;*****************************************************************************
;*
;* 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