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