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--

--      Input file         : std_Pkg.vhd

--      Design name        : std_Pkg

--      Author             : Tamar Kranenburg

--      Company            : Delft University of Technology

--                         : Faculty EEMCS, Department ME&CE

--                         : Systems and Circuits group

--

--      Description        : Package with several standard components.

--

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LIBRARY ieee;

USE ieee.std_logic_1164.ALL;

USE ieee.numeric_std.ALL;

PACKAGE std_Pkg IS

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-- STANDARD COMPONENTS IN STD_PKG

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    COMPONENT sram GENERIC

    (

        WIDTH : positive;

        SIZE  : positive

    );

    PORT

    (

        dat_o : OUT std_ulogic_vector(WIDTH - 1 DOWNTO 0);

        dat_i : IN std_ulogic_vector(WIDTH - 1 DOWNTO 0);

        adr_i : IN std_ulogic_vector(SIZE - 1 DOWNTO 0);

        wre_i : IN std_ulogic;

        ena_i : IN std_ulogic;

        clk_i : IN std_ulogic

    );

    END COMPONENT;

    COMPONENT sram_4en GENERIC

    (

        WIDTH : positive;

        SIZE  : positive

    );

    PORT

    (

        dat_o : OUT std_ulogic_vector(WIDTH - 1 DOWNTO 0);

        dat_i : IN std_ulogic_vector(WIDTH - 1 DOWNTO 0);

        adr_i : IN std_ulogic_vector(SIZE - 1 DOWNTO 0);

        wre_i : IN std_ulogic_vector(3 DOWNTO 0);

        ena_i : IN std_ulogic;

        clk_i : IN std_ulogic

    );

    END COMPONENT;

    COMPONENT dsram GENERIC

    (

        WIDTH : positive;

        SIZE  : positive

    );

    PORT

    (

        dat_o   : OUT std_ulogic_vector(WIDTH - 1 DOWNTO 0);

        adr_i   : IN std_ulogic_vector(SIZE - 1 DOWNTO 0);

        ena_i   : IN std_ulogic;

        dat_w_i : IN std_ulogic_vector(WIDTH - 1 DOWNTO 0);

        adr_w_i : IN std_ulogic_vector(SIZE - 1 DOWNTO 0);

        wre_i   : IN std_ulogic;

        clk_i   : IN std_ulogic

    );

    END COMPONENT;

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-- FUNCTIONS IN STD_PKG

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    FUNCTION v_or(d : std_ulogic_vector) RETURN std_ulogic;

    FUNCTION is_zero(d : std_ulogic_vector) RETURN std_ulogic;

    FUNCTION is_not_zero(d : std_ulogic_vector) RETURN std_ulogic;

    FUNCTION my_conv_integer(a: std_ulogic_vector) RETURN integer;

    FUNCTION notx(d : std_ulogic_vector) RETURN boolean;

    FUNCTION compare(a, b : std_ulogic_vector) RETURN std_ulogic;

    FUNCTION multiply(a, b : std_ulogic_vector) RETURN std_ulogic_vector;

    FUNCTION sign_extend(value: std_ulogic_vector; fill: std_ulogic; size: positive) RETURN std_ulogic_vector;

    FUNCTION add(a, b : std_ulogic_vector; ci: std_ulogic) RETURN std_ulogic_vector;

    FUNCTION increment(a : std_ulogic_vector) RETURN std_ulogic_vector;

    FUNCTION shift(value : std_ulogic_vector(31 DOWNTO 0); shamt: std_ulogic_vector(4 DOWNTO 0); s: std_ulogic; t: std_ulogic) RETURN std_ulogic_vector;

    FUNCTION shift_left(value : std_ulogic_vector(31 DOWNTO 0); shamt : std_ulogic_vector(4 DOWNTO 0)) RETURN std_ulogic_vector;

    FUNCTION shift_right(value : std_ulogic_vector(31 DOWNTO 0); shamt : std_ulogic_vector(4 DOWNTO 0); padding: std_ulogic) RETURN std_ulogic_vector;

END std_Pkg;

PACKAGE BODY std_Pkg IS

-- Unary OR reduction

    FUNCTION v_or(d : std_ulogic_vector) RETURN std_ulogic IS

        VARIABLE z : std_ulogic;

    BEGIN

        z := '0';

        IF notx (d) THEN

            FOR i IN d'range LOOP

                z := z OR d(i);

            END LOOP;

        END IF;

        RETURN z;

    END;

-- Check for ones in the vector

    FUNCTION is_not_zero(d : std_ulogic_vector) RETURN std_ulogic IS

        VARIABLE z : std_ulogic_vector(d'range);

    BEGIN

        z := (OTHERS => '0');

        IF notx(d) THEN

            IF d = z THEN

                RETURN '0';

            ELSE

                RETURN '1';

            END IF;

        ELSE

            RETURN '0';

        END IF;

    END;

-- Check for ones in the vector

    FUNCTION is_zero(d : std_ulogic_vector) RETURN std_ulogic IS

    BEGIN

        RETURN NOT is_not_zero(d);

    END;

    -- rewrite conv_integer to avoid modelsim warnings

    FUNCTION my_conv_integer(a : std_ulogic_vector) RETURN integer IS

        VARIABLE res : integer RANGE 0 TO 2**a'length-1;

    BEGIN

        res := 0;

        IF (notx(a)) THEN

            res := to_integer(unsigned(a));

        END IF;

        RETURN res;

    END;

    FUNCTION compare(a, b : std_ulogic_vector) RETURN std_ulogic IS

        VARIABLE z : std_ulogic;

    BEGIN

        IF notx(a & b) AND a = b THEN

            RETURN '1';

