SHA256Write.c
Author: cmaier@cmassoc.net

    /*====================================================================*
     *
     *   void SHA256Write (struct sha256 * sha256, void const * memory, size_t extent);
     *
     *   SHA256.h
     *
     *   write a block of data to an SHA256 digest; this function behaves
     *   like function write() but returns no value and does not fail; an
     *   unlimited amount of data may be written using successive writes;
     *
     *   to start a new digest, use function SHA266Reset(); to read the
     *   digest, use function SHA256Fetch();
     *
     *   Read standard FIPS180-2 sec 5.3.2 for an explanation;
     *
     *   Motley Tools by Charles Maier <cmaier@cmassoc.net>;
     *   Copyright (c) 2001-2006 by Charles Maier Associates;
     *   Licensed under the Internet Software Consortium License;
     *
     *--------------------------------------------------------------------*/

    #ifndef SHA256WRITE_SOURCE
    #define SHA256WRITE_SOURCE

    #include "../key/SHA256.h"

    void SHA256Write (struct sha256 * sha256, void const * memory, size_t extent)

    {
    	if (extent)
    	{
    		uint8_t * buffer = (uint8_t *)(memory);
    		unsigned left = sha256->count [0] & 0x3F;
    		unsigned fill = sizeof (sha256->block) - left;
    		sha256->count [0] += (uint32_t)(extent);
    		sha256->count [0] &= 0xFFFFFFFF;
    		if (sha256->count [0] < extent)
    		{
    			sha256->count [1]++;
    		}
    		if ((left) && (extent >= fill))
    		{
    			memcpy (sha256->block + left, buffer, fill);
    			SHA256Block (sha256, sha256->block);
    			extent -= fill;
    			buffer += fill;
    			left = 0;
    		}
    		while (extent >= sizeof (sha256->block))
    		{
    			SHA256Block (sha256, buffer);
    			extent -= sizeof (sha256->block);
    			buffer += sizeof (sha256->block);
    		}
    		if (extent)
    		{
    			memcpy (sha256->block + left, buffer, extent);
    		}
    	}
    	return;
    }

    #endif

[PREV] [HOME] [NEXT]