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;* 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 SEGMENTCPU_ID macro db 0fh, 0a2h endm
NONE equ 0PRESENT equ 1Nx586 equ 5UNKNOWN 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 0NexGen_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_exitnot_nx_cpu: mov byte ptr _nxcpu,NONE xor eax,eaxcpuid_exit: pop edi pop esi pop ebx retget_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 CPUdone: pop bx retis_cyrix endp_TEXT ends end
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