newlib/libm/machine/amdgcn/v64df_exp.c

   1 /*
   2  * Copyright 2023 Siemens
   3  *
   4  * The authors hereby grant permission to use, copy, modify, distribute,
   5  * and license this software and its documentation for any purpose, provided
   6  * that existing copyright notices are retained in all copies and that this
   7  * notice is included verbatim in any distributions.  No written agreement,
   8  * license, or royalty fee is required for any of the authorized uses.
   9  * Modifications to this software may be copyrighted by their authors
  10  * and need not follow the licensing terms described here, provided that
  11  * the new terms are clearly indicated on the first page of each file where
  12  * they apply.
  13  */
  14
  15 /*
  16  * Copyright (c) 1994-2009  Red Hat, Inc. All rights reserved.
  17  *
  18  * This copyrighted material is made available to anyone wishing to use,
  19  * modify, copy, or redistribute it subject to the terms and conditions
  20  * of the BSD License.   This program is distributed in the hope that
  21  * it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
  22  * including the implied warranties of MERCHANTABILITY or FITNESS FOR
  23  * A PARTICULAR PURPOSE.  A copy of this license is available at
  24  * http://www.opensource.org/licenses. Any Red Hat trademarks that are
  25  * incorporated in the source code or documentation are not subject to
  26  * the BSD License and may only be used or replicated with the express
  27  * permission of Red Hat, Inc.
  28  */
  29
  30 /******************************************************************
  31  * The following routines are coded directly from the algorithms
  32  * and coefficients given in "Software Manual for the Elementary
  33  * Functions" by William J. Cody, Jr. and William Waite, Prentice
  34  * Hall, 1980.
  35  ******************************************************************/
  36
  37 /* Based on newlib/libm/mathfp/s_exp.c in Newlib.  */
  38
  39 #include "amdgcnmach.h"
  40
  41 v64si v64df_ispos (v64df);
  42 v64si v64df_numtest (v64df);
  43
  44 static const double INV_LN2 = 1.4426950408889634074;
  45 static const double LN2 = 0.6931471805599453094172321;
  46 static const double p[] = { 0.25, 0.75753180159422776666e-2,
  47                             0.31555192765684646356e-4 };
  48 static const double q[] = { 0.5, 0.56817302698551221787e-1,
  49                             0.63121894374398504557e-3,
  50                             0.75104028399870046114e-6 };
  51
  52 #if defined (__has_builtin) && __has_builtin (__builtin_gcn_ldexpv)
  53
  54 DEF_VD_MATH_FUNC (v64df, exp, v64df x)
  55 {
  56   FUNCTION_INIT (v64df);
  57
  58   v64si num_type = v64df_numtest (x);
  59   VECTOR_IF (num_type == NAN, cond)
  60     errno = EDOM;
  61     VECTOR_RETURN (x, cond);
  62   VECTOR_ELSEIF (num_type == INF, cond)
  63     errno = ERANGE;
  64     VECTOR_RETURN (VECTOR_MERGE (VECTOR_INIT (z_infinity.d),
  65                                  VECTOR_INIT (0.0),
  66                                  v64df_ispos (x)),
  67                    cond);
  68   VECTOR_ELSEIF (num_type == 0, cond)
  69     VECTOR_RETURN (VECTOR_INIT (1.0), cond);
  70   VECTOR_ENDIF
  71
  72   /* Check for out of bounds. */
  73   VECTOR_IF ((x > BIGX) | (x < SMALLX), cond)
  74     errno = ERANGE;
  75     VECTOR_RETURN (x, cond);
  76   VECTOR_ENDIF
  77
  78   /* Check for a value too small to calculate. */
  79   VECTOR_RETURN (VECTOR_INIT (1.0),
  80                  (-z_rooteps_f < x) & (x < z_rooteps_f));
  81
  82   /* Calculate the exponent. */
  83   v64si Nneg = __builtin_convertvector (x * INV_LN2 - 0.5, v64si);
  84   v64si Npos = __builtin_convertvector (x * INV_LN2 + 0.5, v64si);
  85   v64si N = VECTOR_MERGE (Nneg, Npos, x < 0.0);
  86
  87   /* Construct the mantissa. */
  88   v64df g = x - __builtin_convertvector (N, v64df) * LN2;
  89   v64df z = g * g;
  90   v64df P = g * ((p[2] * z + p[1]) * z + p[0]);
  91   v64df Q = ((q[3] * z + q[2]) * z + q[1]) * z + q[0];
  92   v64df R = 0.5 + P / (Q - P);
  93
  94   /* Return the floating point value. */
  95   N++;
  96   VECTOR_RETURN (__builtin_gcn_ldexpv (R, N), NO_COND);
  97
  98   FUNCTION_RETURN;
  99 }
 100
 101 DEF_VARIANTS (exp, df, df)
 102
 103 #endif