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https://github.com/yourtion/30dayMakeOS.git
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60 lines
1.8 KiB
C
60 lines
1.8 KiB
C
/* GDT、IDT、descriptor table 关系处理 */
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#include "bootpack.h"
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void init_gdtidt(void)
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{
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struct SEGMENT_DESCRIPTOR *gdt = (struct SEGMENT_DESCRIPTOR *) ADR_GDT;
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struct GATE_DESCRIPTOR *idt = (struct GATE_DESCRIPTOR *) ADR_IDT;
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int i;
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/* GDT初始化 */
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for (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_BOTPAK, ADR_BOTPAK, AR_CODE32_ER);
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load_gdtr(LIMIT_GDT, ADR_GDT);
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/* IDT初始化 */
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for (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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/* IDT设置*/
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set_gatedesc(idt + 0x0c, (int) asm_inthandler0c, 2 * 8, AR_INTGATE32);
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set_gatedesc(idt + 0x0d, (int) asm_inthandler0d, 2 * 8, AR_INTGATE32);
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set_gatedesc(idt + 0x20, (int) asm_inthandler20, 2 * 8, AR_INTGATE32);
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set_gatedesc(idt + 0x21, (int) asm_inthandler21, 2 * 8, AR_INTGATE32);
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set_gatedesc(idt + 0x2c, (int) asm_inthandler2c, 2 * 8, AR_INTGATE32);
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set_gatedesc(idt + 0x40, (int) asm_hrb_api, 2 * 8, AR_INTGATE32 + 0x60);
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return;
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}
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void set_segmdesc(struct SEGMENT_DESCRIPTOR *sd, unsigned int limit, int base, int ar)
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{
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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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return;
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}
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void set_gatedesc(struct GATE_DESCRIPTOR *gd, int offset, int selector, int ar)
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{
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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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return;
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}
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