libtommath/bn_mp_read_signed_bin.c
2019-05-20 05:36:18 +02:00

26 lines
639 B
C

#include "tommath_private.h"
#ifdef BN_MP_READ_SIGNED_BIN_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* read signed bin, big endian, first byte is 0==positive or 1==negative */
mp_err mp_read_signed_bin(mp_int *a, const unsigned char *b, int c)
{
mp_err err;
/* read magnitude */
if ((err = mp_read_unsigned_bin(a, b + 1, c - 1)) != MP_OKAY) {
return err;
}
/* 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