Revision 1324
Added by markw almost 4 years ago
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CHANGING : IN STD_LOGIC;
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DELAYSAWTOOTH : IN STD_LOGIC;
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RINGMOD : IN STD_LOGIC;
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RINGMOD_OSC_MSB : IN STD_LOGIC;
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TEST : IN STD_LOGIC;
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| ... | ... | |
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ARCHITECTURE vhdl OF SID_wavegen IS
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signal wave_reg : std_logic_vector(11 downto 0);
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signal wave_next : std_logic_vector(11 downto 0);
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signal wave0count1_reg : unsigned(9 downto 0);
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signal wave0count1_next : unsigned(9 downto 0);
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signal lfsr_reg : std_logic_vector(22 downto 0);
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signal lfsr_next : std_logic_vector(22 downto 0);
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signal wave_data_needed_reg : std_logic;
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| ... | ... | |
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signal pulse_comparator_reg : std_logic;
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signal pulse_comparator_next : std_logic;
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signal multiple_wave_bits : std_logic;
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signal no_wave_bits : std_logic;
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signal osc_del_reg : std_logic_vector(11 downto 0);
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signal osc_del_next : std_logic_vector(11 downto 0);
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BEGIN
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-- register
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process(clk, reset_n)
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begin
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if (reset_n = '0') then
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wave_reg <= (others=>'0');
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wave0count1_reg <= (others=>'0');
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lfsr_reg <= (others=>'1');
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pulse_comparator_reg <= '0';
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wave_data_needed_reg <= '0';
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osc_del_reg <= (others=>'0');
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elsif (clk'event and clk='1') then
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wave_reg <= wave_next;
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wave0count1_reg <= wave0count1_next;
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lfsr_reg <= lfsr_next;
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pulse_comparator_reg <= pulse_comparator_next;
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wave_data_needed_reg <= wave_data_needed_next;
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osc_del_reg <= osc_del_next;
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end if;
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end process;
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| ... | ... | |
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end process;
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-- next state - wave
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process(multiple_wave_bits,wave_reg,osc_in,waveselect_in,pulse_width_in,lfsr_reg,test,ringmod,ringmod_osc_msb,pulse_comparator_reg,wave_data,wave_data_ready,enable)
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process(no_wave_bits,multiple_wave_bits,wave_reg,osc_in,waveselect_in,pulse_width_in,lfsr_reg,test,ringmod,ringmod_osc_msb,pulse_comparator_reg,wave_data,wave_data_ready,enable,osc_del_reg,delaysawtooth,wave0count1_reg)
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variable noise : std_logic_vector(11 downto 0);
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variable pulse : std_logic_vector(11 downto 0);
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variable triangle : std_logic_vector(11 downto 0);
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| ... | ... | |
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variable triangle_xor : std_logic;
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variable triangle_xor_ext : std_logic_vector(10 downto 0);
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variable osc_xored : std_logic_vector(10 downto 0);
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variable osc_sawtooth : std_logic_vector(11 downto 0);
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variable wave0tmp : unsigned(12 downto 0);
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begin
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wave_next <= wave_reg;
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wave0count1_next <= wave0count1_reg;
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osc_del_next <= osc_del_reg;
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if (enable='1') then
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osc_del_next <= osc_in;
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end if;
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noise:= (others=>'0');
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pulse:= (others=>'0');
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triangle:= (others=>'0');
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| ... | ... | |
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end if;
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--ref: https://sourceforge.net/p/sidplay-residfp/wiki/SID%20internals%20-%20Triangle%20Waveform/
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if (delaysawtooth='1') then
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osc_sawtooth:= osc_del_reg;
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else
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osc_sawtooth := osc_in;
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end if;
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triangle_xor := not(waveselect_in(1)) and -- sawtooth on->disable invert
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((not(ringmod) and osc_in(11)) or -- not ringmod ->msb makes it invert
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(ringmod and (osc_in(11) xnor ringmod_osc_msb))); -- ringmod -> both 0 or 1 -> invert
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((not(ringmod) and osc_sawtooth(11)) or -- not ringmod ->msb makes it invert
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(ringmod and (osc_sawtooth(11) xnor ringmod_osc_msb))); -- ringmod -> both 0 or 1 -> invert
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triangle_xor_ext := (others=>triangle_xor);
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osc_xored:= osc_in(10 downto 0) xor triangle_xor_ext;
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osc_xored:= osc_sawtooth(10 downto 0) xor triangle_xor_ext;
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if (waveselect_in(1)='1') then
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sawtooth := osc_in(11) & osc_xored(10 downto 0);
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sawtooth := osc_sawtooth(11) & osc_xored(10 downto 0);
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end if;
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if (waveselect_in(0)='1') then
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| ... | ... | |
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-- In fact transistors drive against each other with different resistances and
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-- a corrupt waveform is generated.
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-- TODO: Either compute or use flash storage (optionally)
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if (multiple_wave_bits='0') then
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wave_next <= noise or pulse or sawtooth or triangle;
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if (no_wave_bits='1') then
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if (enable='1') then
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wave0count1_next <= unsigned("0"&wave0count1_reg(8 downto 0)) + 1;
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if (wave0count1_reg(9)='1') then -- carry
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wave0tmp := unsigned("0"&wave_reg) - 1; -- head to zero over 2 seconds!
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if (wave0tmp(12) = '1') then
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wave_next <= (others=>'0');
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else
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wave_next <= std_logic_vector(wave0tmp(11 downto 0));
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end if;
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end if;
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end if;
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else
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if (wave_data_ready='1') then
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wave_next <= wave_data and pulse;
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if (multiple_wave_bits='0') then
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wave_next <= noise or pulse or sawtooth or triangle;
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else
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if (wave_data_ready='1') then
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if (waveselect_in(2)='1') then
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wave_next <= wave_data and pulse;
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else
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wave_next <= wave_data;
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end if;
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end if;
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end if;
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end if;
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end process;
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multiple_wave_bits <=
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multiple_wave_bits <= --NPST (?ST) or PS or PT
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not(waveselect_in(3)) and
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(
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(waveselect_in(0) and waveselect_in(1))
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(waveselect_in(2) and (waveselect_in(0) or waveselect_in(1)))
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)
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;
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no_wave_bits <= not(or_reduce(waveselect_in));
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wave_data_needed_next <= (wave_data_needed_reg or (multiple_wave_bits and changing)) and not(wave_data_ready);
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--output
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Also available in: Unified diff
Test driven SID improvements