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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgfortran/] [m4/] [pow.m4] - Rev 748
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`/* Support routines for the intrinsic power (**) operator. Copyright 2004, 2007, 2009 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 3 of the License, or (at your option) any later version. 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. Under Section 7 of GPL version 3, you are granted additional permissions described in the GCC Runtime Library Exception, version 3.1, as published by the Free Software Foundation. You should have received a copy of the GNU General Public License and a copy of the GCC Runtime Library Exception along with this program; see the files COPYING3 and COPYING.RUNTIME respectively. If not, see <http://www.gnu.org/licenses/>. */ #include "libgfortran.h"' include(iparm.m4)dnl /* 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_'rtype_name`) && defined (HAVE_'atype_name`)' rtype_name `pow_'rtype_code`_'atype_code` ('rtype_name` a, 'atype_name` b); export_proto(pow_'rtype_code`_'atype_code`); 'rtype_name` pow_'rtype_code`_'atype_code` ('rtype_name` a, 'atype_name` b) { 'rtype_name` pow, x; 'atype_name` n; GFC_UINTEGER_'atype_kind` u; n = b; x = a; pow = 1; if (n != 0) { if (n < 0) { 'ifelse(rtype_letter,i,`dnl if (x == 1) return 1; if (x == -1) return (n & 1) ? -1 : 1; return (x == 0) ? 1 / x : 0; ',` u = -n; x = pow / x; ')dnl ` } else { u = n; } for (;;) { if (u & 1) pow *= x; u >>= 1; if (u) x *= x; else break; } } return pow; } #endif'
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