tommath/bn_mp_read_signed_bin.c

39 lines
1.0 KiB
C

#include "tommath_private.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.
*
* SPDX-License-Identifier: Unlicense
*/
/* 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] == (unsigned char)0) {
a->sign = MP_ZPOS;
} else {
a->sign = MP_NEG;
}
return MP_OKAY;
}
#endif
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */