bit_stream

virtual class bit_stream #( type T = bit ) extends data_stream #( T, 1 )

A parameterized class that manages a bit stream.

Parameter

T	optional The type of the bit stream. The T must be the single bit data types (bit, logic, or reg). The default type is bit.

Summary

bit_stream	A parameterized class that manages a bit stream.
Types
bs_type	The bit stream type.
Functions
alternate	static Returns a new bit stream with the elements whose values alternate between 0 and 1.
count_zeros	static Counts the number of bit-stream items having value 0.
count_ones	static Counts the number of bit-stream items having value 1.
count_unknowns	static Counts the number of bit-stream items having value X.
count_hizs	static Counts the number of bit-stream items having value Z.

Types

bs_type

typedef T bs_type[]

The bit stream type. The shorthand of the dynamic array of type T.

Functions

alternate

static function bs_type alternate( int unsigned length,
T init_value = 0,
bit randomize_init_value = 0 )

static Returns a new bit stream with the elements whose values alternate between 0 and 1.

Argument

length	The length of the output bit stream.
init_value	optional The value of the first element (0 or 1). The default is 0.
randomize_init_value	optional If 1, the value of the first element is randomized (the init_value argument is ignored). The default is 0.

Returns

A new bit stream with the elements whose values alternate between 0 and 1.

Example

bit expected[] = new[8]( '{ 1, 0, 1, 0, 1, 0, 1, 0 } );
assert( bit_stream#(bit)::alternate( 8, .init_value( 1 ) ) == expected );

count_zeros

static function int count_zeros( bs_type bs )

static Counts the number of bit-stream items having value 0.

Argument

bs	A bit stream.

Returns

The number of items having value 0. If the type T is not a single-bit data type, -1 is returned.

Example

bit bs[] = new[16]( '{ 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1 } );
assert( bit_stream#(bit)::count_zeros( bs ) == 8 );

count_ones

static function int count_ones( bs_type bs )

static Counts the number of bit-stream items having value 1.

Argument

bs	A bit stream.

Returns

The number of items having value 1. If the type T is not a single-bit data type, -1 is returned.

Example

bit bs[] = new[16]( '{ 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1 } );
assert( bit_stream#(bit)::count_ones( bs ) == 8 );

count_unknowns

static function int count_unknowns( bs_type bs )

static Counts the number of bit-stream items having value X.

Argument

bs	A bit stream.

Returns

The number of items having value X. If the type T is not a single-bit data type, -1 is returned.

Example

logic bs[] = new[16]( '{ 0, 0, 0, 0, 1, 1, 1, 1, 'x, 'x, 'x, 'x, 'z, 'z, 'z, 'z } );
assert( bit_stream#(logic)::count_unknowns( bs ) == 4 );

count_hizs

static function int count_hizs( bs_type bs )

static Counts the number of bit-stream items having value Z.

Argument

bs	A bit stream.

Returns

The number of items having value Z. If the type T is not a single-bit data type, -1 is returned.

Example

logic bs[] = new[16]( '{ 0, 0, 0, 0, 1, 1, 1, 1, 'x, 'x, 'x, 'x, 'z, 'z, 'z, 'z } );
assert( bit_stream#(logic)::count_hizs( bs ) == 4 );