83 lines
3.6 KiB
NASM
83 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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;== Name: I4FS, U4FS ==
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;== Operation: Convert Integer types to single precision ==
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;== Inputs: EAX, unsigned or signed integer ==
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;== Outputs: EAX single precision floating point ==
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;== Volatile: none ==
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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 i4fs386
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xdefp __I4FS
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xdefp __U4FS
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defpe __U4FS
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or EAX,EAX ; if number is not zero
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_if ne ; then
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push ECX ; - save ECX
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bsr ECX,EAX ; - find most significant non-zero bit
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mov CH,CL ; - save shift count
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neg CL ; - calculate # of bits to rotate by
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add CL,23 ; - ...
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and CL,1fh ; - just keep last 5 bits
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rol EAX,CL ; - shift bits into position
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and EAX,007FFFFFh ; - mask out sign and exponent bits
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mov CL,CH ; - get shift count
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add CL,7Fh ; - calculate exponent
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and ECX,0FFh ; - isolate exponent
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shl ECX,23 ; - shift exponent into position
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or EAX,ECX ; - place into result
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pop ECX ; - restore ECX
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_endif ; endif
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ret ; return
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endproc __U4FS
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defpe __I4FS
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or EAX,EAX ; check sign
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jns __U4FS ; if positive, just convert
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neg EAX ; take absolute value of number
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call __U4FS ; convert to FS
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or EAX,80000000h ; set sign bit on
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ret ; and return
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endproc __I4FS
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endmod
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end
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