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 31 #include "math.h" 32 #include "math_private.h" 33 34 static const uint32_t k = 235; /* constant for reduction */ 35 static const float kln2 = 162.88958740F; /* k * ln2 */ 36 37 /* 38 * See k_exp.c for details. 39 * 40 * Input: ln(FLT_MAX) <= x < ln(2 * FLT_MAX / FLT_MIN_DENORM) ~= 192.7 41 * Output: 2**127 <= y < 2**128 42 */ 43 static float 44 __frexp_expf(float x, int *expt) 45 { 46 float exp_x; 47 uint32_t hx; 48 49 exp_x = expf(x - kln2); 50 GET_FLOAT_WORD(hx, exp_x); 51 *expt = (hx >> 23) - (0x7f + 127) + k; 52 SET_FLOAT_WORD(exp_x, (hx & 0x7fffff) | ((0x7f + 127) << 23)); 53 return (exp_x); 54 } 55 56 float 57 __ldexp_expf(float x, int expt) 58 { 59 float exp_x, scale; 60 int ex_expt; 61 62 exp_x = __frexp_expf(x, &ex_expt); 63 expt += ex_expt; 64 SET_FLOAT_WORD(scale, (0x7f + expt) << 23); 65 return (exp_x * scale); 66 } 67 68 float complex 69 __ldexp_cexpf(float complex z, int expt) 70 { 71 float c, exp_x, s, scale1, scale2, x, y; 72 int ex_expt, half_expt; 73 74 x = crealf(z); 75 y = cimagf(z); 76 exp_x = __frexp_expf(x, &ex_expt); 77 expt += ex_expt; 78 79 half_expt = expt / 2; 80 SET_FLOAT_WORD(scale1, (0x7f + half_expt) << 23); 81 half_expt = expt - half_expt; 82 SET_FLOAT_WORD(scale2, (0x7f + half_expt) << 23); 83 84 sincosf(y, &s, &c); 85 return (CMPLXF(c * exp_x * scale1 * scale2, 86 s * exp_x * scale1 * scale2)); 87 } 88