100 lines
2.5 KiB
C
100 lines
2.5 KiB
C
#include <stdint.h>
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#include <stddef.h>
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#include <limine.h>
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// The Limine requests can be placed anywhere, but it is important that
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// the compiler does not optimise them away, so, usually, they should
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// be made volatile or equivalent.
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static volatile struct limine_framebuffer_request framebuffer_request = {
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.id = LIMINE_FRAMEBUFFER_REQUEST,
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.revision = 0
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};
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// GCC and Clang reserve the right to generate calls to the following
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// 4 functions even if they are not directly called.
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// Implement them as the C specification mandates.
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// DO NOT remove or rename these functions, or stuff will eventually break!
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// They CAN be moved to a different .c file.
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void *memcpy(void *dest, const void *src, size_t n) {
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uint8_t *pdest = (uint8_t *)dest;
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const uint8_t *psrc = (const uint8_t *)src;
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for (size_t i = 0; i < n; i++) {
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pdest[i] = psrc[i];
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}
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return dest;
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}
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void *memset(void *s, int c, size_t n) {
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uint8_t *p = (uint8_t *)s;
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for (size_t i = 0; i < n; i++) {
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p[i] = (uint8_t)c;
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}
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return s;
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}
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void *memmove(void *dest, const void *src, size_t n) {
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uint8_t *pdest = (uint8_t *)dest;
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const uint8_t *psrc = (const uint8_t *)src;
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if (src > dest) {
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for (size_t i = 0; i < n; i++) {
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pdest[i] = psrc[i];
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}
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} else if (src < dest) {
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for (size_t i = n; i > 0; i--) {
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pdest[i-1] = psrc[i-1];
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}
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}
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return dest;
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}
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int memcmp(const void *s1, const void *s2, size_t n) {
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const uint8_t *p1 = (const uint8_t *)s1;
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const uint8_t *p2 = (const uint8_t *)s2;
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for (size_t i = 0; i < n; i++) {
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if (p1[i] != p2[i]) {
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return p1[i] < p2[i] ? -1 : 1;
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}
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}
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return 0;
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}
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// Halt and catch fire function.
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static void hcf(void) {
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asm ("cli");
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for (;;) {
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asm ("hlt");
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}
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}
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// The following will be our kernel's entry point.
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// If renaming _start() to something else, make sure to change the
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// linker script accordingly.
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void _start(void) {
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// Ensure we got a framebuffer.
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if (framebuffer_request.response == NULL
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|| framebuffer_request.response->framebuffer_count < 1) {
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hcf();
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}
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// Fetch the first framebuffer.
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struct limine_framebuffer *framebuffer = framebuffer_request.response->framebuffers[0];
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// Note: we assume the framebuffer model is RGB with 32-bit pixels.
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for (size_t i = 0; i < 100; i++) {
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uint32_t *fb_ptr = framebuffer->address;
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fb_ptr[i * (framebuffer->pitch / 4) + i] = 0xffffff;
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}
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// We're done, just hang...
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hcf();
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}
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