Chapter 6 Design Organization and Parameterization Part 2 1 - PowerPoint PPT Presentation

Chapter 6 Design Organization and Parameterization Part 2 1 benyamin@mehr.sharif.edu

Array Attributes • ‘RANGE returns range of vector signals • ‘LENGTH returns length of vector signals signal A:BIT_VECTOR(7 downto 0) A’range = A’length-1 downto 0 2 benyamin@mehr.sharif.edu

int2bin Procedure PROCEDURE int2bin (int: IN INTEGER;bin:OUT BIT_VECTOR) IS VARIABLE tmp : INTEGER; BEGIN tmp:=int; FOR I IN 0 TO (bin’LENGTH-1) LOOP IF (tmp MOD 2 = 1) THEN bin(i):=‘1’; ELSE bin(i):=‘0’; END IF; tmp:=tmp/2; END LOOP; END int2bin; 3 benyamin@mehr.sharif.edu

to_integer Function FUNCTION to_integer (bin: BIT_VECTOR) RETURN INTEGER IS VARIABLE result : INTEGER; BEGIN result:=0; FOR I IN bin’RANGE LOOP IF (bin(i)=‘1’) THEN result=result+2**i; END IF; END LOOP; RETURN result; END to_integer; 4 benyamin@mehr.sharif.edu

apply_data Redesign PROCEDURE apply_data ( SIGNAL target: OUT BIT_VECTOR(3 DOWNTO 0); CONSTANT values:IN integers; CONSTANT period:IN TIME) IS VARIABLE buf:BIT_VECTOR(3 DOWNTO 0); BEGIN FOR I in 0 TO 12 LOOP int2bin(values(i),buf); target<=TRANSPORT buf AFTER i*period; END LOOP; END Apply_data; 5 benyamin@mehr.sharif.edu

Packaging Parts and Utilities • Packages construct in VHDL is used for – Grouping components – Packaging commonly used user-defined types – Packaging commonly used subprograms 6 benyamin@mehr.sharif.edu

Package Syntax PACKAGE package_name IS [component declaration] [constant declaration] [type and subtype declaration] [subprogram declaration] END package_name; 7 benyamin@mehr.sharif.edu

Packaging Components PACKAGE simple_gates IS COMPONENT n1 PORT (i1: IN BIT; o1: OUT BIT); END COMPONENT COMPONENT n2 PORT (i1,i2: IN BIT; o1: OUT BIT); END COMPONENT COMPONENT n3 PORT (i1,i2,i3: IN BIT; o1: OUT BIT); END COMPONENT END simple_gates; 8 benyamin@mehr.sharif.edu

Packaging Components USE WORK.simple_gates.ALL; ARCHITECTURE gate_level OF bit_comparator IS FOR ALL:n1 USE ENTITY WORK.inv(single_delay); FOR ALL:n2 USE ENTITY WORK.nand2(single_delay); FOR ALL:n3 USE ENTITY WORK.nand3(single_delay); SIGNAL … BEGIN g0: n1 PORT MAP(…); g1: n2 PORT MAP(…); g2: n3 PORT MAP(…); … END; 9 benyamin@mehr.sharif.edu

Packaging Components USE WORK.simple_gates.ALL; Entire package is USE visible WORK.simple_gates.n1, WORK.simple_gates.n2, n1 becomes visible WORK.simple_gates.n3; 10 benyamin@mehr.sharif.edu

Packaging Subprograms • Function and Procedure declarations part must be defined in PACKAGE. • Function and Procedure Bodies must be defined in PACKAGE BODY. 11 benyamin@mehr.sharif.edu

Package Body Syntax PACKAGE BODY pack_name IS BEGIN procedure and function bodies. END pack_name; 12 benyamin@mehr.sharif.edu

basic_utilities Package PACKAGE basic_utilities IS TYPE integers IS ARRAY (0 TO 12) OF INTEGERS; CONSTANT gnd:BIT:=‘0’; CONSTANT vdd:BIT:=‘1’; FUNCTION to_integer (bin: BIT_VECTOR) RETURN INTEGER; PROCEDURE int2bin (int: IN INTEGER;bin:OUT BIT_VECTOR); PROCEDURE bin2bin (bin:IN BIT_VECTOR;int: OUT INTEGER); PROCEDURE apply_data ( SIGNAL target: OUT BIT_VECTOR(3 DOWNTO 0); CONSTANT values:IN integers; CONSTANT period:IN TIME ); END basic_utilities; 13 benyamin@mehr.sharif.edu

basic_utilities Package Body - 1 PACKAGE BODY basic_utilities IS FUNCTION int2bin (bin: BIT_VECTOR) RETURN INTEGER IS VARIABLE result : INTEGER; BEGIN result:=0; FOR I IN bin’RANGE LOOP IF (bin(i)=‘1’) THEN result=result+2**i; END IF; END LOOP; RETURN result; END int2bin; --next page 14 benyamin@mehr.sharif.edu

basic_utilities Package Body - 2 --from previous page PROCEDURE int2bin (int: IN INTEGER;bin:OUT BIT_VECTOR) IS VARIABLE tmp : INTEGER; BEGIN tmp:=int; FOR I IN 0 TO (bin’LENGTH-1) LOOP IF (tmp MOD 2 = 1) THEN bin(i):=‘1’; ELSE bin(i):=‘0’; END IF; tmp:=tmp/2; END LOOP; END int2bin; --nex page 15 benyamin@mehr.sharif.edu

basic_utilities Package Body - 3 --from previous page PROCEDURE bin2int(bin:IN BIT_VECTOR;int:OUT INTEGER) IS VARIABLE result:INTEGER; BEGIN result:=0; FOR i IN bin’RANGE LOOP IF bin(i)=‘1’ THEN result:=result+2**I; END IF; END FOR; END bin2int; --next page 16 benyamin@mehr.sharif.edu

basic_utilities Package Body - 4 --from previous page PROCEDURE apply_data ( SIGNAL target: OUT BIT_VECTOR(3 DOWNTO 0); CONSTANT values:IN integers; CONSTANT period:IN TIME) IS VARIABLE buf:BIT_VECTOR(3 DOWNTO 0); BEGIN FOR I in 0 TO 12 LOOP int2bin(values(i),buf); target<=TRANSPORT buf AFTER i*period; END LOOP; END Apply_data; END basic_utilities; 17 benyamin@mehr.sharif.edu

Usage of basic_utilities USE WORK.basic_utilities.ALL; USE WORK.basic_utilities.apply_data; USE WORK.basic_utilities.gnd, WORK.basic_utilities.vdd; 18 benyamin@mehr.sharif.edu