tommath/bn_mp_read_unsigned_bin.c
2017-08-30 20:08:58 +02:00

56 lines
1.3 KiB
C

#include <tommath_private.h>
#ifdef BN_MP_READ_UNSIGNED_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, tstdenis82@gmail.com, http://libtom.org
*/
/* reads a unsigned char array, assumes the msb is stored first [big endian] */
int mp_read_unsigned_bin (mp_int * a, const unsigned char *b, int c)
{
int res;
/* make sure there are at least two digits */
if (a->alloc < 2) {
if ((res = mp_grow(a, 2)) != MP_OKAY) {
return res;
}
}
/* zero the int */
mp_zero(a);
/* read the bytes in */
while (c-- > 0) {
if ((res = mp_mul_2d(a, 8, a)) != MP_OKAY) {
return res;
}
#ifndef MP_8BIT
a->dp[0] |= *b++;
a->used += 1;
#else
a->dp[0] = (*b & MP_MASK);
a->dp[1] |= ((*b++ >> 7U) & 1);
a->used += 2;
#endif
}
mp_clamp(a);
return MP_OKAY;
}
#endif
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */