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|
{+-----------------------------------------------------------------------------+
| Author: Christian Hackbart
| Description: Sound
| Copyright (c) 2000 Christian Hackbart
| Stand: 15.12.2000
|
| http://www.tu-ilmenau.de/~hackbart
|
| Translated from VGBC's Sound.cpp, written by Rusty Wagner
+----------------------------------------------------------------------------+}
unit sound;
{$MODE objfpc}{$H+}
interface
(*
FF10 -- SNDREG10 [RW] Sweep [Sound Mode #1]
Bit6-4 Sweep time:
000: SWEEP OFF 010: 15.6ms 100: 31.3ms 110: 46.9ms
001: 7.8ms 011: 23.4ms 101: 39.1ms 111: 54.7ms
Bit3 Frequency increase[0]/decrease[1]
Bit2-0 Number of shifts
------------------------------------------------------------------------------
FF11 -- SNDREG11 [RW] Sound Length/Pattern Duty [Sound Mode #1]
Bit7-6 Wave Pattern Duty [only these bits can be read]:
00: 12.5% 01: 25% 10: 50% 11: 75%
Bit5-0 Length of sound data
------------------------------------------------------------------------------
FF12 -- SNDREG12 [RW] Control [Sound Mode #1]
Bit7-4 Initial value of envelope
Bit3 Envelope up[1]/down[0]
Bit2-0 Number of envelope sweep
------------------------------------------------------------------------------
FF13 -- SNDREG13 [W] Frequency Low [Sound Mode #1]
Lower 8 bits of the 11bit frequency. Higher 3 bits are in SNDREG14.
------------------------------------------------------------------------------
FF14 -- SNDREG14 [RW] Frequency High [Sound Mode #1]
Bit7 When 1 is written into this bit, sound restarts
Bit6 Counter/Consecutive selection [only this bit can be read]
Bit2-0 Higher 3 bits of the 11bit frequency
------------------------------------------------------------------------------
FF16 -- SNDREG21 [RW] Sound Length/Pattern Duty [Sound Mode #2]
Bit7-6 Wave Pattern Duty [only these bits can be read]:
00: 12.5% 01: 25% 10: 50% 11: 75%
Bit5-0 Length of sound data
------------------------------------------------------------------------------
FF17 -- SNDREG22 [RW] Control [Sound Mode #2]
Bit7-4 Initial value of envelope
Bit3 Envelope up[1]/down[0]
Bit2-0 Number of envelope step
------------------------------------------------------------------------------
FF18 -- SNDREG23 [W] Frequency Low [Sound Mode #2]
Lower 8 bits of the 11bit frequency. Higher 3 bits are in SNDREG24.
------------------------------------------------------------------------------
FF19 -- SNDREG24 [RW] Frequency High [Sound Mode #2]
Bit7 When 1 is written into this bit, sound restarts
Bit6 Counter/Consecutive selection [only this bit can be read]
Bit2-0 Higher 3 bits of the 11bit frequency
------------------------------------------------------------------------------
FF1A -- SNDREG30 [RW] Control [Sound Mode #3]
Bit7 Sound on[1]/off[0]
------------------------------------------------------------------------------
FF1B -- SNDREG31 [RW] Sound Length [Sound Mode #3]
------------------------------------------------------------------------------
FF1C -- SNDREG32 [RW] Output Level [Sound Mode #3]
Bit6-5 Output Level:
00: MUTE 01: 100% 10: 50% 11: 25%
------------------------------------------------------------------------------
FF1D -- SNDREG33 [W] Frequency Low [Sound Mode #3]
Lower 8 bits of the 11bit frequency. Higher 3 bits are in SNDREG34.
