pqc/external/libtommath-0.42.0/bn_mp_read_signed_bin.c

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2014-04-14 20:21:46 +00:00
#include <tommath.h>
#ifdef BN_MP_READ_SIGNED_BIN_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
* LibTomMath is a library that provides multiple-precision
* integer arithmetic as well as number theoretic functionality.
*
* The library was designed directly after the MPI library by
* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
*/
/* read signed bin, big endian, first byte is 0==positive or 1==negative */
int mp_read_signed_bin (mp_int * a, const unsigned char *b, int c)
{
int res;
/* read magnitude */
if ((res = mp_read_unsigned_bin (a, b + 1, c - 1)) != MP_OKAY) {
return res;
}
/* first byte is 0 for positive, non-zero for negative */
if (b[0] == 0) {
a->sign = MP_ZPOS;
} else {
a->sign = MP_NEG;
}
return MP_OKAY;
}
#endif
/* $Source$ */
/* $Revision: 0.41 $ */
/* $Date: 2007-04-18 09:58:18 +0000 $ */