A poorly written OS for the x86 arch. (WIP)
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eOS/kernel/idt.c

53 lines
1.2 KiB

#include "idt.h"
typedef struct {
uint16 offset_1; // offset 0 to 15 bits
uint16 selector; // code segment sel
uint8 reserved; // should be zero
uint8 type_attr; // type & attr stuff
uint16 offset_2; // offset 16 to 31
} __attribute__((packed)) idt_entry;
typedef struct {
uint16 limit;
uint base;
} __attribute__((packed)) idtr;
__attribute__((aligned(16)))
static idt_entry IDT[IDT_MAX_DESCS];
static idtr IDTR;
void exception_handler() {
uint* irq_ptr = 0xe222;
uint8 irq = *irq_ptr;
pic_send_eoi(irq);
char* buf;
print("[exc] ", EXC_COLOR);
buf = itoa(irq, buf, 10);
print(buf, 0x0c);
new_line();
}
void idt_set_desc(uint8 idx, void* isr, uint8 flags) {
idt_entry* desc = &IDT[idx]; // get descriptor
desc->offset_1 = (uint) isr & 0xffff;
desc->selector = 0x08; // kernel code selector for the GDT
desc->reserved = 0;
desc->type_attr = flags;
desc->offset_2 = (uint) isr >> 16;
}
extern void* isr_stub_table[];
void idt_init() {
IDTR.base = (uintptr) &IDT[0]; // base offset
IDTR.limit = (uint16) sizeof(idt_entry) * IDT_MAX_DESCS - 1;
for (uint8 idx = 0; idx < 32; idx++)
idt_set_desc(idx, isr_stub_table[idx], 0x8e);
__asm__ __volatile__("lidt %0" : : "m"(IDTR));
__asm__ __volatile__("sti");
}