48 lines
1.4 KiB
C
48 lines
1.4 KiB
C
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#include <Library/BaseLib.h>
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#include <Library/MemoryAllocationLib.h>
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#include <Library/PrintLib.h>
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#include <Library/UefiLib.h>
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#include <Uefi.h>
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#include "io.h"
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UINT64 SegmentDescriptors[] = {
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0x0000000000000000, // NULL Descriptor
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0x00AF9A000000FFFF, // BaseAddress 0 Granularity 1
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// SegmentSize 1048575*4069=4294963200(4GB) Segment Present
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// Plivilege 0 Code Segment Read+Exec
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0x00CF93000000FFFF // BaseAddress 0 Granularity 1
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// SegmentSize 1048575*4069=4294963200(4GB) Segment
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// Present Plivilege 0 Data Segment Read+Write
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};
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IA32_DESCRIPTOR Descriptor;
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void sendparallelstub(UINT8 byte) {
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mapped_io_write(0x378, byte);
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UINT8 control = mapped_io_read(0x37a);
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mapped_io_write(0x37a, control | 1);
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int a;
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for (int i = 0; i < 200; i++) a += control;
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mapped_io_write(0x37a, control);
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}
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void GDT_init() {
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Descriptor.Limit = (UINT16)(sizeof(UINT64) * 3 - 1);
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Descriptor.Base = (UINT32)(UINTN)(VOID *)SegmentDescriptors;
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AsmWriteGdtr(&Descriptor);
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asm volatile(
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"mov $16, %ax\n"
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"mov %ax, %ss\n"
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"mov %ax, %ds\n"
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"mov %ax, %es\n"
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"mov %ax, %fs\n"
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"mov %ax, %gs\n"
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"sub $16,%rsp\n"
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"leaq end(%rip),%rax\n"
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"mov %rax,(%rsp)\n"
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"mov $8,%ax\n"
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"mov %ax,4(%rsp)\n"
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"ljmp *(%rsp)\n"
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"end:\n"
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"add $16,%rsp");
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}
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