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[omim] [coding] Fix bit streams.

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This commit is contained in:
Maxim Pimenov 2015-08-21 17:30:25 +03:00 • committed by Alex Zolotarev
parent 793a26d628
commit 369b126b33
1 changed files with 14 additions and 13 deletions
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27
coding/bit_streams.hpp
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@ -31,14 +31,6 @@ public:
}
}
// Writes up to CHAR_BIT-1 last bits if they have not been written yet
// and pads them with zeros.
void Flush()
{
if (m_bitsWritten % CHAR_BIT != 0)
m_writer.Write(&m_buf, 1);
}
// Returns the number of bits that have been sent to BitWriter,
// including those that are in m_buf and are possibly
// not flushed yet.
@ -77,22 +69,31 @@ public:
}
private:
// Writes up to CHAR_BIT-1 last bits if they have not been written yet
// and pads them with zeros.
// This method cannot be made public because once a byte has been flushed there is no going back.
void Flush()
{
if (m_bitsWritten % CHAR_BIT != 0)
m_writer.Write(&m_buf, 1);
}
TWriter & m_writer;
uint8_t m_buf;
uint64_t m_bitsWritten;
};
template <typename TReader>
template <typename TSource>
class BitReader
{
public:
BitReader(TReader & reader) : m_reader(reader), m_bitsRead(0), m_bufferedBits(0), m_buf(0) {}
BitReader(TSource & src) : m_src(src), m_bitsRead(0), m_bufferedBits(0), m_buf(0) {}
// Returns the total number of bits read from this BitReader.
uint64_t BitsRead() const { return m_bitsRead; }
// Reads n bits and returns them as the least significant bits of an 8-bit number.
// The underlying m_reader is supposed to be byte-aligned (which is the
// The underlying m_src is supposed to be byte-aligned (which is the
// case when it reads from the place that was written to using BitWriter).
// Read may use one lookahead byte.
uint8_t Read(uint32_t n)
@ -111,7 +112,7 @@ public:
else
{
uint8_t nextByte;
m_reader.Read(&nextByte, 1);
m_src.Read(&nextByte, 1);
uint32_t low = n - m_bufferedBits;
result = ((nextByte & (kByteMask >> (CHAR_BIT - low))) << m_bufferedBits) | m_buf;
m_buf = nextByte >> low;
@ -121,7 +122,7 @@ public:
}
private:
TReader & m_reader;
TSource & m_src;
uint64_t m_bitsRead;
uint32_t m_bufferedBits;
uint8_t m_buf;