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◆ main openmsx / src / utils / tiger.hh
2.3 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
/**
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 * The implementation of the tiger() function is based on the corresponding
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 * function in the tigertree project:
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 *    https://sourceforge.net/projects/tigertree/
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 * Which in turn states that the code is almost a literal copy from the
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 * original Tiger authors code. It can be found at:
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 *    http://www.cs.technion.ac.il/~biham/Reports/Tiger
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 *
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 * The functions tiger_int() and tiger_leaf() are implemented by me. These are
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 * built on top of the (internal) tiger_compress() function. These 2 functions
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 * are faster than the generic tiger() function for the specific case of
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 * tiger-tree calculations.
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 */
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#ifndef TIGER_HH
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#define TIGER_HH
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#include <array>
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#include <cstdint>
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#include <span>
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#include <string>
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namespace openmsx {
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/** This struct represents the result of a tiger-hash.
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 * This is a 192-bit value. It can be formatted as a 39-char base32-encoded
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 * string. Similar to the output of the unix 'tthsum' tool.
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 */
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struct TigerHash
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{
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	[[nodiscard]] std::string toString() const;
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	union {
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		std::array<uint64_t, 3> h64;
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		std::array<uint8_t, 24> h8;
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	};
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};
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/** Generic function to calculate a tiger-hash.
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 * input: start-address and size of the block
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 * output: 192-bit hash value
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 * The result is endianness-neutral (on big-endian systems the result is
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 * converted so that, when interpreted as a byte-array, it is identical to
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 * the result obtained on a little-endian system).
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 */
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void tiger(std::span<const uint8_t> input, TigerHash& result);
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/** Use for tiger-tree internal node hash calculations.
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 * Combine two earlier calculated tiger hash values in a specific way (add
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 * marker/padding/length bytes before/after) and calculate a new hash value.
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 * This function is not reentrant.
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 */
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void tiger_int(const TigerHash& h0, const TigerHash& h1, TigerHash& result);
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/** Use for tiger-tree leaf node hash calculations.
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 * Take a 1+1024-byte input block, add some marker/padding/length bytes
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 * before/after and calculate a tiger-hash.
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 * This function is not reentrant.
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 * This function requires that data[0] can be (temporarily) overridden (so
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 * after the function returns the data buffer is unchanged, but temporarily
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 * it is changed, hence the parameter cannot be const).
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 */
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void tiger_leaf(std::span</*const*/uint8_t> data, TigerHash& result);
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} // namespace openmsx
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#endif