interrupts.c

#include "interrupts.h"
#include "pic.h"
#include "io.h"
#include "framebuffer.h"
#include "serial_port.h"
#include "keyboard.h"
#include "paging.h"

#define INTERRUPTS_DESCRIPTOR_COUNT 256 
#define INTERRUPTS_KEYBOARD 33 
#define INTERRUPTS_PAGING 14 

isr_t interrupt_handlers[256];
registers_t regs;

void register_interrupt_handler(u8int n, isr_t handler) {
  interrupt_handlers[n] = handler;
}

struct IDTDescriptor idt_descriptors[INTERRUPTS_DESCRIPTOR_COUNT];
struct IDT idt;

void interrupts_init_descriptor(int index, unsigned int address)
{
	idt_descriptors[index].offset_high = (address >> 16) & 0xFFFF; // offset bits 0..15
	idt_descriptors[index].offset_low = (address & 0xFFFF); // offset bits 16..31

	idt_descriptors[index].segment_selector = 0x08; // The second (code) segment selector in GDT: one segment is 64b.
	idt_descriptors[index].reserved = 0x00; // Reserved.

	idt_descriptors[index].type_and_attr =	(0x01 << 7) |			// P
						(0x00 << 6) | (0x00 << 5) |	// DPL
						0xe;				// 0b1110=0xE 32-bit interrupt gate
}

void interrupts_install_idt()
{
	interrupts_init_descriptor(INTERRUPTS_KEYBOARD, (unsigned int) interrupt_handler_33);
	interrupts_init_descriptor(INTERRUPTS_PAGING, (unsigned int) interrupt_handler_14);


	idt.address = (int) &idt_descriptors;
	idt.size = sizeof(struct IDTDescriptor) * INTERRUPTS_DESCRIPTOR_COUNT;
	load_idt((int) &idt);

	/*pic_remap(PIC_PIC1_OFFSET, PIC_PIC2_OFFSET);*/
	pic_remap(PIC_1_OFFSET, PIC_2_OFFSET);
}


/* Interrupt handlers ********************************************************/

void interrupt_handler(__attribute__((unused)) struct cpu_state cpu, unsigned int interrupt, __attribute__((unused)) struct stack_state stack)
{
	unsigned char scan_code;
	unsigned char ascii;
	switch (interrupt){
		case INTERRUPTS_KEYBOARD:

			scan_code = keyboard_read_scan_code();

			if (scan_code <= KEYBOARD_MAX_ASCII) {
				ascii = keyboard_scan_code_to_ascii(scan_code);

				char str[1];
				str[0] = ascii;

				fb_write(str, 1);
				serial_write(0x3F8,str,1);
			}

			pic_acknowledge(interrupt);
			break;
		case INTERRUPTS_PAGING:
			page_fault(regs);	
			break;
		default:
			break;
    }
}