From 975a9ec96e282e437ccc1bdf1e660dcbf4542791 Mon Sep 17 00:00:00 2001
From: EmulatedSeasons <89668582+EmulatedSeasons@users.noreply.github.com>
Date: Fri, 10 May 2024 01:44:59 -0400
Subject: Added GDT and basic IDT as well as a bitmap drawing function

---
 kernel/arch/x86_64/limine.cpp | 48 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 39 insertions(+), 9 deletions(-)

(limited to 'kernel/arch/x86_64/limine.cpp')

diff --git a/kernel/arch/x86_64/limine.cpp b/kernel/arch/x86_64/limine.cpp
index 9ea2bbc..6d7984e 100644
--- a/kernel/arch/x86_64/limine.cpp
+++ b/kernel/arch/x86_64/limine.cpp
@@ -3,6 +3,8 @@
 #include <stdio.h>
 #include <arch/x86_64/serial.h>
 #include "limine.h"
+#include "gdt.h"
+#include "idt.h"
 #include <framebuffer.h>
 
 namespace {
@@ -42,10 +44,26 @@ extern void (*__init_array_end[])();
 extern "C" void kernel_main();
 
 extern "C" void _start() {
+    asm("cli");
     if (!LIMINE_BASE_REVISION_SUPPORTED) {
         hcf();
     }
 
+    // setup gdt
+    SegDesc segs[5];
+    GDTR gdtr{sizeof(struct SegDesc) * 5 - 1, (uint64_t)&segs};
+
+    gdt_entry(&segs[0], 0, 0, 0, 0); // null desc
+    gdt_entry(&segs[1], 0, 0xFFFFF, 0x9A, 0xA); // kcode
+    gdt_entry(&segs[2], 0, 0xFFFFF, 0x92, 0xA); // kdata
+    gdt_entry(&segs[3], 0, 0xFFFFF, 0xFA, 0xA); // ucode
+    gdt_entry(&segs[4], 0, 0xFFFFF, 0xF2, 0xA); // udata
+    
+    load_gdt(&gdtr);
+    reload_segments();
+
+    setup_idt();
+
     // initialize global constructors
     for (size_t i = 0; &__init_array[i] != __init_array_end; i++) {
         __init_array[i]();
@@ -61,15 +79,27 @@ extern "C" void _start() {
     limine_framebuffer *framebuffer = framebuffer_request.response->framebuffers[0];
 
     // Note: we assume the framebuffer model is RGB with 32-bit pixels.
-    for (size_t i = 0; i < 100; i++) {
-        volatile uint32_t *fb_ptr = static_cast<volatile uint32_t *>(framebuffer->address);
-        fb_ptr[i * (framebuffer->pitch / 4) + i] = 0xffffff;
-    }
-
-    Framebuffer fb((uint32_t*)framebuffer->address, framebuffer->width, framebuffer->height);
-    fb.drawpixel(727, 727, 0x9528fd);
-
-    printf("video modes: %lx", framebuffer->mode_count);
+    // for (size_t i = 0; i < 100; i++) {
+    //     volatile uint32_t *fb_ptr = static_cast<volatile uint32_t *>(framebuffer->address);
+    //     fb_ptr[i * (framebuffer->pitch / 4) + i] = 0xffffff;
+    // }
+
+    asm("xchgw %bx, %bx");
+    fb_init((uint32_t*)framebuffer->address, framebuffer->width, framebuffer->height);
+    draw_pixel(727, 727, 0x9528fd);
+    draw_pixel(0, 0, 0xff0000);
+    draw_pixel(1919, 1079, 0x00ff00);
+    // for (size_t i = 0; i < framebuffer->mode_count; i++) {
+    //     printf("Mode %d\n", i);
+    //     printf("Pitch %d\nWidth %d\nHeight %d\nbpp %d\nmem_model %d\n",
+    //     framebuffer->modes[i]->pitch, framebuffer->modes[i]->width, framebuffer->modes[i]->height,
+    //     framebuffer->modes[i]->bpp, framebuffer->modes[i]->memory_model);
+    // }
+
+    printf("Actual framebuffer:\n");
+    printf("Pitch %d\nWidth %d\nHeight %d\nbpp %d\nmem_model %d\n",
+        framebuffer->pitch, framebuffer->width, framebuffer->height,
+        framebuffer->bpp, framebuffer->memory_model);
 
     kernel_main();
 
-- 
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