checksum each block

[pjrinaldi]

If I want to checksum each block compressed, I can use the following... (adler-32 used in ewf)

uint32_t Expert_Witness_Compression_CRC(
uint8_t *buffer,
size_t buffer_size,
uint32_t previous_key )
{
size_t buffer_iterator = 0;
uint32_t lower_word = previous_key & 0xffff;
uint32_t upper_word = ( previous_key >> 16 ) & 0xffff;

for( buffer_iterator = 0;
     buffer_iterator < buffer_size;
     buffer_iterator++ )
{
	lower_word += buffer[ buffer_iterator ];
	upper_word += lower_word;

	if( ( buffer_iterator != 0 )
	 && ( ( buffer_iterator % 0x15b0 == 0 )
	  || ( buffer_iterator == buffer_size - 1 ) ) )
	{
		lower_word = lower_word % 0xfff1;
		upper_word = upper_word % 0xfff1;
	}
}
return( ( upper_word << 16 ) | lower_word );

}