kc3-lang/libtommath/bn_mp_import.c

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• Hash : 4e3f1344
  Author :
  Date : 2015-11-12T01:49:07
  

  provide tommath_private.h tommath.h contains declarations for the public part of the library. tommath_private.h contains the functions which are private to ltm and should not be exposed to the public.

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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
   *
   * 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
   */
  
  /* based on gmp's mpz_import.
   * see http://gmplib.org/manual/Integer-Import-and-Export.html
   */
  int mp_import(mp_int* rop, size_t count, int order, size_t size, 
                              int endian, size_t nails, const void* op) {
  	int 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] == 4 ? -1 : 1);
  	}
  
  	odd_nails = (nails % 8);
  	odd_nail_mask = 0xff;
  	for (i = 0; i < odd_nails; ++i) {
  		odd_nail_mask ^= (1 << (7 - i));
  	}
  	nail_bytes = nails / 8;
  
  	for (i = 0; i < count; ++i) {
  		for (j = 0; j < size - nail_bytes; ++j) {
  			unsigned char byte = *(
  					(unsigned char*)op + 
  					(order == 1 ? i : count - 1 - i) * size + 
  					(endian == 1 ? j + nail_bytes : size - 1 - j - nail_bytes)
  				);
  
  			if (
  				(result = mp_mul_2d(rop, (j == 0 ? 8 - odd_nails : 8), rop)) != MP_OKAY) {
  				return result;
  			}
  
  			rop->dp[0] |= (j == 0 ? (byte & odd_nail_mask) : byte);
  			rop->used  += 1;
  		}
  	}
  
  	mp_clamp(rop);
  
  	return MP_OKAY;
  }
  
  #endif
  
  /* $Source$ */
  /* $Revision$ */
  /* $Date$ */
  

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