Line data    Source code

       1             : #include "tommath_private.h"
       2             : #ifdef BN_MP_PACK_C
       3             : /* LibTomMath, multiple-precision integer library -- Tom St Denis */
       4             : /* SPDX-License-Identifier: Unlicense */
       5             : 
       6             : /* based on gmp's mpz_export.
       7             :  * see http://gmplib.org/manual/Integer-Import-and-Export.html
       8             :  */
       9           0 : mp_err mp_pack(void *rop, size_t maxcount, size_t *written, mp_order order, size_t size,
      10             :                mp_endian endian, size_t nails, const mp_int *op)
      11             : {
      12           0 :    mp_err err;
      13           0 :    size_t odd_nails, nail_bytes, i, j, count;
      14           0 :    unsigned char odd_nail_mask;
      15             : 
      16           0 :    mp_int t;
      17             : 
      18           0 :    count = mp_pack_count(op, nails, size);
      19             : 
      20           0 :    if (count > maxcount) {
      21           0 :       return MP_BUF;
      22             :    }
      23             : 
      24           0 :    if ((err = mp_init_copy(&t, op)) != MP_OKAY) {
      25           0 :       return err;
      26             :    }
      27             : 
      28           0 :    if (endian == MP_NATIVE_ENDIAN) {
      29           0 :       MP_GET_ENDIANNESS(endian);
      30             :    }
      31             : 
      32           0 :    odd_nails = (nails % 8u);
      33           0 :    odd_nail_mask = 0xff;
      34           0 :    for (i = 0u; i < odd_nails; ++i) {
      35           0 :       odd_nail_mask ^= (unsigned char)(1u << (7u - i));
      36             :    }
      37           0 :    nail_bytes = nails / 8u;
      38             : 
      39           0 :    for (i = 0u; i < count; ++i) {
      40           0 :       for (j = 0u; j < size; ++j) {
      41           0 :          unsigned char *byte = (unsigned char *)rop +
      42           0 :                                (((order == MP_LSB_FIRST) ? i : ((count - 1u) - i)) * size) +
      43           0 :                                ((endian == MP_LITTLE_ENDIAN) ? j : ((size - 1u) - j));
      44             : 
      45           0 :          if (j >= (size - nail_bytes)) {
      46           0 :             *byte = 0;
      47           0 :             continue;
      48             :          }
      49             : 
      50           0 :          *byte = (unsigned char)((j == ((size - nail_bytes) - 1u)) ? (t.dp[0] & odd_nail_mask) : (t.dp[0] & 0xFFuL));
      51             : 
      52           0 :          if ((err = mp_div_2d(&t, (j == ((size - nail_bytes) - 1u)) ? (int)(8u - odd_nails) : 8, &t, NULL)) != MP_OKAY) {
      53           0 :             goto LBL_ERR;
      54             :          }
      55             : 
      56             :       }
      57             :    }
      58             : 
      59           0 :    if (written != NULL) {
      60           0 :       *written = count;
      61             :    }
      62           0 :    err = MP_OKAY;
      63             : 
      64           0 : LBL_ERR:
      65           0 :    mp_clear(&t);
      66           0 :    return err;
      67             : }
      68             : 
      69             : #endif