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#include "idt.h"
#include <stdint.h>
struct __attribute__((packed)) Pointer {
uint16_t limit;
uint32_t base;
};
enum Type {
Null = 0,
Intr = 0x8e, // 1000 1110 32-bit interrupt
};
struct __attribute__((packed)) Gate_t {
uint16_t offset_15_0; // segment offset low
uint16_t selector; // code segment selector
uint8_t __unused; // unused in protected mode
uint8_t type; // interrupt type
uint16_t offset_31_16; // segment offset high
};
_Static_assert(sizeof(struct Gate_t) == 8, "interrupt gate size");
void
Gate(struct Gate_t *entry, void (*f)(struct interrupt_frame *), uint16_t selector)
{
uint32_t f_addr = (uint32_t)f;
entry->offset_15_0 = f_addr & 0xffff;
entry->offset_31_16 = (f_addr >> 16) & 0xffff;
entry->selector = selector;
entry->__unused = 0;
entry->type = Intr;
}
static struct Gate_t interrupt_table[256] __attribute((aligned(4096)));
void
idt_install()
{
// exceptions 0x00~0x13
for (int i = 0; i <= 0x13; ++i) Gate(&interrupt_table[i], &abort_handler, 0x10);
// irq 0x20~0x2f
for (int i = 0x22; i <= 0x2f; ++i) Gate(&interrupt_table[i], &abort_handler, 0x10);
Gate(&interrupt_table[0x20], &irq0x00, 0x10);
Gate(&interrupt_table[0x21], &irq0x01, 0x10);
Gate(&interrupt_table[0x2c], &irq0x0c, 0x10);
// syscall 0x80
Gate(&interrupt_table[0x80], &syscall_handler, 0x10);
const struct Pointer ptr = {.limit = sizeof(interrupt_table) - 1, .base = (unsigned)&interrupt_table};
asm volatile("lidt (%0)" : : "a"(&ptr));
}
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