mkos32/source/idt.h

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5.6 KiB
C
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2024-04-17 10:47:47 +00:00
#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include "print.h"
#include "utils.h"
extern void isr_0();
extern void isr_1();
extern void isr_2();
extern void isr_3();
extern void isr_4();
extern void isr_5();
extern void isr_6();
extern void isr_7();
extern void isr_8();
extern void isr_9();
extern void isr_10();
extern void isr_11();
extern void isr_12();
extern void isr_13();
extern void isr_14();
extern void isr_15();
extern void isr_16();
extern void isr_17();
extern void isr_18();
extern void isr_19();
extern void isr_20();
extern void isr_21();
extern void isr_22();
extern void isr_23();
extern void isr_24();
extern void isr_25();
extern void isr_26();
extern void isr_27();
extern void isr_28();
extern void isr_29();
extern void isr_30();
extern void isr_31();
// Interrupt Gate Entry
struct idt_int_gate
{
uint32_t offset;
uint16_t segment_selector;
bool is_present;
int permission_level;
bool is_32_bit;
};
struct idt_int_gate idt_int_gate_create(
uint16_t segment_selector,
uint32_t offset)
{
struct idt_int_gate new_gate;
new_gate.segment_selector = segment_selector;
new_gate.offset = offset;
new_gate.is_present = true;
new_gate.permission_level = 0;
new_gate.is_32_bit = true;
return new_gate;
}
uint64_t idt_int_gate_encode(struct idt_int_gate gate)
{
uint64_t gate_encoded = 0;
// Insert offset
gate_encoded |= ((((uint64_t) gate.offset) & 0xFFFF0000) << 32);
gate_encoded |= ((((uint64_t) gate.offset) & 0x0000FFFF));
// Insert segment selector
gate_encoded |= ((((uint64_t) gate.segment_selector)) << 16);
// Insert P(resent) bit
gate_encoded |= ((((uint64_t) gate.is_present)) << 47);
// Inesrt DPL
gate_encoded |= ((((uint64_t) gate.permission_level)) << 45);
// Insert D (size of gate)
gate_encoded |= ((((uint64_t) gate.is_32_bit)) << 43);
// Insert some magic bits
uint8_t magic_bits = 0x30;
gate_encoded |= ((((uint64_t) magic_bits)) << 37);
return gate_encoded;
}
struct __attribute__((__packed__)) idt_table
{
// Size in bytes minus one!
uint16_t size_in_bytes_m1;
uint64_t *dest_pointer;
struct idt_int_gate gates[256];
};
void apply_idt_table(struct idt_table table)
{
int entries_count = (table.size_in_bytes_m1 + 1) / 8;
for (int i = 0; i < entries_count; i++)
{
uint64_t entry_encoded = idt_int_gate_encode(table.gates[i]);
uint64_t *dest_address = table.dest_pointer + i;
*dest_address = entry_encoded;
}
__asm__("lidt (%0)": :"r"(&table));
}
void default_int_handler()
{
__asm__("iretl");
}
void clock_int_handler()
{
printf("\n");
set_interrupts(false);
int old_row = terminal_row;
int old_col = terminal_column;
terminal_row = 0;
terminal_column = 0;
display_date();
terminal_row = old_row;
terminal_column = old_col;
// Zero CMOS C register
// Select C register
outb(0x70, 0x0c);
// Read C register contents (which resets it, so RTC can send next requests)
inb(0x71);
// Send EOI to slave PIC (because IRQ 8 from RTC belongs to this PIC)
outb(0xA0, 0x20);
// Send EOI to master PIC (because master also needs to acknowledge
// handling of interrupt even if it came from slave)
outb(0x20, 0x20);
set_interrupts(true);
printf("Updated!");
}
void idt_setup()
{
struct idt_table table;
table.size_in_bytes_m1 = 256 * 8 - 1;
table.dest_pointer = (uint64_t*)0x500000;
// Empty ISR-s, for the sake of completeness
for (int i = 0; i < 256; i++)
{
struct idt_int_gate new_gate
= idt_int_gate_create(0x8, (intptr_t)default_int_handler);
table.gates[i] = new_gate;
}
// Clock ISR
table.gates[0x28] = idt_int_gate_create(0x8, (intptr_t)clock_int_handler);
// 0-31 ISR-s
table.gates[0] = idt_int_gate_create(0x8, (intptr_t)isr_0);
table.gates[1] = idt_int_gate_create(0x8, (intptr_t)isr_1);
table.gates[2] = idt_int_gate_create(0x8, (intptr_t)isr_2);
table.gates[3] = idt_int_gate_create(0x8, (intptr_t)isr_3);
table.gates[4] = idt_int_gate_create(0x8, (intptr_t)isr_4);
table.gates[5] = idt_int_gate_create(0x8, (intptr_t)isr_5);
table.gates[6] = idt_int_gate_create(0x8, (intptr_t)isr_6);
table.gates[7] = idt_int_gate_create(0x8, (intptr_t)isr_7);
table.gates[8] = idt_int_gate_create(0x8, (intptr_t)isr_8);
table.gates[9] = idt_int_gate_create(0x8, (intptr_t)isr_9);
table.gates[10] = idt_int_gate_create(0x8, (intptr_t)isr_10);
table.gates[11] = idt_int_gate_create(0x8, (intptr_t)isr_11);
table.gates[12] = idt_int_gate_create(0x8, (intptr_t)isr_12);
table.gates[13] = idt_int_gate_create(0x8, (intptr_t)isr_13);
table.gates[14] = idt_int_gate_create(0x8, (intptr_t)isr_14);
table.gates[15] = idt_int_gate_create(0x8, (intptr_t)isr_15);
table.gates[16] = idt_int_gate_create(0x8, (intptr_t)isr_16);
table.gates[17] = idt_int_gate_create(0x8, (intptr_t)isr_17);
table.gates[18] = idt_int_gate_create(0x8, (intptr_t)isr_18);
table.gates[19] = idt_int_gate_create(0x8, (intptr_t)isr_19);
table.gates[20] = idt_int_gate_create(0x8, (intptr_t)isr_20);
table.gates[21] = idt_int_gate_create(0x8, (intptr_t)isr_21);
table.gates[22] = idt_int_gate_create(0x8, (intptr_t)isr_22);
table.gates[23] = idt_int_gate_create(0x8, (intptr_t)isr_23);
table.gates[24] = idt_int_gate_create(0x8, (intptr_t)isr_24);
table.gates[25] = idt_int_gate_create(0x8, (intptr_t)isr_25);
table.gates[26] = idt_int_gate_create(0x8, (intptr_t)isr_26);
table.gates[27] = idt_int_gate_create(0x8, (intptr_t)isr_27);
table.gates[28] = idt_int_gate_create(0x8, (intptr_t)isr_28);
table.gates[29] = idt_int_gate_create(0x8, (intptr_t)isr_29);
table.gates[30] = idt_int_gate_create(0x8, (intptr_t)isr_30);
table.gates[31] = idt_int_gate_create(0x8, (intptr_t)isr_31);
apply_idt_table(table);
__asm__ volatile("sti");
}
void isr_common_handler(int number)
{
printf("Interrupt %d\n", number);
}