libcaca/kernel/boot/idt.c

/*
 *'freely' inspired by http://jojo.ouvaton.org/dossiers/boot_sector/tutorial02.html
 * (actually, that's mostly copied, with minor compilation fixes)
 */
#include "kernel.h"
#include "klibc.h"

#define IDTBASE	0		/* GDT Physical address */
#define IDTSIZE	256		/* Max descriptor count */
#define INTGATE 0x8E00  /* Interruptions */
#define TRAPGATE 0x8F00 /* Syscalls */
#define TASKGATE 0x8500 /* Task switching */

/* segment descriptor */
struct idtdesc {
	u16 offset0_15;	
	u16 select;
    u16 type;
	u16 offset16_31;	
}  __attribute__ ((packed));

/* IDTR register */
struct idtr {
	u16 limite;
	u32 base;
}  __attribute__ ((packed));

struct idtr kidtr;

/* IDT table */
struct idtdesc kidt[IDTSIZE] = {{0, 0, 0, 0}};

/* pointer on a free IDT entry */
unsigned int kidtptr = 0;

void default_int(void);
void k_int0(void);
void k_int1(void);
void k_int2(void);
void k_int3(void);
void k_int4(void);
void k_int5(void);
void k_int6(void);
void k_int7(void);
void k_int8(void);
void k_int9(void);
void k_int10(void);
void k_int11(void);
void k_int12(void);
void k_int13(void);
void k_int14(void);
void k_int15(void);
void k_int16(void);
void k_int17(void);
void k_int18(void);
void k_irq0(void);
void k_irq1(void);
void k_irq2(void);
void k_irq3(void);
void k_irq4(void);
void k_irq5(void);
void k_irq6(void);
void k_irq7(void);
void k_irq8(void);


void init_idt_desc(u32 offset, u16 select, u16 type, struct idtdesc* desc) {
	desc->offset0_15 = (offset & 0xffff);
	desc->select = select;
	desc->type = type;
	desc->offset16_31 = (offset & 0xffff0000) >> 16;
	return;
}


void add_idt_desc(struct idtdesc desc) {
	kidt[kidtptr++] = desc;
	return;
}


void init_idt(void) {
	struct idtdesc desc;
	int i;

    
	for(i=0;i<IDTSIZE;i++) {
		init_idt_desc((u32)default_int, 0x08, INTGATE, &desc);
		add_idt_desc(desc);
	}

	init_idt_desc((u32)k_int0, 0x08, INTGATE, &kidt[0]);
	init_idt_desc((u32)k_int1, 0x08, INTGATE, &kidt[1]);
	init_idt_desc((u32)k_int2, 0x08, INTGATE, &kidt[2]);
	init_idt_desc((u32)k_int3, 0x08, INTGATE, &kidt[3]);
	init_idt_desc((u32)k_int4, 0x08, INTGATE, &kidt[4]);
	init_idt_desc((u32)k_int5, 0x08, INTGATE, &kidt[5]);
	init_idt_desc((u32)k_int6, 0x08, INTGATE, &kidt[6]);
	init_idt_desc((u32)k_int7, 0x08, INTGATE, &kidt[7]);
	init_idt_desc((u32)k_int8, 0x08, INTGATE, &kidt[8]);
	init_idt_desc((u32)k_int9, 0x08, INTGATE, &kidt[9]);
	init_idt_desc((u32)k_int10, 0x08, INTGATE, &kidt[10]);
	init_idt_desc((u32)k_int11, 0x08, INTGATE, &kidt[11]);
	init_idt_desc((u32)k_int12, 0x08, INTGATE, &kidt[12]);
	init_idt_desc((u32)k_int13, 0x08, INTGATE, &kidt[13]);
	init_idt_desc((u32)k_int14, 0x08, INTGATE, &kidt[14]);
	init_idt_desc((u32)k_int15, 0x08, INTGATE, &kidt[15]);
	init_idt_desc((u32)k_int16, 0x08, INTGATE, &kidt[16]);
	init_idt_desc((u32)k_int17, 0x08, INTGATE, &kidt[17]);
	init_idt_desc((u32)k_int18, 0x08, INTGATE, &kidt[18]);
    
	init_idt_desc((u32)k_irq0, 0x08, INTGATE, &kidt[32]);
	init_idt_desc((u32)k_irq1, 0x08, INTGATE, &kidt[33]);
	init_idt_desc((u32)k_irq2, 0x08, INTGATE, &kidt[34]);
	init_idt_desc((u32)k_irq3, 0x08, INTGATE, &kidt[35]);
	init_idt_desc((u32)k_irq4, 0x08, INTGATE, &kidt[36]);
	init_idt_desc((u32)k_irq5, 0x08, INTGATE, &kidt[37]);
	init_idt_desc((u32)k_irq6, 0x08, INTGATE, &kidt[38]);
	init_idt_desc((u32)k_irq7, 0x08, INTGATE, &kidt[39]);
	init_idt_desc((u32)k_irq8, 0x08, INTGATE, &kidt[40]);
    
    kidtr.limite = IDTSIZE*8;
	kidtr.base = IDTBASE;
    
	memcpy((void*)kidtr.base, kidt, kidtr.limite);
#define printf(format, ...) { char __str[255]; sprintf (__str, format, __VA_ARGS__); print(__str);}

    printf("Loading IDT from 0x%x\n", kidtr);
#undef printf
    
    asm("lidtl (kidtr)");
}