56 lines
1.3 KiB
ArmAsm
56 lines
1.3 KiB
ArmAsm
! getprocessor() - determine processor type Author: Kees J. Bot
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! 26 Jan 1994
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.sect .text; .sect .rom; .sect .data; .sect .bss
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.sect .text
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! int getprocessor(void);
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! Return 386, 486, 586, ...
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.define _getprocessor
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_getprocessor:
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push ebp
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mov ebp, esp
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and esp, 0xFFFFFFFC ! Align stack to avoid AC fault
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mov ecx, 0x00040000 ! Try to flip the AC bit introduced on the 486
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call flip
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mov eax, 386 ! 386 if it didn't react to "flipping"
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jz gotprocessor
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mov ecx, 0x00200000 ! Try to flip the ID bit introduced on the 586
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call flip
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mov eax, 486 ! 486 if it didn't react
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jz gotprocessor
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pushf
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pusha ! Save the world
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mov eax, 1
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.data1 0x0F, 0xA2 ! CPUID instruction tells the processor type
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andb ah, 0x0F ! Extract the family (5, 6, ...)
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movzxb eax, ah
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cmp eax, 15 ! 15: extended family
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jne direct
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mov eax, 6 ! Make it 686
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direct:
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imul eax, 100 ! 500, 600, ...
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add eax, 86 ! 586, 686, ...
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mov 7*4(esp), eax ! Pass eax through
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popa
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popf
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gotprocessor:
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leave
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ret
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flip:
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pushf ! Push eflags
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pop eax ! eax = eflags
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mov edx, eax ! Save original eflags
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xor eax, ecx ! Flip the bit to test
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push eax ! Push modified eflags value
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popf ! Load modified eflags register
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pushf
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pop eax ! Get it again
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push edx
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popf ! Restore original eflags register
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xor eax, edx ! See if the bit changed
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test eax, ecx
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ret
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