kc3-lang/libtommath/bn_mp_import.c

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• Hash : 4534056c
  Author :
  Date : 2019-05-13T00:22:18
  

  use enums mp_err, mp_ord, mp_bool, mp_sign * MP_USE_ENUMS enables enums * Wc++-compat catches some implicit conversions if MP_USE_ENUMS is defined * 100% backwards compatible API/ABI if MP_USE_ENUMS is not defined

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• bn_mp_import.c

• #include "tommath_private.h"
  #ifdef BN_MP_IMPORT_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis */
  /* SPDX-License-Identifier: Unlicense */
  
  /* based on gmp's mpz_import.
   * see http://gmplib.org/manual/Integer-Import-and-Export.html
   */
  mp_err mp_import(mp_int *rop, size_t count, int order, size_t size,
                   int endian, size_t nails, const void *op)
  {
     mp_err result;
     size_t odd_nails, nail_bytes, i, j;
     unsigned char odd_nail_mask;
  
     mp_zero(rop);
  
     if (endian == 0) {
        union {
           unsigned int i;
           char c[4];
        } lint;
        lint.i = 0x01020304;
  
        endian = (lint.c[0] == '\x04') ? -1 : 1;
     }
  
     odd_nails = (nails % 8u);
     odd_nail_mask = 0xff;
     for (i = 0; i < odd_nails; ++i) {
        odd_nail_mask ^= (unsigned char)(1u << (7u - i));
     }
     nail_bytes = nails / 8u;
  
     for (i = 0; i < count; ++i) {
        for (j = 0; j < (size - nail_bytes); ++j) {
           unsigned char byte = *((const unsigned char *)op +
                                  (((order == 1) ? i : ((count - 1u) - i)) * size) +
                                  ((endian == 1) ? (j + nail_bytes) : (((size - 1u) - j) - nail_bytes)));
  
           if ((result = mp_mul_2d(rop, (j == 0u) ? (int)(8u - odd_nails) : 8, rop)) != MP_OKAY) {
              return result;
           }
  
           rop->dp[0] |= (j == 0u) ? (mp_digit)(byte & odd_nail_mask) : (mp_digit)byte;
           rop->used  += 1;
        }
     }
  
     mp_clamp(rop);
  
     return MP_OKAY;
  }
  
  #endif
  

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