71 lines
1.5 KiB
C
71 lines
1.5 KiB
C
/* TomsFastMath, a fast ISO C bignum library.
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*
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* This project is meant to fill in where LibTomMath
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* falls short. That is speed ;-)
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*
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* This project is public domain and free for all purposes.
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*
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* Tom St Denis, tomstdenis@gmail.com
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*/
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#include "bignum_fast.h"
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int fp_read_radix(fp_int *a, const char *str, int radix)
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{
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int y, neg;
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char ch;
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/* make sure the radix is ok */
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if (radix < 2 || radix > 64) {
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return FP_VAL;
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}
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/* if the leading digit is a
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* minus set the sign to negative.
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*/
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if (*str == '-') {
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++str;
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neg = FP_NEG;
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} else {
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neg = FP_ZPOS;
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}
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/* set the integer to the default of zero */
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fp_zero (a);
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/* process each digit of the string */
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while (*str) {
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/* if the radix < 36 the conversion is case insensitive
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* this allows numbers like 1AB and 1ab to represent the same value
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* [e.g. in hex]
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*/
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ch = (char) ((radix < 36) ? toupper (*str) : *str);
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for (y = 0; y < 64; y++) {
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if (ch == fp_s_rmap[y]) {
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break;
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}
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}
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/* if the char was found in the map
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* and is less than the given radix add it
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* to the number, otherwise exit the loop.
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*/
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if (y < radix) {
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fp_mul_d (a, (fp_digit) radix, a);
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fp_add_d (a, (fp_digit) y, a);
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} else {
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break;
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}
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++str;
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}
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/* set the sign only if a != 0 */
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if (fp_iszero(a) != FP_YES) {
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a->sign = neg;
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}
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return FP_OKAY;
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}
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/* $Source: /cvs/libtom/tomsfastmath/src/bin/fp_read_radix.c,v $ */
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/* $Revision: 1.1 $ */
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/* $Date: 2006/12/31 21:25:53 $ */
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