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Rewrite output mixer.

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Tweak DAC outputs to map more accurately.
This commit is contained in:
Mark Johnson
2023-04-15 00:27:49 +01:00
parent e860fb5178
commit 2fb9af272e
1 changed files with 29 additions and 27 deletions
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56
rtl/gbc_snd.vhd
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@@ -1822,38 +1822,40 @@ begin
variable snd_left_in : signed(5 downto 0);
variable snd_right_in : signed(5 downto 0);
variable snd_tmp : signed(10 downto 0);
constant DC_OFFSET : std_logic_vector(3 downto 0) := "1000";
variable wav : std_logic_vector(3 downto 0);
-- Convert a DAC input code to a pseudo-analog value
function dac_out(
wav : std_logic_vector(3 downto 0)
) return signed is
begin
return resize(signed(wav xor "0111"), snd_left_in'length);
end function;
begin
snd_left_in := (others => '0');
snd_left_in := (others => '0');
snd_right_in := (others => '0');
if ch_map(0) = '1' then
snd_right_in := snd_right_in + resize(signed(sq1_wav - DC_OFFSET), snd_right_in'length);
end if;
if ch_map(1) = '1' then
snd_right_in := snd_right_in + resize(signed(sq2_wav - DC_OFFSET), snd_right_in'length);
end if;
if ch_map(2) = '1' then
snd_right_in := snd_right_in + resize(signed(wav_wav - DC_OFFSET), snd_right_in'length);
end if;
if ch_map(3) = '1' then
snd_right_in := snd_right_in + resize(signed(noi_wav - DC_OFFSET), snd_right_in'length);
end if;
for k in 0 to 7 loop
case k mod 4 is
when 0 => wav := sq1_wav;
when 1 => wav := sq2_wav;
when 2 => wav := wav_wav;
when 3 => wav := noi_wav;
when others => null;
end case;
if ch_map(4) = '1' then
snd_left_in := snd_left_in + resize(signed(sq1_wav - DC_OFFSET), snd_left_in'length);
end if;
if ch_map(5) = '1' then
snd_left_in := snd_left_in + resize(signed(sq2_wav - DC_OFFSET), snd_left_in'length);
end if;
if ch_map(6) = '1' then
snd_left_in := snd_left_in + resize(signed(wav_wav - DC_OFFSET), snd_left_in'length);
end if;
if ch_map(7) = '1' then
snd_left_in := snd_left_in + resize(signed(noi_wav - DC_OFFSET), snd_left_in'length);
end if;
if k < 4 then
if ch_map(k) = '1' then
snd_right_in := snd_right_in + dac_out(wav);
end if;
else
if ch_map(k - 4) = '1' then
snd_left_in := snd_left_in + dac_out(wav);
end if;
end if;
end loop;
snd_tmp := snd_right_in * signed(("00" & ch_vol(2 downto 0)) + '1');
snd_tmp := snd_right_in * signed(("00" & ch_vol(2 downto 0)) + '1');
snd_right <= std_logic_vector(snd_tmp) & "00000";
snd_tmp := snd_left_in * signed(("00" & ch_vol(6 downto 4)) + '1');