1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2011 David Schultz <das@FreeBSD.ORG>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <complex.h>
30#include <math.h>
31
32#include "math_private.h"
33
34static const uint32_t
35exp_ovfl  = 0x42b17218,		/* MAX_EXP * ln2 ~= 88.722839355 */
36cexp_ovfl = 0x43400074;		/* (MAX_EXP - MIN_DENORM_EXP) * ln2 */
37
38float complex
39cexpf(float complex z)
40{
41	float c, exp_x, s, x, y;
42	uint32_t hx, hy;
43
44	x = crealf(z);
45	y = cimagf(z);
46
47	GET_FLOAT_WORD(hy, y);
48	hy &= 0x7fffffff;
49
50	/* cexp(x + I 0) = exp(x) + I 0 */
51	if (hy == 0)
52		return (CMPLXF(expf(x), y));
53	GET_FLOAT_WORD(hx, x);
54	/* cexp(0 + I y) = cos(y) + I sin(y) */
55	if ((hx & 0x7fffffff) == 0) {
56		sincosf(y, &s, &c);
57		return (CMPLXF(c, s));
58	}
59
60	if (hy >= 0x7f800000) {
61		if ((hx & 0x7fffffff) != 0x7f800000) {
62			/* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */
63			return (CMPLXF(y - y, y - y));
64		} else if (hx & 0x80000000) {
65			/* cexp(-Inf +- I Inf|NaN) = 0 + I 0 */
66			return (CMPLXF(0.0, 0.0));
67		} else {
68			/* cexp(+Inf +- I Inf|NaN) = Inf + I NaN */
69			return (CMPLXF(x, y - y));
70		}
71	}
72
73	if (hx >= exp_ovfl && hx <= cexp_ovfl) {
74		/*
75		 * x is between 88.7 and 192, so we must scale to avoid
76		 * overflow in expf(x).
77		 */
78		return (__ldexp_cexpf(z, 0));
79	} else {
80		/*
81		 * Cases covered here:
82		 *  -  x < exp_ovfl and exp(x) won't overflow (common case)
83		 *  -  x > cexp_ovfl, so exp(x) * s overflows for all s > 0
84		 *  -  x = +-Inf (generated by exp())
85		 *  -  x = NaN (spurious inexact exception from y)
86		 */
87		exp_x = expf(x);
88		sincosf(y, &s, &c);
89		return (CMPLXF(exp_x * c, exp_x * s));
90	}
91}
92