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1 | /* origin: FreeBSD /usr/src/lib/msun/src/s_cexpf.c */ |
2 | /*- | |
3 | * Copyright (c) 2011 David Schultz <das@FreeBSD.ORG> | |
4 | * All rights reserved. | |
5 | * | |
6 | * Redistribution and use in source and binary forms, with or without | |
7 | * modification, are permitted provided that the following conditions | |
8 | * are met: | |
9 | * 1. Redistributions of source code must retain the above copyright | |
10 | * notice, this list of conditions and the following 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 AND CONTRIBUTORS ``AS IS'' AND | |
16 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
17 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
18 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE | |
19 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
20 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
21 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
22 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
23 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
24 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
25 | * SUCH DAMAGE. | |
26 | */ | |
27 | ||
d4db3fa2 | 28 | #include "complex_impl.h" |
320054e8 DG |
29 | |
30 | static const uint32_t | |
31 | exp_ovfl = 0x42b17218, /* MAX_EXP * ln2 ~= 88.722839355 */ | |
32 | cexp_ovfl = 0x43400074; /* (MAX_EXP - MIN_DENORM_EXP) * ln2 */ | |
33 | ||
34 | float complex cexpf(float complex z) | |
35 | { | |
36 | float x, y, exp_x; | |
37 | uint32_t hx, hy; | |
38 | ||
39 | x = crealf(z); | |
40 | y = cimagf(z); | |
41 | ||
42 | GET_FLOAT_WORD(hy, y); | |
43 | hy &= 0x7fffffff; | |
44 | ||
45 | /* cexp(x + I 0) = exp(x) + I 0 */ | |
46 | if (hy == 0) | |
47 | return CMPLXF(expf(x), y); | |
48 | GET_FLOAT_WORD(hx, x); | |
49 | /* cexp(0 + I y) = cos(y) + I sin(y) */ | |
50 | if ((hx & 0x7fffffff) == 0) | |
51 | return CMPLXF(cosf(y), sinf(y)); | |
52 | ||
53 | if (hy >= 0x7f800000) { | |
54 | if ((hx & 0x7fffffff) != 0x7f800000) { | |
55 | /* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */ | |
56 | return CMPLXF(y - y, y - y); | |
57 | } else if (hx & 0x80000000) { | |
58 | /* cexp(-Inf +- I Inf|NaN) = 0 + I 0 */ | |
59 | return CMPLXF(0.0, 0.0); | |
60 | } else { | |
61 | /* cexp(+Inf +- I Inf|NaN) = Inf + I NaN */ | |
62 | return CMPLXF(x, y - y); | |
63 | } | |
64 | } | |
65 | ||
66 | if (hx >= exp_ovfl && hx <= cexp_ovfl) { | |
67 | /* | |
68 | * x is between 88.7 and 192, so we must scale to avoid | |
69 | * overflow in expf(x). | |
70 | */ | |
71 | return __ldexp_cexpf(z, 0); | |
72 | } else { | |
73 | /* | |
74 | * Cases covered here: | |
75 | * - x < exp_ovfl and exp(x) won't overflow (common case) | |
76 | * - x > cexp_ovfl, so exp(x) * s overflows for all s > 0 | |
77 | * - x = +-Inf (generated by exp()) | |
78 | * - x = NaN (spurious inexact exception from y) | |
79 | */ | |
80 | exp_x = expf(x); | |
81 | return CMPLXF(exp_x * cosf(y), exp_x * sinf(y)); | |
82 | } | |
83 | } |