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Annotation of embedaddon/php/ext/bcmath/libbcmath/src/raisemod.c, revision 1.1.1.1

1.1       misho       1: /* raisemod.c: bcmath library file. */
                      2: /*
                      3:     Copyright (C) 1991, 1992, 1993, 1994, 1997 Free Software Foundation, Inc.
                      4:     Copyright (C) 2000 Philip A. Nelson
                      5: 
                      6:     This library is free software; you can redistribute it and/or
                      7:     modify it under the terms of the GNU Lesser General Public
                      8:     License as published by the Free Software Foundation; either
                      9:     version 2 of the License, or (at your option) any later version.
                     10: 
                     11:     This library is distributed in the hope that it will be useful,
                     12:     but WITHOUT ANY WARRANTY; without even the implied warranty of
                     13:     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
                     14:     Lesser General Public License for more details.  (COPYING.LIB)
                     15: 
                     16:     You should have received a copy of the GNU Lesser General Public
                     17:     License along with this library; if not, write to:
                     18: 
                     19:       The Free Software Foundation, Inc.
                     20:       59 Temple Place, Suite 330
                     21:       Boston, MA 02111-1307 USA.
                     22: 
                     23:     You may contact the author by:
                     24:        e-mail:  philnelson@acm.org
                     25:       us-mail:  Philip A. Nelson
                     26:                 Computer Science Department, 9062
                     27:                 Western Washington University
                     28:                 Bellingham, WA 98226-9062
                     29:        
                     30: *************************************************************************/
                     31: 
                     32: #include <config.h>
                     33: #include <stdio.h>
                     34: #include <assert.h>
                     35: #include <stdlib.h>
                     36: #include <ctype.h>
                     37: #include <stdarg.h>
                     38: #include "bcmath.h"
                     39: #include "private.h"
                     40: 
                     41: /* Raise BASE to the EXPO power, reduced modulo MOD.  The result is
                     42:    placed in RESULT.  If a EXPO is not an integer,
                     43:    only the integer part is used.  */
                     44: 
                     45: int
                     46: bc_raisemod (bc_num base, bc_num expo, bc_num mod, bc_num *result, int scale TSRMLS_DC)
                     47: {
                     48:   bc_num power, exponent, parity, temp;
                     49:   int rscale;
                     50: 
                     51:   /* Check for correct numbers. */
                     52:   if (bc_is_zero(mod TSRMLS_CC)) return -1;
                     53:   if (bc_is_neg(expo)) return -1;
                     54: 
                     55:   /* Set initial values.  */
                     56:   power = bc_copy_num (base);
                     57:   exponent = bc_copy_num (expo);
                     58:   temp = bc_copy_num (BCG(_one_));
                     59:   bc_init_num(&parity TSRMLS_CC);
                     60: 
                     61:   /* Check the base for scale digits. */
                     62:   if (base->n_scale != 0)
                     63:       bc_rt_warn ("non-zero scale in base");
                     64: 
                     65:   /* Check the exponent for scale digits. */
                     66:   if (exponent->n_scale != 0)
                     67:     {
                     68:       bc_rt_warn ("non-zero scale in exponent");
                     69:       bc_divide (exponent, BCG(_one_), &exponent, 0 TSRMLS_CC); /*truncate */
                     70:     }
                     71: 
                     72:   /* Check the modulus for scale digits. */
                     73:   if (mod->n_scale != 0)
                     74:       bc_rt_warn ("non-zero scale in modulus");
                     75: 
                     76:   /* Do the calculation. */
                     77:   rscale = MAX(scale, base->n_scale);
                     78:   while ( !bc_is_zero(exponent TSRMLS_CC) )
                     79:     {
                     80:       (void) bc_divmod (exponent, BCG(_two_), &exponent, &parity, 0 TSRMLS_CC);
                     81:       if ( !bc_is_zero(parity TSRMLS_CC) )
                     82:        {
                     83:          bc_multiply (temp, power, &temp, rscale TSRMLS_CC);
                     84:          (void) bc_modulo (temp, mod, &temp, scale TSRMLS_CC);
                     85:        }
                     86: 
                     87:       bc_multiply (power, power, &power, rscale TSRMLS_CC);
                     88:       (void) bc_modulo (power, mod, &power, scale TSRMLS_CC);
                     89:     }
                     90: 
                     91:   /* Assign the value. */
                     92:   bc_free_num (&power);
                     93:   bc_free_num (&exponent);
                     94:   bc_free_num (result);
                     95:   bc_free_num (&parity);
                     96:   *result = temp;
                     97:   return 0;    /* Everything is OK. */
                     98: }