Program SBPlay;

{------------------------------------
 SB compatible digital sound routines

      Copyright Tapio Žij„l„ 1994.

     Use and distribute freely, but
    please notice me in somewhere on
     your product if you use these
               routines!

                Thanks.
 ------------------------------------}

Uses crt;

Const DmaChannel                                : Array [0..3,1..3] of Byte =
                                                  (($87,$0,$1),($83,$2,$3),($81,$2,$3),($82,$6,$7));

Var   Reset, ReadData, WriteData, DataAvailable : Word;
      Offset, Page                              : Word;

Function InitSoundSystem(Base : Word) : Byte;

{Check out Sound Blaster from given base address}

Begin
 InitSoundSystem := 1;
 Base := Base * $10;
 Reset := Base + $206;
 ReadData := Base + $20A;
 WriteData := Base + $20C;
 DataAvailable := Base + $20E;
 Port[Reset] := 1;
 Delay(1);
 Port[Reset] := 0;
 Delay(1);
 If (Port[DataAvailable] And $80 = $80) And (Port[ReadData] = $AA) then Begin
  InitSoundSystem := 0;
 End;
End;

Procedure WriteDSP(Data : Byte);

{Write a one byte to DSP.}

Begin
 While Port[WriteData] And $80 <> 0 Do;
 Port[WriteData] := Data;
End;

Function ReadDSP : Byte;

{Read a one byte from DSP.}

Begin
 While Port[DataAvailable] And $80 = 0 Do;
 ReadDSP := Port[ReadData];
End;

Procedure SpeakerOn;

{Send sound to line output.}

Begin
 WriteDSP($D1);
End;

Procedure SpeakerOff;

{Don't send anything to line output. Playing will continue, but you don't
 hear anything!}

Begin
 WriteDSP($D3);
End;

Procedure DMAStop;

{Stop DMA-transfer}

Begin
 WriteDSP($D0);
End;

Procedure DMAContinue;

{Continue DMA-transfer}

Begin
 WriteDSP($D4);
End;

Procedure PlaySample(Sample : Pointer; Size : Word; Freq : Word; DMACh : Byte);

{Play data from pointer sample through SB:

 Size           Size of data block (Max. 64 Kb in one time!)
 Freq           Sampling rate in herts
 DMACh          Number of DMA-channel (0-3)}

Begin
 SpeakerOn;
 Dec(Size);
 Offset := Seg(Sample^) Shl 4 + Ofs(Sample^);
 Page := (Seg(Sample^) + Ofs(Sample^) Shr 4) Shr 12;
 Port[$0A] := $4 + DMACh;
 Port[$0C] := 0; {Clear the internal DMA flip-flop}
 Port[$0B] := $48 + DMACh;
 Port[DMAChannel[1,2]] := Lo(Offset);
 Port[DMAChannel[1,2]] := Hi(Offset);
 Port[DMAChannel[1,1]] := Page;
 Port[DMAChannel[1,3]] := Lo(Size);
 Port[DMAChannel[1,3]] := Hi(Size);
 Port[$0A] := DMACh;
 WriteDSP($40);
 WriteDSP(256 - 1000000 Div Freq);
 WriteDSP($14);
 WriteDSP(Lo(Size));
 WriteDSP(Hi(Size));
End;

Begin
 If InitSoundSystem($2) <> 0 then Writeln('Error in initializing soundcard!'); {Check out for SB in give base address!}
 PlaySample(Ptr($B800,0),65535,14000,1); {Plays data from video memory through SB!}
End.