| 范例：opencore组织RISCMCU IP Core全套最新代码 _freqdiv | ----------------------------------------------------------------------------
---- ----
---- WISHBONE RISCMCU IP Core ----
---- ----
---- This file is part of the RISCMCU project ----
---- http://www.opencores.org/projects/riscmcu/ ----
---- ----
---- Description ----
---- Implementation of a RISC Microcontroller based on Atmel AVR ----
---- AT90S1200 instruction set and features with Altera Flex10k20 FPGA. ----
---- ----
---- Author(s): ----
---- - Yap Zi He, yapzihe@hotmail.com ----
---- ----
----------------------------------------------------------------------------
---- ----
---- Copyright (C) 2001 Authors and OPENCORES.ORG ----
---- ----
---- This source file may be used and distributed without ----
---- restriction provided that this copyright statement is not ----
---- removed from the file and that any derivative work contains ----
---- the original copyright notice and the associated disclaimer. ----
---- ----
---- This source file is free software; you can redistribute it ----
---- and/or modify it under the terms of the GNU Lesser General ----
---- Public License as published by the Free Software Foundation; ----
---- either version 2.1 of the License, or (at your option) any ----
---- later version. ----
---- ----
---- This source is distributed in the hope that it will be ----
---- useful, but WITHOUT ANY WARRANTY; without even the implied ----
---- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ----
---- PURPOSE. See the GNU Lesser General Public License for more ----
---- details. ----
---- ----
---- You should have received a copy of the GNU Lesser General ----
---- Public License along with this source; if not, download it ----
---- from http://www.opencores.org/lgpl.shtml ----
---- ----
----------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
entity v_freqdiv is
port( clock : in std_logic;
div2, div4, div8, div16 : buffer std_logic);
end v_freqdiv;
architecture myfreqdiv of v_freqdiv is
begin
process(clock)
begin
if clock'event and clock = '1' then
div2 <= not div2;
if div2 = '1' then
div4 <= not div4;
if div4 = '1' then
div8 <= not div8;
if div8 = '1' then
div16 <= not div16;
end if;
end if;
end if;
end if;
end process;
end myfreqdiv;
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