stratixii_atoms.vhd

free hardware ip core about sparcv8,a soc cpu in vhdl

                end if;
            end if;
            -- end the loop if the denomitor has overflown or the numerator is zero (no remainder during this round)
            if (((d_value > max_denom) and (max_denom /= -1)) or (num = 0)) then
                i_max_iter := loop_iter;
            end if;
        end if;
        -- swap the numerator and denominator for the next round
        swap := den;
        den := num;
        num := swap;
    end loop;
end find_simple_integer_fraction;

-- find the greatest common denominator of X and Y
function gcd (X: integer; Y: integer) return integer is
variable L, S, R, G : integer := 1;
begin
    if (X < Y) then -- find which is smaller.
        S := X;
        L := Y;
    else
        S := Y;
        L := X;
    end if;

    R := S;
    while ( R > 1) loop
        S := L;
        L := R;
        R := S rem L;   -- divide bigger number by smaller.
                        -- remainder becomes smaller number.
    end loop;
    if (R = 0) then  -- if evenly divisible then L is gcd else it is 1.
        G := L;
    else
        G := R;
    end if;

    return G;
end gcd;

-- count the number of digits in the given integer
function count_digit (X: integer)
        return integer is
variable count, result: integer := 0;
begin
    result := X;
    while (result /= 0) loop
        result := (result / 10);
        count := count + 1;
    end loop;

    return count;
end count_digit;

-- reduce the given huge number to Y significant digits
function scale_num (X: integer; Y: integer)
        return integer is
variable count : integer := 0;
variable lc, fac_ten, result: integer := 1;
begin
    count := count_digit(X);

    for lc in 1 to (count-Y) loop
        fac_ten := fac_ten * 10;
    end loop;

    result := (X / fac_ten);

    return result;
end scale_num;

-- find the least common multiple of A1 to A10
function lcm (A1: integer; A2: integer; A3: integer; A4: integer;
            A5: integer; A6: integer; A7: integer;
            A8: integer; A9: integer; A10: integer; P: integer)
        return integer is
variable M1, M2, M3, M4, M5 , M6, M7, M8, M9, R: integer := 1;
begin
    M1 := (A1 * A2)/gcd(A1, A2);
    M2 := (M1 * A3)/gcd(M1, A3);
    M3 := (M2 * A4)/gcd(M2, A4);
    M4 := (M3 * A5)/gcd(M3, A5);
    M5 := (M4 * A6)/gcd(M4, A6);
    M6 := (M5 * A7)/gcd(M5, A7);
    M7 := (M6 * A8)/gcd(M6, A8);
    M8 := (M7 * A9)/gcd(M7, A9);
    M9 := (M8 * A10)/gcd(M8, A10);
    if (M9 < 3) then
        R := 10;
    elsif ((M9 <= 10) and (M9 >= 3)) then
        R := 4 * M9;
    elsif (M9 > 1000) then
        R := scale_num(M9,3);
    else
        R := M9 ;
    end if;

    return R;
end lcm;

-- find the factor of division of the output clock frequency compared to the VCO
function output_counter_value (clk_divide: integer; clk_mult: integer ;
                                M: integer; N: integer ) return integer is
variable R: integer := 1;
begin
    R := (clk_divide * M)/(clk_mult * N);

    return R;
end output_counter_value;

-- find the mode of each PLL counter - bypass, even or odd
function counter_mode (duty_cycle: integer; output_counter_value: integer)
        return string is
variable R: string (1 to 6) := "      ";
variable counter_value: integer := 1;
begin
    counter_value := (2*duty_cycle*output_counter_value)/100;
    if output_counter_value = 1 then
        R := "bypass";
    elsif (counter_value REM 2) = 0 then
        R := "  even";
    else
        R := "   odd";
    end if;

    return R;
end counter_mode;

-- find the number of VCO clock cycles to hold the output clock high
function counter_high (output_counter_value: integer := 1; duty_cycle: integer)
        return integer is
variable R: integer := 1;
variable half_cycle_high : integer := 1;
begin
    half_cycle_high := (duty_cycle * output_counter_value *2)/100 ;
    if (half_cycle_high REM 2 = 0) then
        R := half_cycle_high/2 ;
    else
        R := (half_cycle_high/2) + 1;
    end if;

    return R;
end;

-- find the number of VCO clock cycles to hold the output clock low
function counter_low (output_counter_value: integer; duty_cycle: integer)
        return integer is
variable R, R1: integer := 1;
variable half_cycle_high : integer := 1;
begin
    half_cycle_high := (duty_cycle * output_counter_value*2)/100 ;
    if (half_cycle_high REM 2 = 0) then
        R1 := half_cycle_high/2 ;
    else
        R1 := (half_cycle_high/2) + 1;
    end if;

    R := output_counter_value - R1;

    return R;
end;

-- find the smallest time delay amongst t1 to t10
function mintimedelay (t1: integer; t2: integer; t3: integer; t4: integer;
                        t5: integer; t6: integer; t7: integer; t8: integer;
                        t9: integer; t10: integer) return integer is
variable m1,m2,m3,m4,m5,m6,m7,m8,m9 : integer := 0;
begin
    if (t1 < t2) then m1 := t1; else m1 := t2; end if;
    if (m1 < t3) then m2 := m1; else m2 := t3; end if;
    if (m2 < t4) then m3 := m2; else m3 := t4; end if;
    if (m3 < t5) then m4 := m3; else m4 := t5; end if;
    if (m4 < t6) then m5 := m4; else m5 := t6; end if;
    if (m5 < t7) then m6 := m5; else m6 := t7; end if;
    if (m6 < t8) then m7 := m6; else m7 := t8; end if;
    if (m7 < t9) then m8 := m7; else m8 := t9; end if;
    if (m8 < t10) then m9 := m8; else m9 := t10; end if;
    if (m9 > 0) then return m9; else return 0; end if;
end;

