/* -*- C++ -*-

 * This code is derived from (original license follows):

 *

 * This is an OpenSSL-compatible implementation of the RSA Data Security, Inc.

 * MD5 Message-Digest Algorithm (RFC 1321).

 *

 * Homepage:

 * http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5

 *

 * Author:

 * Alexander Peslyak, better known as Solar Designer <solar at openwall.com>

 *

 * This software was written by Alexander Peslyak in 2001.  No copyright is

 * claimed, and the software is hereby placed in the public domain.

 * In case this attempt to disclaim copyright and place the software in the

 * public domain is deemed null and void, then the software is

 * Copyright (c) 2001 Alexander Peslyak and it is hereby released to the

 * general public under the following terms:

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted.

 *

 * There's ABSOLUTELY NO WARRANTY, express or implied.

 *

 * See md5.c for more information.

 */

#ifndef LLVM_SUPPORT_MD5_H

#define LLVM_SUPPORT_MD5_H

#include "llvm/ADT/StringRef.h"

#include "llvm/Support/Endian.h"

#include <array>

#include <cstdint>

namespace llvm {

template <unsigned N> class SmallString;

template <typename T> class ArrayRef;

class MD5 {

  // Any 32-bit or wider unsigned integer data type will do.

  typedef uint32_t MD5_u32plus;

  MD5_u32plus a = 0x67452301;

  MD5_u32plus b = 0xefcdab89;

  MD5_u32plus c = 0x98badcfe;

  MD5_u32plus d = 0x10325476;

  MD5_u32plus hi = 0;

  MD5_u32plus lo = 0;

  uint8_t buffer[64];

  MD5_u32plus block[16];

public:

  struct MD5Result {

    std::array<uint8_t, 16> Bytes;

    operator std::array<uint8_t, 16>() const { return Bytes; }

    const uint8_t &operator[](size_t I) const { return Bytes[I]; }

    uint8_t &operator[](size_t I) { return Bytes[I]; }

    SmallString<32> digest() const;

    uint64_t low() const {

      // Our MD5 implementation returns the result in little endian, so the low

      // word is first.

      using namespace support;

      return endian::read<uint64_t, little, unaligned>(Bytes.data());

    }

    uint64_t high() const {

      using namespace support;

      return endian::read<uint64_t, little, unaligned>(Bytes.data() + 8);

    }

    std::pair<uint64_t, uint64_t> words() const {

      using namespace support;

      return std::make_pair(high(), low());

    }

  };

  MD5();

  /// Updates the hash for the byte stream provided.

  void update(ArrayRef<uint8_t> Data);

  /// Updates the hash for the StringRef provided.

  void update(StringRef Str);

  /// Finishes off the hash and puts the result in result.

  void final(MD5Result &Result);

  /// Translates the bytes in \p Res to a hex string that is

  /// deposited into \p Str. The result will be of length 32.

  static void stringifyResult(MD5Result &Result, SmallString<32> &Str);

  /// Computes the hash for a given bytes.

  static std::array<uint8_t, 16> hash(ArrayRef<uint8_t> Data);

private:

  const uint8_t *body(ArrayRef<uint8_t> Data);

};

inline bool operator==(const MD5::MD5Result &LHS, const MD5::MD5Result &RHS) {

  return LHS.Bytes == RHS.Bytes;

}

/// Helper to compute and return lower 64 bits of the given string's MD5 hash.

inline uint64_t MD5Hash(StringRef Str) {

  using namespace support;

  MD5 Hash;

  Hash.update(Str);

  MD5::MD5Result Result;

  Hash.final(Result);

  // Return the least significant word.

  return Result.low();

}

} // end namespace llvm

#endif // LLVM_SUPPORT_MD5_H