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#include <stdint.h>
struct mb2_tag_header {
uint32_t type;
uint32_t size;
} __attribute__((packed, aligned(8)));
typedef struct mb2_tag_header mb2_tag_header;
struct mb2_tag_fb {
uint32_t type;
uint32_t size;
uint64_t framebuffer_addr;
uint32_t framebuffer_pitch;
uint32_t framebuffer_width;
uint32_t framebuffer_height;
uint8_t framebuffer_bpp;
uint8_t framebuffer_type;
} __attribute__((packed, aligned(8)));
typedef struct mb2_tag_fb mb2_tag_fb;
// multiboot2 magic check
#define MB2_MAGIC 0x36D76289
// multiboot2 tag
#define MB2_TAG_END 0
#define MB2_TAG_CMDLINE 1
#define MB2_TAG_BOOTLOADER 2
#define MB2_TAG_MODULES 3
#define MB2_TAG_MEM 4
#define MB2_TAG_BIOS 5
#define MB2_TAG_MMAP 6
#define MB2_TAG_VBE 7
#define MB2_TAG_FB 8
void breakpoint(void)
{
__asm__ volatile ("xchgw %bx, %bx;");
}
void put_in_r8(uint64_t value)
{
__asm__ volatile ("movq %0, %%r8;" : : "r"(value) : "%r8");
}
void put_in_r9(uint64_t value)
{
__asm__ volatile ("movq %0, %%r9;" : : "r"(value) : "%r9");
}
void put_in_r10(uint64_t value)
{
__asm__ volatile ("movq %0, %%r10;" : : "r"(value) : "%r10");
}
int kernel_main(mb2_tag_header* multiboot_bootinfo, uint32_t multiboot_magic)
{
if (multiboot_magic != MB2_MAGIC) {
// not loaded by multiboot2 bootloader
__asm__ volatile ("hlt;");
}
// we will store framebuffer information here
static mb2_tag_fb* tag_fb;
// skip first 8 bytes (total_size + reserved)
mb2_tag_header* tag_header = multiboot_bootinfo + 1;
while (tag_header->type != MB2_TAG_END) {
// process tag_type
switch(tag_header->type) {
case MB2_TAG_FB:
tag_fb = (mb2_tag_fb*)tag_header;
break;
default:
break;
}
// next mb2_tag
tag_header += tag_header->size / 8 + ((tag_header->size % 8) > 0);
}
uint64_t* framebuffer_addr = (uint64_t*)tag_fb->framebuffer_addr;
uint32_t framebuffer_width = tag_fb->framebuffer_width;
uint32_t framebuffer_height = tag_fb->framebuffer_height;
//uint8_t framebuffer_bpp = tag_fb->framebuffer_bpp;
uint32_t framebuffer_pitch = tag_fb->framebuffer_pitch;
put_in_r8(framebuffer_width);
put_in_r9(framebuffer_height);
put_in_r10(framebuffer_pitch);
breakpoint();
uint32_t value = 0x0000;
for (uint32_t x = 0 ; x < framebuffer_width; x++) {
for (uint32_t y = 0; y < framebuffer_height; y++) {
framebuffer_addr[y*framebuffer_width + x] = value;
value += 0x250;
}
}
return 0;
}
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