nw_prbs_pkg Package Body Reference

Package Body >> nw_prbs_pkg

Functions
t_slv_arr	f_gen_prbs ( poly: in std_logic_vector data_width: in positive length: in positive msb_first: in boolean init: in std_logic_vector )
	Create PRBS sequence.
t_slv_arr	f_gen_prbs ( poly: in std_logic_vector data_width: in positive length: in positive msb_first: in boolean true )	[ impure ]
	Create PRBS sequence.
std_logic_vector	f_gen_seed ( data_width: in positive )	[ impure ]
	Create random seed.
integer	f_randnat ( minval: in natural 0 , maxval: in natural integer'high )	[ impure ]
	Return random integer (natural)
std_logic_vector	f_randslv ( data_width: in positive )	[ impure ]
	Return random std_logic_vector.
std_logic_vector	f_randsel ( data: in t_slv_arr )	[ impure ]
	Return random element.

Member Function/Procedure/Process Documentation

f_gen_prbs() [1/2]

t_slv_arr f_gen_prbs (   poly in std_logic_vector ,   data_width in positive ,   length in positive ,   msb_first in boolean ,   init in std_logic_vector   )

Function

Create PRBS sequence.

Parameters

poly	Polynomial to use
data_width	Data width
length	Number of data words
msb_first	Pack bits MSB in data words first (True), or LSB (False)
init	LFSR init value

Returns

PRBS sequence in data array

Generate a PRBS sequence of given length and data width. The LFSR uses Galois configuration. Example maximum length polynomials up to order 32 can be found as constants. Init value cannot be zero (would return all zero array).

Example use

array_8bit := f_gen_prbs(C_POLY_X6_X5_1, 8, 6, C_MSB_FIRST, "1111111");

f_gen_prbs() [2/2]

t_slv_arr f_gen_prbs (   poly in std_logic_vector ,   data_width in positive ,   length in positive ,   msb_first in boolean true   ) impure

Function

Create PRBS sequence.

Parameters

poly	Polynomial to use
data_width	Data width
length	Number of data words
msb_first	Pack bits MSB in data words first (True, default), or LSB (False)

Returns

PRBS sequence in data array

This is an overloaded verison of f_gen_prbs with init value set to a random seed using f_gen_seed().

Example use

array_8bit := f_gen_prbs(C_POLY_X6_X5_1, 8, 6);

f_gen_seed()

std_logic_vector f_gen_seed (   data_width in positive   ) impure

Function

Create random seed.

Parameters

data_width

Seed vector length

Returns

Random seed

A random, non-zero seed is returned. The seed is based on the current simulation time.

Example use

seed_16bit := f_gen_seed(16);

f_randnat()

integer f_randnat (   minval in natural 0 ,   maxval in natural integer'high   ) impure

Function

Return random integer (natural)

Parameters

minval	Minimum value
maxval	Maximum value

Returns

Random integer

Return a random integer >= 0.

Example use

val := f_randnat(0, 42);

f_randslv()

std_logic_vector f_randslv (   data_width in positive   ) impure

Function

Return random std_logic_vector.

Parameters

data_width

Vector width

Returns

Random std_logic_vector

Return a random std_logic_vector.

Example use

val_64bit := f_randslv(64);

f_randsel()

std_logic_vector f_randsel (   data in t_slv_arr   ) impure

Function

Return random element.

Parameters

data

Array

Returns

Random element

Return a random element from std_logic_vector array.

Example use

constant C_SELECTION : t_slv_arr(0 to 4)(7 downto 0) := (x"12", x"15", x"20", x"33", x"42");
 
val_8bit := f_randsel(C_SELECTION);

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The documentation for this design unit was generated from the following file:

• nw_util/src/nw_prbs_pkg.vhd