93 lines
2 KiB
ArmAsm
Executable file
93 lines
2 KiB
ArmAsm
Executable file
! getprocessor() - determine processor type Author: Kees J. Bot
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! 26 Jan 1994
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.text
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o32 = 0x66 ! 32 bit operand size prefix
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! int getprocessor(void);
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! Return 86, 186, 286, 386, 486, 586, ...
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.define _getprocessor
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_getprocessor:
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push bp
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mov bp, sp
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push sp ! see if pushed sp == sp
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pop ax
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cmp ax, sp
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jz new_processor
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mov cx, #0x0120 ! see if shifts are mod 32
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shlb ch, cl ! zero tells if 86
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mov ax, #86
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jz got_processor
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mov ax, #186
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jmp got_processor
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new_processor: ! see if high bits are set in saved IDT
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sub sp, #6 ! space for IDT ptr
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sidt -6(bp) ! save 3 word IDT ptr
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cmpb -1(bp), #0xFF ! top byte of IDT ptr is always FF on 286
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mov ax, #286
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je got_processor
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! 386, 486, 586
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and sp, #0xFFFC ! Align stack to avoid AC fault (needed?)
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mov cx, #0x0004 ! Try to flip the AC bit introduced on the 486
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call flip
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mov ax, #386 ! 386 if it didn't react to "flipping"
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jz got_processor
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mov cx, #0x0020 ! Try to flip the ID bit introduced on the 586
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call flip
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mov ax, #486 ! 486 if it didn't react
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jz got_processor
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.data1 o32
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pushf
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.data1 o32
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pusha ! Save the world
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.data1 o32
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xor ax, ax
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inc ax ! 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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movb al, ah
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movb ah, #100
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mulb ah ! 500, 600, ...
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add ax, #86 ! 586, 686, ...
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mov bx, sp
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mov 7*4(bx), ax ! Pass ax through
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.data1 o32
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popa
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.data1 o32
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popf
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got_processor:
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mov sp, bp
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pop bp
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ret
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flip:
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push bx ! Save bx and realign stack to multiple of 4
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.data1 o32 ! About to operate on a 32 bit object
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pushf ! Push eflags
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pop ax
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pop dx ! dx:ax = eflags
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mov bx, dx ! Save original eflags (high word only)
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xor dx, cx ! Flip the bit to test
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push dx
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push ax ! Push modified eflags value
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.data1 o32
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popf ! Load modified eflags register
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.data1 o32
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pushf
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pop ax
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pop dx ! Get it again
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push bx
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push ax
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.data1 o32
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popf ! Restore original eflags register
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xor dx, bx ! See if the bit changed
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test dx, cx
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pop bx ! Restore bx
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ret
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