Subversion Repositories scalable_arbiter

/*

 * Copyright (c) 2008, Kendall Correll

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF

 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 */

function integer min (

        input integer a, b

);

begin

        min = a < b ? a : b;

end

endfunction

function integer max (

        input integer a, b

);

begin

        max = a > b ? a : b;

end

endfunction

// compute the log base 2 of a number, rounded down to the

// nearest whole number

function integer flog2 (

        input integer number

);

integer i;

integer count;

begin

        flog2 = 0;

        for(i = 0; i < 32; i = i + 1)

        begin

                if(number&(1<<i))

                        flog2 = i;

        end

end

endfunction

// compute the log base 2 of a number, rounded up to the

// nearest whole number

function integer clog2 (

        input integer number

);

integer i;

integer count;

begin

        clog2 = 0;

        count = 0;

        for(i = 0; i < 32; i = i + 1)

        begin

                if(number&(1<<i))

                begin

                        clog2 = i;

                        count = count + 1;

                end

        end

        // clog2 holds the largest set bit position and count

        // holds the number of bits set. More than one bit set

        // indicates that the input was not an even power of 2,

        // so round the result up.

        if(count > 1)

                clog2 = clog2 + 1;

end

endfunction

// compute the size of the interconnect for the arbiter's

// 'select' muxes

function integer mux_sum (

        input integer width, select_width

);

integer i, number;

begin

        mux_sum = 0;

        number = 1;

        for(i = select_width; i > 0 && number <= width; i = i - 1)

        begin

                mux_sum = mux_sum + i*(number);

                number = number * 2;

        end

end

endfunction