1/*-
2 * Copyright (c) 2017,2023 Steven G. Kargl
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice unmodified, this list of conditions, and the following
10 *    disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27/*
28 * See ../src/s_tanpi.c for implementation details.
29 */
30
31#define INLINE_KERNEL_TANDF
32
33#include "math.h"
34#include "math_private.h"
35#include "k_tanf.c"
36
37static const float
38pi_hi =  3.14160156e+00F,	/* 0x40491000 */
39pi_lo = -8.90890988e-06F;	/* 0xb715777a */
40
41static inline float
42__kernel_tanpif(float x)
43{
44	float t;
45
46	if (x < 0.25F)
47		t = __kernel_tandf(M_PI * x, 1);
48	else if (x > 0.25F)
49		t = -__kernel_tandf(M_PI * (0.5 - x), -1);
50	else
51		t = 1;
52
53	return (t);
54}
55
56volatile static const float vzero = 0;
57
58float
59tanpif(float x)
60{
61	float ax, hi, lo, odd, t;
62	uint32_t hx, ix, j0;
63
64	GET_FLOAT_WORD(hx, x);
65	ix = hx & 0x7fffffff;
66	SET_FLOAT_WORD(ax, ix);
67
68	if (ix < 0x3f800000) {			/* |x| < 1 */
69		if (ix < 0x3f000000) {		/* |x| < 0.5 */
70			if (ix < 0x38800000) {	/* |x| < 0x1p-14 */
71				if (ix == 0)
72					return (x);
73				SET_FLOAT_WORD(hi, hx & 0xffff0000);
74				hi *= 0x1p23F;
75				lo = x * 0x1p23F - hi;
76				t = (pi_lo + pi_hi) * lo + pi_lo * hi +
77				    pi_hi * hi;
78				return (t * 0x1p-23F);
79			}
80			t = __kernel_tanpif(ax);
81		} else if (ix == 0x3f000000)
82			t = 1 / vzero;
83		else
84			t = - __kernel_tanpif(1 - ax);
85		return ((hx & 0x80000000) ? -t : t);
86	}
87
88	if (ix < 0x4b000000) {		/* 1 <= |x| < 0x1p23 */
89		FFLOORF(x, j0, ix);	/* Integer part of ax. */
90		odd = (uint32_t)x & 1 ? -1 : 1;
91		ax -= x;
92		GET_FLOAT_WORD(ix, ax);
93
94		if (ix < 0x3f000000)		/* |x| < 0.5 */
95			t = ix == 0 ? copysignf(0, odd) : __kernel_tanpif(ax);
96		else if (ix == 0x3f000000)
97			t = odd / vzero;
98		else
99			t = - __kernel_tanpif(1 - ax);
100		return ((hx & 0x80000000) ? -t : t);
101	}
102
103	/* x = +-inf or nan. */
104	if (ix >= 0x7f800000)
105		return (vzero / vzero);
106
107	/*
108	 * For 0x1p23 <= |x| < 0x1p24 need to determine if x is an even
109	 * or odd integer to set t = +0 or -0.
110	 * For |x| >= 0x1p24, it is always an even integer, so t = 0.
111	 */
112	t = ix >= 0x4b800000 ? 0 : (copysignf(0, (ix & 1) ? -1 : 1));
113	return ((hx & 0x80000000) ? -t : t);
114}
115