kc3-lang/libtommath/bn_mp_export.c

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• Hash : f51249b6
  Author :
  Date : 2018-02-02T12:07:21
  

  clean-up file headers

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• bn_mp_export.c

• #include <tommath_private.h>
  #ifdef BN_MP_EXPORT_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.
   */
  
  /* based on gmp's mpz_export.
   * see http://gmplib.org/manual/Integer-Import-and-Export.html
   */
  int mp_export(void *rop, size_t *countp, int order, size_t size,
                int endian, size_t nails, const mp_int *op)
  {
     int result;
     size_t odd_nails, nail_bytes, i, j, bits, count;
     unsigned char odd_nail_mask;
  
     mp_int t;
  
     if ((result = mp_init_copy(&t, op)) != MP_OKAY) {
        return result;
     }
  
     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;
  
     bits = (size_t)mp_count_bits(&t);
     count = (bits / ((size * 8u) - nails)) + (((bits % ((size * 8u) - nails)) != 0u) ? 1u : 0u);
  
     for (i = 0; i < count; ++i) {
        for (j = 0; j < size; ++j) {
           unsigned char *byte = (unsigned char *)rop +
                                 (((order == -1) ? i : ((count - 1u) - i)) * size) +
                                 ((endian == -1) ? j : ((size - 1u) - j));
  
           if (j >= (size - nail_bytes)) {
              *byte = 0;
              continue;
           }
  
           *byte = (unsigned char)((j == ((size - nail_bytes) - 1u)) ? (t.dp[0] & odd_nail_mask) : (t.dp[0] & 0xFFuL));
  
           if ((result = mp_div_2d(&t, (j == ((size - nail_bytes) - 1u)) ? (int)(8u - odd_nails) : 8, &t, NULL)) != MP_OKAY) {
              mp_clear(&t);
              return result;
           }
        }
     }
  
     mp_clear(&t);
  
     if (countp != NULL) {
        *countp = count;
     }
  
     return MP_OKAY;
  }
  
  #endif
  
  /* ref:         $Format:%D$ */
  /* git commit:  $Format:%H$ */
  /* commit time: $Format:%ai$ */
  

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