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https://github.com/RGBCube/serenity
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AK: Move bit streams from LibCore
This commit is contained in:
Tim Schumacher
Andrew Kaster
parent
94f139c111
commit
2470dd3bb5
14 changed files with 167 additions and 158 deletions
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@ -1,407 +0,0 @@
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/*
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* Copyright (c) 2021, kleines Filmröllchen <filmroellchen@serenityos.org>.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/ByteBuffer.h>
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#include <AK/Concepts.h>
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#include <AK/Error.h>
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#include <AK/MaybeOwned.h>
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#include <AK/NonnullOwnPtr.h>
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#include <AK/NonnullRefPtr.h>
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#include <AK/OwnPtr.h>
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#include <AK/Span.h>
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#include <AK/StdLibExtraDetails.h>
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#include <AK/Types.h>
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#include <LibCore/Stream.h>
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namespace Core::Stream {
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/// A stream wrapper class that allows you to read arbitrary amounts of bits
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/// in big-endian order from another stream.
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class BigEndianInputBitStream : public AK::Stream {
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public:
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static ErrorOr<NonnullOwnPtr<BigEndianInputBitStream>> construct(MaybeOwned<Stream> stream)
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{
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return adopt_nonnull_own_or_enomem<BigEndianInputBitStream>(new BigEndianInputBitStream(move(stream)));
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}
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// ^Stream
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virtual ErrorOr<Bytes> read(Bytes bytes) override
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{
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if (m_current_byte.has_value() && is_aligned_to_byte_boundary()) {
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bytes[0] = m_current_byte.release_value();
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return m_stream->read(bytes.slice(1));
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}
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align_to_byte_boundary();
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return m_stream->read(bytes);
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}
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virtual ErrorOr<size_t> write(ReadonlyBytes bytes) override { return m_stream->write(bytes); }
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virtual ErrorOr<void> write_entire_buffer(ReadonlyBytes bytes) override { return m_stream->write_entire_buffer(bytes); }
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virtual bool is_eof() const override { return m_stream->is_eof() && !m_current_byte.has_value(); }
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virtual bool is_open() const override { return m_stream->is_open(); }
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virtual void close() override
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{
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m_stream->close();
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align_to_byte_boundary();
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}
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ErrorOr<bool> read_bit()
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{
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return read_bits<bool>(1);
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}
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/// Depending on the number of bits to read, the return type can be chosen appropriately.
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/// This avoids a bunch of static_cast<>'s for the user.
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// TODO: Support u128, u256 etc. as well: The concepts would be quite complex.
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template<Unsigned T = u64>
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ErrorOr<T> read_bits(size_t count)
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{
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if constexpr (IsSame<bool, T>) {
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VERIFY(count == 1);
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}
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T result = 0;
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size_t nread = 0;
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while (nread < count) {
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if (m_current_byte.has_value()) {
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if constexpr (!IsSame<bool, T> && !IsSame<u8, T>) {
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// read as many bytes as possible directly
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if (((count - nread) >= 8) && is_aligned_to_byte_boundary()) {
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// shift existing data over
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result <<= 8;
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result |= m_current_byte.value();
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nread += 8;
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m_current_byte.clear();
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} else {
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auto const bit = (m_current_byte.value() >> (7 - m_bit_offset)) & 1;
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result <<= 1;
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result |= bit;
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++nread;
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if (m_bit_offset++ == 7)
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m_current_byte.clear();
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}
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} else {
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// Always take this branch for booleans or u8: there's no purpose in reading more than a single bit
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auto const bit = (m_current_byte.value() >> (7 - m_bit_offset)) & 1;
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if constexpr (IsSame<bool, T>)
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result = bit;
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else {
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result <<= 1;
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result |= bit;
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}
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++nread;
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if (m_bit_offset++ == 7)
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m_current_byte.clear();
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}
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} else {
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auto temp_buffer = TRY(ByteBuffer::create_uninitialized(1));
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TRY(m_stream->read(temp_buffer.bytes()));
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m_current_byte = temp_buffer[0];
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m_bit_offset = 0;
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}
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}
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return result;
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}
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/// Discards any sub-byte stream positioning the input stream may be keeping track of.
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/// Non-bitwise reads will implicitly call this.
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void align_to_byte_boundary()
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{
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m_current_byte.clear();
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m_bit_offset = 0;
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}
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/// Whether we are (accidentally or intentionally) at a byte boundary right now.
