#include <bit-stream-utils.h>

Collaboration diagram for impala::BitReader:

Public Member Functions
	BitReader (uint8_t *buffer, int buffer_len)
	'buffer' is the buffer to read from. The buffer's length is 'buffer_len'. More...

	BitReader ()

template<typename T >
bool	GetValue (int num_bits, T *v)

template<typename T >
bool	GetAligned (int num_bytes, T *v)

bool	GetVlqInt (int32_t *v)

int	bytes_left ()

Static Public Attributes
static const int	MAX_VLQ_BYTE_LEN = 5
	Maximum byte length of a vlq encoded int. More...

Private Attributes
uint8_t *	buffer_

int	max_bytes_

uint64_t	buffered_values_

int	byte_offset_

int	bit_offset_

Detailed Description

Utility class to read bit/byte stream. This class can read bits or bytes that are either byte aligned or not. It also has utilities to read multiple bytes in one read (e.g. encoded int).

Definition at line 92 of file bit-stream-utils.h.

Constructor & Destructor Documentation

impala::BitReader::BitReader	(	uint8_t *	buffer,
		int	buffer_len
	)

inline

'buffer' is the buffer to read from. The buffer's length is 'buffer_len'.

Definition at line 95 of file bit-stream-utils.h.

References buffer_, buffered_values_, byte_offset_, and max_bytes_.

impala::BitReader::BitReader ( )

inline

Definition at line 104 of file bit-stream-utils.h.

Member Function Documentation

int impala::BitReader::bytes_left ( )

inline

Returns the number of bytes left in the stream, not including the current byte (i.e., there may be an additional fraction of a byte).

Definition at line 124 of file bit-stream-utils.h.

References bit_offset_, byte_offset_, impala::BitUtil::Ceil(), and max_bytes_.

template<typename T >

bool impala::BitReader::GetAligned	(	int	num_bytes,
		T *	v
	)

inline

Reads a 'num_bytes'-sized value from the buffer and stores it in 'v'. T needs to be a little-endian native type and big enough to store 'num_bytes'. The value is assumed to be byte-aligned so the stream will be advanced to the start of the next byte before 'v' is read. Returns false if there are not enough bytes left.

Definition at line 115 of file bit-stream-utils.inline.h.

References bit_offset_, buffer_, buffered_values_, byte_offset_, impala::BitUtil::Ceil(), LIKELY, max_bytes_, and UNLIKELY.

Referenced by impala::RleDecoder::Get().

template<typename T >

bool impala::BitReader::GetValue	(	int	num_bits,
		T *	v
	)

inline

Gets the next value from the buffer. Returns true if 'v' could be read or false if there are not enough bytes left. num_bits must be <= 32.

Definition at line 85 of file bit-stream-utils.inline.h.

References bit_offset_, buffer_, buffered_values_, byte_offset_, LIKELY, max_bytes_, impala::BitUtil::TrailingBits(), and UNLIKELY.

Referenced by impala::RleDecoder::Get(), impala::HdfsParquetScanner::BoolColumnReader::ReadSlot(), impala::TEST(), and TestBitWriterDecode().

bool impala::BitReader::GetVlqInt ( int32_t * v )

inline

Reads a vlq encoded int from the stream. The encoded int must start at the beginning of a byte. Return false if there were not enough bytes in the buffer.

Definition at line 136 of file bit-stream-utils.inline.h.

References MAX_VLQ_BYTE_LEN.

Referenced by impala::RleDecoder::Get().