1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
23 */
24/*
25 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
26 * Use is subject to license terms.
27 */
28
29	.file	"lround.s"
30
31#include "libm.h"
32LIBM_ANSI_PRAGMA_WEAK(lround,function)
33
34	.section .rodata
35	.align	4
36.Lhalf:	.float	0.5
37
38	ENTRY(lround)
39	movl	%esp,%ecx
40	subl	$8,%esp
41	fstcw	-8(%ecx)
42	fldl	4(%ecx)
43	movw	-8(%ecx),%dx
44	andw	$0xf3ff,%dx
45	movw	%dx,-4(%ecx)
46	fldcw	-4(%ecx)		/ set RD = to_nearest
47	fld	%st(0)
48	frndint				/ [x],x
49	fstcw	-4(%ecx)
50	movw	-4(%ecx),%dx
51	andw	$0xf3ff,%dx
52	movw	-8(%ecx),%ax
53	andw	$0x0c00,%ax
54	orw	%dx,%ax
55	movw	%ax,-8(%ecx)
56	fldcw	-8(%ecx)		/ restore RD
57	fucom				/ check if x is already an integer
58	fstsw	%ax
59	sahf
60	jp	0f
61	je	0f
62	fxch				/ x,[x]
63	fsub	%st(1),%st		/ x-[x],[x]
64	fabs				/ |x-[x]|,[x]
65	PIC_SETUP(1)
66	fcoms	PIC_L(.Lhalf)
67	PIC_WRAPUP
68	fnstsw	%ax
69	sahf
70	jae	2f			/ if |x-[x]| = 0.5 goto halfway,
71					/ most cases will not take branch.
720:
73	fstp	%st(0)
741:
75	fistpl	-8(%ecx)
76	fwait
77	movl	-8(%ecx),%eax
78	addl	$8,%esp
79	ret
802:
81    / x = n+0.5, recompute lround(x) as x+sign(x)*0.5
82	fldl	4(%ecx)			/ x, 0.5, [x]
83	movl	8(%ecx),%eax		/ high part of x
84	andl	$0x80000000,%eax
85	jnz	3f
86	faddp
87	fstp	%st(1)
88	jmp	1b
893:
90	/ here, x is negative, so return x-0.5
91	fsubp	%st,%st(1)		/ x-0.5,[x]
92	fstp	%st(1)
93	jmp	1b
94	.align	4
95	SET_SIZE(lround)
96