75 lines
2.3 KiB
NASM
75 lines
2.3 KiB
NASM
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; File:
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; cpu.asm
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; Description:
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; Query basic CPU running on
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;
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; DOS-C
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; Copyright (c) 2012
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; FreeDOS
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; All Rights Reserved
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;
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; This file is part of DOS-C.
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;
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; DOS-C is free software; you can redistribute it and/or
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; modify it under the terms of the GNU General Public License
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; as published by the Free Software Foundation; either version
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; 2, or (at your option) any later version.
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;
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; DOS-C is distributed in the hope that it will be useful, but
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; WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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; the GNU General Public License for more details.
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;
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;
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%include "segs.inc"
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segment INIT_TEXT
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CPU 386
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;*********************************************************************
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;
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; UWORD query_cpu() based on Eric Auer's public domain cpulevel.asm
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; input: none
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; output: ax = cpu, 0=8086/8088, 1=186/188, 2=286, 3=386+
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global _query_cpu
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_query_cpu:
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; save registers, assumes enough space on stack & valid stack frame setup
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;push ax - no need to save, return value saved here
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push bx
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push cx
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pushf ; save flags
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; begin check, assume x86 unless later family detected
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xor bx, bx ; 808x or 186 highest detected family stored in bx
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push bx
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popf ; try to clear all flag bits
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pushf ; copy flags to ax so we can test if clear succeeded
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pop ax
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and ax, 0f000h
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cmp ax, 0f000h
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jnz is286 ; no the 4 msb stuck set to 1, so is a 808x or 8018x
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mov ax,1 ; determine if 8086 or 186
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mov cl,64 ; try to shift further than size of ax
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shr ax,cl
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or ax,ax
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jz is086 ; 186 ignores the upper bits of cl
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mov bx, 1 ; 186: above 808x, below 286
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is086: jmp short cleanup
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is286: mov bx, 2 ; at least 286
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mov ax, 0f000h
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push ax
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popf ; try to set 4 msb of flags
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pushf ; copy flags to ax so we can test if clear succeeded
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pop ax
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test ax, 0f000h
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jz cleanup ; 4 msb stuck to 0: 80286
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mov bx, 3 ; at least 386
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cleanup:
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mov ax, bx ; return CPU family
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popf
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pop cx
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pop bx
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retn
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