/**
* \brief Struct holding a md5 checksum
*
* The proper way to print this checksum is:
* \code
* int i;
* for (i = 0; i < 16; i++)
* {
*     printf("%02x", ((unsigned char*)md5.h)[i]);
* }
* printf("\n");
* \endcode
*/
typedef struct md5_t
{
   unsigned int h[4];
} md5_t;

/**
* \brief Struct holding data needed while creating a md5 checksum
*/
typedef struct md5_tmp_t
{
   md5_t md5;
   char block[64];
   int size;
} md5_tmp_t;

/**
* \brief Creates a md5 struct and fills it with the initial values
*
* The struct can be used for md5_process_data() afterwards.
*
* Note that you have to call md5_finish() to get a useful md5 hash as padding
* has to be done!
*/
md5_tmp_t md5_initialize(void);
/**
* \brief Adds data to the md5 checksum
*/
void md5_process_data(md5_tmp_t* md5, const void* data, int length);
/**
* \brief Computes the final md5 checksum
*/
md5_t md5_finish(md5_tmp_t* md5);

/**
* \brief Creates a checksum from data
*/
md5_t md5_process(const void* data, unsigned int length);

/**
* \brief Copies the md5 data to a string.
*
* s must point to at least 33 bytes of allocated memory!
*/
void md5_to_string(md5_t md5, char* s);

/**
* \brief Reads in a file and stores the checksum in md5.
* \return Returns 0 if successful, -1 if not.
*/
int md5_process_file(md5_t *md5, const char* filename);