Topic       : The GFA-Basic Compendium
Author      : GFA Systemtechnik GmbH
Version     : GFABasic.HYP v2.98 (12/31/2023)
Subject     : Documentation/Programming
Nodes       : 899
Index Size  : 28056
HCP-Version : 3
Compiled on : Atari
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View Ref-FileDMACONTROL ctrl
DMASOUND beg,end,rate[,ctrl]

beg, end, rate, ctrl: iexp

These commands allow sampled 8-bit DMA sound to be played on STE compatible
hardware.

The DMACONTROL command controls the method used to play back the sound as
follows:

    Method        Bits  ctrl
    Stop sound    %00   0
    Play once     %01   1
    -             %10   -
    Play in loop  %11   3

The DMASOUND command causes the sound to be played. The parameters are as
follows:

    beg  - Sample starting address
    end  - Sample ending address
    rate - Sample rate:
           0 = 6.25 kHz  (not supported on the Atari Falcon030)
           1 = 12.5 kHz
           2 = 25 kHz
           3 = 50 kHz
    ctrl - See command DMACONTROL above.

Example:

    ' Try each of the DMASOUND lines for different effect.
    n%=360*32
    DIM a|(n%)
    ' DMASOUND V:a|(0),V:a|(n%),0,3
    ' DMASOUND V:a|(0),V:a|(n%),1,3
    ' DMASOUND V:a|(0),V:a|(n%),2,3
    DMASOUND V:a|(0),V:a|(n%),3,3
    FOR i%=0 TO n%
      a|(i%)=128+SINQ(i%*i%/7200)*127
    NEXT i%
    REPEAT
    UNTIL MOUSEK
    DMACONTROL 0

Memo: Sound playback can be prematurely halted with DMACONTROL 0.

      The DMASOUND command could allow 16-bit playback on the Falcon030 if
      bit 6 was set in the rate, however GFA clobbers that bit assuming it
      won't ever be used.

      The DMASOUND command can be used to play mono sound samples if bit 7 is
      set to 'on' in the rate parameter. Example: rate&=BSET(rate&,7)

      DMA sound data format: signed (-128 to 127) 8-bit PCM

      Mono: sample must be of even length
      Stereo 8-bit: word (15--left--8/7--right--0)

      DMASOUND defaults to 'play in loop' due to a bug if ctrl is omitted.

      DMASOUND does not work if the sample buffer is located in fastram!
      Care must be taken when allocating sample buffers and also pay close
      attention to the program header flags when compiling.

      If you use the XBIOS sound functions, the program header flags must be
      set Global or Super, otherwise a call to Buffoper() results in a crash.

The Falcon030 Sound System+, Locksnd()+, Unlocksnd()+, Soundcmd()+,
Setbuffer()+, Setmode()+, Settracks()+, Setmontracks()+, Setinterrupt()+,
Buffoper()+, Dsptristate()+, Gpio()+, Devconnect()+, Sndstatus()+, Buffptr()+