write-be32.c 1.57 KB
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/* write-be32.c */

/* nettle, low-level cryptographics library
 *
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 * Copyright (C) 2001 Niels Möller
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 *  
 * The nettle library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 *
 * The nettle library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with the nettle library; see the file COPYING.LIB.  If not, write to
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 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02111-1301, USA.
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 */

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include <stdlib.h>

#include "nettle-write.h"

#include "macros.h"

void
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_nettle_write_be32(size_t length, uint8_t *dst,
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		   uint32_t *src)
{
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  size_t i;
  size_t words;
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  unsigned leftover;
  
  words = length / 4;
  leftover = length % 4;

  for (i = 0; i < words; i++, dst += 4)
    WRITE_UINT32(dst, src[i]);

  if (leftover)
    {
      uint32_t word;
      unsigned j = leftover;
      
      word = src[i];
      
      switch (leftover)
	{
	default:
	  abort();
	case 3:
	  dst[--j] = (word >> 8) & 0xff;
	  /* Fall through */
	case 2:
	  dst[--j] = (word >> 16) & 0xff;
	  /* Fall through */
	case 1:
	  dst[--j] = (word >> 24) & 0xff;
	}
    }
}