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ALWAYS_INLINE bool is_aligned_to_byte_boundary() const { return m_bit_offset == 0; }
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private:
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BigEndianInputBitStream(MaybeOwned<Stream> stream)
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: m_stream(move(stream))
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{
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}
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Optional<u8> m_current_byte;
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size_t m_bit_offset { 0 };
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MaybeOwned<Stream> m_stream;
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};
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/// A stream wrapper class that allows you to read arbitrary amounts of bits
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/// in little-endian order from another stream.
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class LittleEndianInputBitStream : public AK::Stream {
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public:
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static ErrorOr<NonnullOwnPtr<LittleEndianInputBitStream>> construct(MaybeOwned<Stream> stream)
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{
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return adopt_nonnull_own_or_enomem<LittleEndianInputBitStream>(new LittleEndianInputBitStream(move(stream)));
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}
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LittleEndianInputBitStream(MaybeOwned<Stream> stream)
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: m_stream(move(stream))
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{
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}
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// ^Stream
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virtual ErrorOr<Bytes> read(Bytes bytes) override
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{
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if (m_current_byte.has_value() && is_aligned_to_byte_boundary()) {
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bytes[0] = m_current_byte.release_value();
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return m_stream->read(bytes.slice(1));
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}
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align_to_byte_boundary();
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return m_stream->read(bytes);
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}
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virtual ErrorOr<size_t> write(ReadonlyBytes bytes) override { return m_stream->write(bytes); }
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virtual ErrorOr<void> write_entire_buffer(ReadonlyBytes bytes) override { return m_stream->write_entire_buffer(bytes); }
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virtual bool is_eof() const override { return m_stream->is_eof() && !m_current_byte.has_value(); }
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virtual bool is_open() const override { return m_stream->is_open(); }
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virtual void close() override
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{
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m_stream->close();
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align_to_byte_boundary();
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}
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ErrorOr<bool> read_bit()
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{
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return read_bits<bool>(1);
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}
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/// Depending on the number of bits to read, the return type can be chosen appropriately.
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/// This avoids a bunch of static_cast<>'s for the user.
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// TODO: Support u128, u256 etc. as well: The concepts would be quite complex.
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template<Unsigned T = u64>
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ErrorOr<T> read_bits(size_t count)
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{
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if constexpr (IsSame<bool, T>) {
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VERIFY(count == 1);
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}
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T result = 0;
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size_t nread = 0;
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while (nread < count) {
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if (m_current_byte.has_value()) {
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if constexpr (!IsSame<bool, T> && !IsSame<u8, T>) {
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// read as many bytes as possible directly
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if (((count - nread) >= 8) && is_aligned_to_byte_boundary()) {
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// shift existing data over
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result |= (m_current_byte.value() << nread);
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nread += 8;
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m_current_byte.clear();
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} else {
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auto const bit = (m_current_byte.value() >> m_bit_offset) & 1;
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result |= (bit << nread);
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++nread;
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if (m_bit_offset++ == 7)
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m_current_byte.clear();
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}
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} else {
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// Always take this branch for booleans or u8: there's no purpose in reading more than a single bit
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auto const bit = (m_current_byte.value() >> m_bit_offset) & 1;
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if constexpr (IsSame<bool, T>)
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result = bit;
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else
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result |= (bit << nread);
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++nread;
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if (m_bit_offset++ == 7)
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m_current_byte.clear();
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}
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} else {
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auto temp_buffer = TRY(ByteBuffer::create_uninitialized(1));
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auto read_bytes = TRY(m_stream->read(temp_buffer.bytes()));
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if (read_bytes.is_empty())
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return Error::from_string_literal("eof");
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m_current_byte = temp_buffer[0];
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m_bit_offset = 0;
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}
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}
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return result;
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}
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/// Discards any sub-byte stream positioning the input stream may be keeping track of.
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/// Non-bitwise reads will implicitly call this.
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u8 align_to_byte_boundary()
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{
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u8 remaining_bits = m_current_byte.value_or(0) >> m_bit_offset;
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m_current_byte.clear();
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m_bit_offset = 0;
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return remaining_bits;
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}
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/// Whether we are (accidentally or intentionally) at a byte boundary right now.
