//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.

//  This source code is licensed under both the GPLv2 (found in the

//  COPYING file in the root directory) and Apache 2.0 License

//  (found in the LICENSE.Apache file in the root directory).

//

// Copyright (c) 2011 The LevelDB Authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE file. See the AUTHORS file for names of contributors.

#include "util/coding.h"

#include <algorithm>

#include "rocksdb/slice.h"

#include "rocksdb/slice_transform.h"

namespace ROCKSDB_NAMESPACE {

// conversion' conversion from 'type1' to 'type2', possible loss of data

#if defined(_MSC_VER)

#pragma warning(push)

#pragma warning(disable : 4244)

#endif

char* EncodeVarint32(char* dst, uint32_t v) {

  // Operate on characters as unsigneds

  unsigned char* ptr = reinterpret_cast<unsigned char*>(dst);

  static const int B = 128;

  if (v < (1 << 7)) {

    *(ptr++) = v;

  } else if (v < (1 << 14)) {

    *(ptr++) = v | B;

    *(ptr++) = v >> 7;

  } else if (v < (1 << 21)) {

    *(ptr++) = v | B;

    *(ptr++) = (v >> 7) | B;

    *(ptr++) = v >> 14;

  } else if (v < (1 << 28)) {

    *(ptr++) = v | B;

    *(ptr++) = (v >> 7) | B;

    *(ptr++) = (v >> 14) | B;

    *(ptr++) = v >> 21;

  } else {

    *(ptr++) = v | B;

    *(ptr++) = (v >> 7) | B;

    *(ptr++) = (v >> 14) | B;

    *(ptr++) = (v >> 21) | B;

    *(ptr++) = v >> 28;

  }

  return reinterpret_cast<char*>(ptr);

}

#if defined(_MSC_VER)

#pragma warning(pop)

#endif

const char* GetVarint32PtrFallback(const char* p, const char* limit,

                                   uint32_t* value) {

  uint32_t result = 0;

  for (uint32_t shift = 0; shift <= 28 && p < limit; shift += 7) {

    uint32_t byte = *(reinterpret_cast<const unsigned char*>(p));

    p++;

    if (byte & 128) {

      // More bytes are present

      result |= ((byte & 127) << shift);

    } else {

      result |= (byte << shift);

      *value = result;

      return reinterpret_cast<const char*>(p);

    }

  }

  return nullptr;

}

const char* GetVarint64Ptr(const char* p, const char* limit, uint64_t* value) {

  uint64_t result = 0;

  for (uint32_t shift = 0; shift <= 63 && p < limit; shift += 7) {

    uint64_t byte = *(reinterpret_cast<const unsigned char*>(p));

    p++;

    if (byte & 128) {

      // More bytes are present

      result |= ((byte & 127) << shift);

    } else {

      result |= (byte << shift);

      *value = result;

      return reinterpret_cast<const char*>(p);

    }

  }

  return nullptr;

}

}  // namespace ROCKSDB_NAMESPACE