•1CPE 528: Session #9 Department of Electrical and Computer Engineering University of Alabama in HuntsvilleOutline® Review: VHDL Packages for Synthesis® Review: VHDL for Combinational Logic Synthesis® VHDL for Sequential Logic Synthesis® VHDL for RTL Level Synthesis® Structural VHDL® Implementation Technology Considerations® SummaryVHDL Packages for SynthesisBase Types® Standard bit types may be used® Typically IEEE 1164 Std. types are used® std_ulogic type® Values ‘U’, ‘X’, ‘W’, and ‘-’ are called metalogical values for synthesisTYPE std_ulogic IS ( 'U', -- Uninitialized'X', -- Forcing Unknown'0', -- Forcing 0'1', -- Forcing 1'Z', -- High Impedance 'W', -- Weak Unknown'L', -- Weak 0 'H', -- Weak 1 '-' -- Don't care);TYPE std_ulogic IS ( 'U', -- Uninitialized'X', -- Forcing Unknown'0', -- Forcing 0'1', -- Forcing 1'Z', -- High Impedance 'W', -- Weak Unknown'L', -- Weak 0 'H', -- Weak 1 '-' -- Don't care);® std_logic type - resolved std_ulogic typeUSE IEEE.std_logic_1164.ALL;USE IEEE.std_logic_1164.ALL;VHDL Packages for SynthesisBase Types (cont.)® The std_logic_1164 package also contains:® Vectors of std_ulogic and std_logic® Subtypes of std_logic - X01, X01Z, UX01, UX10Z® Logic functions with various arguments - std_ulogic, std_logic, std_logic_vectorFUNCTION “and” (l,r : std_ulogic;) RETURN UX01;FUNCTION “nand” (l,r : std_ulogic;) RETURN UX01;FUNCTION “or” (l,r : std_ulogic;) RETURN UX01;FUNCTION “nor” (l,r : std_ulogic;) RETURN UX01;FUNCTION “xor” (l,r : std_ulogic;) RETURN UX01;FUNCTION “xnor” (l,r : std_ulogic;) return ux01;FUNCTION "not" (l,r : std_ulogic) RETURN UX01;FUNCTION “and” (l,r : std_ulogic;) RETURN UX01;FUNCTION “nand” (l,r : std_ulogic;) RETURN UX01;FUNCTION “or” (l,r : std_ulogic;) RETURN UX01;FUNCTION “nor” (l,r : std_ulogic;) RETURN UX01;FUNCTION “xor” (l,r : std_ulogic;) RETURN UX01;FUNCTION “xnor” (l,r : std_ulogic;) return ux01;FUNCTION "not" (l,r : std_ulogic) RETURN UX01;® Conversion functionsFUNCTION To_bit(s:std_ulogic) RETURN bit;FUNCTION To_bitvector(s:std_ulogic_vector) RETURN bit_vector;FUNCTION To_StdULogic(b:bit) RETURN std_ulogic;FUNCTION To_bit(s:std_ulogic) RETURN bit;FUNCTION To_bitvector(s:std_ulogic_vector) RETURN bit_vector;FUNCTION To_StdULogic(b:bit) RETURN std_ulogic;•2VHDL Packages for SynthesisBase Types (cont.)® Unknown functionsFUNCTION rising_edge (SIGNAL s:std_ulogic) RETURN boolean;FUNCTION falling_edge (SIGNAL s:std_ulogic) RETURN boolean;FUNCTION rising_edge (SIGNAL s:std_ulogic) RETURN boolean;FUNCTION falling_edge (SIGNAL s:std_ulogic) RETURN boolean;® Clock edge functionsFUNCTION Is_X (s:std_ulogic_vector) RETURN boolean;FUNCTION Is_X (s:std_logic_vector) RETURN boolean;FUNCTION Is_X (s:std_ulogic) RETURN boolean;FUNCTION Is_X (s:std_ulogic_vector) RETURN boolean;FUNCTION Is_X (s:std_logic_vector) RETURN boolean;FUNCTION Is_X (s:std_ulogic) RETURN boolean;04/02/2003 UAH-CPE528 6VHDL Packages for SynthesisArithmetic Packages® All synthesis tools support some type of arithmetic packages® Synopsis developed packages based on std_logic_1164 package - supported by many other synthesis