86 lines
2.0 KiB
C
86 lines
2.0 KiB
C
#include <tommath.h>
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#ifdef BN_MP_READ_RADIX_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
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*
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* LibTomMath is a library that provides multiple-precision
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* integer arithmetic as well as number theoretic functionality.
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*
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* The library was designed directly after the MPI library by
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* Michael Fromberger but has been written from scratch with
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* additional optimizations in place.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*
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* Tom St Denis, tstdenis82@gmail.com, http://libtom.org
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*/
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/* read a string [ASCII] in a given radix */
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int mp_read_radix (mp_int * a, const char *str, int radix)
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{
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int y, res, neg;
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char ch;
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/* zero the digit bignum */
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mp_zero(a);
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/* make sure the radix is ok */
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if (radix < 2 || radix > 64) {
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return MP_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 = MP_NEG;
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} else {
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neg = MP_ZPOS;
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}
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/* set the integer to the default of zero */
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mp_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 ((int)*str) : *str);
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for (y = 0; y < 64; y++) {
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if (ch == mp_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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if ((res = mp_mul_d (a, (mp_digit) radix, a)) != MP_OKAY) {
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return res;
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}
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if ((res = mp_add_d (a, (mp_digit) y, a)) != MP_OKAY) {
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return res;
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}
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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 (mp_iszero(a) != 1) {
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a->sign = neg;
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}
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return MP_OKAY;
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}
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#endif
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/* $Source$ */
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/* $Revision$ */
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/* $Date$ */
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