Initial version

git-svn-id: http://moon:8086/svn/vhdl/trunk@224 cc03376c-175c-47c8-b038-4cd826a8556b

lib/fixed/fixed_util_pkg.vhd

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+
+library IEEE;
+use IEEE.STD_LOGIC_1164.ALL;
+use IEEE.NUMERIC_STD.ALL;
+use IEEE.MATH_REAL.ALL;
+
+library ieee_proposed;
+use ieee_proposed.math_utility_pkg.all;
+use ieee_proposed.fixed_pkg.all;
+
+package fixed_util_pkg is
+
+	-------------------------------------------------------------
+	-- Frequently used constants
+	constant pi			: real := 3.141592653589793e+000;
+	constant sqrt2		: real := 1.414213562373095e+000;
+	constant sqrt2_inv	: real := 7.071067811865475e-001;
+
+	-- Constructor helpers
+	-- Use: variable v8u6 : ufixed_t(ufixed(8,6)'range);
+	function uproto (nbits : integer; nbits_frac : integer) return ufixed;
+
+	-- Use: variable v8s6 : sfixed_t(sfixed(8,6)'range);
+	function sproto (nbits : integer; nbits_frac : integer) return sfixed;
+
+	-- Safe variant of uproto
+	function uhi (nbits : integer; nbits_frac : integer) return integer;
+	function ulo (nbits : integer; nbits_frac : integer) return integer;
+
+	-- Safe variant of sproto
+	function shi (nbits : integer; nbits_frac : integer) return integer;
+	function slo (nbits : integer; nbits_frac : integer) return integer;
+
+	function to_unsigned (src : ufixed) return UNSIGNED;
+	function to_signed (src : sfixed) return SIGNED;
+
+	type real_array_t is array (natural range <>) of real;
+	type ufixed_array_t is array (natural range <>, integer range <>) of STD_LOGIC;
+	type sfixed_array_t is array (natural range <>, integer range <>) of STD_LOGIC;
+
+	function to_sfixed_array(x : real_array_t; proto : sfixed) return sfixed_array_t;
+	function to_sfixed_array(x : real_array_t; nbits, nbits_int : integer) return sfixed_array_t;
+
+	-- Slicing functions for unconstrained array types
+	function to_ufixed(src : ufixed_array_t; index : integer) return ufixed;
+	function to_sfixed(src : sfixed_array_t; index : integer) return sfixed;
+	
+-------------------------------------------------------------------------------
+end; -- package fixed_util_pkg;
+
+package body fixed_util_pkg is
+
+	-------------------------------------------------------------
+	-- Constuctor helpers
+	function uproto (nbits : integer; nbits_frac : integer) return ufixed is
+	constant result : ufixed (uhi(nbits,nbits_frac) downto ulo(nbits,nbits_frac)) := (others => '0');
+	begin 
+	return result(uhi(nbits,nbits_frac) downto ulo(nbits,nbits_frac));
+	end uproto;
+
+	-------------------------------------------------------------
+	function sproto (nbits : integer; nbits_frac : integer) return sfixed is
+	constant result : sfixed (shi(nbits,nbits_frac) downto slo(nbits,nbits_frac)) := (others => '0');
+	begin 
+	return result(shi(nbits,nbits_frac) downto slo(nbits,nbits_frac));
+	end sproto;
+
+	-------------------------------------------------------------
+	function uhi (nbits : integer; nbits_frac : integer) return integer is
+	begin 
+	return nbits-nbits_frac-1;
+	end uhi;
+
+	-------------------------------------------------------------
+	function ulo (nbits : integer; nbits_frac : integer) return integer is
+	begin 
+	return -nbits_frac;
+	end ulo;
+
+	-------------------------------------------------------------
+	function shi (nbits : integer; nbits_frac : integer) return integer is
+	begin 
+	return nbits-nbits_frac;
+	end shi;
+
+	-------------------------------------------------------------
+	function slo (nbits : integer; nbits_frac : integer) return integer is
+	begin 
+	return -nbits_frac+1;
+	end slo;
+
+	-------------------------------------------------------------
+	function to_unsigned (src : ufixed) return UNSIGNED is
+	subtype  t is UNSIGNED(src'high - src'low downto 0);
+	variable slv : t;
+	begin
+	slv := t(src);
+	return UNSIGNED(to_X01(std_logic_vector(slv)));
+
+	end function to_unsigned;
+
+	-------------------------------------------------------------
+	function to_signed (src : sfixed) return SIGNED is
+	subtype  t is SIGNED(src'high - src'low downto 0);
+	variable slv : t;
+	begin
+	slv := t(src);
+	return SIGNED(to_X01(std_logic_vector(slv)));
+
+	end function to_signed;
+	
+	function to_sfixed_array(x : real_array_t; proto : sfixed) return sfixed_array_t is
+	variable res : sfixed_array_t(0 to x'length-1, proto'range);
+	variable tt : sfixed(proto'range);
+	begin
+		for i in x'range loop
+			tt := to_sfixed(x(i), proto);
+			for j in proto'range loop
+				res(i,j) := tt(j);
+			end loop;	
+		end loop;
+		return res;
+	end to_sfixed_array;	
+
+	---------------------------------------------------------------------------
+	function to_sfixed_array(x : real_array_t; nbits, nbits_int : integer) return sfixed_array_t is
+	variable p : sfixed(shi(nbits, nbits_int) downto slo(nbits, nbits_int));
+	begin
+		return to_sfixed_array(x, p);
+	end to_sfixed_array;	
+		
+	-------------------------------------------------------------------------------
+	-- ufixed <= ufixed_array(i)
+	function to_ufixed(src : ufixed_array_t; index : integer) return ufixed is
+	variable dst : ufixed(src'range(2));
+	begin
+		for j in src'range(2) loop
+			dst(j) := src(index, j);
+		end loop;
+		
+		return dst;
+		
+	end to_ufixed;	
+	
+	-------------------------------------------------------------------------------
+	-- sfixed <= sfixed_array(i)
+	function to_sfixed(src : sfixed_array_t; index : integer) return sfixed is
+	variable dst : sfixed(src'range(2));
+	begin
+		for j in src'range(2) loop
+			dst(j) := src(index, j);
+		end loop;
+		
+		return dst;
+		
+	end to_sfixed;	
+
+-------------------------------------------------------------------------------
+end; -- package fixed_util_pkg;