------------------------------------------------------------------------------
FF1E -- SNDREG34 [RW] Frequency High [Sound Mode #3]
Bit7 When 1 is written into this bit, sound restarts
Bit6 Counter/Consecutive selection [only this bit can be read]
Bit2-0 Higher 3 bits of the 11bit frequency
------------------------------------------------------------------------------
FF20 -- SNDREG41 [RW] Sound Length/Pattern Duty [Sound Mode #4]
Bit5-0 Length of sound data
------------------------------------------------------------------------------
FF21 -- SNDREG42 [RW] Control [Sound Mode #4]
Bit7-4 Initial value of envelope
Bit3 Envelope up[1]/down[0]
Bit2-0 Number of envelope step
------------------------------------------------------------------------------
FF22 -- SNDREG43 [RW] Polynomial Counter [Sound Mode #4]
Bit7-4 Shift clock frequency for the counter
0000: Dividing ratio of frequencies / 2
0001: Dividing ratio of frequencies / 2^2
0010: Dividing ratio of frequencies / 2^3
.... ....
1101: Dividing ratio of frequencies / 2^14
1100: Prohibited
1111: Prohibited
Bit3 Number of steps: 7 [1]/15 [0]
Bit2-0 Dividing ratio of frequences
000: f*2 010: f/2 100: f/4 110: f/6 where f = 4.194304Mhz/8
001: f*1 011: f/3 101: f/5 111: f/7
------------------------------------------------------------------------------
FF23 -- SNDREG44 [RW] Frequency High [Sound Mode #4]
Bit7 When 1 is written into this bit, sound restarts
Bit6 Counter/Consecutive selection [only this bit can be read]
------------------------------------------------------------------------------
FF24 -- SNDREG50 [RW] Channel and Volume Control
Bit7 Vin -> SO2 on[1]/off[0]
Bit6-4 Volume on SO2
Bit3 Vin -> SO1 on[1]/off[0]
Bit2-0 Volume on SO1
------------------------------------------------------------------------------
FF25 -- SNDREG51 [RW] Sound Output Terminal Selector
Bit7 Sound 4 -> SO2 |
Bit6 Sound 3 -> SO2 |
Bit5 Sound 2 -> SO2 | SO1 and SO2 are two sound outputs connected to the
Bit4 Sound 1 -> SO2 | headphones. Vin is an input terminal in the cartridge
Bit3 Sound 4 -> SO1 | slot.
Bit2 Sound 3 -> SO1 |
Bit1 Sound 2 -> SO1 |
Bit0 Sound 1 -> SO1 |
----------------------+-------------------------------------------------------
FF26 -- SNDREG52 [RW] Sound ON/OFF
Bit7 All sound on[1]/off[0]
Bit3 Sound 4 on[1]/off[0]
Bit2 Sound 3 on[1]/off[0]
Bit1 Sound 2 on[1]/off[0]
Bit0 Sound 1 on[1]/off[0]
*)
uses Classes, sysutils, sdl2, LazLoggerBase;
const
SAMPLE_BUFFER_SIZE = 1024;
PlaybackFrequency = 44100;
type
PSingle = ^Single;
TSampleBuffer = record
BufferL, BufferR: array[0..SAMPLE_BUFFER_SIZE] of Integer;
Cursor: Integer;
end;
procedure StartPlayback;
procedure StopPlayback;
procedure LockPlayback;
procedure UnlockPlayback;
procedure AudioCallback(userdata: Pointer; stream: PUInt8; len: Integer) cdecl;
