bootsetup.c.svn-base

来自「SImple Microkernel Distributed Operating」· SVN-BASE 代码 · 共 88 行

#include <string.h>
#include <system.h>
#include "bootsetup.h"

struct gdt_desc{
	__word	lim_0_15;
	__word	bas_0_15;
	__byte	bas_16_23;
	__byte 	access;
	__byte 	gran;
	__byte 	bas_24_31;
}__attribute__((packed));

struct idt_desc{
	__word	bas_0_15;
	__word	sel;
	__byte	always0;
	__byte	flags;
	__word	bas_16_31;
}__attribute__((packed));

struct table_reg{
	__word	  table_lim;
	__dword   table_linear;	
}__attribute__((packed));

struct task_state{

}__attribute__((packed));

struct gdt_desc		gdt[3];
struct idt_desc	   	idt[256];
struct table_reg   	app_gdt_ram;
struct table_reg   	app_idt_ram;

extern void gdt_flush();
extern void idt_load();

void gdt_set_gate(unsigned short n, __dword base, \
		__dword limit, __byte access, __byte gran)
{
	gdt[n].bas_0_15 = (base & 0xFFFF);
	gdt[n].bas_16_23 = (base >> 16) & 0xFF;
	gdt[n].bas_24_31 = (base >> 24) & 0xFF;

	gdt[n].lim_0_15 = (limit & 0xFFFF);
	gdt[n].gran = ((limit >> 16) & 0x0F);

	gdt[n].gran |= (gran & 0xF0);
	gdt[n].access = access;
}

void idt_set_gate(unsigned short n, __dword base, \
		__word sel, __byte flags)
{
	return;
}

void gdt_install()
{
	app_gdt_ram.table_lim       	 = (sizeof(struct gdt_desc) * 3) - 1;
	app_gdt_ram.table_linear	 = (__dword)gdt;

	gdt_set_gate(0, 0, 0, 0, 0);
	gdt_set_gate(1, 0, 0xFFFFFFFF, 0x9A, 0xCF);
	gdt_set_gate(2, 0, 0xFFFFFFFF, 0x92, 0xCF);

	gdt_flush();
}


void idt_install()
{
	app_idt_ram.table_lim    = (sizeof(struct idt_desc) * 256) - 1;
	app_idt_ram.table_linear = (__dword)idt;

	memset(&idt, 0, sizeof(struct idt_desc) * 256);

	idt_load();
}


void install_desc()
{
	idt_install();
	gdt_install();
}