-- find the numerically largest negative number, and return its absolute value
function maxnegabs (t1: integer; t2: integer; t3: integer; t4: integer;
                    t5: integer; t6: integer; t7: integer; t8: integer;
                    t9: integer; t10: integer) return integer is
variable m1,m2,m3,m4,m5,m6,m7,m8,m9 : integer := 0;
begin
    if (t1 < t2) then m1 := t1; else m1 := t2; end if;
    if (m1 < t3) then m2 := m1; else m2 := t3; end if;
    if (m2 < t4) then m3 := m2; else m3 := t4; end if;
    if (m3 < t5) then m4 := m3; else m4 := t5; end if;
    if (m4 < t6) then m5 := m4; else m5 := t6; end if;
    if (m5 < t7) then m6 := m5; else m6 := t7; end if;
    if (m6 < t8) then m7 := m6; else m7 := t8; end if;
    if (m7 < t9) then m8 := m7; else m8 := t9; end if;
    if (m8 < t10) then m9 := m8; else m9 := t10; end if;
    if (m9 < 0) then return (0 - m9); else return 0; end if;
end;

-- adjust the phase (tap_phase) with the largest negative number (ph_base)
function ph_adjust (tap_phase: integer; ph_base : integer) return integer is
begin
    return (tap_phase + ph_base);
end;

-- find the time delay for each PLL counter
function counter_time_delay (clk_time_delay: integer;
                            m_time_delay: integer; n_time_delay: integer)
        return integer is
variable R: integer := 0;
begin
    R := clk_time_delay + m_time_delay - n_time_delay;

    return R;
end;

-- calculate the given phase shift (in ps) in terms of degrees
function get_phase_degree (phase_shift: integer; clk_period: integer)
        return integer is
variable result: integer := 0;
begin
    result := ( phase_shift * 360 ) / clk_period;
    -- to round up the calculation result
    if (result > 0) then
        result := result + 1;
    elsif (result < 0) then
        result := result - 1;
    else
        result := 0;
    end if;

    return result;
end;

-- find the number of VCO clock cycles to wait initially before the first rising
-- edge of the output clock
function counter_initial (tap_phase: integer; m: integer; n: integer)
        return integer is
variable R: integer;
variable R1: real;
begin
    R1 := (real(abs(tap_phase)) * real(m))/(360.0 * real(n)) + 0.5;
    -- Note NCSim VHDL had problem in rounding up for 0.5 - 0.99.
    -- This checking will ensure that the rounding up is done.
    if (R1 >= 0.5) and (R1 <= 1.0) then
        R1 := 1.0;
    end if;

    R := integer(R1);

    return R;
end;

-- find which VCO phase tap (0 to 7) to align the rising edge of the output clock to
function counter_ph (tap_phase: integer; m: integer; n: integer) return integer is
variable R: integer := 0;
begin
    -- 0.5 is added for proper rounding of the tap_phase.
    R := (integer(real(tap_phase * m / n)+ 0.5) REM 360)/45;

    return R;
end;

-- convert given string to length 6 by padding with spaces
function translate_string (mode : string) return string is
variable new_mode : string (1 to 6) := "      ";
begin
    if (mode = "bypass") then
        new_mode := "bypass";
    elsif (mode = "even") then
        new_mode := "  even";
    elsif (mode = "odd") then
        new_mode := "   odd";
    end if;

    return new_mode;
end;

function str2int (s : string) return integer is
variable len : integer := s'length;
variable newdigit : integer := 0;
variable sign : integer := 1;
variable digit : integer := 0;
begin
    for i in 1 to len loop
        case s(i) is
            when '-' =>
                if i = 1 then
                    sign := -1;
                else
                    ASSERT FALSE
                    REPORT "Illegal Character "&  s(i) & "i n string parameter! "
                    SEVERITY ERROR;
                end if;
            when '0' =>
                digit := 0;
            when '1' =>
                digit := 1;
            when '2' =>
                digit := 2;
            when '3' =>
                digit := 3;
            when '4' =>
                digit := 4;
            when '5' =>
                digit := 5;
            when '6' =>
                digit := 6;
            when '7' =>
                digit := 7;
            when '8' =>
                digit := 8;
            when '9' =>
                digit := 9;
            when others =>
                ASSERT FALSE
                REPORT "Illegal Character "&  s(i) & "in string parameter! "
                SEVERITY ERROR;
        end case;
        newdigit := newdigit * 10 + digit;
    end loop;

    return (sign*newdigit);
end;

function dqs_str2int (s : string) return integer is
variable len : integer := s'length;
variable newdigit : integer := 0;
variable sign : integer := 1;
variable digit : integer := 0;
variable err : boolean := false;
begin
    for i in 1 to len loop
        case s(i) is
            when '-' =>
                if i = 1 then
                    sign := -1;
                else
                    ASSERT FALSE
                    REPORT "Illegal Character "&  s(i) & " in string parameter! "
                    SEVERITY ERROR;
                    err := true;
                end if;
            when '0' =>
                digit := 0;
            when '1' =>
                digit := 1;
            when '2' =>
                digit := 2;
            when '3' =>
                digit := 3;