50 lines
1.5 KiB
C
50 lines
1.5 KiB
C
#include "desctbl.h"
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#include "int.h"
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#include "timer.h"
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void init_gdtidt(void) {
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struct SegmentDescriptor *gdt = (struct SegmentDescriptor *)ADR_GDT;
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struct GateDescriptor *idt = (struct GateDescriptor *)ADR_IDT;
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for (int i = 0; i <= LIMIT_GDT / 8; i++) {
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set_segmdesc(gdt + i, 0, 0, 0);
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}
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set_segmdesc(gdt + 1, 0xffffffff, 0x00000000, AR_DATA32_RW);
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set_segmdesc(gdt + 2, LIMIT_BOOTPACK, ADR_BOOTPACK, AR_CODE32_ER);
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load_gdtr(LIMIT_GDT, ADR_GDT);
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for (int i = 0; i <= LIMIT_IDT / 8; i++) {
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set_gatedesc(idt + i, 0, 0, 0);
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}
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load_idtr(LIMIT_IDT, ADR_IDT);
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set_gatedesc(idt + 0x20, (int)asm_int_handler20, 2 * 8, AR_INTGATE32);
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set_gatedesc(idt + 0x21, (int)asm_int_handler21, 2 * 8, AR_INTGATE32);
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set_gatedesc(idt + 0x27, (int)asm_int_handler27, 2 * 8, AR_INTGATE32);
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set_gatedesc(idt + 0x2c, (int)asm_int_handler2c, 2 * 8, AR_INTGATE32);
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}
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void set_segmdesc(struct SegmentDescriptor *sd, unsigned int limit, int base,
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int ar) {
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if (limit > 0xfffff) {
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ar |= 0x8000; // G_bit = 1
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limit /= 0x1000;
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}
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sd->limit_low = limit & 0xffff;
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sd->base_low = base & 0xffff;
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sd->base_mid = (base >> 16) & 0xff;
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sd->access_right = ar & 0xff;
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sd->limit_high = ((limit >> 16) & 0x0f) | ((ar >> 8) | 0xf0);
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sd->base_high = (base >> 24) & 0xff;
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}
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void set_gatedesc(struct GateDescriptor *gd, int offset, int selector, int ar) {
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gd->offset_low = offset & 0xffff;
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gd->selector = selector;
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gd->dw_count = (ar >> 8) & 0xff;
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gd->access_right = ar & 0xff;
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gd->offset_high = (offset >> 16) & 0xffff;
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}
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