compiler/stdc/math/s_cexpf.c

   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 //__FBSDID("$FreeBSD: src/lib/msun/src/s_cexpf.c,v 1.3 2011/10/21 06:27:56 das Exp $");
  28
  29 #include <complex.h>
  30 #include "math.h"
  31
  32 #include "math_private.h"
  33
  34 static const uint32_t
  35 exp_ovfl  = 0x42b17218,         /* MAX_EXP * ln2 ~= 88.722839355 */
  36 cexp_ovfl = 0x43400074;         /* (MAX_EXP - MIN_DENORM_EXP) * ln2 */
  37
  38 float complex
  39 cexpf(float complex z)
  40 {
  41         float x, y, exp_x;
  42         uint32_t hx, hy;
  43
  44         x = crealf(z);
  45         y = cimagf(z);
  46
  47         GET_FLOAT_WORD(hy, y);
  48         hy &= 0x7fffffff;
  49
  50         /* cexp(x + I 0) = exp(x) + I 0 */
  51         if (hy == 0)
  52                 return (CMPLXF(expf(x), y));
  53         GET_FLOAT_WORD(hx, x);
  54         /* cexp(0 + I y) = cos(y) + I sin(y) */
  55         if ((hx & 0x7fffffff) == 0)
  56                 return (CMPLXF(cosf(y), sinf(y)));
  57
  58         if (hy >= 0x7f800000) {
  59                 if ((hx & 0x7fffffff) != 0x7f800000) {
  60                         /* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */
  61                         return (CMPLXF(y - y, y - y));
  62                 } else if (hx & 0x80000000) {
  63                         /* cexp(-Inf +- I Inf|NaN) = 0 + I 0 */
  64                         return (CMPLXF(0.0, 0.0));
  65                 } else {
  66                         /* cexp(+Inf +- I Inf|NaN) = Inf + I NaN */
  67                         return (CMPLXF(x, y - y));
  68                 }
  69         }
  70
  71         if (hx >= exp_ovfl && hx <= cexp_ovfl) {
  72                 /*
  73                  * x is between 88.7 and 192, so we must scale to avoid
  74                  * overflow in expf(x).
  75                  */
  76                 return (__ldexp_cexpf(z, 0));
  77         } else {
  78                 /*
  79                  * Cases covered here:
  80                  *  -  x < exp_ovfl and exp(x) won't overflow (common case)
  81                  *  -  x > cexp_ovfl, so exp(x) * s overflows for all s > 0
  82                  *  -  x = +-Inf (generated by exp())
  83                  *  -  x = NaN (spurious inexact exception from y)
  84                  */
  85                 exp_x = expf(x);
  86                 return (CMPLXF(exp_x * cosf(y), exp_x * sinf(y)));
  87         }
  88 }