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Annotation of embedaddon/php/ext/bcmath/libbcmath/src/raise.c, revision 1.1

1.1     ! misho       1: /* raise.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: 
        !            42: /* Raise NUM1 to the NUM2 power.  The result is placed in RESULT.
        !            43:    Maximum exponent is LONG_MAX.  If a NUM2 is not an integer,
        !            44:    only the integer part is used.  */
        !            45: 
        !            46: void
        !            47: bc_raise (bc_num num1, bc_num num2, bc_num *result, int scale TSRMLS_DC)
        !            48: {
        !            49:    bc_num temp, power;
        !            50:    long exponent;
        !            51:    int rscale;
        !            52:    int pwrscale;
        !            53:    int calcscale;
        !            54:    char neg;
        !            55: 
        !            56:    /* Check the exponent for scale digits and convert to a long. */
        !            57:    if (num2->n_scale != 0)
        !            58:      bc_rt_warn ("non-zero scale in exponent");
        !            59:    exponent = bc_num2long (num2);
        !            60:    if (exponent == 0 && (num2->n_len > 1 || num2->n_value[0] != 0))
        !            61:        bc_rt_error ("exponent too large in raise");
        !            62: 
        !            63:    /* Special case if exponent is a zero. */
        !            64:    if (exponent == 0)
        !            65:      {
        !            66:        bc_free_num (result);
        !            67:        *result = bc_copy_num (BCG(_one_));
        !            68:        return;
        !            69:      }
        !            70: 
        !            71:    /* Other initializations. */
        !            72:    if (exponent < 0)
        !            73:      {
        !            74:        neg = TRUE;
        !            75:        exponent = -exponent;
        !            76:        rscale = scale;
        !            77:      }
        !            78:    else
        !            79:      {
        !            80:        neg = FALSE;
        !            81:        rscale = MIN (num1->n_scale*exponent, MAX(scale, num1->n_scale));
        !            82:      }
        !            83: 
        !            84:    /* Set initial value of temp.  */
        !            85:    power = bc_copy_num (num1);
        !            86:    pwrscale = num1->n_scale;
        !            87:    while ((exponent & 1) == 0)
        !            88:      {
        !            89:        pwrscale = 2*pwrscale;
        !            90:        bc_multiply (power, power, &power, pwrscale TSRMLS_CC);
        !            91:        exponent = exponent >> 1;
        !            92:      }
        !            93:    temp = bc_copy_num (power);
        !            94:    calcscale = pwrscale;
        !            95:    exponent = exponent >> 1;
        !            96: 
        !            97:    /* Do the calculation. */
        !            98:    while (exponent > 0)
        !            99:      {
        !           100:        pwrscale = 2*pwrscale;
        !           101:        bc_multiply (power, power, &power, pwrscale TSRMLS_CC);
        !           102:        if ((exponent & 1) == 1) {
        !           103:         calcscale = pwrscale + calcscale;
        !           104:         bc_multiply (temp, power, &temp, calcscale TSRMLS_CC);
        !           105:        }
        !           106:        exponent = exponent >> 1;
        !           107:      }
        !           108: 
        !           109:    /* Assign the value. */
        !           110:    if (neg)
        !           111:      {
        !           112:        bc_divide (BCG(_one_), temp, result, rscale TSRMLS_CC);
        !           113:        bc_free_num (&temp);
        !           114:      }
        !           115:    else
        !           116:      {
        !           117:        bc_free_num (result);
        !           118:        *result = temp;
        !           119:        if ((*result)->n_scale > rscale)
        !           120:         (*result)->n_scale = rscale;
        !           121:      }
        !           122:    bc_free_num (&power);
        !           123: }
        !           124: