newlib/libm/machine/amdgcn/v64df_atangent.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_atangent.c in Newlib.  */
  38
  39 #include <float.h>
  40 #include "amdgcnmach.h"
  41
  42 #if defined (__has_builtin) \
  43         && __has_builtin (__builtin_gcn_fabsv) \
  44         && __has_builtin (__builtin_gcn_frexpv_exp)
  45
  46 DEF_VD_MATH_FUNC (v64df, atangent, v64df x, v64df v, v64df u, int arctan2)
  47 {
  48   static const double ROOT3 = 1.73205080756887729353;
  49   static const double a[] = { 0.0, 0.52359877559829887308, 1.57079632679489661923,
  50                               1.04719755119659774615 };
  51   static const double q[] = { 0.41066306682575781263e+2,
  52                               0.86157349597130242515e+2,
  53                               0.59578436142597344465e+2,
  54                               0.15024001160028576121e+2 };
  55   static const double p[] = { -0.13688768894191926929e+2,
  56                               -0.20505855195861651981e+2,
  57                               -0.84946240351320683534e+1,
  58                               -0.83758299368150059274 };
  59   static const float z_rooteps = 7.4505859692e-9;
  60
  61   FUNCTION_INIT (v64df);
  62
  63   v64df zero = VECTOR_INIT (0.0);
  64   v64df pi = VECTOR_INIT (__PI);
  65   v64df pi_over_two = VECTOR_INIT (__PI_OVER_TWO);
  66   v64df res;
  67   v64si branch = VECTOR_INIT (0);
  68
  69   /* Preparation for calculating arctan2. */
  70   if (arctan2)
  71     {
  72       VECTOR_IF (u == 0.0, cond)
  73         VECTOR_IF2 (v == 0.0, cond2, cond)
  74           errno = ERANGE;
  75           VECTOR_RETURN (VECTOR_INIT (0.0), cond2);
  76         VECTOR_ELSE2 (cond2, cond)
  77           VECTOR_COND_MOVE (branch, VECTOR_INIT (-1), cond2);
  78           VECTOR_COND_MOVE (res, pi_over_two,  cond2);
  79         VECTOR_ENDIF
  80       VECTOR_ENDIF
  81
  82       VECTOR_IF (~branch, cond)
  83         /* Get the exponent values of the inputs. */
  84         v64si expv = __builtin_gcn_frexpv_exp (v);
  85         v64si expu = __builtin_gcn_frexpv_exp (u);
  86
  87         /* See if a divide will overflow. */
  88         v64si e = expv - expu;
  89
  90         VECTOR_IF2 (e > DBL_MAX_EXP, cond2, cond)
  91           VECTOR_COND_MOVE (branch, VECTOR_INIT (-1), cond2);
  92           VECTOR_COND_MOVE (res, pi_over_two, cond2);
  93         VECTOR_ENDIF
  94
  95         /* Also check for underflow. */
  96         VECTOR_IF2 (e < DBL_MIN_EXP, cond2, cond)
  97           VECTOR_COND_MOVE (branch, VECTOR_INIT (-1), cond2);
  98           VECTOR_COND_MOVE (res, zero, cond2);
  99         VECTOR_ENDIF
 100       VECTOR_ENDIF
 101     }
 102
 103   VECTOR_IF (~branch, cond)
 104     v64df f;
 105     v64si N = VECTOR_INIT (0);
 106
 107     if (arctan2)
 108       f = __builtin_gcn_fabsv (v / u);
 109     else
 110       f = __builtin_gcn_fabsv (x);
 111
 112     VECTOR_IF2 (__builtin_convertvector(f > 1.0, v64si), cond2, cond)
 113       VECTOR_COND_MOVE (f, 1.0 / f, cond2);
 114       VECTOR_COND_MOVE (N, VECTOR_INIT (2), cond2);
 115     VECTOR_ENDIF
 116
 117     VECTOR_IF2 (__builtin_convertvector(f > (2.0 - ROOT3), v64si), cond2, cond)
 118       double A = ROOT3 - 1.0;
 119       VECTOR_COND_MOVE (f, (((A * f - 0.5) - 0.5) + f) / (ROOT3 + f),
 120                         cond2);
 121       N += cond2 & 1;
 122     VECTOR_ENDIF
 123
 124     /* Check for values that are too small. */
 125     VECTOR_IF2 (__builtin_convertvector((-z_rooteps < f) & (f < z_rooteps), v64si), cond2, cond)
 126       VECTOR_COND_MOVE (res, f, cond2);
 127
 128     /* Calculate the Taylor series. */
 129     VECTOR_ELSE2 (cond2, cond)
 130       v64df g = f * f;
 131       v64df P = (((p[3] * g + p[2]) * g + p[1]) * g + p[0]) * g;
 132       v64df Q = (((g + q[3]) * g + q[2]) * g + q[1]) * g + q[0];
 133       v64df R = P / Q;
 134
 135       VECTOR_COND_MOVE (res, f + f * R, cond2);
 136     VECTOR_ENDIF
 137
 138     VECTOR_COND_MOVE (res, -res, cond & (N > 1));
 139
 140     res += VECTOR_MERGE (VECTOR_INIT (a[1]), zero, cond & (N == 1));
 141     res += VECTOR_MERGE (VECTOR_INIT (a[2]), zero, cond & (N == 2));
 142     res += VECTOR_MERGE (VECTOR_INIT (a[3]), zero, cond & (N == 3));
 143   VECTOR_ENDIF
 144
 145   if (arctan2)
 146     {
 147       /*if (u < 0.0)*/
 148         VECTOR_COND_MOVE (res, pi - res, u < 0.0);
 149       /*if (v < 0.0)*/
 150         VECTOR_COND_MOVE (res, -res, v < 0.0);
 151     }
 152   /*else if (x < 0.0) */
 153   else
 154     VECTOR_COND_MOVE (res, -res, x < 0.0);
 155
 156   VECTOR_RETURN (res, NO_COND);
 157
 158   FUNCTION_RETURN;
 159 }
 160
 161 #endif