mirror of
https://github.com/KolibriOS/kolibrios.git
synced 2024-12-01 21:17:05 +03:00
119 lines
4.7 KiB
NASM
119 lines
4.7 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!
|
|
;*
|
|
;*****************************************************************************
|
|
|
|
|
|
include mdef.inc
|
|
include struct.inc
|
|
|
|
modstart fdmd386
|
|
|
|
xdefp "C",_dieeetomsbin
|
|
defpe _dieeetomsbin
|
|
|
|
ifdef __STACK__
|
|
mov eax,dword ptr +4H[esp] ; load src double ptr
|
|
mov edx,dword ptr +8H[esp] ; load dst double ptt
|
|
else
|
|
push ecx ; save register
|
|
endif
|
|
|
|
; At this point:
|
|
; eax - ptr to IEEE source double
|
|
; edx - ptr to MBF dest double
|
|
; ecx - spare register
|
|
|
|
; Check for IEEE Underflow first
|
|
mov ecx,+4h[eax] ; load IEEE double (hi)
|
|
rol ecx,1 ; rotate sign bit away for comparisons
|
|
cmp ecx,6fe00000H ; exponent < 1023 - 128 ?
|
|
jae IEEENoUnderflow ; yes, jump
|
|
|
|
; IEEE Underflow, store MBF 0.0
|
|
xor eax,eax ; make 0
|
|
mov [edx],eax ; store MBF 0.0 (lo)
|
|
mov +4h[edx],eax ; store MBF 0.0 (hi)
|
|
ifndef __STACK__
|
|
pop ecx ; clean up
|
|
endif
|
|
ret ; return 0 (no overflow)
|
|
|
|
; Check for IEEE Overflow
|
|
IEEENoUnderflow:
|
|
cmp ecx,8fc00000H ; exponent >= 1023 + 127 ?
|
|
jae IEEEOverflow ; yes, jump
|
|
|
|
; General IEEE case, load rest of double
|
|
mov eax,[eax] ; load IEEE double (lo)
|
|
ror ecx,1 ; rotate sign bit back into place
|
|
|
|
; At this point:
|
|
; ecx:eax - IEEE source double
|
|
; edx - ptr to MBF dest double
|
|
|
|
push ecx ; save sign bit
|
|
|
|
; shift exponent & mantissa into place
|
|
shld ecx,eax,3 ; shift exponent and mantissa
|
|
shl eax,3 ; :
|
|
mov [edx],eax ; save mantissa
|
|
rol ecx,9 ; convert IEEE exponent to MBF
|
|
shr ecx,1 ; :
|
|
adc cl,cl ; :
|
|
add cl,82h ; correct MBF exponent
|
|
pop eax ; restore sign bit
|
|
add eax,eax ; shift sign bit into carry
|
|
adc ecx,ecx ; add in sign bit
|
|
ror ecx,9 ; MBF double (hi)
|
|
mov +4h[edx],ecx ; store MBF double (hi)
|
|
xor eax,eax ; 0
|
|
ifndef __STACK__
|
|
pop ecx ; clean up
|
|
endif
|
|
ret ; return 0 (no overflow)
|
|
|
|
; IEEE Overflow, store maximum MBF, preserving sign
|
|
IEEEOverflow: or ecx,0FFFFFFFFEh ; set MBF exponent and mantissa to maximum
|
|
mov eax,ecx ; :
|
|
ror ecx,9 ; rotate sign bit into place for MBF
|
|
sar eax,1 ; now -1
|
|
mov +4h[edx],ecx ; store IEEE double (hi)
|
|
mov [edx],eax ; store IEEE double (lo)
|
|
neg eax ; 1
|
|
ifndef __STACK__
|
|
pop ecx ; clean up
|
|
endif
|
|
ret ; return 1 (overflow)
|
|
|
|
endproc _dieeetomsbin
|
|
|
|
endmod
|
|
end
|