CnC_Remastered_Collection/REDALERT/CPUID.ASM

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;
; Copyright 2020 Electronic Arts Inc.
;
; TiberianDawn.DLL and RedAlert.dll and corresponding source code is free
; software: you can redistribute it and/or modify it under the terms of
; the GNU General Public License as published by the Free Software Foundation,
; either version 3 of the License, or (at your option) any later version.
; TiberianDawn.DLL and RedAlert.dll and corresponding source code is distributed
; in the hope that it will be useful, but with permitted additional restrictions
; under Section 7 of the GPL. See the GNU General Public License in LICENSE.TXT
; distributed with this program. You should have received a copy of the
; GNU General Public License along with permitted additional restrictions
; with this program. If not, see [https://github.com/electronicarts/CnC_Remastered_Collection]>.
; $Header: F:\projects\c&c0\vcs\code\cpuid.asv 5.0 11 Nov 1996 09:40:28 JOE_BOSTIC $
;***************************************************************************
;** C O N F I D E N T I A L --- W E S T W O O D S T U D I O S I N C **
;***************************************************************************
;* *
;* Project Name : Command & Conquer *
;* *
;* File Name : MMX.ASM *
;* *
;* Programmer : Steve Tall *
;* *
;* Start Date : May 19th, 1996 *
;* *
;* Last Update : May 19th 1996 [ST] *
;* *
;*-------------------------------------------------------------------------*
;* Functions: *
;* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - *
.586
.model flat
;
; Variables externs
;
GLOBAL C CPUType:byte
;externdef C CPUType:byte
GLOBAL C VendorID:byte
;externdef C VendorID:byte
;
; Function externs
;
GLOBAL C Detect_MMX_Availability:near
;externdef C Detect_MMX_Availability:near
.code
;*********************************************************************************************
;* Detect_MMX_Availability -- Detect the presence of MMX technology. *
;* *
;* *
;* INPUT: Nothing *
;* *
;* OUTPUT: True if MMX technology is available. *
;* *
;* Warnings: *
;* *
;* Note: Based in part on CPUID32.ASM by Intel *
;* *
;* HISTORY: *
;* 05/19/96 ST : Created. *
;*===========================================================================================*
Detect_MMX_Availability proc C
local idflag:byte
local cputype:byte
;assume processor is at least 386
;
;check whether AC bit in eflags can be toggled.
;If not then processor is 386
mov [idflag],0
pushfd ;get Eflags in EAX
pop eax
mov ecx,eax ;save eflags
xor eax,40000h ;toggle AC bit in eflags
push eax ;new eflags on stack
popfd ;move new value into eflags
pushfd ;get new eflags back into eax
pop eax
xor eax,ecx ;if AC bit not toggled then CPU=386
mov [cputype],3
jz @@end_get_cpu ;cpu is 386
push ecx
popfd ;restore AC bit in eflags
;processor is at least 486
;
;Check for ability to set/clear ID flag in EFLAGS
;ID flag indicates ability of processor to execute the CPUID instruction.
;486 not guaranteed to have CPUID inst?
;
mov [cputype],4
mov eax,ecx ;original EFLAGS
xor eax,200000h ;toggle ID bit
push eax
popfd
pushfd
pop eax
xor eax,ecx ;check if still toggled
jz @@end_get_cpu
; Execute CPUID instruction to determine vendor, family,
; model and stepping.
;
mov [idflag],1 ;flag ID is available
xor eax,eax
cpuid
mov dword ptr [VendorID],ebx
mov dword ptr [VendorID+4],edx
mov dword ptr [VendorID+8],ecx
mov dword ptr [VendorID+12]," "
cmp eax,1 ;check if 1 is valid
jl @@end_get_cpu ;inp for cpuid inst.
xor eax,eax
inc eax
cpuid ;get stepping, model and family
and ax,0f00H
shr ax,08H
mov [cputype],al
@@end_get_cpu: mov al,[cputype]
mov [CPUType],al
;
; We have the CPU type in al now.
; If we arent on at least a pentium then we can assume there is no MMX
;
cmp al,5
jl @@no_mmx
mov eax,1
cpuid
test edx,00800000h
jz @@no_mmx
;
; MMX detected - return true
;
mov eax,1
ret
@@no_mmx: xor eax,eax
ret
Detect_MMX_Availability endp
.data
CPUType db 0
VendorID db "Not available",0,0,0,0,0,0
end