'===========================================================================
' Subject: PLAY NOTE VIA SB CARD             Date: Unknown Date           
' Author:  Brandon Callison                  Code: QB, QBasic, PDS        
' Origin:  QBTIPS                          Packet: SOUND.ABC
'===========================================================================
'                        Sound Blaster Source Code
'                         Made by Brandon Callison
'        Register 388h is the address/status port, and 389h is the data port.
'This is, of course, only for the FM music.  (The cannels 1-11)  which are
'compatible with Ad-Lib, Sound Blaster, SB Pro, Thunder Board, and many
'others.  All boards advertised as compatible with Ad-Lib or Sound Blaster
'are compatible with this.  Explainations of the mysterious code will be
'throughout the program.

DEFINT A-Z

DECLARE SUB SBStop ()
DECLARE SUB SBReset ()
DECLARE SUB SBOutPort (reg, x)
DECLARE SUB SBPlayNote (freq#, oct)

' vvvvvvvvvvvvvvvvvvvvvvv
' The following are his variable declarations; I'm leaving them in so you
' can see what all the variables are for:
'
'float freq;                          /* Frequency                */
'int oct;                             /* Octave                   */
'int reg;                             /* Register no.             */
'int x;                               /* Poke number to register  */
'int i;                               /* GLOBAL Dummy loop signal */
'
' ^^^^^^^^^^^^^^^^^^^^^^^

SBReset
SBPlayNote 277.2, 5                  'Middle C sharp on octave 5
SLEEP 2
SBStop                               'Must be called to cut sound

END

SUB SBOutPort (reg, x)

OUT &H388, reg              'Outputs the register to be written to

FOR I = 1 TO 6

    reg = INP(&H388)

NEXT I

'   ^- This loop requires some explaining.  The sound card must allow time
'to process it's code.  6 reads from the status port will cause it to wait
'for 2.3 microseconds.  You MUST NOT make any outputs to the sound card port
'without waiting at least this amount of time in-between calls.  The same
'applies below, except the wait is 23 microseconds, by 35 reads from the data
'port.

OUT &H389, x
FOR I = 1 TO 35                 'Outputs the data into the register
    reg = INP(&H389)
NEXT I

END SUB

SUB SBPlayNote (freq#, oct)

freq2 = INT(1.31 * freq#)          'Convert from hz to raw frequency?!?!
SBOutPort &H60, &HF0
SBOutPort &HC0, 1
SBOutPort &HA0, freq2 AND &HFF
SBOutPort &HB0, ((freq2 AND &HFF00) / &H100) OR (oct * 4) OR 32
       '   ^- for different channels, do anywhere from the register
       '   0xB0 to 0xBA.  (channels 1-11)
END SUB

SUB SBReset

FOR I = 1 TO 244         ' The sound card has 244 data ports.  Just clears
    OUT &H388, 0         ' all of them.
NEXT I

END SUB

SUB SBStop

  SBOutPort &HB0, 0       ' As I said earlier for different channels

END SUB