| 1 |
3 |
mgeng |
----------------------------------------------------------------------
|
| 2 |
|
|
---- ----
|
| 3 |
|
|
---- Auxiliary package with mathematical functions. ----
|
| 4 |
|
|
---- ----
|
| 5 |
|
|
---- This file is part of the simu_mem project ----
|
| 6 |
|
|
---- ----
|
| 7 |
|
|
---- Authors: ----
|
| 8 |
|
|
---- - Michael Geng, vhdl@MichaelGeng.de ----
|
| 9 |
|
|
---- ----
|
| 10 |
|
|
----------------------------------------------------------------------
|
| 11 |
|
|
---- ----
|
| 12 |
|
|
---- Copyright (C) 2008 Authors ----
|
| 13 |
|
|
---- ----
|
| 14 |
|
|
---- This source file may be used and distributed without ----
|
| 15 |
|
|
---- restriction provided that this copyright statement is not ----
|
| 16 |
|
|
---- removed from the file and that any derivative work contains ----
|
| 17 |
|
|
---- the original copyright notice and the associated disclaimer. ----
|
| 18 |
|
|
---- ----
|
| 19 |
|
|
---- This source file is free software; you can redistribute it ----
|
| 20 |
|
|
---- and/or modify it under the terms of the GNU Lesser General ----
|
| 21 |
|
|
---- Public License as published by the Free Software Foundation; ----
|
| 22 |
|
|
---- either version 2.1 of the License, or (at your option) any ----
|
| 23 |
|
|
---- later version. ----
|
| 24 |
|
|
---- ----
|
| 25 |
|
|
---- This source is distributed in the hope that it will be ----
|
| 26 |
|
|
---- useful, but WITHOUT ANY WARRANTY; without even the implied ----
|
| 27 |
|
|
---- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ----
|
| 28 |
|
|
---- PURPOSE. See the GNU Lesser General Public License for more ----
|
| 29 |
|
|
---- details. ----
|
| 30 |
|
|
---- ----
|
| 31 |
|
|
---- You should have received a copy of the GNU Lesser General ----
|
| 32 |
|
|
---- Public License along with this source; if not, download it ----
|
| 33 |
|
|
---- from http://www.gnu.org/licenses/lgpl.html ----
|
| 34 |
|
|
---- ----
|
| 35 |
|
|
----------------------------------------------------------------------
|
| 36 |
|
|
-- CVS Revision History
|
| 37 |
|
|
--
|
| 38 |
|
|
-- $Log: not supported by cvs2svn $
|
| 39 |
|
|
--
|
| 40 |
|
|
PACKAGE math_pkg IS
|
| 41 |
|
|
-- linear congruential generator (a random number generator)
|
| 42 |
|
|
-- use result for the seed in the next call
|
| 43 |
|
|
-- preferably use bits 30...16
|
| 44 |
|
|
FUNCTION lcg (seed : IN NATURAL) RETURN NATURAL;
|
| 45 |
|
|
END PACKAGE math_pkg;
|
| 46 |
|
|
|
| 47 |
|
|
PACKAGE BODY math_pkg IS
|
| 48 |
|
|
FUNCTION lcg (seed : IN NATURAL) RETURN NATURAL IS
|
| 49 |
|
|
-- Constants from: http://en.wikipedia.org/wiki/Linear_congruential_generator
|
| 50 |
|
|
CONSTANT a : NATURAL := 16807;
|
| 51 |
|
|
CONSTANT c : NATURAL := 0;
|
| 52 |
|
|
CONSTANT m : NATURAL := 2 ** 31 - 1;
|
| 53 |
|
|
BEGIN
|
| 54 |
|
|
RETURN (a * seed + c) MOD m;
|
| 55 |
|
|
END FUNCTION;
|
| 56 |
|
|
END PACKAGE BODY math_pkg;
|
