Added string.h

2026-11-03 18:22:22 +00:00 · 2025-03-20 12:01:24 +01:00
parent 05561cd857
commit 5076d1c56b
6 changed files with 364 additions and 10 deletions
@@ -0,0 +1,102 @@
+#include <kernel.h>
+#include <string.h>
+#include <gdt.h>
+
+static struct gdt_entries gdt;
+static struct gdt_pointer gdtp;
+static struct tss_pointer tss;
+struct tss_pointer* tssp = &tss;
+
+void gdt_loadTss(struct tss_pointer* ptr) {
+	size_t addr = (size_t)ptr;
+
+	gdt.tss.baseLow = (uint16_t)addr;
+	gdt.tss.baseMid = (uint8_t)(addr >> 16);
+	gdt.tss.flags1 = 0x89;
+	gdt.tss.flags2 = 0;
+	gdt.tss.baseHigh = (uint8_t)(addr >> 24);
+	
+	__asm__ volatile ("ltr %0" : : "rm"(SEGMENT_SEL(0, 0, 7)));
+}
+
+void gdt_reload(void) {
+	__asm__ volatile (
+		"cli\n"
+        	"lgdt (%0)\n"
+		"ljmp $0x08, $1f\n"
+        	"1:\n"
+        	"movw $0x10, %%ax\n"
+        	"movw %%ax, %%ds\n"
+        	"movw %%ax, %%es\n"
+        	"movw %%ax, %%fs\n"
+        	"movw %%ax, %%gs\n"
+        	"movw %%ax, %%ss\n"
+        	:
+		: "m" (gdtp)
+        	: "memory", "rax"
+	);
+}
+
+int gdt_init(void) {
+	// Null descriptor (0)
+	gdt.descriptors[0].limit = 0;
+	gdt.descriptors[0].baseLow = 0;
+	gdt.descriptors[0].baseMid = 0;
+	gdt.descriptors[0].access = 0;
+	gdt.descriptors[0].granulatiry = 0;
+	gdt.descriptors[0].baseHigh = 0;
+
+	// Kernel code (8)
+	gdt.descriptors[1].limit = 0xffff;
+	gdt.descriptors[1].baseLow = 0;
+	gdt.descriptors[1].baseMid = 0;
+	gdt.descriptors[1].access = 0x9a;
+	gdt.descriptors[1].granulatiry = 0xcf;
+	gdt.descriptors[1].baseHigh = 0;
+
+	// Kernel data (16)
+	gdt.descriptors[2].limit = 0xffff;
+	gdt.descriptors[2].baseLow = 0;
+	gdt.descriptors[2].baseMid = 0;
+	gdt.descriptors[2].access = 0x90;
+	gdt.descriptors[2].granulatiry = 0xcf;
+	gdt.descriptors[2].baseHigh = 0;
+
+	// SYSENTER/SYSEXIT
+	gdt.descriptors[3] = (struct gdt_entry){ 0 }; // (24)
+	gdt.descriptors[4] = (struct gdt_entry){ 0 }; // (32)
+
+	// User code (40)
+	gdt.descriptors[5].limit = 0;
+	gdt.descriptors[5].baseLow = 0;
+	gdt.descriptors[5].baseMid = 0;
+	gdt.descriptors[5].access = 0xfa;
+	gdt.descriptors[5].granulatiry = 0x20;
+	gdt.descriptors[5].baseHigh = 0;
+
+	// User data (48)
+	gdt.descriptors[6].limit = 0;
+	gdt.descriptors[6].baseLow = 0;
+	gdt.descriptors[6].baseMid = 0;
+	gdt.descriptors[6].access = 0xf2;
+	gdt.descriptors[6].granulatiry = 0;
+	gdt.descriptors[6].baseHigh = 0;
+
+	// TSS (56)
+	gdt.tss.length = 104;
+	gdt.tss.baseLow = 0;
+	gdt.tss.baseMid = 0;
+	gdt.tss.flags1 = 0x89;
+	gdt.tss.flags2 = 0;
+	gdt.tss.baseHigh = 0;
+
+	gdtp.limit = sizeof(struct gdt_entries) - 1;
+	gdtp.base = (uint32_t)&gdt;
+
+	gdt_reload();
+
+	memset(tssp, 0, sizeof(struct tss_pointer));
+	gdt_loadTss(tssp);
+	return 0;
+}
+