        ELSE

            RETURN '0';

        END IF;

    END;

-- Unary NOT X test

    FUNCTION notx(d : std_ulogic_vector) RETURN boolean IS

        VARIABLE res : boolean;

    BEGIN

        res := true;

-- pragma translate_off

        res := NOT is_x(d);

-- pragma translate_on

        RETURN (res);

    END;

-- -- 32 bit shifter

-- -- SYNOPSIS:

-- --    value: value to be shifted

-- --    shamt: shift amount

-- --    s 0 / 1: shift right / left

-- --    t 0 / 1: shift logical / arithmetic

-- -- PSEUDOCODE (from microblaze reference guide)

-- --     if S = 1 then

-- --          (rD) ← (rA) << (rB)[27:31]

-- --     else

-- --      if T = 1 then

-- --         if ((rB)[27:31]) ≠ 0 then

-- --              (rD)[0:(rB)[27:31]-1] ← (rA)[0]

-- --              (rD)[(rB)[27:31]:31] ← (rA) >> (rB)[27:31]

-- --         else

-- --              (rD) ← (rA)

-- --      else

-- --         (rD) ← (rA) >> (rB)[27:31]

    FUNCTION shift(value: std_ulogic_vector(31 DOWNTO 0); shamt: std_ulogic_vector(4 DOWNTO 0); s: std_ulogic; t: std_ulogic) RETURN std_ulogic_vector IS

    BEGIN

        IF s = '1' THEN

            -- left arithmetic or logical shift

            RETURN shift_left(value, shamt);

        ELSE

            IF t = '1' THEN

                -- right arithmetic shift

                RETURN shift_right(value, shamt, value(31));

            ELSE

                -- right logical shift

                RETURN shift_right(value, shamt, '0');

            END IF;

        END IF;

    END;

    FUNCTION shift_left(value: std_ulogic_vector(31 DOWNTO 0); shamt: std_ulogic_vector(4 DOWNTO 0)) RETURN std_ulogic_vector IS

        VARIABLE result: std_ulogic_vector(31 DOWNTO 0);

        VARIABLE paddings: std_ulogic_vector(15 DOWNTO 0);

    BEGIN

        paddings := (OTHERS => '0');

        result := value;

        IF (shamt(4) = '1') THEN result := result(15 DOWNTO 0) & paddings(15 DOWNTO 0); END IF;

        IF (shamt(3) = '1') THEN result := result(23 DOWNTO 0) & paddings( 7 DOWNTO 0); END IF;

        IF (shamt(2) = '1') THEN result := result(27 DOWNTO 0) & paddings( 3 DOWNTO 0); END IF;

        IF (shamt(1) = '1') THEN result := result(29 DOWNTO 0) & paddings( 1 DOWNTO 0); END IF;

        IF (shamt(0) = '1') THEN result := result(30 DOWNTO 0) & paddings( 0 );         END IF;

        RETURN result;

    END;

    FUNCTION shift_right(value: std_ulogic_vector(31 DOWNTO 0); shamt: std_ulogic_vector(4 DOWNTO 0); padding: std_ulogic) RETURN std_ulogic_vector IS

        VARIABLE result: std_ulogic_vector(31 DOWNTO 0);

        VARIABLE paddings: std_ulogic_vector(15 DOWNTO 0);

    BEGIN

        paddings := (OTHERS => padding);

        result := value;

        IF (shamt(4) = '1') THEN result := paddings(15 DOWNTO 0) & result(31 DOWNTO 16); END IF;

        IF (shamt(3) = '1') THEN result := paddings( 7 DOWNTO 0) & result(31 DOWNTO  8); END IF;

        IF (shamt(2) = '1') THEN result := paddings( 3 DOWNTO 0) & result(31 DOWNTO  4); END IF;

        IF (shamt(1) = '1') THEN result := paddings( 1 DOWNTO 0) & result(31 DOWNTO  2); END IF;

        IF (shamt(0) = '1') THEN result := paddings( 0 )         & result(31 DOWNTO  1); END IF;

        RETURN result;

    END;

    FUNCTION multiply(a, b: std_ulogic_vector) RETURN std_ulogic_vector IS

        VARIABLE x: std_ulogic_vector (a'length + b'length - 1 DOWNTO 0);

    BEGIN

        x := std_ulogic_vector(signed(a) * signed(b));

        RETURN x(31 DOWNTO 0);

    END;

    FUNCTION sign_extend(value: std_ulogic_vector; fill: std_ulogic; size: positive) RETURN std_ulogic_vector IS

        VARIABLE a: std_ulogic_vector (size - 1 DOWNTO 0);

    BEGIN

        a(size - 1 DOWNTO value'length) := (OTHERS => fill);

        a(value'length - 1 DOWNTO 0) := value;

        return a;

    END;

    FUNCTION add(a, b : std_ulogic_vector; ci: std_ulogic) RETURN std_ulogic_vector IS

        VARIABLE x : std_ulogic_vector(a'length + 1 DOWNTO 0);

    BEGIN

        x := (OTHERS => '0');

        IF notx (a & b & ci) THEN

            x := std_ulogic_vector(signed('0' & a & '1') + signed('0' & b & ci));

        END IF;

        RETURN x(a'length + 1 DOWNTO 1);

    END;

    FUNCTION increment(a : std_ulogic_vector) RETURN std_ulogic_vector IS

        VARIABLE x : std_ulogic_vector(a'length-1 DOWNTO 0);

    BEGIN

        x := (OTHERS => '0');

        IF notx (a) THEN

            x := std_ulogic_vector(signed(a) + 1);

        END IF;

        RETURN x;

    END;

END std_Pkg;