procedure EnableSound;
procedure DisableSound;
procedure ResetSound;
procedure SoundUpdate(cycles: integer);
procedure BeginWritingSoundToStream(Stream: TStream);
procedure BeginWritingChannelsToStreams(MixStream, Ch1Stream, Ch2Stream, Ch3Stream, Ch4Stream: TStream);
procedure EndWritingSoundToStream;
var
soundEnable: boolean;
sndRegChange: boolean;
snd: array[1..4] of record
// public:
ChannelOFF: boolean; // (un)mute Channel
// private:
enable: boolean;
Freq: integer;
Vol: shortint;
Len: integer;
swpCnt: byte;
EnvCnt: byte;
bit: byte;
cnt: integer;
end;
SampleBuffers: array[0..4] of TSampleBuffer;
implementation
uses mainloop, vars;
const
SampleSize = SizeOf(Single)*2;
SampleCycles: LongInt = (8192 * 1024) div PlaybackFrequency;
StreamFlushBytes = 32768;
var
PlayStream: TSDL_AudioDeviceID;
bufCycles: integer;
bufLVals, bufRVals: array[0..4] of Integer;
sndBuffer: ^Single;
sndBytesWritten: Integer;
lfsr: Cardinal = 0;
WritingSoundToStream: Boolean;
SoundStreams: array[0..4] of TStream;
StreamBuffers: array[0..4] of array[0..StreamFlushBytes-1] of Byte;
StreamBufferUsed: array[0..4] of Integer;
procedure ResetSound;
var
i: Integer;
begin
for i := Low(Snd) to High(snd) do begin
with snd[i] do begin
ChannelOFF := False;
enable := False;
Freq := 0;
Vol := 0;
Len := 0;
swpCnt := 0;
EnvCnt := 0;
bit := 0;
cnt := 0;
end;
end;
end;
procedure FlushStreamBuffer(Idx: Integer);
begin
if (SoundStreams[Idx] <> nil) and (StreamBufferUsed[Idx] > 0) then
SoundStreams[Idx].Write(StreamBuffers[Idx], StreamBufferUsed[Idx]);
StreamBufferUsed[Idx] := 0;
end;
procedure BeginWritingSoundToStream(Stream: TStream);
var
I: Integer;
begin
SoundStreams[0] := Stream;
for I := 1 to 4 do SoundStreams[I] := nil;
for I := 0 to 4 do StreamBufferUsed[I] := 0;
WritingSoundToStream := True;
end;
procedure BeginWritingChannelsToStreams(MixStream, Ch1Stream, Ch2Stream, Ch3Stream, Ch4Stream: TStream);
var
I: Integer;
begin
SoundStreams[0] := MixStream;
SoundStreams[1] := Ch1Stream;
SoundStreams[2] := Ch2Stream;
SoundStreams[3] := Ch3Stream;
SoundStreams[4] := Ch4Stream;
for I := 0 to 4 do StreamBufferUsed[I] := 0;
WritingSoundToStream := True;
end;
procedure EndWritingSoundToStream;
var
I: Integer;
begin
for I := 0 to 4 do FlushStreamBuffer(I);
WritingSoundToStream := False;
for I := 0 to 4 do SoundStreams[I] := nil;
end;
procedure StartPlayback;
begin
SDL_PauseAudioDevice(PlayStream, 0);
end;
procedure StopPlayback;
begin
SDL_PauseAudioDevice(PlayStream, 1);
end;
procedure LockPlayback;
begin
SDL_LockAudioDevice(PlayStream);
end;
procedure UnlockPlayback;
begin
SDL_UnlockAudioDevice(PlayStream);
end;
procedure AudioCallback(userdata: Pointer; stream: PUInt8; len: Integer) cdecl;
begin
sndBuffer := PSingle(Stream);
sndBytesWritten := 0;
while sndBytesWritten < len do
