minix/lib/i386/misc/getprocessor.s
2005-04-21 14:53:53 +00:00

52 lines
1.2 KiB
ArmAsm
Executable file

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