rftafas / stdexpert

A numeric_std compatible replacement for std_logic_arith and std_logic_unsigned

std_logic_expert

Description

A numeric_std compatible replacement for std_logic_arith and std_logic_unsigned.

ALL STD_LOGIC_VECTORS are considered UNSIGNED. If SIGNED operation is needed, due to very specific and INTENDED behavior, it should be used the SIGNED type on NUMERIC_STD.

Types and Typecasts

Types

RANGE_T: record that includes "low" and "high" fields. Used to expand the ranges on VHDL.

USE:

signal|variable myrange : range_t := ( high => <integer>, low => <integer> );

STD_LOGIC_ARRAY: An unconstrained array of unconstrained std_logic_vector. Some tools take a problem with it.

USE:

signal|variable myarray : std_logic_array(y downto 0)(x downto 0) := ( 0 => <vector0>, 1 => <vector1>, others => <vector> );

Type CASTs

Function	Input Types
TO_INTEGER(input)	STD_LOGIC_VECTOR
TO_STD_LOGIC_VECTOR(input)	INTEGER,SIGNED,UNSIGEND
TO_UNSIGNED(input)	STD_LOGIC_VECTOR,SIGNED
TO_SIGNED(input)	UNSIGNED

Operators

It covers following operators:

Operator	LEFT	RIGHT	RESULT	Description
+ , - , * , /	STD_LOGIC_VECTOR	STD_LOGIC_VECTOR, INTEGER, UNSIGNED	STD_LOGIC_VECTOR	Arithmetic operator
	INTEGER	STD_LOGIC_VECTOR	STD_LOGIC_VECTOR
	UNSIGNED	STD_LOGIC_VECTOR	STD_LOGIC_VECTOR
> , < , >= , <= , = , /=	STD_LOGIC_VECTOR	INTEGER	BOOLEAN	Comparator operator
	INTEGER	STD_LOGIC_VECTOR	BOOLEAN
rol , ror	STD_LOGIC_VECTOR	STD_LOGIC_VECTOR	STD_LOGIC_VECTOR	Rotation, getting the bit and placing back to begining.

Functions

Function	Use	Description
size_of	size_of(number,)	Return the minimum number of bits that an integer requires to be represented. If a word size is provided, the minimum number of words to represent that number.
index_of	index_of(vector)	Return the relative position of that register inside a larger register. (i.e. for byte, the byte number of that slice)
rebase	rebase(vector)	Returns an std_logic_vector starting with 0 and little endian.
range_of	range_of(vector)	Returns a range_t containing vector'high and vector'low
get_slice	get_slice(vector,word_size,index)	Returns a smaller vector (size of word_size) a portion of input vector corresponding to a word number (example: byte0 is 7..0, byte1 is 15..8)
set_slice	set_slice(vector,word,index)	Retruns a vector replacing a portion of vector corresponding to a word number (example: byte0 is 7..0, byte1 is 15..8). Works best ir size_of(vector) is a multiple of size_of(word)
to_range	to_range(vector)	Returns a range_t containing vector'high and vector'low
index_of_1	index_of_1(vector)	Returns the index of highest '1' bit.
index_of_0	index_of_0(vector)	Returns the index of highest '0' bit.
all_1	all_1(input)	Returns an "all ones" vector sized input-1 downto 0
all_0	all_0(input)	Returns an "all zeroes" vector sized input-1 downto 0