+            }
+
+            if chunk_count > 0 {
+                let rows_buffered = chunk_count / clip_w;
+                unsafe {
+                    userlib_sys::blit(
+                        clip_x0 as u16,
+                        chunk_row0 as u16,
+                        clip_w as u16,
+                        rows_buffered as u16,
+                        CHUNK.as_ptr(),
+                        chunk_count,
+                    );
+                }
+            }
+
+            Ok(())
+        }
     }
 }
 

userlib_sys/src/lib.rs

@@ -12,7 +12,7 @@ use strum::{EnumCount, EnumIter};
 
 pub type EntryFn = fn();
 
-pub const SYS_CALL_TABLE_COUNT: usize = 15;
+pub const SYS_CALL_TABLE_COUNT: usize = 17;
 const _: () = assert!(SYS_CALL_TABLE_COUNT == SyscallTable::COUNT);
 
 #[derive(Clone, Copy, EnumIter, EnumCount)]
@@ -33,6 +33,8 @@ pub enum SyscallTable {
     ReconfigureAudioSampleRate = 12,
     AudioBufferReady = 13,
     SendAudioBuffer = 14,
+    FillRect = 15,
+    Blit = 16,
 }
 
 #[unsafe(no_mangle)]
@@ -152,6 +154,27 @@ pub extern "C" fn draw_iter(ptr: *const CPixel, len: usize) {
     f(ptr, len);
 }
 
+/// Fills an axis-aligned rectangle with a single color in one call, instead
+/// of marshaling it as a stream of individual `CPixel`s through `draw_iter`.
+pub type FillRect = extern "C" fn(x: u16, y: u16, w: u16, h: u16, color: u16);
+
+#[unsafe(no_mangle)]
+pub extern "C" fn fill_rect(x: u16, y: u16, w: u16, h: u16, color: u16) {
+    let f: FillRect =
+        unsafe { core::mem::transmute(SYS_CALL_TABLE[SyscallTable::FillRect as usize]) };
+    f(x, y, w, h, color);
+}
+
+/// Writes a row-major block of raw RGB565 colors into a rectangle in one
+/// call, instead of marshaling it pixel-by-pixel through `draw_iter`.
+pub type Blit = extern "C" fn(x: u16, y: u16, w: u16, h: u16, colors: *const u16, len: usize);
+
+#[unsafe(no_mangle)]
+pub extern "C" fn blit(x: u16, y: u16, w: u16, h: u16, colors: *const u16, len: usize) {
+    let f: Blit = unsafe { core::mem::transmute(SYS_CALL_TABLE[SyscallTable::Blit as usize]) };
+    f(x, y, w, h, colors, len);
+}
+
 pub mod keyboard {
     use crate::{SYS_CALL_TABLE, SyscallTable};