mp_from_sbin.c

   1 #include "tommath_private.h"
   2 #ifdef MP_FROM_SBIN_C
   3 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
   4 /* SPDX-License-Identifier: Unlicense */
   5
   6 /* read signed bin, big endian, first byte is 0==positive or 1==negative */
   7 mp_err mp_from_sbin(mp_int *a, const uint8_t *buf, size_t size)
   8 {
   9    mp_err err;
  10
  11    /* read magnitude */
  12    if ((err = mp_from_ubin(a, buf + 1, size - 1u)) != MP_OKAY) {
  13       return err;
  14    }
  15
  16    /* first byte is 0 for positive, non-zero for negative */
  17    a->sign = (buf[0] != (uint8_t)0) ? MP_NEG : MP_ZPOS;
  18
  19    return MP_OKAY;
  20 }
  21 #endif