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46 lines
879 B
ArmAsm
46 lines
879 B
ArmAsm
.code16gcc
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#include "assembly.h"
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.section .init
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ENTRY(pm_entry)
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xor %ax, %ax
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mov %ax, %ds
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mov %ax, %es
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mov %ax, %fs
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mov %ax, %gs
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mov %ax, %ss
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mov $0x7c00, %sp
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mov %cr0, %eax
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and $~((1 << 30) | (1 << 29)), %eax # clear CD and NW
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or $1, %al
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mov %eax, %cr0
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lgdtl %cs:0xff80 + gdt32_descr - pm_entry
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ljmpl $8, $0xffffff80 + 2f - pm_entry
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2:
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.code32
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mov $16, %ax
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mov %ax, %ds
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mov %ax, %es
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mov %ax, %fs
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mov %ax, %gs
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mov %ax, %ss
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ljmp $8, $0xffff0000
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gdt32:
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.quad 0
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.quad 0x00cf9b000000ffff // flat 32-bit code segment
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.quad 0x00cf93000000ffff // flat 32-bit data segment
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.quad 0x000f9b0f0000ffff // 64K 16-bit code segment at 0xF0000
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.quad 0x000f93000000ffff // 64K 16-bit data segment at 0x0
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gdt32_end:
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gdt32_descr:
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.word gdt32_end - gdt32 - 1
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.long 0xffffff80 + gdt32 - pm_entry
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ENTRY_END(pm_entry)
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.code16gcc
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.section .resetvector
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jmp pm_entry
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