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Diffstat (limited to 'libgfortran/generated/pow_r4_i16.c')
-rw-r--r-- | libgfortran/generated/pow_r4_i16.c | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/libgfortran/generated/pow_r4_i16.c b/libgfortran/generated/pow_r4_i16.c new file mode 100644 index 00000000000..635e627e9d6 --- /dev/null +++ b/libgfortran/generated/pow_r4_i16.c @@ -0,0 +1,76 @@ +/* Support routines for the intrinsic power (**) operator. + Copyright 2004 Free Software Foundation, Inc. + Contributed by Paul Brook + +This file is part of the GNU Fortran 95 runtime library (libgfortran). + +Libgfortran is free software; you can redistribute it and/or +modify it under the terms of the GNU General Public +License as published by the Free Software Foundation; either +version 2 of the License, or (at your option) any later version. + +In addition to the permissions in the GNU General Public License, the +Free Software Foundation gives you unlimited permission to link the +compiled version of this file into combinations with other programs, +and to distribute those combinations without any restriction coming +from the use of this file. (The General Public License restrictions +do apply in other respects; for example, they cover modification of +the file, and distribution when not linked into a combine +executable.) + +Libgfortran is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public +License along with libgfortran; see the file COPYING. If not, +write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, +Boston, MA 02110-1301, USA. */ + +#include "config.h" +#include "libgfortran.h" + +/* Use Binary Method to calculate the powi. This is not an optimal but + a simple and reasonable arithmetic. See section 4.6.3, "Evaluation of + Powers" of Donald E. Knuth, "Seminumerical Algorithms", Vol. 2, "The Art + of Computer Programming", 3rd Edition, 1998. */ + +#if defined (HAVE_GFC_REAL_4) && defined (HAVE_GFC_INTEGER_16) + +GFC_REAL_4 pow_r4_i16 (GFC_REAL_4 a, GFC_INTEGER_16 b); +export_proto(pow_r4_i16); + +GFC_REAL_4 +pow_r4_i16 (GFC_REAL_4 a, GFC_INTEGER_16 b) +{ + GFC_REAL_4 pow, x; + GFC_INTEGER_16 n, u; + + n = b; + x = a; + pow = 1; + if (n != 0) + { + if (n < 0) + { + + n = -n; + x = pow / x; + } + u = n; + for (;;) + { + if (u & 1) + pow *= x; + u >>= 1; + if (u) + x *= x; + else + break; + } + } + return pow; +} + +#endif |