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