35 lines
1.4 KiB
C
35 lines
1.4 KiB
C
#ifndef GDT_H
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#define GDT_H
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#include <stdint.h>
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typedef struct {
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uint16_t size;
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uint16_t offset_lower;
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uint16_t offset_upper;
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uint16_t _reserved;
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} gdtr_t;
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typedef uint64_t gdt_entry_t;
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#define gdt_build_entry(base, limit, pr, privl, s, ex, dc, rw, ac, gr, sz, l) \
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(gdt_entry_t)( \
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(((gdt_entry_t)base << 32) & 0xFF00000000000000ull) | /* Base 0:15 */ \
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(((gdt_entry_t)gr & 0x1u) << 55) | /* Granularity (0 = bytes, 1 = blocks) */ \
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(((gdt_entry_t)sz & 0x1u) << 54) | /* Size (0 = 16-bit, 1 = 32-bit) */ \
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(((gdt_entry_t)l & 0x1u) << 53) | /* L flag (x86_64 code) */ \
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(((gdt_entry_t)limit << 32) & 0x000F000000000000ull) | /* Limit 16:19 */ \
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(((gdt_entry_t)pr & 0x1u) << 47) | /* Present flag */ \
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(((gdt_entry_t)privl & 0x3u) << 45) | /* Privilege (ring level) */ \
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(((gdt_entry_t)s & 0x1u) << 44) | /* Type (0 = system, 1 = code/data) */ \
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(((gdt_entry_t)ex & 0x1u) << 43) | /* Executable flag */ \
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(((gdt_entry_t)dc & 0x1u) << 42) | /* Direction/Conforming */ \
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(((gdt_entry_t)rw & 0x1u) << 41) | /* Readable/Writable */ \
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(((gdt_entry_t)ac & 0x1u) << 40) | /* Accessed flag */ \
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(((gdt_entry_t)base << 16) & 0x000000FFFFFF0000ull) | /* Base 0:23 */ \
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((gdt_entry_t)limit & 0x000000000000FFFFull)) /* Limit 0:15 */
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void gdt_init(void);
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void gdt_set(void);
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#endif
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