z80_decode;
if sndBytesWritten > len then
DebugLn('[WARNING] Audio callback wrote into uninitialized ram! (%d written, %d requested)', [sndBytesWritten, len]);
end;
procedure EnableSound;
var
Want, Have: TSDL_AudioSpec;
begin
if soundEnable then
exit;
Want := Default(TSDL_AudioSpec);
Have := Default(TSDL_AudioSpec);
SDL_Init(SDL_INIT_AUDIO);
Want.freq := playbackFrequency;
Want.format := AUDIO_F32;
Want.channels := 2;
Want.samples := 1024;
Want.callback := @AudioCallback;
PlayStream := SDL_OpenAudioDevice(nil, 0, @Want, @Have, 0);
soundEnable := True;
bufCycles := 0;
FillChar(bufLVals, SizeOf(bufLVals), 0);
FillChar(bufRVals, SizeOf(bufRVals), 0);
end;
procedure DisableSound;
begin
if not soundEnable then
exit;
SDL_CloseAudioDevice(PlayStream);
SDL_Quit;
soundEnable := False;
end;
procedure SoundDoOut(const ls, rs: array of Integer; cycles: integer);
var
I: Integer;
buf: array[0..1] of Single;
begin
for I := 0 to 4 do begin
Inc(bufLVals[I], ls[I] * cycles);
Inc(bufRVals[I], rs[I] * cycles);
end;
Inc(bufCycles, cycles);
if bufCycles >= sampleCycles then
begin
if WritingSoundToStream then begin
for I := 0 to 4 do begin
if SoundStreams[I] <> nil then begin
buf[0] := ((bufRVals[I] div sampleCycles) / 512.0);
buf[1] := ((bufLVals[I] div sampleCycles) / 512.0);
Move(buf, StreamBuffers[I][StreamBufferUsed[I]], SampleSize);
Inc(StreamBufferUsed[I], SampleSize);
if StreamBufferUsed[I] >= StreamFlushBytes then
FlushStreamBuffer(I);
end;
end;
end
else begin
buf[0] := ((bufRVals[0] div sampleCycles) / 512.0);
buf[1] := ((bufLVals[0] div sampleCycles) / 512.0);
sndBuffer^ := buf[0];
Inc(sndBuffer);
sndBuffer^ := buf[1];
Inc(sndBuffer);
Inc(sndBytesWritten, SampleSize);
end;
bufCycles := 0;
for I := 0 to 4 do begin
bufLVals[I] := 0;
bufRVals[I] := 0;
end;
end;
end;
procedure SoundOutBits(const ls, rs: array of Integer; cycles: integer);
var
left: integer;
begin
if not soundEnable then
exit;
while bufCycles + cycles > sampleCycles do
begin
left := sampleCycles - bufCycles;
SoundDoOut(ls, rs, left);
Dec(cycles, left);
end;
SoundDoOut(ls, rs, cycles);
end;
const
bit: array[0..3, 0..7] of integer =
((1, 0, 0, 0, 0, 0, 0, 0),
(1, 1, 0, 0, 0, 0, 0, 0),
(1, 1, 1, 1, 0, 0, 0, 0),
(1, 1, 1, 1, 1, 1, 0, 0));
vol: array[0..15] of integer = (0, 8, 17, 25, 34, 42, 51, 59, 68, 76, 85, 93, 102, 110, 119, 127);
var
swpClk, envClk, lenClk, freqClk, freq4Clk: longint;
// Yanked from SameBoy: https://github.com/LIJI32/SameBoy/blob/master/Core/apu.c#L489
function NextLFSRBit(Narrow: Boolean): Byte;
var
HighBitMask: Cardinal;
NewHighBit: Boolean;
begin
if Narrow then
HighBitMask := $4040
else
HighBitMask := $4000;
NewHighBit := (((lfsr xor (lfsr shr 1)) xor 1) and 1) <> 0;
lfsr := lfsr shr 1;
if NewHighBit then
lfsr := lfsr or HighBitMask
else
