1 /*- 2 * Copyright (c) 2011 David Schultz <das (at) 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 } 88
