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: }
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