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82 lines
2.0 KiB
82 lines
2.0 KiB
title "Processor type and stepping detection"
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;++
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;
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; Copyright (c) 1989 Microsoft Corporation
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;
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; Module Name:
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;
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; cpu.asm
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;
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; Abstract:
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;
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; This module implements the assembley code necessary to determine
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; cpu type and stepping information.
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;
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; Author:
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;
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; Shie-Lin Tzong (shielint) 28-Oct-1991.
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;
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; Environment:
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;
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; 80x86
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;
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; Revision History:
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;
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;--
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.386p
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_TEXT SEGMENT DWORD PUBLIC 'CODE'
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ASSUME DS:FLAT, ES:FLAT, SS:NOTHING, FS:NOTHING, GS:NOTHING
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CR0_AM equ 40000h
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EFLAGS_AC equ 40000h
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;++
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;
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; BOOLEAN
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; SlIs386(
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; VOID
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; )
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;
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; Routine Description:
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;
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; This function determines whether the processor we're running on
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; is a 386. If not a 386, it is assumed that the processor is
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; a 486 or greater.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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; (al) = 1 - processor is a 386
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; (al) = 0 - processor is a 486 or greater.
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;
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;--
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public _SlIs386@0
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_SlIs386@0 proc
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mov eax,cr0
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push eax ; save current cr0
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and eax,not CR0_AM ; mask out alignment check bit
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mov cr0,eax ; disable alignment check
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pushfd ; save flags
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pushfd ; turn on alignment check bit in
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or dword ptr [esp],EFLAGS_AC ; a copy of the flags register
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popfd ; and try to load flags
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pushfd
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pop ecx ; get new flags into ecx
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popfd ; restore original flags
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pop eax ; restore original cr0
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mov cr0,eax
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xor al,al ; prepare for return, assume not 386
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and ecx,EFLAGS_AC ; did AC bit get set?
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jnz short @f ; yes, we don't have a 386
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inc al ; we have a 386
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@@: ret
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_SlIs386@0 endp
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_TEXT ends
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end
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