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ALWAYS_INLINE bool is_aligned_to_byte_boundary() const { return m_bit_offset == 0; }
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private:
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Optional<u8> m_current_byte;
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size_t m_bit_offset { 0 };
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MaybeOwned<Stream> m_stream;
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};
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/// A stream wrapper class that allows you to write arbitrary amounts of bits
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/// in big-endian order to another stream.
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class BigEndianOutputBitStream : public AK::Stream {
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public:
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static ErrorOr<NonnullOwnPtr<BigEndianOutputBitStream>> construct(MaybeOwned<Stream> stream)
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{
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return adopt_nonnull_own_or_enomem<BigEndianOutputBitStream>(new BigEndianOutputBitStream(move(stream)));
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}
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virtual ErrorOr<Bytes> read(Bytes) override
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{
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return Error::from_errno(EBADF);
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}
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virtual ErrorOr<size_t> write(ReadonlyBytes bytes) override
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{
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VERIFY(m_bit_offset == 0);
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return m_stream->write(bytes);
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}
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template<Unsigned T>
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ErrorOr<void> write_bits(T value, size_t bit_count)
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{
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VERIFY(m_bit_offset <= 7);
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while (bit_count > 0) {
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u8 next_bit = (value >> (bit_count - 1)) & 1;
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bit_count--;
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m_current_byte <<= 1;
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m_current_byte |= next_bit;
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m_bit_offset++;
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if (m_bit_offset > 7) {
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TRY(m_stream->write({ &m_current_byte, sizeof(m_current_byte) }));
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m_bit_offset = 0;
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m_current_byte = 0;
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}
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}
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return {};
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}
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virtual bool is_eof() const override
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{
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return true;
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}
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virtual bool is_open() const override
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{
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return m_stream->is_open();
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}
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virtual void close() override
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{
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}
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size_t bit_offset() const
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{
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return m_bit_offset;
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}
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ErrorOr<void> align_to_byte_boundary()
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{
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if (m_bit_offset == 0)
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return {};
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TRY(write_bits(0u, 8 - m_bit_offset));
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VERIFY(m_bit_offset == 0);
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return {};
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}
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private:
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BigEndianOutputBitStream(MaybeOwned<Stream> stream)
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: m_stream(move(stream))
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{
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}
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MaybeOwned<Stream> m_stream;
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u8 m_current_byte { 0 };
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size_t m_bit_offset { 0 };
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};
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/// A stream wrapper class that allows you to write arbitrary amounts of bits
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/// in little-endian order to another stream.
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class LittleEndianOutputBitStream : public AK::Stream {
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public:
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static ErrorOr<NonnullOwnPtr<LittleEndianOutputBitStream>> construct(MaybeOwned<Stream> stream)
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{
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return adopt_nonnull_own_or_enomem<LittleEndianOutputBitStream>(new LittleEndianOutputBitStream(move(stream)));
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}
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virtual ErrorOr<Bytes> read(Bytes) override
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{
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return Error::from_errno(EBADF);
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}
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virtual ErrorOr<size_t> write(ReadonlyBytes bytes) override
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{
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VERIFY(m_bit_offset == 0);
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return m_stream->write(bytes);
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}
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template<Unsigned T>
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ErrorOr<void> write_bits(T value, size_t bit_count)
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{
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VERIFY(m_bit_offset <= 7);
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size_t input_offset = 0;
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while (input_offset < bit_count) {
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u8 next_bit = (value >> input_offset) & 1;
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input_offset++;
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m_current_byte |= next_bit << m_bit_offset;
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m_bit_offset++;
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if (m_bit_offset > 7) {
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TRY(m_stream->write({ &m_current_byte, sizeof(m_current_byte) }));
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m_bit_offset = 0;
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m_current_byte = 0;
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}
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}
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return {};
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}
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virtual bool is_eof() const override
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{
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return true;
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}
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virtual bool is_open() const override
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{
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return m_stream->is_open();
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}
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virtual void close() override
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{
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}
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size_t bit_offset() const
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{
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return m_bit_offset;
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}
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ErrorOr<void> align_to_byte_boundary()
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{
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if (m_bit_offset == 0)
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return {};
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TRY(write_bits(0u, 8 - m_bit_offset));
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VERIFY(m_bit_offset == 0);
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return {};
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}
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private:
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LittleEndianOutputBitStream(MaybeOwned<Stream> stream)
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: m_stream(move(stream))
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{
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}
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MaybeOwned<Stream> m_stream;
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u8 m_current_byte { 0 };
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size_t m_bit_offset { 0 };
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};
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}
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