newlib/libm/machine/amdgcn/v64df_sqrt.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_sqrt.c in Newlib.  */
  38
  39 #include "amdgcnmach.h"
  40
  41 v64si v64df_numtest (v64df);
  42 v64si v64df_ispos (v64df);
  43
  44 #if defined (__has_builtin) \
  45         && __has_builtin (__builtin_gcn_frexpv_mant) \
  46         && __has_builtin (__builtin_gcn_frexpv_exp) \
  47         && __has_builtin (__builtin_gcn_ldexpv)
  48
  49 DEF_VD_MATH_FUNC (v64df, sqrt, v64df x)
  50 {
  51   FUNCTION_INIT (v64df);
  52
  53   /* Check for special values. */
  54   v64si num_type = v64df_numtest (x);
  55   VECTOR_IF (num_type == NAN, cond)
  56     errno = EDOM;
  57     VECTOR_RETURN (x, cond);
  58   VECTOR_ELSEIF (num_type == INF, cond)
  59     VECTOR_IF2 (v64df_ispos (x), cond2, cond)
  60       errno = EDOM;
  61       VECTOR_RETURN (VECTOR_INIT (z_notanum.d), cond2);
  62     VECTOR_ELSE2 (cond2,cond)
  63       errno = ERANGE;
  64       VECTOR_RETURN (VECTOR_INIT (z_infinity.d), cond);
  65     VECTOR_ENDIF
  66   VECTOR_ENDIF
  67
  68   /* Initial checks are performed here. */
  69   VECTOR_IF (x == 0.0, cond)
  70     VECTOR_RETURN (VECTOR_INIT (0.0), cond);
  71   VECTOR_ENDIF
  72   VECTOR_IF (x < 0.0, cond)
  73     errno = EDOM;
  74     VECTOR_RETURN (VECTOR_INIT (z_notanum.d), cond);
  75   VECTOR_ENDIF
  76
  77   /* Find the exponent and mantissa for the form x = f * 2^exp. */
  78   v64df f = __builtin_gcn_frexpv_mant (x);
  79   v64si exp = __builtin_gcn_frexpv_exp (x);
  80   v64si odd = (exp & 1) != 0;
  81
  82   /* Get the initial approximation. */
  83   v64df y = 0.41731 + 0.59016 * f;
  84
  85   f *= 0.5f;
  86   /* Calculate the remaining iterations. */
  87   y = y * 0.5f + f / y;
  88   y = y * 0.5f + f / y;
  89   y = y * 0.5f + f / y;
  90
  91   /* Calculate the final value. */
  92   VECTOR_COND_MOVE (y, y * __SQRT_HALF, odd);
  93   VECTOR_COND_MOVE (exp, exp + 1, odd);
  94   exp >>= 1;
  95   y = __builtin_gcn_ldexpv (y, exp);
  96
  97   VECTOR_RETURN (y, NO_COND);
  98
  99   FUNCTION_RETURN;
 100 }
 101
 102 DEF_VARIANTS (sqrt, df, df)
 103
 104 #endif