//  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"

namespace doris {

uint8_t* encode_varint32(uint8_t* dst, uint32_t v) {

    // Operate on characters as unsigneds

    static const int B = 128;

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

        *(dst++) = uint8_t(v);

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

        *(dst++) = uint8_t(v | B);

        *(dst++) = uint8_t(v >> 7);

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

        *(dst++) = uint8_t(v | B);

        *(dst++) = uint8_t((v >> 7) | B);

        *(dst++) = uint8_t(v >> 14);

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

        *(dst++) = uint8_t(v | B);

        *(dst++) = uint8_t((v >> 7) | B);

        *(dst++) = uint8_t((v >> 14) | B);

        *(dst++) = uint8_t(v >> 21);

    } else {

        *(dst++) = uint8_t(v | B);

        *(dst++) = uint8_t((v >> 7) | B);

        *(dst++) = uint8_t((v >> 14) | B);

        *(dst++) = uint8_t((v >> 21) | B);

        *(dst++) = uint8_t(v >> 28);

    }

    return dst;

}

const uint8_t* decode_varint32_ptr_fallback(const uint8_t* p, const uint8_t* limit,

                                            uint32_t* value) {

    uint32_t result = 0;

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

        uint32_t byte = *p;

        p++;

        if (byte & 128) {

            // More bytes are present

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

        } else {

            result |= (byte << shift);

            *value = result;

            return p;

        }

    }

    return nullptr;

}

const uint8_t* decode_varint64_ptr(const uint8_t* p, const uint8_t* limit, uint64_t* value) {

    uint64_t result = 0;

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

        uint64_t byte = *p;

        p++;

        if (byte & 128) {

            // More bytes are present

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

        } else {

            result |= (byte << shift);

            *value = result;

            return p;

        }

    }

    return nullptr;

}

} // namespace doris