compiler/stdc/math/s_cexp.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_cexp.c,v 1.3 2011/10/21 06:27:56 das Exp $");
  28
  29 #include <float.h>
  30 #include <complex.h>
  31 #include "math.h"
  32
  33 #include "math_private.h"
  34
  35 static const uint32_t
  36 exp_ovfl  = 0x40862e42,                 /* high bits of MAX_EXP * ln2 ~= 710 */
  37 cexp_ovfl = 0x4096b8e4;                 /* (MAX_EXP - MIN_DENORM_EXP) * ln2 */
  38
  39 double complex
  40 cexp(double complex z)
  41 {
  42         double x, y, exp_x;
  43         uint32_t hx, hy, lx, ly;
  44
  45         x = creal(z);
  46         y = cimag(z);
  47
  48         EXTRACT_WORDS(hy, ly, y);
  49         hy &= 0x7fffffff;
  50
  51         /* cexp(x + I 0) = exp(x) + I 0 */
  52         if ((hy | ly) == 0)
  53                 return (CMPLX(exp(x), y));
  54         EXTRACT_WORDS(hx, lx, x);
  55         /* cexp(0 + I y) = cos(y) + I sin(y) */
  56         if (((hx & 0x7fffffff) | lx) == 0)
  57                 return (CMPLX(cos(y), sin(y)));
  58
  59         if (hy >= 0x7ff00000) {
  60                 if (lx != 0 || (hx & 0x7fffffff) != 0x7ff00000) {
  61                         /* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */
  62                         return (CMPLX(y - y, y - y));
  63                 } else if (hx & 0x80000000) {
  64                         /* cexp(-Inf +- I Inf|NaN) = 0 + I 0 */
  65                         return (CMPLX(0.0, 0.0));
  66                 } else {
  67                         /* cexp(+Inf +- I Inf|NaN) = Inf + I NaN */
  68                         return (CMPLX(x, y - y));
  69                 }
  70         }
  71
  72         if (hx >= exp_ovfl && hx <= cexp_ovfl) {
  73                 /*
  74                  * x is between 709.7 and 1454.3, so we must scale to avoid
  75                  * overflow in exp(x).
  76                  */
  77                 return (__ldexp_cexp(z, 0));
  78         } else {
  79                 /*
  80                  * Cases covered here:
  81                  *  -  x < exp_ovfl and exp(x) won't overflow (common case)
  82                  *  -  x > cexp_ovfl, so exp(x) * s overflows for all s > 0
  83                  *  -  x = +-Inf (generated by exp())
  84                  *  -  x = NaN (spurious inexact exception from y)
  85                  */
  86                 exp_x = exp(x);
  87                 return (CMPLX(exp_x * cos(y), exp_x * sin(y)));
  88         }
  89 }
  90
  91 #if     LDBL_MANT_DIG == DBL_MANT_DIG
  92 AROS_MAKE_ASM_SYM(typeof(cexpl), cexpl, AROS_CSYM_FROM_ASM_NAME(cexpl), AROS_CSYM_FROM_ASM_NAME(cexp));
  93 AROS_EXPORT_ASM_SYM(AROS_CSYM_FROM_ASM_NAME(cexpl));
  94 #endif