notetabs.vhd

几个VHDL实现的源程序及其代码

library ieee;
use ieee.std_logic_1164.all;

entity notetabs is
port(
     clk : in std_logic;
     toneindex : out integer range 0 to 15);
end notetabs;

architecture behav of notetabs is
signal counter : integer range 0 to 138;
begin
cnt8: process(clk)
begin
if counter=138 then
counter<=0;
elsif clk'event and clk='1' then
counter<=counter+1;
end if;
end process;
search : process(counter)
begin
case counter is
when 00=>toneindex<=3;
when 01=>toneindex<=3;
when 02=>toneindex<=3;
when 03=>toneindex<=3;
when 04=>toneindex<=5;
when 05=>toneindex<=5;
when 06=>toneindex<=5;
when 07=>toneindex<=6;
when 08=>toneindex<=8;
when 09=>toneindex<=8;
when 10=>toneindex<=8;
when 11=>toneindex<=9;
when 12=>toneindex<=6;
when 13=>toneindex<=8;
when 14=>toneindex<=5;
when 15=>toneindex<=5;
when 16=>toneindex<=12;
when 17=>toneindex<=12;
when 18=>toneindex<=12;
when 19=>toneindex<=15;
when 20=>toneindex<=13;
when 21=>toneindex<=12;
when 22=>toneindex<=10;
when 23=>toneindex<=12;
when 24=>toneindex<=9;
when 25=>toneindex<=9;
when 26=>toneindex<=9;
when 27=>toneindex<=9;
when 28=>toneindex<=9;
when 29=>toneindex<=9;
when 30=>toneindex<=9;
when 31=>toneindex<=0;
when 32=>toneindex<=9;
when 33=>toneindex<=9;
when 34=>toneindex<=9;
when 35=>toneindex<=10;
when 36=>toneindex<=7;
when 37=>toneindex<=7;
when 38=>toneindex<=6;
when 39=>toneindex<=6;
when 40=>toneindex<=5;
when 41=>toneindex<=5;
when 42=>toneindex<=5;
when 43=>toneindex<=6;
when 44=>toneindex<=8;
when 45=>toneindex<=8;
when 46=>toneindex<=9;
when 47=>toneindex<=9;
when 48=>toneindex<=3;
when 49=>toneindex<=3;
when 50=>toneindex<=8;
when 51=>toneindex<=8;
when 52=>toneindex<=6;
when 53=>toneindex<=5;
when 54=>toneindex<=6;
when 55=>toneindex<=8;
when 56=>toneindex<=5;
when 57=>toneindex<=5;
when 58=>toneindex<=5;
when 59=>toneindex<=5;
when 60=>toneindex<=5;
when 61=>toneindex<=5;
when 62=>toneindex<=5;
when 63=>toneindex<=5;
when 64=>toneindex<=10;
when 65=>toneindex<=10;
when 66=>toneindex<=10;
when 67=>toneindex<=12;
when 68=>toneindex<=7;
when 69=>toneindex<=7;
when 70=>toneindex<=9;
when 71=>toneindex<=9;
when 72=>toneindex<=6;
when 73=>toneindex<=8;
when 74=>toneindex<=5;
when 75=>toneindex<=5;
when 76=>toneindex<=5;
when 77=>toneindex<=5;
when 78=>toneindex<=5;
when 79=>toneindex<=5;
when 80=>toneindex<=3;
when 81=>toneindex<=5;
when 82=>toneindex<=3;
when 83=>toneindex<=3;
when 84=>toneindex<=5;
when 85=>toneindex<=6;
when 86=>toneindex<=7;
when 87=>toneindex<=9;
when 88=>toneindex<=6;
when 89=>toneindex<=6;
when 90=>toneindex<=6;
when 91=>toneindex<=6;
when 92=>toneindex<=6;
when 93=>toneindex<=6;
when 94=>toneindex<=5;
when 95=>toneindex<=6;
when 96=>toneindex<=8;
when 97=>toneindex<=8;
when 98=>toneindex<=8;
when 99=>toneindex<=9;
when 100=>toneindex<=12;
when 101=>toneindex<=12;
when 102=>toneindex<=12;
when 103=>toneindex<=10;
when 104=>toneindex<=9;
when 105=>toneindex<=9;
when 106=>toneindex<=10;
when 107=>toneindex<=9;
when 108=>toneindex<=8;
when 109=>toneindex<=8;
when 110=>toneindex<=6;
when 111=>toneindex<=5;
when 112=>toneindex<=3;
when 113=>toneindex<=3;
when 114=>toneindex<=3;
when 115=>toneindex<=3;
when 116=>toneindex<=8;
when 117=>toneindex<=8;
when 118=>toneindex<=8;
when 119=>toneindex<=8;
when 120=>toneindex<=6;
when 121=>toneindex<=8;
when 122=>toneindex<=6;
when 123=>toneindex<=5;
when 124=>toneindex<=3;
when 125=>toneindex<=5;
when 126=>toneindex<=6;
when 127=>toneindex<=8;
when 128=>toneindex<=5;
when 129=>toneindex<=5;
when 130=>toneindex<=5;
when 131=>toneindex<=5;
when 132=>toneindex<=5;
when 133=>toneindex<=5;
when 134=>toneindex<=5;
when 135=>toneindex<=5;
when 136=>toneindex<=0;
when 137=>toneindex<=0;
when 138=>toneindex<=0;
when others=>null;
end case;
end process;
end behav;