mirror of
https://github.com/KolibriOS/kolibrios.git
synced 2024-12-24 07:36:48 +03:00
85 lines
3.7 KiB
NASM
85 lines
3.7 KiB
NASM
;*****************************************************************************
|
|
;*
|
|
;* Open Watcom Project
|
|
;*
|
|
;* Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
|
|
;*
|
|
;* ========================================================================
|
|
;*
|
|
;* This file contains Original Code and/or Modifications of Original
|
|
;* Code as defined in and that are subject to the Sybase Open Watcom
|
|
;* Public License version 1.0 (the 'License'). You may not use this file
|
|
;* except in compliance with the License. BY USING THIS FILE YOU AGREE TO
|
|
;* ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
|
|
;* provided with the Original Code and Modifications, and is also
|
|
;* available at www.sybase.com/developer/opensource.
|
|
;*
|
|
;* The Original Code and all software distributed under the License are
|
|
;* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
|
|
;* EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
|
|
;* ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF
|
|
;* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR
|
|
;* NON-INFRINGEMENT. Please see the License for the specific language
|
|
;* governing rights and limitations under the License.
|
|
;*
|
|
;* ========================================================================
|
|
;*
|
|
;* Description: WHEN YOU FIGURE OUT WHAT THIS FILE DOES, PLEASE
|
|
;* DESCRIBE IT HERE!
|
|
;*
|
|
;*****************************************************************************
|
|
|
|
|
|
;=========================================================================
|
|
;== Name: FDFS ==
|
|
;== Operation: Float double to float single conversion ==
|
|
;== Inputs: EDX:EAX double precision float ==
|
|
;== Outputs: EAX single precision float ==
|
|
;== Volatile: EDX destroyed ==
|
|
;=========================================================================
|
|
include mdef.inc
|
|
include struct.inc
|
|
|
|
modstart fdfs386
|
|
|
|
xdefp __FDFS
|
|
|
|
defpe __FDFS
|
|
push EBX ; save EBX
|
|
test EDX,07ff00000h ; check exponent
|
|
je short retzero ; if exponent = 0 then just return 0
|
|
sub EBX,EBX ; set to 0
|
|
_shl EAX,1 ; shift number over
|
|
_rcl EDX,1 ; ...
|
|
rcr EBX,1 ; save sign
|
|
add EAX,20000000h ; round floating point number
|
|
adc EDX,0 ; ...
|
|
je oflow ; overflow if exponent went to 0
|
|
cmp EDX,(03ffh+80h) shl 21 ; check for maximum exponent
|
|
jae oflow ; overflow if above or equal
|
|
cmp EDX,(03ffh-7eh) shl 21 ; check for minimum exponent
|
|
jb uflow ; underflow if below
|
|
sub EDX,(03ffh-7fh) shl 21 ; correct bias
|
|
_shl EAX,1 ; do rest of shift
|
|
_rcl EDX,1 ; ...
|
|
_shl EAX,1 ; ...
|
|
_rcl EDX,1 ; ...
|
|
or EDX,EBX ; put in sign bit
|
|
mov EAX,EDX ; get result into EAX
|
|
pop EBX ; restore EBX
|
|
ret ; return
|
|
|
|
oflow: mov EAX,7F800000h ; return maximum possible number
|
|
or EAX,EBX ; put in sign bit
|
|
pop EBX ; restore EBX
|
|
ret ; and return
|
|
|
|
uflow:
|
|
retzero:sub EAX,EAX ; set result to 0
|
|
pop EBX ; restore EBX
|
|
ret
|
|
endproc __FDFS
|
|
|
|
endmod
|
|
end
|