86 lines
3.6 KiB
NASM
86 lines
3.6 KiB
NASM
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;*****************************************************************************
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;*
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;* Open Watcom Project
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;*
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;* Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
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;*
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;* ========================================================================
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;*
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;* This file contains Original Code and/or Modifications of Original
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;* Code as defined in and that are subject to the Sybase Open Watcom
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;* Public License version 1.0 (the 'License'). You may not use this file
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;* except in compliance with the License. BY USING THIS FILE YOU AGREE TO
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;* ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
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;* provided with the Original Code and Modifications, and is also
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;* available at www.sybase.com/developer/opensource.
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;*
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;* The Original Code and all software distributed under the License are
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;* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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;* EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
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;* ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF
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;* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR
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;* NON-INFRINGEMENT. Please see the License for the specific language
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;* governing rights and limitations under the License.
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;*
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;* ========================================================================
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;*
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;* Description: WHEN YOU FIGURE OUT WHAT THIS FILE DOES, PLEASE
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;* DESCRIBE IT HERE!
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;*
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;*****************************************************************************
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;<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
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;<>
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;<> __FDC - floating double comparison
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;<> input: EDX:EAX - operand 1
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;<> ECX:EBX - operand 2
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;<> if op1 > op2, 1 is returned in EAX
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;<> if op1 < op2, -1 is returned in EAX
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;<> if op1 = op2, 0 is returned in EAX
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;<>
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;<>
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;<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
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include mdef.inc
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include struct.inc
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modstart fdc386
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xdefp __FDC
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defpe __FDC
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push EBP ; save BP
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test EDX,07ff00000h ; check for zero
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_if e ; if it is then
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sub EDX,EDX ; - make whole damn thing a zero
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_endif ; endif
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test ECX,07ff00000h ; check op2 for zero
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_if e ; if it is then
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sub ECX,ECX ; - make whole damn thing a zero
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_endif ; endif
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mov EBP,ECX ; save op2 exponent
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xor EBP,EDX ; see about signs of the operands
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mov EBP,0 ; clear result
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js short cmpdone ; quif arg1 & arg2 have diff signs
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_guess ; guess
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cmp EDX,ECX ; - compare high words of arg1, arg2
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_quif ne ; - quif not equal
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cmp EAX,EBX ; - compare 2nd words of arg1, arg2
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_endguess ; endguess
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_if ne ; if arg1 <> arg2
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rcr ECX,1 ; - save carry in CX
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xor EDX,ECX ; - sign of BX is sign of result
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cmpdone: _shl EDX,1 ; - get sign of result into carry
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sbb EBP,0 ; - BP gets sign of result
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_shl EBP,1 ; - double BP
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inc EBP ; - make BP -1 or 1
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_endif ; endif
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mov EAX,EBP ; get result
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pop EBP ; restore BP
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ret ; return to caller
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endproc __FDC
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endmod
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end
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