| /* origin: FreeBSD /usr/src/lib/msun/src/k_expf.c */ |
| /*- |
| * Copyright (c) 2011 David Schultz <das@FreeBSD.ORG> |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| */ |
| |
| #include "complex_impl.h" |
| |
| static const uint32_t k = 235; /* constant for reduction */ |
| static const float kln2 = 162.88958740F; /* k * ln2 */ |
| |
| /* |
| * See __cexp.c for details. |
| * |
| * Input: ln(FLT_MAX) <= x < ln(2 * FLT_MAX / FLT_MIN_DENORM) ~= 192.7 |
| * Output: 2**127 <= y < 2**128 |
| */ |
| static float __frexp_expf(float x, int *expt) |
| { |
| float exp_x; |
| uint32_t hx; |
| |
| exp_x = expf(x - kln2); |
| GET_FLOAT_WORD(hx, exp_x); |
| *expt = (hx >> 23) - (0x7f + 127) + k; |
| SET_FLOAT_WORD(exp_x, (hx & 0x7fffff) | ((0x7f + 127) << 23)); |
| return exp_x; |
| } |
| |
| float complex __ldexp_cexpf(float complex z, int expt) |
| { |
| float x, y, exp_x, scale1, scale2; |
| int ex_expt, half_expt; |
| |
| x = crealf(z); |
| y = cimagf(z); |
| exp_x = __frexp_expf(x, &ex_expt); |
| expt += ex_expt; |
| |
| half_expt = expt / 2; |
| SET_FLOAT_WORD(scale1, (0x7f + half_expt) << 23); |
| half_expt = expt - half_expt; |
| SET_FLOAT_WORD(scale2, (0x7f + half_expt) << 23); |
| |
| return CMPLXF(cosf(y) * exp_x * scale1 * scale2, |
| sinf(y) * exp_x * scale1 * scale2); |
| } |