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// MIT License, Copyright (c) 2020 Marvin Borner
#include <cpu.h>
#include <def.h>
#include <interrupts.h>
#include <serial.h>
/**
* IDT
*/
void idt_set_gate(u8 num, u32 base, u16 sel, u8 flags)
{
// Specify the interrupt routine's base address
idt[num].base_low = (u16)(base & 0xFFFF);
idt[num].base_high = (u16)((base >> 16) & 0xFFFF);
// Set selector/segment of IDT entry
idt[num].sel = sel;
idt[num].always0 = 0;
idt[num].flags = (u8)(flags | 0x60);
}
// Install IDT
void idt_install()
{
// Set IDT pointer and limit
idt_ptr.limit = (sizeof(struct idt_entry) * 256) - 1;
idt_ptr.base = &idt;
// Clear IDT by setting memory cells to 0 // TODO
//memset(&idt, 0, sizeof(struct idt_entry) * 256);
__asm__("lidt %0" : : "m"(idt_ptr));
}
/**
* IRQ
*/
void (*irq_routines[16])(struct regs *) = { 0 };
// Install IRQ handler
void irq_install_handler(int irq, void (*handler)(struct regs *r))
{
irq_routines[irq] = handler;
}
// Remove IRQ handler
void irq_uninstall_handler(int irq)
{
irq_routines[irq] = 0;
}
// Remap the IRQ table
void irq_remap()
{
outb(0x20, 0x11);
outb(0xA0, 0x11);
outb(0x21, 0x20);
outb(0xA1, 0x28);
outb(0x21, 0x04);
outb(0xA1, 0x02);
outb(0x21, 0x01);
outb(0xA1, 0x01);
outb(0x21, 0x00);
outb(0xA1, 0x00);
}
// Handle IRQ ISRs
__attribute__((interrupt)) void irq_handler(struct regs *r)
{
__asm__("cli");
void (*handler)(struct regs * r);
// Execute custom handler if exists
handler = irq_routines[r->int_no - 32];
if (handler)
handler(r);
// Send EOI to second (slave) PIC
if (r->int_no >= 40)
outb(0xA0, 0x20);
// Send EOI to master PIC
outb(0x20, 0x20);
__asm__("sti");
}
// Map ISRs to the correct entries in the IDT
void irq_install()
{
irq_remap();
for (int i = 32; i < 48; i++)
idt_set_gate(i, (u32)irq_handler, 0x08, 0x8E);
}
/**
* ISR
*/
void (*isr_routines[256])(struct regs *) = { 0 };
void isr_install_handler(int isr, void (*handler)(struct regs *r))
{
isr_routines[isr] = handler;
}
void isr_uninstall_handler(int isr)
{
isr_routines[isr] = 0;
}
__attribute__((interrupt)) void isr_handler(struct regs *r)
{
__asm__("cli");
void (*handler)(struct regs * r);
// Execute fault handler if exists
handler = isr_routines[r->int_no];
if (handler) {
handler(r);
} else if (r->int_no <= 32) {
serial_print("Exception, halting!\n");
__asm__("cli");
while (1) {
};
}
__asm__("sti");
}
void isr_install()
{
for (int i = 0; i < 32; i++)
idt_set_gate(i, (u32)isr_handler, 0x08, 0x8E);
}
/**
* Combined
*/
void interrupts_install()
{
idt_install();
isr_install();
irq_install();
__asm__("sti");
}
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