lfsr := lfsr and not HighBitMask;
Result := (lfsr and 1);
end;
procedure SoundUpdate(cycles: integer);
var
n, stage: integer;
ls: array[1..4] of Integer = (0, 0, 0, 0);
rs: array[1..4] of Integer = (0, 0, 0, 0);
chanLs, chanRs: array[0..4] of Integer;
masterL, masterR: Double;
l, r: Integer;
I: Integer;
begin
if (not soundEnable) then
exit;
l := 0;
r := 0;
if sndRegChange then
begin
snd[1].Freq := m_iram[$FF13] or ((m_iram[$FF14] and 7) shl 8);
snd[2].Freq := m_iram[$FF18] or ((m_iram[$FF19] and 7) shl 8);
snd[3].Freq := m_iram[$FF1d] or ((m_iram[$FF1e] and 7) shl 8);
case m_iram[$FF22] and 7 of
0: snd[4].Freq := (512 * 1024 * 2) shr ((m_iram[$FF22] shr 4) + 1);
1: snd[4].Freq := (512 * 1024) shr ((m_iram[$FF22] shr 4) + 1);
2: snd[4].Freq := ((512 * 1024) div 2) shr ((m_iram[$FF22] shr 4) + 1);
3: snd[4].Freq := ((512 * 1024) div 3) shr ((m_iram[$FF22] shr 4) + 1);
4: snd[4].Freq := ((512 * 1024) div 4) shr ((m_iram[$FF22] shr 4) + 1);
5: snd[4].Freq := ((512 * 1024) div 5) shr ((m_iram[$FF22] shr 4) + 1);
6: snd[4].Freq := ((512 * 1024) div 6) shr ((m_iram[$FF22] shr 4) + 1);
7: snd[4].Freq := ((512 * 1024) div 7) shr ((m_iram[$FF22] shr 4) + 1);
end;
snd[4].Freq := (8192 * 1024) div snd[4].Freq;
snd[3].Enable := m_iram[$FF1a] and $80 > 0;
if m_iram[$FF14] and $80 > 0 then
begin
snd[1].Vol := m_iram[$FF12] shr 4;
snd[1].Len := 64 - (m_iram[$FF11] and 63);
snd[1].Cnt := 0;
m_iram[$FF14] := m_iram[$FF14] and $7f;
snd[1].Enable := True;
end;
if m_iram[$FF19] and $80 > 0 then
begin
snd[2].Vol := m_iram[$FF17] shr 4;
snd[2].Len := 64 - (m_iram[$FF16] and 63);
snd[2].Cnt := 0;
m_iram[$FF19] := m_iram[$FF19] and $7f;
snd[2].Enable := True;
end;
if m_iram[$FF1e] and $80 > 0 then
begin
snd[3].Len := (256 - byte(m_iram[$FF1b]));// shl 7;
snd[3].Cnt := 0;
m_iram[$FF1e] := m_iram[$FF1e] and $7f;
snd[3].Enable := True;
m_iram[$ff1a] := m_iram[$ff1a] or %10000000;
end;
if m_iram[$FF23] and $80 > 0 then
begin
snd[4].Vol := m_iram[$FF21] shr 4;
snd[4].Len := 64 - (m_iram[$FF20] and 63);
m_iram[$FF23] := m_iram[$FF23] and $7f;
snd[4].Enable := True;
lfsr := 0;
end;
sndRegChange := False;
end;
if (snd[1].Enable) and (m_iram[$FF10] and $70 > 0) then
begin
Inc(swpClk, cycles);
if swpClk >= (8192 * 1024 div 128) then
begin
Dec(swpClk, 8192 * 1024 div 128);
Inc(snd[1].SwpCnt);
if snd[1].SwpCnt >= ((m_iram[$FF10] shr 4) and 7) then
begin
snd[1].SwpCnt := 0;
if m_iram[$FF10] and 8 > 0 then
begin
Dec(snd[1].Freq, snd[1].Freq shr (m_iram[$FF10] and 7));
if snd[1].Freq < 0 then
snd[1].Freq := 0;
end
else
begin
Inc(snd[1].Freq, snd[1].Freq shr (m_iram[$FF10] and 7));
if snd[1].Freq > 2047 then
begin
snd[1].Freq := 2047;
snd[1].Enable := False;
end;
end;
end;
end;
end;
Inc(envClk, cycles);
if envClk >= 8192 * 1024 div 64 then
begin
Dec(envClk, 8192 * 1024 div 64);
