| 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 | |
| 32 | #include "math.h" |
| 33 | #include "math_private.h" |
| 34 | |
| 35 | static const uint32_t k = 235; /* constant for reduction */ |
| 36 | static const float kln2 = 162.88958740F; /* k * ln2 */ |
| 37 | |
| 38 | /* |
| 39 | * See k_exp.c for details. |
| 40 | * |
| 41 | * Input: ln(FLT_MAX) <= x < ln(2 * FLT_MAX / FLT_MIN_DENORM) ~= 192.7 |
| 42 | * Output: 2**127 <= y < 2**128 |
| 43 | */ |
| 44 | static float |
| 45 | __frexp_expf(float x, int *expt) |
| 46 | { |
| 47 | float exp_x; |
| 48 | uint32_t hx; |
| 49 | |
| 50 | exp_x = expf(x - kln2); |
| 51 | GET_FLOAT_WORD(hx, exp_x); |
| 52 | *expt = (hx >> 23) - (0x7f + 127) + k; |
| 53 | SET_FLOAT_WORD(exp_x, (hx & 0x7fffff) | ((0x7f + 127) << 23)); |
| 54 | return (exp_x); |
| 55 | } |
| 56 | |
| 57 | float |
| 58 | __ldexp_expf(float x, int expt) |
| 59 | { |
| 60 | float exp_x, scale; |
| 61 | int ex_expt; |
| 62 | |
| 63 | exp_x = __frexp_expf(x, &ex_expt); |
| 64 | expt += ex_expt; |
| 65 | SET_FLOAT_WORD(scale, (0x7f + expt) << 23); |
| 66 | return (exp_x * scale); |
| 67 | } |
| 68 | |
| 69 | float complex |
| 70 | __ldexp_cexpf(float complex z, int expt) |
| 71 | { |
| 72 | float x, y, exp_x, scale1, scale2; |
| 73 | int ex_expt, half_expt; |
| 74 | |
| 75 | x = crealf(z); |
| 76 | y = cimagf(z); |
| 77 | exp_x = __frexp_expf(x, &ex_expt); |
| 78 | expt += ex_expt; |
| 79 | |
| 80 | half_expt = expt / 2; |
| 81 | SET_FLOAT_WORD(scale1, (0x7f + half_expt) << 23); |
| 82 | half_expt = expt - half_expt; |
| 83 | SET_FLOAT_WORD(scale2, (0x7f + half_expt) << 23); |
| 84 | |
| 85 | return (cpackf(cosf(y) * exp_x * scale1 * scale2, |
| 86 | sinf(y) * exp_x * scale1 * scale2)); |
| 87 | } |