dsp::Mark4TwoBitTable Class Reference

Look-up tables for conversion from Mark4 two-bit to floating point numbers. More...

#include <Mark4TwoBitTable.h>

Inheritance diagram for dsp::Mark4TwoBitTable:

Public Member Functions
	Mark4TwoBitTable (Type type)
	Constructor.
	~Mark4TwoBitTable ()
	Destructor.
virtual unsigned	twobit (unsigned byte, unsigned sample) const
	Return the 2-bit number from byte corresponding to sample. More...
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 unsigned	extract (unsigned byte, unsigned i) const
	Extract the ith sample from byte. 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 Mark4 two-bit to floating point numbers.

The conversion scheme is specific to the ordering of bits in Mark4 data

Member Function Documentation

twobit()

unsigned dsp::Mark4TwoBitTable::twobit ( unsigned  byte, unsigned  sample  ) const

virtual

Return the 2-bit number from byte corresponding to sample.

Each byte is interpreted as follows:

MSB: l3 l2 l1 l0 m3 m2 m1 m0 :LSB

Where each two bit timesample is given by its most significant bit, mX, and least significant bit, lX, and each byte contains four time samples: m0l0, m1l1, m2l2, m3l3.

Parameters

byte	the byte pattern containing four time samples
sample	the sample to extract from the byte

---

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

• Mark4TwoBitTable.h
• Mark4TwoBitTable.C