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kolibrios/programs/develop/open watcom/trunk/clib/cgsupp/fsi8386.asm
Sergey Semyonov (Serge) 836c97f0ac Clib string & memory functions
git-svn-id: svn://kolibrios.org@553 a494cfbc-eb01-0410-851d-a64ba20cac60
2007-06-26 00:54:22 +00:00

151 lines
5.6 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!
;*
;*****************************************************************************
;
; from float to signed/unsigned int64
;
include mdef.inc
include struct.inc
modstart fsi8386
xref __U8LS
xref __U8RS
; Convert single precision float to unsigned 64-bit integer with truncation
; Input: [EAX] = 32-bit float
; Output: [EDX, EAX] = 64-bit integer
xdefp __FSU8
defp __FSU8
push ECX ; save ECX
mov CL,7fh+64 ; maximum number 2^64-1
call __FSU ; convert float to unsigned __int64
pop ECX ; restore ECX
ret ; return
endproc __FSU8
; Convert single precision float to signed 64-bit integer with truncation
; Input: [EAX] = 32-bit float
; Output: [EDX, EAX] = 64-bit integer
xdefp __FSI8
defp __FSI8
push ECX ; save ECX
mov CL,7fh+63 ; maximum number 2^63-1
call __FSI ; convert float to signed __int64
pop ECX ; restore ECX
ret ; return
endproc __FSI8
__FSI proc near
__FSU: ; what? they both do the same thing
or EAX,EAX ; check sign bit
jns short __FSAbs ; treat as unsigned if positive
call __FSAbs ; otherwise convert number
neg EDX ; negate the result
neg EAX ;
sbb EDX,0 ;
ret ; return
endproc __FSI
__FSAbs proc near
or EAX,EAX ; check if number 0
je short fltzero ; if so, just return 0
_shl EAX,1 ; shift mantissa over
rol EAX,8 ; get exponent to bottom
cmp AL,7fh ; quit if number < 1.0
jb short fltuflow ; ...
push EBX ; save EBX
mov CH,AL ; save exponent
stc ; set carry for implied bit
rcr EAX,1 ; put implied '1' bit in
shr EAX,8 ; remove exponent and extra bit
mov EDX,EAX ; put into 64-bit hi part
xor EAX,EAX ; zero 64-bit lo part
cmp CH,CL ; check if exponent exceeds maximum
jae short fltmax ; return maximum value if so
sub CH,7fh+55 ; calculate amount to shift (+ve -> left)
jae short fltm_left ; jump if left shift/no shift
xchg CH,CL ; get shift count
neg CL ; make positive
mov BX,CX
call __U8RS ; shift mantissa right
pop EBX ; restore EBX
ret ; return
fltm_left:
_if ne ; done if exponent exactly 55
mov BL,CH ; - get shift count
call __U8LS ; - shift mantissa left
_endif ; endif
pop EBX ; restore EBX
ret ; return
; CL = 7fh+64 for unsigned
; 7fh+63 for signed
fltmax:
mov EAX,0FFFFFFFFh ; return maximum value
mov EDX,EAX ;
sub CL,7fh+64 ; subtract bias + 64, results in 0 or -1
neg CL ; get shift count
mov BL,CL ; set shift count
call __U8RS ; shift mantissa right 1 bit for signed
pop EBX ; restore EBX
ret ; return
fltuflow:
sub EAX,EAX ; ensure entire number 0
fltzero:
sub EDX,EDX ;
ret ; return
endproc __FSAbs
; Convert single precision float to unsigned 64-bit integer with rounding
; Input: [EAX] = 32-bit float
; xdefp __RSU8
; defp __RSU8
; not implemented
; endproc __RSU8
; Convert single precision float to signed 64-bit integer with rounding
; Input: [EAX] = 32-bit float
; xdefp __RSI8
; defp __RSI8
; not implemented
; endproc __RSI8
endmod
end