video: Add support for BGRA framebuffers

moon/src/main.rs

@@ -1,6 +1,8 @@
 #![no_std]
 #![no_main]
 
+#![feature(core_intrinsics)]
+
 mod video;
 mod bootboot;
 mod panic;

moon/src/video.rs

@@ -1,6 +1,6 @@
 #![allow(dead_code)]
 
-use crate::bootboot::{BOOTBOOT, BOOTBOOT_FB};
+use crate::bootboot::{BOOTBOOT, BOOTBOOT_FB, FB_ARGB, FB_BGRA};
 use crate::util::get_bootboot;
 
 use BOOTBOOT_FB as FB;
@@ -27,10 +27,31 @@ pub enum Color {
     White = 0xffffffff,
 }
 
+use core::intrinsics::bswap;
+
+impl Color {
+
+    fn to_argb(self) -> u32 {
+        self as u32
+    }
+
+    fn to_bgra(self) -> u32 {
+        bswap(self as u32)
+    }
+
+    fn to_layout(self, layout: u32) -> u32 {
+        match layout {
+            FB_ARGB => self.to_argb(),
+            FB_BGRA => self.to_bgra(),
+            _ => panic!("unsupported framebuffer data layout"),
+        }
+    }
+}
+
 pub fn put_pixel(x: u32, y: u32, color: Color) -> () {
     let boot: BOOTBOOT = get_bootboot();
     let ptr: u64 = FB + (boot.fb_scanline * y) as u64 + (x * 4) as u64;
-    unsafe { *(ptr as *mut u32) = color as u32 };
+    unsafe { *(ptr as *mut u32) = color.to_layout(boot.fb_type as u32) };
 }
 
 pub fn draw_rect(x: u32, y: u32, width: u32, height: u32, color: Color) -> () {
@@ -40,7 +61,7 @@ pub fn draw_rect(x: u32, y: u32, width: u32, height: u32, color: Color) -> () {
         let addr: u64 = FB + (boot.fb_scanline * i) as u64 + (x * 4) as u64;
         for ptr in (addr..(addr + (width*4) as u64)).step_by(4)
         {
-            unsafe { *(ptr as *mut u32) = color as u32 };
+            unsafe { *(ptr as *mut u32) = color.to_layout(boot.fb_type as u32) };
         }
     }
 }