Fix example and speedup performance

ctru-rs/examples/camera-image.rs

@@ -9,9 +9,9 @@ const WIDTH: usize = 400;
 const HEIGHT: usize = 240;
 
 // The screen size is the width and height multiplied by 2 (RGB565 store pixels in 2 bytes)
-// const BUF_SIZE: usize = WIDTH * HEIGHT * 2;
+const BUF_SIZE: usize = WIDTH * HEIGHT * 2;
 
-const WAIT_TIMEOUT: Duration = Duration::from_micros(300);
+const WAIT_TIMEOUT: Duration = Duration::from_millis(300);
 
 fn main() {
     ctru::use_panic_handler();
@@ -56,7 +56,7 @@ fn main() {
             .expect("Failed to disable trimming");
     }
 
-    let mut buf;
+    let mut buf = vec![0; BUF_SIZE];
 
     println!("\nPress R to take a new picture");
     println!("Press Start to exit to Homebrew Launcher");
@@ -74,8 +74,9 @@ fn main() {
 
             let camera = &mut cam.outer_right_cam;
 
-            buf = camera
+            camera
                 .take_picture(
+                    &mut buf,
                     WIDTH.try_into().unwrap(),
                     HEIGHT.try_into().unwrap(),
                     WAIT_TIMEOUT,
@@ -85,15 +86,12 @@ fn main() {
             cam.play_shutter_sound(CamShutterSoundType::NORMAL)
                 .expect("Failed to play shutter sound");
 
-            let img = rotate_image(&buf, WIDTH, HEIGHT);
-
-            unsafe {
-                gfx.top_screen
-                    .borrow_mut()
-                    .get_raw_framebuffer()
-                    .ptr
-                    .copy_from(img.as_ptr(), img.len());
-            }
+            rotate_image_to_screen(
+                &buf,
+                gfx.top_screen.borrow_mut().get_raw_framebuffer().ptr,
+                WIDTH,
+                HEIGHT,
+            );
 
             gfx.flush_buffers();
             gfx.swap_buffers();
@@ -104,9 +102,8 @@ fn main() {
 
 // The 3DS' screens are 2 vertical LCD panels rotated by 90 degrees.
 // As such, we'll need to write a "vertical" image to the framebuffer to have it displayed properly.
-// This functions handles the rotation of an horizontal image to a vertical one.
-fn rotate_image(img: &[u8], width: usize, height: usize) -> Vec<u8> {
-    let mut res = vec![0u8; img.len()];
+// This functions rotates an horizontal image by 90 degrees to the right.
+fn rotate_image_to_screen(src: &[u8], framebuf: *mut u8, width: usize, height: usize) {
     for j in 0..height {
         for i in 0..width {
             // Y-coordinate of where to draw in the frame buffer
@@ -121,9 +118,11 @@ fn rotate_image(img: &[u8], width: usize, height: usize) -> Vec<u8> {
             // Initial index of where to draw in the frame buffer based on y and x coordinates
             let draw_index = (draw_x * height + draw_y) * 2; // This 2 stands for the number of bytes per pixel (16 bits)
 
-            res[draw_index] = img[read_index];
-            res[draw_index + 1] = img[read_index + 1];
+            unsafe {
+                let pixel_pointer = framebuf.offset(draw_index as isize);
+                *pixel_pointer = src[read_index];
+                *pixel_pointer.offset(1) = src[read_index + 1];
+            }
         }
     }
-    res
 }

ctru-rs/src/error.rs

@@ -21,7 +21,11 @@ impl Try for ResultCode {
     }
 
     fn branch(self) -> ControlFlow<Self::Residual, Self::Output> {
-        if self.0 < 0 {
+        // Wait timeouts aren't counted as "failures" in libctru, but an unfinished task means unsafety for us.
+        // Luckily all summary cases are for system failures (except RS_SUCCESS).
+        // I don't know if there are any cases in libctru where a Result holds a "failing" summary but a "success" code, so we'll just check for both.
+        if ctru_sys::R_FAILED(self.0) || ctru_sys::R_SUMMARY(self.0) != ctru_sys::RS_SUCCESS as i32
+        {
             ControlFlow::Break(self.into())
         } else {
             ControlFlow::Continue(())

ctru-rs/src/services/cam.rs

@@ -704,12 +704,16 @@ pub trait Camera {
         }
     }
 
-    /// Requests the camera to take a picture and returns a vector containing the image bytes.
+    /// Requests the camera to take a picture and write it in a buffer.
     ///
     /// # Errors
     ///
     /// This will error if the camera is busy or if the timeout duration is reached.
     ///
+    /// # Panics
+    ///
+    /// This function will panic if `buffer.len() < (width * height * 2)`.
+    ///
     /// # Arguments
     ///
     /// * `width` - Width of the desired image
@@ -717,10 +721,11 @@ pub trait Camera {
     /// * `timeout` - Duration to wait for the image
     fn take_picture(
         &mut self,
+        buffer: &mut [u8],
         width: u16,
         height: u16,
         timeout: Duration,
-    ) -> crate::Result<Vec<u8>> {
+    ) -> crate::Result<()> {
         let transfer_unit = unsafe {
             let mut buf_size = 0;
             ResultCode(ctru_sys::CAMU_GetMaxBytes(
@@ -731,10 +736,6 @@ pub trait Camera {
             Ok::<u32, i32>(buf_size)
         }?;
 
-        let screen_size = u32::from(width) * u32::from(height) * 2;
-
-        let mut buf = vec![0u8; usize::try_from(screen_size).unwrap()];
-
         unsafe {
             ResultCode(ctru_sys::CAMU_SetTransferBytes(
                 self.port_as_raw(),
@@ -744,6 +745,11 @@ pub trait Camera {
             ))?;
         };
 
+        let screen_size = u32::from(width) * u32::from(height) * 2;
+        if buffer.len() < screen_size as usize {
+            panic!("Provided buffer's length is shorter than the desired width and height matrix.")
+        }
+
         unsafe {
             ResultCode(ctru_sys::CAMU_Activate(self.camera_as_raw()))?;
             ResultCode(ctru_sys::CAMU_ClearBuffer(self.port_as_raw()))?;
@@ -754,7 +760,7 @@ pub trait Camera {
             let mut completion_handle: Handle = 0;
             ResultCode(ctru_sys::CAMU_SetReceiving(
                 &mut completion_handle,
-                buf.as_mut_ptr() as *mut ::libc::c_void,
+                buffer.as_mut_ptr() as *mut ::libc::c_void,
                 self.port_as_raw(),
                 screen_size,
                 transfer_unit.try_into().unwrap(),
@@ -763,16 +769,21 @@ pub trait Camera {
         }?;
 
         unsafe {
-            ResultCode(ctru_sys::svcWaitSynchronization(
+            // Panicking without closing an SVC handle causes an ARM exception, we have to handle it carefully (TODO: SVC module)
+            let wait_result = ResultCode(ctru_sys::svcWaitSynchronization(
                 receive_event,
                 timeout.as_nanos().try_into().unwrap(),
-            ))?;
+            ));
+
+            // We close everything first, then we check for possible errors
+            ResultCode(ctru_sys::svcCloseHandle(receive_event));
             ResultCode(ctru_sys::CAMU_StopCapture(self.port_as_raw()))?;
-            ResultCode(ctru_sys::svcCloseHandle(receive_event))?;
             ResultCode(ctru_sys::CAMU_Activate(ctru_sys::SELECT_NONE))?;
+
+            wait_result?;
         };
 
-        Ok(buf)
+        Ok(())
     }
 }