First Try

src/framebuffer.rs

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+use crate::{
+    mailbox::{read_mailbox, write_mailbox},
+    peripherals::uart::{print, print_u32},
+};
+
+const ALLOCATE_BUFFER: u32 = 0x00040001;
+const GET_PHYSICAL_DISPLAY_WH: u32 = 0x00040003;
+const SET_PHYSICAL_DISPLAY_WH: u32 = 0x00048003;
+const SET_VIRTUAL_DISPLAY_WH: u32 = 0x00048004;
+const SET_PIXEL_DEPTH: u32 = 0x00048005;
+const SET_PIXEL_ORDER: u32 = 0x00048006;
+const SET_FB_OFFSET: u32 = 0x00048009;
+
+pub fn init_fb() {
+    let mut mailbox = [0; 32];
+    mailbox[0] = 32 * 4;
+    mailbox[1] = 0;
+
+    mailbox[2] = SET_PHYSICAL_DISPLAY_WH;
+    mailbox[3] = 8;
+    mailbox[4] = 8;
+    mailbox[5] = 1920;
+    mailbox[6] = 1200;
+
+    mailbox[7] = SET_VIRTUAL_DISPLAY_WH;
+    mailbox[8] = 8;
+    mailbox[9] = 8;
+    mailbox[10] = 1920;
+    mailbox[11] = 1200;
+
+    mailbox[12] = SET_PIXEL_DEPTH;
+    mailbox[13] = 4;
+    mailbox[14] = 4;
+    mailbox[15] = 32; // 32 bit per pixel
+
+    mailbox[16] = SET_PIXEL_ORDER;
+    mailbox[17] = 4;
+    mailbox[18] = 4;
+    mailbox[19] = 0x1; // RGB
+
+    mailbox[20] = SET_FB_OFFSET;
+    mailbox[21] = 8;
+    mailbox[22] = 8;
+    mailbox[24] = 0; // X in pixels
+    mailbox[25] = 0; // Y in pixels
+
+    mailbox[26] = ALLOCATE_BUFFER;
+    mailbox[27] = 8;
+    mailbox[28] = 4;
+    mailbox[29] = 4096; // Alignment
+    mailbox[30] = 0;
+
+    mailbox[31] = 0; // End tag
+
+    // TODO: validate responses
+
+    let addr = core::ptr::addr_of!(mailbox[0]) as u32;
+
+    write_mailbox(8, addr);
+
+    let _ = read_mailbox(8);
+    if mailbox[1] == 0 {
+        print("Failed\r\n");
+    }
+
+    print_u32(mailbox[29]);
+
+    mailbox[29] = (mailbox[29] & 0x00FF_FFFF) | 0x3F00_0000;
+
+    let mut fb: *mut u32 = mailbox[29] as *mut u32;
+
+    fb = unsafe { fb.add(1920 * 500 + 500) };
+
+    for x in 0..500 {
+        for y in 0..10 {
+            unsafe {
+                *fb = 0xFFFFBB00;
+                fb = fb.add(1);
+            };
+        }
+    }
+}
+
+pub fn print_display_resolution() {
+    let mut mailbox = [0; 8];
+    mailbox[0] = 8 * 4;
+    mailbox[1] = 0;
+    mailbox[2] = GET_PHYSICAL_DISPLAY_WH;
+    mailbox[3] = 8;
+    mailbox[4] = 0;
+    mailbox[5] = 0;
+    mailbox[6] = 0;
+    mailbox[7] = 0;
+
+    let addr = core::ptr::addr_of!(mailbox[0]) as u32;
+
+    write_mailbox(8, addr);
+
+    let _ = read_mailbox(8);
+    if mailbox[1] == 0 {
+        print("Failed\r\n");
+    }
+
+    print("Width x Height: ");
+    print_u32(mailbox[5]);
+    print(" x ");
+    print_u32(mailbox[6]);
+    print("\r\n");
+}