1/* ix87 specific implementation of arctanh function.
2   Copyright (C) 1996, 1999 Free Software Foundation, Inc.
3   This file is part of the GNU C Library.
4   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
5
6   The GNU C Library is free software; you can redistribute it and/or
7   modify it under the terms of the GNU Lesser General Public
8   License as published by the Free Software Foundation; either
9   version 2.1 of the License, or (at your option) any later version.
10
11   The GNU C Library is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   Lesser General Public License for more details.
15
16   You should have received a copy of the GNU Lesser General Public
17   License along with the GNU C Library; if not, write to the Free
18   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19   02111-1307 USA.  */
20
21#include <machine/asm.h>
22
23#ifdef __ELF__
24	.section .rodata
25#else
26	.text
27#endif
28
29	.align ALIGNARG(4)
30	ASM_TYPE_DIRECTIVE(half,@object)
31half:	.double 0.5
32	ASM_SIZE_DIRECTIVE(half)
33	ASM_TYPE_DIRECTIVE(one,@object)
34one:	.double 1.0
35	ASM_SIZE_DIRECTIVE(one)
36	ASM_TYPE_DIRECTIVE(limit,@object)
37limit:	.double 0.29
38	ASM_SIZE_DIRECTIVE(limit)
39	ASM_TYPE_DIRECTIVE(ln2_2,@object)
40ln2_2:	.tfloat 0.3465735902799726547086160
41	ASM_SIZE_DIRECTIVE(ln2_2)
42
43#ifdef PIC
44#define MO(op) op##@GOTOFF(%edx)
45#else
46#define MO(op) op
47#endif
48
49	.text
50ENTRY(__ieee754_atanh)
51	movl	8(%esp), %ecx
52
53	movl	%ecx, %eax
54	andl	$0x7fffffff, %eax
55	cmpl	$0x7ff00000, %eax
56	jae	5f
577:
58
59#ifdef PIC
60	call	1f
611:	popl	%edx
62	addl	$_GLOBAL_OFFSET_TABLE_+[.-1b], %edx
63#endif
64
65	andl	$0x80000000, %ecx // ECX == 0 iff X >= 0
66
67	fldt	MO(ln2_2)	// 0.5*ln2
68	xorl	%ecx, 8(%esp)
69	fldl	4(%esp)		// |x| : 0.5*ln2
70	fcoml	MO(half)	// |x| : 0.5*ln2
71	fld	%st		// |x| : |x| : 0.5*ln2
72	fnstsw			// |x| : |x| : 0.5*ln2
73	sahf
74	jae	2f
75	fadd	%st, %st(1)	// |x| : 2*|x| : 0.5*ln2
76	fld	%st		// |x| : |x| : 2*|x| : 0.5*ln2
77	fsubrl	MO(one)		// 1-|x| : |x| : 2*|x| : 0.5*ln2
78	fxch			// |x| : 1-|x| : 2*|x| : 0.5*ln2
79	fmul	%st(2)		// 2*|x|^2 : 1-|x| : 2*|x| : 0.5*ln2
80	fdivp			// (2*|x|^2)/(1-|x|) : 2*|x| : 0.5*ln2
81	faddp			// 2*|x|+(2*|x|^2)/(1-|x|) : 0.5*ln2
82	fcoml	MO(limit)	// 2*|x|+(2*|x|^2)/(1-|x|) : 0.5*ln2
83	fnstsw			// 2*|x|+(2*|x|^2)/(1-|x|) : 0.5*ln2
84	sahf
85	jae	4f
86	fyl2xp1			// 0.5*ln2*ld(1+2*|x|+(2*|x|^2)/(1-|x|))
87	jecxz	3f
88	fchs			// 0.5*ln2*ld(1+2*x+(2*x^2)/(1-x))
893:	ret
90
91	.align ALIGNARG(4)
924:	faddl	MO(one)		// 1+2*|x|+(2*|x|^2)/(1-|x|) : 0.5*ln2
93	fyl2x			// 0.5*ln2*ld(1+2*|x|+(2*|x|^2)/(1-|x|))
94	jecxz	3f
95	fchs			// 0.5*ln2*ld(1+2*x+(2*x^2)/(1-x))
963:	ret
97
98	.align ALIGNARG(4)
992:	faddl	MO(one)		// 1+|x| : |x| : 0.5*ln2
100	fxch			// |x| : 1+|x| : 0.5*ln2
101	fsubrl	MO(one)		// 1-|x| : 1+|x| : 0.5*ln2
102	fdivrp			// (1+|x|)/(1-|x|) : 0.5*ln2
103	fyl2x			// 0.5*ln2*ld((1+|x|)/(1-|x|))
104	jecxz	3f
105	fchs			// 0.5*ln2*ld((1+x)/(1-x))
1063:	ret
107
108	// x == NaN or �Inf
1095:	ja	6f
110	cmpl	$0, 4(%esp)
111	je	7b
1126:	fldl	4(%esp)
113	ret
114END(__ieee754_atanh)
115