ldivide.s revision 7257d1b4d25bfac0c802847390e98a464fd787ac
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
.file "%M%"
/ Double long divide routine.
#include "SYS.h"
.set lop,16
.set rop,24
.set ans,0
ENTRY(ldivide)
popl %eax
xchgl %eax,0(%esp)
pushl %eax
pushl %esi
pushl %edi
movl lop(%esp),%eax
movl lop+4(%esp),%edx
/ the following code is only for compatibility with original ldivide code
orl %edx,%edx / force numerator positive
jns .ldiv1
notl %edx
negl %eax
sbbl $0xffffffff,%edx
.ldiv1:
testl $0x80000000,rop+4(%esp)
jz .ldiv2
notl rop+4(%esp) / force denominator positive
negl rop(%esp)
sbbl $0xffffffff,rop+4(%esp)
.ldiv2:
/ end of compatibility code
xorl %esi,%esi / initialize remainder to 0
movl %esi,%edi
movl $64,%ecx / initialize counter for 64-bits
.div_mod_loop:
shll $1,%edi
rcll $1,%esi / remainder * 2
shll $1,%eax
rcll $1,%edx / numerator * 2 (also quotient)
adcl $0,%edi / add in any carry from the shift
subl rop(%esp),%edi / subtract denominator from remainder
sbbl rop+4(%esp),%esi
incl %eax / turn on quotient bit for now
jnc .inc_remainder / inc didn't affect carry flag
/ can't subtract the denominator from the remainder, add it back
addl rop(%esp),%edi
adcl rop+4(%esp),%esi
decl %eax / turn quotient bit off
.inc_remainder:
loop .div_mod_loop
/ at this point, %edx:%eax has the quotient and %edi:%esi has the remainder
popl %edi
popl %esi
movl %eax,%ecx
popl %eax
movl %ecx,ans(%eax)
movl %edx,ans+4(%eax)
ret
SET_SIZE(ldivide)