122 lines
4.0 KiB
C
122 lines
4.0 KiB
C
#include "idt.h"
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#include "../libc/string.h"
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#include "ports.h"
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// Internal method
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extern void idt_flush(idt_ptr_t*); // defined on cpu/idt.asm
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static void init_idt();
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static void idt_set_gate(uint8_t idx, void(*base), uint16_t selector, idt_flags_t flags);
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static void pic_remap(uint8_t offset1, uint8_t offset2);
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idt_entry_t idt_entries[256]; // 256 interrupts
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idt_ptr_t idt_ptr;
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// This method will be called by the kernel
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void idt_setup() {
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init_idt();
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}
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static void idt_set_gate(uint8_t idx, void(*base), uint16_t selector, idt_flags_t flags) {
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idt_entries[idx] = (struct idt_entry) {
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.base_low = (uint32_t)base & 0xFFFF,
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.base_high = ((uint32_t)base >> 16) & 0xFFFF,
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.seg_sel = selector,
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.flags = flags
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};
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}
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static void init_idt() {
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idt_ptr.limit = sizeof(idt_entry_t) * 256 - 1;
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idt_ptr.base = idt_entries;
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memset(&idt_entries, 0, sizeof(idt_entry_t) * 256);
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idt_flags_t flags = {
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.reserved = IDT_FLAG_RESERVED, // Always 0x0E
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.dpl = 0,
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.p = 1
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};
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// Remap IDT with ISRs
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idt_set_gate(0, isr0, 0x08, flags);
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idt_set_gate(1, isr1, 0x08, flags);
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idt_set_gate(2, isr2, 0x08, flags);
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idt_set_gate(3, isr3, 0x08, flags);
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idt_set_gate(4, isr4, 0x08, flags);
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idt_set_gate(5, isr5, 0x08, flags);
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idt_set_gate(6, isr6, 0x08, flags);
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idt_set_gate(7, isr7, 0x08, flags);
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idt_set_gate(8, isr8, 0x08, flags);
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idt_set_gate(9, isr9, 0x08, flags);
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idt_set_gate(10, isr10, 0x08, flags);
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idt_set_gate(11, isr11, 0x08, flags);
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idt_set_gate(12, isr12, 0x08, flags);
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idt_set_gate(13, isr13, 0x08, flags);
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idt_set_gate(14, isr14, 0x08, flags);
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idt_set_gate(15, isr15, 0x08, flags);
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idt_set_gate(16, isr16, 0x08, flags);
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idt_set_gate(17, isr17, 0x08, flags);
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idt_set_gate(18, isr18, 0x08, flags);
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idt_set_gate(19, isr19, 0x08, flags);
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idt_set_gate(20, isr20, 0x08, flags);
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idt_set_gate(21, isr21, 0x08, flags);
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idt_set_gate(22, isr22, 0x08, flags);
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idt_set_gate(23, isr23, 0x08, flags);
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idt_set_gate(24, isr24, 0x08, flags);
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idt_set_gate(25, isr25, 0x08, flags);
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idt_set_gate(26, isr26, 0x08, flags);
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idt_set_gate(27, isr27, 0x08, flags);
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idt_set_gate(28, isr28, 0x08, flags);
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idt_set_gate(29, isr29, 0x08, flags);
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idt_set_gate(30, isr30, 0x08, flags);
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idt_set_gate(31, isr31, 0x08, flags);
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// Remap PIC
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pic_remap(PIC1_START_INTERRUPT, PIC2_START_INTERRUPT);
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// Also remap 15 entries for IRQs
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idt_set_gate(32, irq0, 0x08, flags);
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idt_set_gate(33, irq1, 0x08, flags);
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idt_set_gate(34, irq2, 0x08, flags);
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idt_set_gate(35, irq3, 0x08, flags);
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idt_set_gate(36, irq4, 0x08, flags);
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idt_set_gate(37, irq5, 0x08, flags);
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idt_set_gate(38, irq6, 0x08, flags);
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idt_set_gate(39, irq7, 0x08, flags);
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idt_set_gate(40, irq8, 0x08, flags);
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idt_set_gate(41, irq9, 0x08, flags);
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idt_set_gate(42, irq10, 0x08, flags);
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idt_set_gate(43, irq11, 0x08, flags);
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idt_set_gate(44, irq12, 0x08, flags);
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idt_set_gate(45, irq13, 0x08, flags);
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idt_set_gate(46, irq14, 0x08, flags);
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idt_set_gate(47, irq15, 0x08, flags);
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idt_flush(&idt_ptr);
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// Finally enable hardware interrupts with an assembly instruction
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__asm__ __volatile__ ("sti");
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}
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// Taken from: http://wiki.osdev.org/8259_PIC
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static void pic_remap(uint8_t offset1, uint8_t offset2) {
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uint8_t a1, a2;
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a1 = inb(PIC1_DATA); // Save masks
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a2 = inb(PIC2_DATA);
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outb(PIC1_COMMAND, ICW1_INIT+ICW1_ICW4); // Start init sequence
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outb(PIC2_COMMAND, ICW1_INIT+ICW1_ICW4);
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outb(PIC1_DATA, offset1);
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outb(PIC2_DATA, offset2);
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outb(PIC1_DATA, 4); // Tell master PIC that there is a slave PIC at IRQ2
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outb(PIC1_DATA, 2); // Tell salve PIC it's cascade identity
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outb(PIC1_DATA, ICW4_8086);
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outb(PIC2_DATA, ICW4_8086);
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// Restore saved masks
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outb(PIC1_DATA, a1);
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outb(PIC2_DATA, a2);
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} |