Line data    Source code

       1             : #include "tommath_private.h"
       2             : #ifdef BN_MP_UNPACK_C
       3             : /* LibTomMath, multiple-precision integer library -- Tom St Denis */
       4             : /* SPDX-License-Identifier: Unlicense */
       5             : 
       6             : /* based on gmp's mpz_import.
       7             :  * see http://gmplib.org/manual/Integer-Import-and-Export.html
       8             :  */
       9           0 : mp_err mp_unpack(mp_int *rop, size_t count, mp_order order, size_t size,
      10             :                  mp_endian endian, size_t nails, const void *op)
      11             : {
      12           0 :    mp_err err;
      13           0 :    size_t odd_nails, nail_bytes, i, j;
      14           0 :    unsigned char odd_nail_mask;
      15             : 
      16           0 :    mp_zero(rop);
      17             : 
      18           0 :    if (endian == MP_NATIVE_ENDIAN) {
      19           0 :       MP_GET_ENDIANNESS(endian);
      20             :    }
      21             : 
      22           0 :    odd_nails = (nails % 8u);
      23           0 :    odd_nail_mask = 0xff;
      24           0 :    for (i = 0; i < odd_nails; ++i) {
      25           0 :       odd_nail_mask ^= (unsigned char)(1u << (7u - i));
      26             :    }
      27           0 :    nail_bytes = nails / 8u;
      28             : 
      29           0 :    for (i = 0; i < count; ++i) {
      30           0 :       for (j = 0; j < (size - nail_bytes); ++j) {
      31           0 :          unsigned char byte = *((const unsigned char *)op +
      32           0 :                                 (((order == MP_MSB_FIRST) ? i : ((count - 1u) - i)) * size) +
      33           0 :                                 ((endian == MP_BIG_ENDIAN) ? (j + nail_bytes) : (((size - 1u) - j) - nail_bytes)));
      34             : 
      35           0 :          if ((err = mp_mul_2d(rop, (j == 0u) ? (int)(8u - odd_nails) : 8, rop)) != MP_OKAY) {
      36           0 :             return err;
      37             :          }
      38             : 
      39           0 :          rop->dp[0] |= (j == 0u) ? (mp_digit)(byte & odd_nail_mask) : (mp_digit)byte;
      40           0 :          rop->used  += 1;
      41             :       }
      42             :    }
      43             : 
      44           0 :    mp_clamp(rop);
      45             : 
      46           0 :    return MP_OKAY;
      47             : }
      48             : 
      49             : #endif