tools® std_logic_arith® std_logic_signed® std_logic_unsigned® Actel synthesis tools support their own package® asyl.arith® IEEE has developed standard packages for synthesis IEEE Std. 1076.3® Numeric_Bit® Numeric_Std04/02/2003 UAH-CPE528 7IEEE Std 1076.3 PackagesNumeric_Bit® Type declarations for signed and unsigned numbersTYPE unsigned IS ARRAY (natural RANGE <> ) OF bit;TYPE signed IS ARRAY (natural RANGE <> ) OF bit;TYPE unsigned IS ARRAY (natural RANGE <> ) OF bit;TYPE signed IS ARRAY (natural RANGE <> ) OF bit;® Arithmetic operators - various combinations of signed and unsigned argumentsFUNCTION “abs” (arg:unsigned) RETURN unsigned;FUNCTION “-” (arg:unsigned) RETURN unsigned;FUNCTION “+” (l,r:unsigned) RETURN unsigned;FUNCTION “-” (l,r:unsigned) RETURN unsigned;FUNCTION “*” (l,r:unsigned) RETURN unsigned;FUNCTION “/” (l,r:unsigned) RETURN unsigned;FUNCTION “rem” (l,r:unsigned) RETURN unsigned;FUNCTION “mod” (l,r:unsigned) RETURN unsigned;FUNCTION “abs” (arg:unsigned) RETURN unsigned;FUNCTION “-” (arg:unsigned) RETURN unsigned;FUNCTION “+” (l,r:unsigned) RETURN unsigned;FUNCTION “-” (l,r:unsigned) RETURN unsigned;FUNCTION “*” (l,r:unsigned) RETURN unsigned;FUNCTION “/” (l,r:unsigned) RETURN unsigned;FUNCTION “rem” (l,r:unsigned) RETURN unsigned;FUNCTION “mod” (l,r:unsigned) RETURN unsigned;USE IEEE.numeric_bit.ALL;USE IEEE.numeric_bit.ALL;04/02/2003 UAH-CPE528 8IEEE Std 1076.3 PackagesNumeric_Bit® Comparison operators - various combinations of signed and unsigned argumentsFUNCTION “>” (l,r:unsigned) RETURN boolean;FUNCTION “<” (l,r:unsigned) RETURN boolean;FUNCTION “<=” (l,r:unsigned) RETURN boolean;FUNCTION “>=” (l,r:unsigned) RETURN boolean;FUNCTION “=” (l,r:unsigned) RETURN boolean;FUNCTION “/=” (l,r:unsigned) RETURN boolean;FUNCTION “>” (l,r:unsigned) RETURN boolean;FUNCTION “<” (l,r:unsigned) RETURN boolean;FUNCTION “<=” (l,r:unsigned) RETURN boolean;FUNCTION “>=” (l,r:unsigned) RETURN boolean;FUNCTION “=” (l,r:unsigned) RETURN boolean;FUNCTION “/=” (l,r:unsigned) RETURN boolean;® Shift and rotate functionsFUNCTION shift_left (arg:unsigned; count:natural) RETURN unsigned;FUNCTION shift_right (arg:unsigned; count:natural) RETURN unsigned;FUNCTION rotate_left (arg:unsigned; count:natural) RETURN unsigned;FUNCTION rotate_right (arg:unsigned; count:natural) RETURN unsigned;FUNCTION sll (arg:unsigned; count:natural) RETURN unsigned;FUNCTION slr (arg:unsigned; count:natural) RETURN unsigned;FUNCTION rol (arg:unsigned; count:natural) RETURN unsigned;FUNCTION ror (arg:unsigned; count:natural) RETURN unsigned;FUNCTION shift_left (arg:unsigned; count:natural) RETURN unsigned;FUNCTION shift_right (arg:unsigned; count:natural) RETURN unsigned;FUNCTION rotate_left (arg:unsigned; count:natural) RETURN unsigned;FUNCTION rotate_right (arg:unsigned; count:natural) RETURN unsigned;FUNCTION sll (arg:unsigned; count:natural) RETURN unsigned;FUNCTION slr (arg:unsigned; count:natural) RETURN unsigned;FUNCTION rol (arg:unsigned; count:natural) RETURN unsigned;FUNCTION ror (arg:unsigned; count:natural) RETURN unsigned;•304/02/2003 UAH-CPE528 9IEEE Std