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// Copyright (c) 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Utility methods to convert between absolute indexing (used in the dynamic
// table), relative indexing used on the encoder stream, and relative indexing
// and post-base indexing used on request streams (in header blocks). See:
// https://quicwg.org/base-drafts/draft-ietf-quic-qpack.html#indexing
// https://quicwg.org/base-drafts/draft-ietf-quic-qpack.html#relative-indexing
// https://quicwg.org/base-drafts/draft-ietf-quic-qpack.html#post-base
#ifndef QUICHE_QUIC_CORE_QPACK_QPACK_INDEX_CONVERSIONS_H_
#define QUICHE_QUIC_CORE_QPACK_QPACK_INDEX_CONVERSIONS_H_
#include <cstdint>
#include "quiche/quic/platform/api/quic_export.h"
namespace quic {
// Conversion functions used in the encoder do not check for overflow/underflow.
// Since the maximum index is limited by maximum dynamic table capacity
// (represented on uint64_t) divided by minimum header field size (defined to be
// 32 bytes), overflow is not possible. The caller is responsible for providing
// input that does not underflow.
QUIC_EXPORT_PRIVATE uint64_t QpackAbsoluteIndexToEncoderStreamRelativeIndex(
uint64_t absolute_index, uint64_t inserted_entry_count);
QUIC_EXPORT_PRIVATE uint64_t QpackAbsoluteIndexToRequestStreamRelativeIndex(
uint64_t absolute_index, uint64_t base);
// Conversion functions used in the decoder operate on input received from the
// network. These functions return false on overflow or underflow.
QUIC_EXPORT_PRIVATE bool QpackEncoderStreamRelativeIndexToAbsoluteIndex(
uint64_t relative_index, uint64_t inserted_entry_count,
uint64_t* absolute_index);
// On success, |*absolute_index| is guaranteed to be strictly less than
// std::numeric_limits<uint64_t>::max().
QUIC_EXPORT_PRIVATE bool QpackRequestStreamRelativeIndexToAbsoluteIndex(
uint64_t relative_index, uint64_t base, uint64_t* absolute_index);
// On success, |*absolute_index| is guaranteed to be strictly less than
// std::numeric_limits<uint64_t>::max().
QUIC_EXPORT_PRIVATE bool QpackPostBaseIndexToAbsoluteIndex(
uint64_t post_base_index, uint64_t base, uint64_t* absolute_index);
} // namespace quic
#endif // QUICHE_QUIC_CORE_QPACK_QPACK_INDEX_CONVERSIONS_H_