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/*
* Copyright (c) 2020, the SerenityOS developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/Optional.h>
#include <AK/Stream.h>
namespace AK {
class InputBitStream final : public InputStream {
public:
explicit InputBitStream(InputStream& stream)
: m_stream(stream)
{
}
size_t read(Bytes bytes) override
{
if (has_any_error())
return 0;
size_t nread = 0;
if (bytes.size() >= 1) {
if (m_next_byte.has_value()) {
bytes[0] = m_next_byte.value();
m_next_byte.clear();
++nread;
}
}
return nread + m_stream.read(bytes.slice(nread));
}
bool read_or_error(Bytes bytes) override
{
if (read(bytes) != bytes.size()) {
set_fatal_error();
return false;
}
return true;
}
bool unreliable_eof() const override { return !m_next_byte.has_value() && m_stream.unreliable_eof(); }
bool discard_or_error(size_t count) override
{
if (count >= 1) {
if (m_next_byte.has_value()) {
m_next_byte.clear();
--count;
}
}
return m_stream.discard_or_error(count);
}
u32 read_bits(size_t count)
{
u32 result = 0;
size_t nread = 0;
while (nread < count) {
if (m_stream.has_any_error()) {
set_fatal_error();
return 0;
}
if (m_next_byte.has_value()) {
const auto bit = (m_next_byte.value() >> m_bit_offset) & 1;
result |= bit << nread;
++nread;
if (m_bit_offset++ == 7)
m_next_byte.clear();
} else {
m_stream >> m_next_byte;
m_bit_offset = 0;
}
}
return result;
}
bool read_bit() { return static_cast<bool>(read_bits(1)); }
void align_to_byte_boundary()
{
if (m_next_byte.has_value())
m_next_byte.clear();
}
private:
Optional<u8> m_next_byte;
size_t m_bit_offset { 0 };
InputStream& m_stream;
};
}
using AK::InputBitStream;
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