100 lines
3.5 KiB
NASM
100 lines
3.5 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!
|
|
;*
|
|
;*****************************************************************************
|
|
|
|
|
|
include mdef.inc
|
|
include struct.inc
|
|
|
|
.8087
|
|
modstart _7fu8386
|
|
|
|
xdefp __FSU87
|
|
xdefp __FDU87
|
|
|
|
defpe __FSU87
|
|
sub esp,12
|
|
mov [esp],eax
|
|
fld dword ptr [esp]
|
|
jmp short convert
|
|
|
|
defpe __FDU87
|
|
sub esp,12
|
|
mov [esp],eax
|
|
mov 4[esp],edx
|
|
fld qword ptr [esp]
|
|
|
|
; fall through
|
|
|
|
convert:
|
|
push ecx
|
|
fstp tbyte ptr 4[esp] ; get number out in memory
|
|
mov ax,12[esp] ; pick up sign/exponent
|
|
and ax,7fffh ; isolate exponent
|
|
sub ax,16383 ; remove bias
|
|
jl ret_zero ; if less than .5, return zero
|
|
cmp ax,64 ; are we too big?
|
|
jae ret_inf ; if so, return infinity
|
|
mov cl,63 ; calculate shift count
|
|
sub cl,al ; ...
|
|
mov eax,4[esp] ; pick up mantissa
|
|
mov edx,8[esp] ; ...
|
|
je negate ; skip out if no shifting
|
|
L2:
|
|
shr edx,1 ; shift down one bit
|
|
rcr eax,1 ; ...
|
|
dec cl ; are we done?
|
|
jne L2 ; do it again if not
|
|
negate:
|
|
test byte ptr 13[esp],80h ; is number negative?
|
|
jns done ; if not, we're done
|
|
neg edx ; negate number
|
|
neg eax ; ...
|
|
sbb edx,0 ; ...
|
|
done:
|
|
pop ecx ; ...
|
|
add esp,12 ; outta here
|
|
ret ; ...
|
|
|
|
ret_zero:
|
|
xor edx,edx
|
|
xor eax,eax
|
|
jmp done
|
|
|
|
ret_inf:
|
|
mov edx,0ffffffffh
|
|
mov eax,edx
|
|
jmp done
|
|
endproc __FDU87
|
|
endproc __FSU87
|
|
|
|
endmod
|
|
end
|