if (snd[1].Enable) and (m_iram[$FF12] and 7 > 0) then
begin
Inc(snd[1].EnvCnt);
if snd[1].EnvCnt >= (m_iram[$FF12] and 7) then
begin
snd[1].EnvCnt := 0;
if m_iram[$FF12] and 8 > 0 then
begin
Inc(snd[1].Vol);
if (snd[1].Vol > $f) then
snd[1].Vol := $f;
m_iram[$FF12] := (m_iram[$FF12] and $f) or (snd[1].Vol shl 4);
end
else
begin
Dec(snd[1].Vol);
if (snd[1].Vol < 0) then
snd[1].Vol := 0;
m_iram[$FF12] := (m_iram[$FF12] and $f) or (snd[1].Vol shl 4);
end;
end;
end;
if (snd[2].Enable) and (m_iram[$FF17] and 7 > 0) then
begin
Inc(snd[2].EnvCnt);
if snd[2].EnvCnt >= (m_iram[$FF17] and 7) then
begin
snd[2].EnvCnt := 0;
if m_iram[$FF17] and 8 > 0 then
begin
Inc(snd[2].Vol);
if (snd[2].Vol > $f) then
snd[2].Vol := $f;
m_iram[$FF17] := (m_iram[$FF17] and $f) or (snd[2].Vol shl 4);
end
else
begin
Dec(snd[2].Vol);
if (snd[2].Vol < 0) then
snd[2].Vol := 0;
m_iram[$FF17] := (m_iram[$FF17] and $f) or (snd[2].Vol shl 4);
end;
end;
end;
if (snd[4].Enable) and (m_iram[$FF21] and 7 > 0) then
begin
Inc(snd[4].EnvCnt);
if snd[4].EnvCnt >= m_iram[$FF21] and 7 then
begin
snd[4].EnvCnt := 0;
if m_iram[$FF21] and 8 > 0 then
begin
Inc(snd[4].Vol);
if snd[4].Vol > $f then
snd[4].Vol := $f;
m_iram[$FF21] := (m_iram[$FF21] and $f) or (snd[4].Vol shl 4);
end
else
begin
Dec(snd[4].Vol);
if (snd[4].Vol < 0) then
snd[4].Vol := 0;
m_iram[$FF21] := (m_iram[$FF21] and $f) or (snd[4].Vol shl 4);
end;
end;
end;
end;
Inc(lenClk, cycles);
if lenClk >= 8192 * 1024 div 256 then
begin
Dec(lenClk, 8192 * 1024 div 256);
if snd[1].Enable then
begin
Dec(snd[1].Len);
if (snd[1].Len <= 0) and (m_iram[$FF14] and $40 > 0) then
snd[1].Enable := False;
end;
if snd[2].Enable then
begin
Dec(snd[2].Len);
if (snd[2].Len <= 0) and (m_iram[$FF19] and $40 > 0) then
snd[2].Enable := False;
end;
if snd[3].Enable then
begin
Dec(snd[3].Len);
if (snd[3].Len <= 0) and (m_iram[$FF1e] and $40 > 0) then
begin
snd[3].Enable := False;
m_iram[$ff1a] := m_iram[$ff1a] and $7f;
end;
end;
if snd[4].Enable then
begin
Dec(snd[4].Len);
if (snd[4].Len <= 0) and (m_iram[$FF23] and $40 > 0) then
snd[4].Enable := False;
end;
end;
m_iram[$FF13] := snd[1].Freq and $ff;
m_iram[$FF14] := (m_iram[$FF14] and $f8) or ((snd[1].Freq shr 8) and 7);
Inc(freqClk, cycles);
if freqClk >= 4 then
begin
n := freqClk shr 2;
Dec(freqClk, n shl 2);
if snd[1].Enable then
begin
Inc(snd[1].Cnt, n);
while snd[1].Cnt >= ((2048 - snd[1].Freq) shl 4) do
Dec(snd[1].Cnt, ((2048 - snd[1].Freq) shl 4));
end;
if snd[2].Enable then
begin
Inc(snd[2].Cnt, n);
while snd[2].Cnt >= ((2048 - snd[2].Freq) shl 4) do
Dec(snd[2].Cnt, ((2048 - snd[2].Freq) shl 4));
end;
if snd[3].Enable then
begin
Inc(snd[3].Cnt, n);
while snd[3].Cnt >= ((2048 - snd[3].Freq) shl 5) do
Dec(snd[3].Cnt, ((2048 - snd[3].Freq) shl 5));
end;
end;
if not snd[1].channelOFF then
begin
