/*
* 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 2011 Nexenta Systems, Inc. All rights reserved.
*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
.file "round.s"
#include "libm.h"
LIBM_ANSI_PRAGMA_WEAK(round,function)
.section .rodata
.align 4
.Lhalf: .float 0.5
ENTRY(round)
movl %esp,%ecx
subl $8,%esp
fstcw -8(%ecx)
fldl 4(%ecx)
movw -8(%ecx),%dx
andw $0xf3ff,%dx
movw %dx,-4(%ecx)
fldcw -4(%ecx) / set RD = to_nearest
fld %st(0)
frndint / [x],x
fstcw -4(%ecx)
movw -4(%ecx),%dx
andw $0xf3ff,%dx
movw -8(%ecx),%ax
andw $0x0c00,%ax
orw %dx,%ax
movw %ax,-8(%ecx)
fldcw -8(%ecx) / restore RD
fucom / check if x is already an integer
fstsw %ax
sahf
jp 0f
je 0f
fxch / x,[x]
fsub %st(1),%st / x-[x],[x]
fabs / |x-[x]|,[x]
PIC_SETUP(1)
fcoms PIC_L(.Lhalf)
PIC_WRAPUP
fnstsw %ax
sahf
jae 2f / if |x-[x]| = 0.5 goto halfway,
/ most cases will not take branch.
0:
addl $8,%esp
fstp %st(0)
ret
2:
/ x = n+0.5, recompute round(x) as x+sign(x)*0.5
fldl 4(%ecx) / x, 0.5, [x]
movl 8(%ecx),%eax / high part of x
andl $0x80000000,%eax
jnz 3f
faddp
addl $8,%esp
fstp %st(1)
ret
3:
/ here, x is negative, so return x-0.5
fsubp %st,%st(1) / x-0.5,[x]
addl $8,%esp
fstp %st(1)
ret
.align 4
SET_SIZE(round)