denyhosts/clamscan/libclamav/tomsfastmath/bin/fp_read_radix.c
2022-10-22 18:41:00 +08:00

71 lines
1.5 KiB
C

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