91 lines
3.7 KiB
NASM
91 lines
3.7 KiB
NASM
;*****************************************************************************
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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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include mdef.inc
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include struct.inc
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modstart i4fd386
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xdefp __I4FD
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xdefp __U4FD
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;[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]
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;[]
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;[] __I4FD convert signed 32-bit integer in EAX into double float
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;[] __U4FD convert unsigned 32-bit integer in EAX into double float
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;[] Input: EAX - 32-bit integer
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;[] Output: EDX:EAX - double precision representation of integer
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;[]
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;[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]
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defpe __I4FD
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or EAX,EAX ; if number is negative
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_if s ; then
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neg EAX ; - negate number
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mov EDX,00000BFFh ; - set exponent
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_else ; else
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; convert unsigned 32-bit integer to double
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defpe __U4FD
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mov EDX,000003FFh ; - set exponent
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_endif ; endif
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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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mov CL,31 ; - calculate # of bits to shift by
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sub CL,CH ; - ...
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shl EAX,CL ; - shift bits into position
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_shl EAX,1 ; - one more to get rid of implied 1 bit
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mov CL,CH ; - get shift count
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movzx ECX,CH ; - get shift count
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add ECX,EDX ; - calculate exponent
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mov EDX,EAX ; - get the bits
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and EDX,0FFFFF000h ; - keep 20 bits
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or EDX,ECX ; - get exponent in there
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ror EDX,12 ; - rotate into position
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shl EAX,20 ; - get last 12 bits into place
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pop ECX ; - restore ECX
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ret ; - return
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_endif ; endif
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sub EDX,EDX ; zero EDX
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ret ; return
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endproc __U4FD
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endproc __I4FD
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endmod
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end
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