got basic framebuffer

include/framebuffer.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include "stdint.h"
+
+struct FrameBuffer
+{
+    struct 
+    {
+        uint32_t width;
+        uint32_t height;
+    } physicalDisplay;
+
+    struct 
+    {
+        uint32_t width;
+        uint32_t height;
+        uint32_t xOffset;
+        uint32_t yOffset;
+    } virtualDisplay;
+
+    uint32_t pitch;
+    uint32_t bitsPerPixel;
+    uint8_t* pixels;
+    uint32_t size;
+};
+
+struct FrameBuffer* framebuffer_init(unsigned int width, unsigned int height);
+void framebuffer_release(void);
+
+void draw_test_image(void);

include/mb.h

@@ -2,5 +2,9 @@
 
 #include "stdint.h"
 
+struct FrameBuffer;
+
 uint32_t get_vc_firmware_rev(void);
-uint8_t* get_board_mac_address(uint8_t* buffer);
+uint8_t* get_board_mac_address(uint8_t* buffer);
+
+void create_framebuffer(struct FrameBuffer* buffer, unsigned int width, unsigned int height);

src/framebuffer.c

@@ -0,0 +1,35 @@
+#include "framebuffer.h"
+
+#include "mb.h"
+#include "memory.h"
+#include "io.h"
+
+static struct FrameBuffer framebuffer;
+
+struct FrameBuffer* framebuffer_init(unsigned int width, unsigned int height)
+{
+    create_framebuffer(&framebuffer, width, height);
+
+    return &framebuffer;
+}
+
+void framebuffer_release(void)
+{
+    
+}
+
+void draw_test_image(void)
+{
+    for(uint32_t y = 0; y < framebuffer.virtualDisplay.height; y++)
+    {
+        for(uint32_t x = 0; x < framebuffer.virtualDisplay.width; x++)
+        {
+            size_t offset = y * framebuffer.pitch + (x * (framebuffer.bitsPerPixel / 8));
+
+            framebuffer.pixels[offset + 0] = 255;
+            framebuffer.pixels[offset + 1] = y * 255 / framebuffer.virtualDisplay.height;
+            framebuffer.pixels[offset + 2] = x * 255 / framebuffer.virtualDisplay.width;
+            framebuffer.pixels[offset + 3] = 100;
+        }
+    }
+}

src/kernel.c

@@ -3,6 +3,7 @@
 #include "string.h"
 #include "memory.h"
 #include "mb.h"
+#include "framebuffer.h"
 
 void print_clippy();
 char* get_user_input(char* buffer);
@@ -36,6 +37,18 @@ void main()
     uart_puts("Started execution at 0x");
     uart_puts(ultoa((long)&_start, buffer, 16));
 
+    struct FrameBuffer* framebuffer = framebuffer_init(1920, 1080);
+    uart_puts("\n\nFramebuffer info\n---------------\n");
+    uart_puts("Physical display  : ");  uart_puts(utoa(framebuffer->physicalDisplay.width, buffer, 10));    uart_puts("x"); uart_puts(utoa(framebuffer->physicalDisplay.height, buffer, 10));  uart_puts(" pixels\n");
+    uart_puts("Virtual display   : ");  uart_puts(utoa(framebuffer->virtualDisplay.width, buffer, 10));    uart_puts("x"); uart_puts(utoa(framebuffer->virtualDisplay.height, buffer, 10));  uart_puts(" pixels\n");
+    uart_puts("Virt. disp. offset: ("); uart_puts(utoa(framebuffer->virtualDisplay.xOffset, buffer, 10));    uart_puts(","); uart_puts(utoa(framebuffer->virtualDisplay.yOffset, buffer, 10));  uart_puts(")\n");
+    uart_puts("Pitch:            : ");  uart_puts(utoa(framebuffer->pitch, buffer, 10));    uart_puts(" bytes\n");
+    uart_puts("Bit depth         : ");  uart_puts(utoa(framebuffer->bitsPerPixel, buffer, 10)); uart_puts(" bits per pixel\n");
+    uart_puts("Memory location   : 0x");  uart_puts(ultoa((unsigned long)framebuffer->pixels, buffer, 16));   uart_puts("\n");
+    uart_puts("Size              : ");  uart_puts(utoa(framebuffer->size, buffer, 10)); uart_puts(" bytes\n\n");
+
+    draw_test_image();
+
     for(;;)
     {
         uart_puts("\n\nPlease enter first operand\n");

src/mb.c

@@ -3,6 +3,7 @@
 #include "memory.h"
 #include "io.h"
 #include "convert.h"
+#include "framebuffer.h"
 
 volatile uint32_t __attribute__((aligned(16))) mailbox[36];
 
@@ -118,4 +119,75 @@ uint8_t* get_board_mac_address(uint8_t* buffer)
         buffer[i] = mac_address[i];
 
     return buffer;
+}
+
+void create_framebuffer(struct FrameBuffer* buffer, unsigned int width, unsigned int height)
+{
+    mailbox[0] = 35 * sizeof(uint32_t);  // buffer size
+    mailbox[1] = 0;
+
+    // Set physical display dimensions
+    mailbox[2] = 0x00048003;
+    mailbox[3] = 2 * sizeof(uint32_t);
+    mailbox[4] = 0;
+    mailbox[5] = width;
+    mailbox[6] = height;
+
+    // Set virtual display dimensions
+    mailbox[7] = 0x00048004;
+    mailbox[8] = 2 * sizeof(uint32_t);
+    mailbox[9] = 0;
+    mailbox[10] = width;
+    mailbox[11] = height;
+
+    // Set bit depth
+    mailbox[12] = 0x00048005;
+    mailbox[13] = 1 * sizeof(uint32_t);
+    mailbox[14] = 0;
+    mailbox[15] = 32;
+
+    // Set pixel order
+    mailbox[16] = 0x00048006;
+    mailbox[17] = 1 * sizeof(uint32_t);
+    mailbox[18] = 0;
+    mailbox[19] = 1;
+
+    // Set virtual offset
+    mailbox[20] = 0x00048009;
+    mailbox[21] = 2 * sizeof(uint32_t);
+    mailbox[22] = 0;
+    mailbox[23] = 0;
+    mailbox[24] = 0;
+
+    // Allocate buffer
+    mailbox[25] = 0x00040001;
+    mailbox[26] = 8;
+    mailbox[27] = 0;
+    mailbox[28] = 4096; 
+    mailbox[29] = 0;
+
+    // Get pitch
+    mailbox[30] = 0x00040008;
+    mailbox[31] = 1 * sizeof(uint32_t);
+    mailbox[32] = 0;
+    mailbox[33] = 0;
+
+    mailbox[34] = 0;
+
+    mailbox_call(8);
+
+    mailbox[28] &= 0x3FFFFFFF;
+
+    buffer->physicalDisplay.width = mailbox[5];
+    buffer->physicalDisplay.height = mailbox[6];
+
+    buffer->virtualDisplay.width = mailbox[10];
+    buffer->virtualDisplay.height = mailbox[11];
+    buffer->virtualDisplay.xOffset = mailbox[23];
+    buffer->virtualDisplay.yOffset = mailbox[24];
+
+    buffer->bitsPerPixel = mailbox[15];
+    buffer->pitch = mailbox[33];
+    buffer->pixels = (uint8_t*)((uint64_t)mailbox[28]);
+    buffer->size = mailbox[29];
 }