| Elliott Hughes | a0ee078 | 2013-01-30 19:06:37 -0800 | [diff] [blame] | 1 | /*- |
| 2 | * Copyright (c) 2011 David Schultz <das@FreeBSD.ORG> |
| 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, this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer in the |
| 12 | * documentation and/or other materials provided with the distribution. |
| 13 | * |
| 14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| 15 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 16 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 17 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| 18 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 19 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 20 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 21 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 22 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 23 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 24 | * SUCH DAMAGE. |
| 25 | */ |
| 26 | |
| 27 | #include <sys/cdefs.h> |
| 28 | __FBSDID("$FreeBSD$"); |
| 29 | |
| 30 | #include <complex.h> |
| 31 | #include <math.h> |
| 32 | |
| 33 | #include "math_private.h" |
| 34 | |
| 35 | static const uint32_t |
| 36 | exp_ovfl = 0x42b17218, /* MAX_EXP * ln2 ~= 88.722839355 */ |
| 37 | cexp_ovfl = 0x43400074; /* (MAX_EXP - MIN_DENORM_EXP) * ln2 */ |
| 38 | |
| 39 | float complex |
| 40 | cexpf(float complex z) |
| 41 | { |
| 42 | float x, y, exp_x; |
| 43 | uint32_t hx, hy; |
| 44 | |
| 45 | x = crealf(z); |
| 46 | y = cimagf(z); |
| 47 | |
| 48 | GET_FLOAT_WORD(hy, y); |
| 49 | hy &= 0x7fffffff; |
| 50 | |
| 51 | /* cexp(x + I 0) = exp(x) + I 0 */ |
| 52 | if (hy == 0) |
| 53 | return (cpackf(expf(x), y)); |
| 54 | GET_FLOAT_WORD(hx, x); |
| 55 | /* cexp(0 + I y) = cos(y) + I sin(y) */ |
| 56 | if ((hx & 0x7fffffff) == 0) |
| 57 | return (cpackf(cosf(y), sinf(y))); |
| 58 | |
| 59 | if (hy >= 0x7f800000) { |
| 60 | if ((hx & 0x7fffffff) != 0x7f800000) { |
| 61 | /* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */ |
| 62 | return (cpackf(y - y, y - y)); |
| 63 | } else if (hx & 0x80000000) { |
| 64 | /* cexp(-Inf +- I Inf|NaN) = 0 + I 0 */ |
| 65 | return (cpackf(0.0, 0.0)); |
| 66 | } else { |
| 67 | /* cexp(+Inf +- I Inf|NaN) = Inf + I NaN */ |
| 68 | return (cpackf(x, y - y)); |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | if (hx >= exp_ovfl && hx <= cexp_ovfl) { |
| 73 | /* |
| 74 | * x is between 88.7 and 192, so we must scale to avoid |
| 75 | * overflow in expf(x). |
| 76 | */ |
| 77 | return (__ldexp_cexpf(z, 0)); |
| 78 | } else { |
| 79 | /* |
| 80 | * Cases covered here: |
| 81 | * - x < exp_ovfl and exp(x) won't overflow (common case) |
| 82 | * - x > cexp_ovfl, so exp(x) * s overflows for all s > 0 |
| 83 | * - x = +-Inf (generated by exp()) |
| 84 | * - x = NaN (spurious inexact exception from y) |
| 85 | */ |
| 86 | exp_x = expf(x); |
| 87 | return (cpackf(exp_x * cosf(y), exp_x * sinf(y))); |
| 88 | } |
| 89 | } |