if snd[1].Enable then
begin
stage := (snd[1].Cnt div (2048 - snd[1].Freq)) shr 1;
if stage > 7 then
stage := 7;
snd[1].Bit := bit[m_iram[$FF11] shr 6][stage];
end;
if m_iram[$FF25] and 1 > 0 then
if snd[1].Bit > 0 then
Inc(ls[1], vol[snd[1].Vol])
else
Dec(ls[1], vol[snd[1].Vol]);
if m_iram[$FF25] and $10 > 0 then
if snd[1].bit > 0 then
Inc(rs[1], vol[snd[1].Vol])
else
Dec(rs[1], vol[snd[1].Vol]);
end;
if not snd[2].channelOFF then
begin
if snd[2].Enable then
begin
stage := (snd[2].Cnt div (2048 - snd[2].Freq)) shr 1;
if stage > 7 then
stage := 7;
snd[2].Bit := bit[m_iram[$FF16] shr 6][stage];
end;
if m_iram[$FF25] and 2 > 0 then
if snd[2].bit > 0 then
Inc(ls[2], vol[snd[2].Vol])
else
Dec(ls[2], vol[snd[2].Vol]);
if m_iram[$FF25] and $20 > 0 then
if snd[2].Bit > 0 then
Inc(rs[2], vol[snd[2].Vol])
else
Dec(rs[2], vol[snd[2].Vol]);
end;
if not snd[3].channelOFF then
begin
if snd[3].Enable then
begin
stage := snd[3].Cnt div (2048 - snd[3].Freq);
if stage > 31 then
stage := 31;
snd[3].Bit := m_iram[$FF30 + (stage shr 1)];
if stage and 1 > 0 then
snd[3].Bit := snd[3].Bit and $f
else
snd[3].Bit := snd[3].Bit shr 4;
case (m_iram[$FF1c] shr 5) and 3 of
0: snd[3].Bit := 8;
1: ;
2: snd[3].Bit := 8 or (snd[3].Bit shr 1);
3: snd[3].Bit := $c or (snd[3].Bit shr 2);
end;
if m_iram[$FF25] and 4 > 0 then
Inc(ls[3], (snd[3].Bit shl 4) - $80);
if m_iram[$FF25] and $40 > 0 then
Inc(rs[3], (snd[3].Bit shl 4) - $80);
end;
end;
if not snd[4].channelOFF then
begin
if snd[4].Enable then
begin
Inc(freq4Clk, cycles);
if (freq4Clk >= snd[4].Freq) then
begin
freq4Clk := freq4Clk mod snd[4].Freq;
snd[4].Bit := NextLFSRBit((m_iram[$FF22] and %1000) <> 0);
end;
if (m_iram[$FF25] and 8) > 0 then
if snd[4].Bit > 0 then
Inc(ls[4], vol[snd[4].Vol])
else
Dec(ls[4], vol[snd[4].Vol]);
if (m_iram[$FF25] and $80) > 0 then
if snd[4].Bit > 0 then
Inc(rs[4], vol[snd[4].Vol])
else
Dec(rs[4], vol[snd[4].Vol]);
end;
end;
for I := 1 to 4 do begin
SampleBuffers[I].BufferL[SampleBuffers[I].Cursor] := ls[I];
SampleBuffers[I].BufferR[SampleBuffers[I].Cursor] := rs[I];
SampleBuffers[I].Cursor := (SampleBuffers[I].Cursor + 1) mod SAMPLE_BUFFER_SIZE;
end;
masterL := ((m_iram[$FF24] and 7) + 1) / 8;
masterR := (((m_iram[$FF24] shr 4) and 7) + 1) / 8;
l := Trunc((ls[1] + ls[2] + ls[3] + ls[4]) * masterL);
r := Trunc((rs[1] + rs[2] + rs[3] + rs[4]) * masterR);
SampleBuffers[0].BufferL[SampleBuffers[0].Cursor] := l;
SampleBuffers[0].BufferR[SampleBuffers[0].Cursor] := r;
SampleBuffers[0].Cursor := (SampleBuffers[0].Cursor + 1) mod SAMPLE_BUFFER_SIZE;
chanLs[0] := l;
chanRs[0] := r;
for I := 1 to 4 do begin
chanLs[I] := Trunc(ls[I] * masterL);
chanRs[I] := Trunc(rs[I] * masterR);
end;
SoundOutBits(chanLs, chanRs, cycles);
end;
begin
ResetSound
end.
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