;* Procdi.asm - Processor Identification routines
;*
;* (C) Copyright Microsoft Corp., 1995
;*
;* Processor ID
;*
;* Origin:
;*
;* Change history:
;*
;* Date Who Description
;* --------- --------- -------------------------------------------------
;* 12-Oct-95 MikeG Created
;*
.386p
.387
.model flat
;************************** Include Files ************************
; include winbase.inc
; include winerror.inc
; include kernel32.inc
; include segs.inc
; include regstr.inc
;******************** Data Declerations **************************
.data
_DATA SEGMENT
CPU_ID macro
db 0fh, 0a2h
endm
NONE equ 0
PRESENT equ 1
Nx586 equ 5
UNKNOWN equ 0
_nxcpu db NONE ;default to none
_cputype db UNKNOWN ;default to unknown
_cpuid_flag db NONE ;default to no CPUID
_vendor_id db "************"
_cpu_signature dd 0
_features_ecx dd 0
_features_edx dd 0
_features_ebx dd 0
NexGen_id db "NexGenDriven"
;*********************** Prototypes ******************************
;************************** Code *********************************
.code
_TEXT SEGMENT
;==========================================================================
; _get_nxcpu_type
; This routine identifies NexGen's processor type in following steps:
;
; if (no AC flag) { //current Nx586 does not support AC flag
; set ZF=1;
; execute DIV to result a none zero value;
; if (ZF=0) { //ZF is changed
; not a NexGen processor;
; exit;
; } else { //Nx586 does not change ZF on DIV instruction
; if (ID bit not writeable) {
; CPU is Nx586 with no CPUID support
; } else { //Nx586 with CPUID support
; execute CPUID instruction;
; save CPU information;
; }
; }
; } else {
; if (ID bit not writeable) {
; not a NexGen processor;
; } else { //NexGen future processors support CPUID
; execute CPUID instruction;
; save CPU information;
; }
; }
;
;==========================================================================
get_nxcpu_type proc C cdecl:DWORD
push ebx
push esi
push edi
mov byte ptr _nxcpu,PRESENT ; default to present
; test AC bit on EFLAGS register
mov bx,sp ; save the current stack pointer
and sp,not 3 ; align the stack to avoid AC fault
pushfd ;
pop eax ; get the original EFLAGS
mov ecx,eax ; save original flag
xor eax,40000h ; flip AC bit in EFLAGS
push eax ; save for EFLAGS
popfd ; copy it to EFLAGS
pushfd ;
pop eax ; get the new EFLAGS value
mov sp,bx ; restore stack pointer
xor eax,ecx ; if the AC bit is unchanged
je test_zf ; goto second step
jmp nx_future_cpu
test_zf:
; test ZF on DIV instruction
mov ax,5555h ; init AX with a non-zero value
xor dx,dx ; set ZF=1
mov cx,2
div cx ; Nx586 processor does not modify ZF on DIV
jnz not_nx_cpu ; not a NexGen processor if ZF=0 (modified)
test_cpuid:
; test if CPUID instruction is available
; new Nx586 or future CPU supports CPUID instruction
pushfd ; get EFLAGs
pop eax
mov ecx,eax ; save it
xor eax,200000h ; modify ID bit
push eax
popfd ; save it in new EFLAGS
pushfd ; get new EFLAGS
pop eax ;
xor eax,ecx ; is ID bit changed?
jnz cpuid_present ; yes
mov byte ptr _cputype,Nx586 ; no, current Nx586
mov eax,1 ; set return code == true
jz cpuid_exit ; stop testing
nx_future_cpu:
; all NexGen's future processors feature a CPUID instruction
mov eax,ecx ; get original EFLAGS
xor eax,200000h ; modify ID bit
push eax
popfd ; save it in new EFLAGS
pushfd ; get new EFLAGS
pop eax ;
xor eax,ecx ; is ID bit changed?
jz not_nx_cpu ; no, not a NexGen processor
cpuid_present:
; execute CPUID instruction to get vendor name, stepping and feature info
xor eax,eax
CPU_ID
mov dword ptr _vendor_id,ebx
mov dword ptr _vendor_id[+4],edx
mov dword ptr _vendor_id[+8],ecx
mov bx,ds
mov es,bx
mov esi,offset _vendor_id
mov edi,offset NexGen_id
mov cx,12
cld
repe cmpsb ; compare vendor ID string
jne not_nx_cpu
mov byte ptr _cpuid_flag,PRESENT
cmp eax,1 ; check highest level
jl cpuid_exit
mov eax,1
CPU_ID
mov _cpu_signature,eax
mov _features_ecx,ecx
mov _features_edx,edx
mov _features_ebx,ebx
shr eax,8
and al,0fh
mov _cputype,al
jmp cpuid_exit
not_nx_cpu:
mov byte ptr _nxcpu,NONE
xor eax,eax
cpuid_exit:
pop edi
pop esi
pop ebx
ret
get_nxcpu_type endp
;**************************************************************************
; Function: int is_cyrix ()
;
; Purpose: Determine if Cyrix CPU is present
; Technique: Cyrix CPUs do not change flags where flags change
; in an undefined manner on other CPUs
; Inputs: none
; Output: ax == 1 Cyrix present, 0 if not
;**************************************************************************
is_cyrix proc C __cdecl:WORD
.486
push bx
xor ax, ax ; clear ax
sahf ; clear flags, bit 1 is always 1 in flags
mov ax, 5
mov bx, 2
div bl ; do an operation that does not change flags
lahf ; get flags
cmp ah, 2 ; check for change in flags
jne not_cyrix ; flags changed not Cyrix
mov ax, 1 ; TRUE Cyrix CPU
jmp done
not_cyrix:
mov ax, 0 ; FALSE NON-Cyrix CPU
done:
pop bx
ret
is_cyrix endp
_TEXT ends
end