;*****************************************************************************
;*
;* 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!
;*
;*****************************************************************************
; This module converts a string to long_double
; void __ZBuf2LD( char *buf, long_double *value );
;
include mdef.inc
include struct.inc
modstart bufld386
xdefp __ZBuf2LD
;<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
;<> <>
;<> __ZBuf2LD - convert buffer of significant digits into floating <>
;<> void __ZBuf2LD( char *buf, long_double *value ) <>
;<> <>
;<> input: EAX - address of buffer of significant digits <>
;<> EDX - place to store value <>
;<> output: [EDX] - floating-point number <>
;<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
defpe __ZBuf2LD
push EBP ; save EBP
push ESI ; save ESI
push EDI ; save EDI
push ECX ; save ECX
push EBX ; save EBX
push EDX ; save pointer to result
mov ESI,EAX ; get address of buffer
sub EDX,EDX ; set 96-bit integer to 0
sub ECX,ECX ; ...
sub EBP,EBP ; ...
sub EAX,EAX ; zero out EAX
_loop ; loop (convert digits into 64-bit int)
mov AL,[ESI] ; - get next digit
cmp AL,0 ; - quit if at end of buffer
_quif e ; - . . .
;[] multiply current value in EDX:ECX:EBP by 10
mov EDI,EDX ; - save current value
mov EBX,ECX ; - ...
mov EAX,EBP ; - ...
_shl EBP,1 ; - multiply number by 4
_rcl ECX,1 ; - by shifting left 2 places
_rcl EDX,1 ; - ...
_shl EBP,1 ; - ...
_rcl ECX,1 ; - ...
_rcl EDX,1 ; - ...
add EBP,EAX ; - add original value
adc ECX,EBX ; - (this will make it times 5)
adc EDX,EDI ; - ...
_shl EBP,1 ; - shift left to make it times 10
_rcl ECX,1 ; - ...
_rcl EDX,1 ; - ...
sub EAX,EAX ; - zero eax
mov AL,[ESI] ; - get next digit
and AL,0Fh ; - isolate binary digit
add EBP,EAX ; - add in current digit
adc ECX,0 ; - ...
adc EDX,0 ; - ...
inc ESI ; - point to next digit in buffer
_endloop ; endloop
mov EAX,ECX ; get low order word into EAX
;[] Turn the integer in EDX:EAX:EBP into a real number
mov EDI,3FFFh+63+32 ; set exponent
call Norm ; convert the 64 bit integer to a float
pop EBP ; restore pointer to result
mov 4[EBP],EDX ; store result
mov 0[EBP],EAX ; ...
mov 8[EBP],SI ; ...
pop EBX ; restore EBX
pop ECX ; restore ECX
pop EDI ; restore EDI
pop ESI ; restore ESI
pop EBP ; restore EBP
ret ; return to caller
endproc __ZBuf2LD
;[] Norm normalizes an unsigned real in EDX:EAX:EBP i.e grab top 64 bits
;[] expects the exponent to be in EDI.
;[] SI contains the new exponent
Norm proc near ; normalize floating point number
sub ESI,ESI ; clear out SI
or ESI,EAX ; see if the integer is zero
or ESI,EDX ; ...
or ESI,EBP ; ...
_if ne ; if number is non-zero
or EDX,EDX ; - see if high word is 0
_if e ; - if high word is 0
mov EDX,EAX ; - - shift by 32-bits
mov EAX,EBP ; - - ...
sub EBP,EBP ; - - ...
sub EDI,32 ; - - adjust exponent by 32
_endif ; - endif
or EDX,EDX ; - see if high word is 0
_if e ; - if high word is 0
mov EDX,EAX ; - - shift by 32-bits
mov EAX,EBP ; - - ...
sub EBP,EBP ; - - ...
sub EDI,32 ; - - adjust exponent by 32
_endif ; - endif
_loop ; - loop
or EDX,EDX ; - - quit if high bit is on
_quif s ; - - ...
dec EDI ; - - decrement exponent
_shl EBP,1 ; - - shift integer left by 1 bit
_rcl EAX,1 ; - - ...
_rcl EDX,1 ; - - ...
_endloop ; - endloop
_shl EBP,1 ; - get top bit of extra word
adc EAX,0 ; - round up
adc EDX,0 ; - ...
_if c ; - if carry out the top
rcr EDX,1 ; - - shift fraction back 1
inc EDI ; - - increment exponent
_endif ; - endif
mov ESI,EDI ; - get exponent
_endif ; endif
ret ; return
endproc Norm
endmod
end