dsp::VDIFTwoBitTable Class Reference

Look-up tables for conversion from VDIF two-bit to floating point numbers. More...

#include <VDIFTwoBitTable.h>

Inheritance diagram for dsp::VDIFTwoBitTable:

Public Member Functions
	VDIFTwoBitTable (Type type)
	Constructor.
	~VDIFTwoBitTable ()
	Destructor.
virtual unsigned	extract (unsigned byte, unsigned sample) const
	Return the 2-bit number from byte corresponding to sample.
Public Member Functions inherited from dsp::TwoBitTable
	TwoBitTable (Type type, bool reverse_bits=false)
	Constructor.
void	set_lo_val (float lo_val)
	Set the value of the low voltage state.
float	get_lo_val () const
	Return the value of the low voltage state.
void	set_hi_val (float hi_val)
	Set the value of the high voltage state.
float	get_hi_val () const
	Return the value of the high voltage state.
void	set_reverse_2bit (bool flag=true)
	Set the reverse_2bit attribute.
bool	get_reverse_2bit () const
	Get the reverse_2bit value.
void	rebuild ()
	Build a two-bit table with the current attributes.
void	generate_unique_values (float *vals) const
	Generate a look-up table for 2-bit to floating point conversion.
Public Member Functions inherited from dsp::BitTable
	BitTable (unsigned nbit, Type type, bool reverse_bits=false)
	Constructor.
virtual	~BitTable ()
	Destructor.
void	set_effective_nbit (unsigned bits)
	Set the effective number of bits. More...
unsigned	get_effective_nbit () const
void	set_order (Order)
	Set the order of the samples in each byte.
Order	get_order () const
void	set_zero_is_a_threshold (bool)
	Set to true if zero is a threshold; set to false if zero is a value. More...
bool	get_zero_is_a_threshold () const
unsigned	get_values_per_byte () const
	Get the number of floating point values per byte, 8/N.
unsigned	get_unique_values () const
	Get the number of unique values of an N-bit integer, 2^N.
double	get_scale () const
	Get the scale factor used to normalize the variance to unity.
Type	get_type () const
	Return the digitization convention.
const float *	get_values (unsigned byte=0) const
	Returns pointer to values_per_byte floats represented by byte.
void	generate (float *table) const
	Generate a look-up table for conversion to floating point. More...
virtual double	get_optimal_variance () const
	Return the optimal variance of normally distributed samples.
virtual double	get_nlow_threshold () const
	Return the optimal threshold closest to and less than unity.
virtual void	get_nlow_lookup (char *nlow_lookup) const
	Return the number of low voltage states in each of 256 bytes.
Public Member Functions inherited from Reference::Able
	Able (const Able &)
Able &	operator= (const Able &)
unsigned	get_reference_count () const
Public Member Functions inherited from Reference::HeapTracked
	HeapTracked (const HeapTracked &)
HeapTracked &	operator= (const HeapTracked &)
bool	__is_on_heap () const

Additional Inherited Members
Public Types inherited from dsp::BitTable
enum	Type { OffsetBinary, TwosComplement, SignMagnitude }
	Interpretation of the bits in each value.
enum	Order { MostToLeast, LeastToMost }
	The order of values in each byte (bit significance)
Static Public Member Functions inherited from Reference::Able
static size_t	get_instance_count ()
Static Public Member Functions inherited from Reference::HeapTracked
static void *	operator new (size_t size, void *ptr=0)
static void	operator delete (void *location, void *ptr)
static void	operator delete (void *location)
static size_t	get_heap_queue_size ()
Static Public Attributes inherited from dsp::BitTable
static const unsigned	bits_per_byte = 8
	Number of bits per bytes.
static const unsigned	unique_bytes = 1 << bits_per_byte
	Number of unique 8-bit combinations.
Protected Member Functions inherited from dsp::BitTable
void	build ()
	Build the lookup table.
void	destroy ()
	Destroy the lookup table.
Protected Member Functions inherited from Reference::Able
Handle *	__reference (bool active) const
void	__dereference (bool auto_delete=true) const
Protected Attributes inherited from dsp::TwoBitTable
float	lo_val
	Value of voltage in low state.
float	hi_val
	Value of voltage in high state.
bool	reverse_2bit
	Flip the two data bits - that is SignMag becomes MagSign.
Protected Attributes inherited from dsp::BitTable
float *	table
	For each unsigned char, values of the two output voltage states.
Type	type
	Digitization convention.
const unsigned	nbit
	Number of bits.
unsigned	zero_is_a_threshold
	Zero is a threshold.
unsigned	effective_nbit
	The effective number of bits.
const bool	reverse_bits
	Reverse the order of the bits.
Order	order
	The order of the samples in each byte.
const unsigned	values_per_byte
	Number of N-bit values per byte.
const unsigned	unique_values
	Number of unique N-bit values.
const unsigned	nbit_mask
	N-bit mask.
double	scale
	The scale factor used to normalize the variance to unity.

Detailed Description

Look-up tables for conversion from VDIF two-bit to floating point numbers.

VDIF defines bits to run in time order from LSB to MSB, this is the opposite of the standard dspsr TwoBitTable convention so we need to override the 'extract' function here.

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The documentation for this class was generated from the following files:

• VDIFTwoBitTable.h
• VDIFTwoBitTable.C