apu constants cleanup

3 files changed, 24 insertions, 10 deletions

diff --git a/basys3/basys3.srcs/apu_consts.vhd b/basys3/basys3.srcs/apu_consts.vhd
new file mode 100644
index 0000000..5c4edcf
--- /dev/null
+++ b/basys3/basys3.srcs/apu_consts.vhd
@@ -0,0 +1,8 @@
+
+
+
+package apu_consts is
+    constant SAMPLE_SIZE_WIDTH : natural := 8; -- data width for sample size
+    constant SAMPLE_SIZE : natural := 256; -- max value in sample size
+
+end package apu_consts;
\ No newline at end of file
diff --git a/basys3/basys3.srcs/apu_lut_reader.vhd b/basys3/basys3.srcs/apu_lut_reader.vhd
index 2f92eca..b3b0ca4 100644
--- a/basys3/basys3.srcs/apu_lut_reader.vhd
+++ b/basys3/basys3.srcs/apu_lut_reader.vhd
@@ -2,20 +2,23 @@ library ieee;
 use ieee.std_logic_1164.all;
 use ieee.numeric_std.all;
 
+library work;
+use work.apu_consts.all;
+
 entity apu_lut_reader is
     port (
         clk : in std_logic;
         rst : in std_logic;
         freq : in std_logic_vector(11 downto 0);
         wave : in std_logic_vector(1 downto 0);
-        value : out std_logic_vector(7 downto 0)
+        value : out std_logic_vector(SAMPLE_SIZE_WIDTH-1 downto 0)
     );
 end entity;
 
 architecture behavioral of apu_lut_reader is
 
-    constant AMPLITUDE : natural := 0;
-    constant SAMPLE_SIZE : natural := 256;
+    -- amplitude (currently) only applies to square waves
+    constant AMPLITUDE : natural := SAMPLE_SIZE/2; -- less or equals SAMPLE_SIZE/2 (Amplitude around SAMPLE_SIZE/2)
 
     signal idx : unsigned := (others => '0');
     signal buf : unsigned := (others => '0');
@@ -23,6 +26,9 @@ architecture behavioral of apu_lut_reader is
 begin
 
     process (clk)
+    variable val_min : unsigned := to_unsigned(SAMPLE_SIZE/2 - integer(AMPLITUDE),SAMPLE_SIZE_WIDTH-1);
+    variable val_max : unsigned := to_unsigned(SAMPLE_SIZE/2 + integer(AMPLITUDE),SAMPLE_SIZE_WIDTH-1);
+
     begin
         if rst = '1' then
             idx <= x"00";
@@ -35,9 +41,9 @@ begin
                 value <= std_logic_vector( idx );
             elsif wave = "01" then  -- Square
                 if idx < (SAMPLE_SIZE/2) then
-                    value <= x"00"; --std_logic_vector( SAMPLE_SIZE-AMPLITUDE ); -- TODO: make so that this work with a changable amplitude (for square wave)
+                    value <= std_logic_vector(val_min); --std_logic_vector( SAMPLE_SIZE-AMPLITUDE ); -- TODO: make so that this work with a changable amplitude (for square wave)
                 else
-                    value <= x"FF";
+                    value <= std_logic_vector(val_max);
                 end if;
             elsif wave = "10" then  -- Triangle
                 if idx < (SAMPLE_SIZE/2) then
diff --git a/basys3/basys3.srcs/apu_note_to_frequency.vhd b/basys3/basys3.srcs/apu_note_to_frequency.vhd
index 810cef9..48defa3 100644
--- a/basys3/basys3.srcs/apu_note_to_frequency.vhd
+++ b/basys3/basys3.srcs/apu_note_to_frequency.vhd
@@ -2,6 +2,9 @@ library ieee;
 use ieee.std_logic_1164.all;
 use ieee.numeric_std.all;
 
+library work;
+use work.apu_consts.all;
+
 entity apu_note_to_frequency is port (
 	-- clk : in std_logic;
 	-- rst : in std_logic;
@@ -10,7 +13,6 @@ entity apu_note_to_frequency is port (
 end entity;
 
 architecture Behavioral of apu_note_to_frequency is
-	signal buff_small : std_logic_vector(7 downto 0) := (others => '0');
 	signal buff : std_logic_vector(15 downto 0) := (others => '0');
 	signal shift : integer;
 begin
@@ -18,7 +20,7 @@ begin
     shift <= to_integer(unsigned( data(2 downto 0) ));
 
     buff <= 
-        x"1F0" when data(6 downto 3) = (x"1") else -- C     496
+        x"1F0" when data(6 downto 3) = (x"1") else -- C     496 --values are calculated for 8kHz sample rate
         x"1D0" when data(6 downto 3) = (x"2") else -- C#/Db 464
         x"1B0" when data(6 downto 3) = (x"3") else -- D     432
         x"1A0" when data(6 downto 3) = (x"4") else -- D#/Eb 416
@@ -32,8 +34,6 @@ begin
         x"100" when data(6 downto 3) = (x"C") else -- B     256
         x"000";
 
-    -- buff <= x"1" & buff_small;
-    freq <= std_logic_vector( shift_right(unsigned(buff), shift) );
-    -- freq <= (others => '0') & buff(11 downto shift); -- bitshift values out (or div by powers of 2) -- TODO: NO WORKY!!! (concat (others => '0');)
+    freq <= std_logic_vector( shift_right(unsigned(buff), natural(shift)) ); -- TODO: MAYBE WORKY???
 
 end architecture;