/**

 * The implementation of the tiger() function is based on the corresponding

 * function in the tigertree project:

 *    https://sourceforge.net/projects/tigertree/

 * Which in turn states that the code is almost a literal copy from the

 * original Tiger authors code. It can be found at:

 *    http://www.cs.technion.ac.il/~biham/Reports/Tiger

 *

 * The functions tiger_int() and tiger_leaf() are implemented by me. These are

 * built on top of the (internal) tiger_compress() function. These 2 functions

 * are faster than the generic tiger() function for the specific case of

 * tiger-tree calculations.

 */

#ifndef TIGER_HH

#define TIGER_HH

#include <array>

#include <cstdint>

#include <span>

#include <string>

namespace openmsx {

/** This struct represents the result of a tiger-hash.

 * This is a 192-bit value. It can be formatted as a 39-char base32-encoded

 * string. Similar to the output of the unix 'tthsum' tool.

 */

struct TigerHash

{

	[[nodiscard]] std::string toString() const;

	union {

		std::array<uint64_t, 3> h64;

		std::array<uint8_t, 24> h8;

	};

};

/** Generic function to calculate a tiger-hash.

 * input: start-address and size of the block

 * output: 192-bit hash value

 * The result is endianness-neutral (on big-endian systems the result is

 * converted so that, when interpreted as a byte-array, it is identical to

 * the result obtained on a little-endian system).

 */

void tiger(std::span<const uint8_t> input, TigerHash& result);

/** Use for tiger-tree internal node hash calculations.

 * Combine two earlier calculated tiger hash values in a specific way (add

 * marker/padding/length bytes before/after) and calculate a new hash value.

 * This function is not reentrant.

 */

void tiger_int(const TigerHash& h0, const TigerHash& h1, TigerHash& result);

/** Use for tiger-tree leaf node hash calculations.

 * Take a 1+1024-byte input block, add some marker/padding/length bytes

 * before/after and calculate a tiger-hash.

 * This function is not reentrant.

 * This function requires that data[0] can be (temporarily) overridden (so

 * after the function returns the data buffer is unchanged, but temporarily

 * it is changed, hence the parameter cannot be const).

 */

void tiger_leaf(std::span</*const*/uint8_t> data, TigerHash& result);

} // namespace openmsx

#endif