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gdt.c
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132 lines (118 loc) · 5.95 KB
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/* ** por compatibilidad se omiten tildes **
================================================================================
TRABAJO PRACTICO 3 - System Programming - ORGANIZACION DE COMPUTADOR II - FCEN
================================================================================
definicion de la tabla de descriptores globales
*/
#include "gdt.h"
/* Definicion de la GDT */
/* -------------------------------------------------------------------------- */
gdt_entry gdt[31] = {
/* Descriptor nulo*/
/* Offset = 0x000 */
[0] = (gdt_entry) {
(unsigned short) 0x0000, /* limit[0:15] */
(unsigned short) 0x0000, /* base[0:15] */
(unsigned char) 0x00, /* base[23:16] */
(unsigned char) 0x00, /* type */
(unsigned char) 0x00, /* s */
(unsigned char) 0x00, /* dpl */
(unsigned char) 0x00, /* p */
(unsigned char) 0x00, /* limit[16:19] */
(unsigned char) 0x00, /* avl */
(unsigned char) 0x00, /* l */
(unsigned char) 0x00, /* db */
(unsigned char) 0x00, /* g */
(unsigned char) 0x00, /* base[31:24] */
},
/* Descriptor codigo nivel 0
Offset = 0x040 */
[8] = (gdt_entry) {
(unsigned short) 0xF3FF, /* limit[0:15] */
(unsigned short) 0x0000, /* base[0:15] */
(unsigned char) 0x00, /* base[23:16] */
(unsigned char) 0x0A, /* type */
(unsigned char) 0x01, /* s */
(unsigned char) 0x00, /* dpl */
(unsigned char) 0x01, /* p */
(unsigned char) 0x01, /* limit[16:19] */
(unsigned char) 0x00, /* avl */
(unsigned char) 0x00, /* l */
(unsigned char) 0x01, /* db */
(unsigned char) 0x01, /* g */
(unsigned char) 0x00, /* base[31:24] */
},
/* Descriptor datos nivel 0
Offset = 0x048 */
[9] = (gdt_entry) {
(unsigned short) 0xF3FF, /* limit[0:15] */
(unsigned short) 0x0000, /* base[0:15] */
(unsigned char) 0x00, /* base[23:16] */
(unsigned char) 0x02, /* type */
(unsigned char) 0x01, /* s */
(unsigned char) 0x00, /* dpl */
(unsigned char) 0x01, /* p */
(unsigned char) 0x01, /* limit[16:19] */
(unsigned char) 0x00, /* avl */
(unsigned char) 0x00, /* l */
(unsigned char) 0x01, /* db */
(unsigned char) 0x01, /* g */
(unsigned char) 0x00, /* base[31:24] */
},
/* Descriptor codigo nivel 3
Offset = 0x050 */
[10] = (gdt_entry) {
(unsigned short) 0xF3FF, /* limit[0:15] */
(unsigned short) 0x0000, /* base[0:15] */
(unsigned char) 0x00, /* base[23:16] */
(unsigned char) 0x0A, /* type */
(unsigned char) 0x01, /* s */
(unsigned char) 0x03, /* dpl */
(unsigned char) 0x01, /* p */
(unsigned char) 0x01, /* limit[16:19] */
(unsigned char) 0x00, /* avl */
(unsigned char) 0x00, /* l */
(unsigned char) 0x01, /* db */
(unsigned char) 0x01, /* g */
(unsigned char) 0x00, /* base[31:24] */
},
/* Descriptor datos nivel 3*/
/* Offset = 0x058 */
[11] = (gdt_entry) {
(unsigned short) 0xF3FF, /* limit[0:15] */
(unsigned short) 0x0000, /* base[0:15] */
(unsigned char) 0x00, /* base[23:16] */
(unsigned char) 0x02, /* type */
(unsigned char) 0x01, /* s */
(unsigned char) 0x03, /* dpl */
(unsigned char) 0x01, /* p */
(unsigned char) 0x01, /* limit[16:19] */
(unsigned char) 0x00, /* avl */
(unsigned char) 0x00, /* l */
(unsigned char) 0x01, /* db */
(unsigned char) 0x01, /* g */
(unsigned char) 0x00, /* base[31:24] */
},
/* Segmento pa'l video*/
/* Offset = 0x060 */
/* ZAVA NO SABE SI EL LIMITE ESTA BIEN, ESTARIA CREYENDO QUE NO */
[12] = (gdt_entry) {
(unsigned short) 0x0F9F, /* limit[0:15] */
(unsigned short) 0x8000, /* base[0:15] */
(unsigned char) 0x0B, /* base[23:16] */
(unsigned char) 0x02, /* type */
(unsigned char) 0x01, /* s */
(unsigned char) 0x00, /* dpl */
(unsigned char) 0x01, /* p */
(unsigned char) 0x0B, /* limit[16:19] */
(unsigned char) 0x00, /* avl */
(unsigned char) 0x00, /* l */
(unsigned char) 0x01, /* db */
(unsigned char) 0x00, /* g */
(unsigned char) 0x00, /* base[31:24] */
},
};
gdt_descriptor GDT_DESC = {
sizeof(gdt) - 1,
(unsigned int) &gdt
};