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#pragma once
#include <util/system/types.h>
namespace NYT {
////////////////////////////////////////////////////////////////////////////////
//! MSB-first bit writer over a caller-owned buffer.
/*!
* Bits are flushed to the buffer in 4-byte chunks, so the buffer must have room
* for up to 3 bytes beyond the last logically-written byte before #Finish is
* called.
*/
class TBitWriter
{
public:
explicit TBitWriter(char* ptr);
//! Appends the #width low bits of #value. Requires 0 <= #width <= 32 and
//! #value < 2^#width (for #width == 32 any value is accepted).
void WriteBits(ui32 value, int width);
//! Pads the last partial byte with zero low bits and returns the
//! one-past-end pointer.
char* Finish();
private:
char* Ptr_;
ui64 Accumulator_ = 0;
int BitCount_ = 0;
};
//! MSB-first bit reader.
/*!
* Reads bits written by #TBitWriter. Assumes up to 8 bytes past the logical end
* of the stream are safe to read.
*/
class TBitReader
{
public:
explicit TBitReader(const char* ptr);
//! Reads and returns #width bits (0 <= #width <= 32).
ui32 ReadBits(int width);
//! Returns the one-past-end pointer; the (< 8) buffered sub-byte bits, which
//! are the writer's zero padding, are dropped.
const char* Finish();
private:
const ui8* Ptr_;
ui64 Accumulator_ = 0;
int BitCount_ = 0;
};
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT
#define BIT_IO_INL_H_
#include "bit_io-inl.h"
#undef BIT_IO_INL_H_
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