Sound Routines

• DSP_Init -- This function uses the SoundLib291 SB_Init routine to initialize the sound card and install the ISR. It also sets the callback of the SB Interrupt to our new DSP handler

  ; ----------------------------------------------
  ; DSP_Init
  ;
  ; Inputs: None
  ;
  ; Outputs: Carry set if install failed
  ;
  ; Input/Output: Nothing.
  ;
  ; Purpose: This routine calls the soundlib init and setcallback functions
  ; to prepare the audio card for the playing of WAV's
  ;
  ; Written by: Nathan Hamstra
  ; -----------------------------------------------

• DSP_Play -- uses the soundlib291 sb_play to open a sound and play it. This function also takes care of all the file management and buffer loading

  ; ----------------------------------------------
  ; DSP_Play
  ;
  ; Inputs: AX -- The index of the WAV file in the table of filenames to play
  ;
  ; Outputs: Plays the wave file from the speakers
  ;
  ; Input/Output: Nothing.
  ;
  ; Purpose: This will open and laod a WAV file and set up the DMA for the
  ; SBLib291 call.
  ;
  ; Written by: Nathan Hamstra
  ; -----------------------------------------------

• DSP_Clean -- This is called at the exit of the main program to reset the ISR's and the interrupt controller

  ; ----------------------------------------------
  ; DSP_Clean
  ;
  ; Inputs:None
  ;
  ; Outputs:None
  ;
  ; Input/Output: None
  ;
  ; Purpose: Just uses a SBLib291 call to restore the the soundcard
  ; to it's previous settings
  ;
  ; Written by: Nathan Hamstra
  ; -----------------------------------------------

• PlayMidi -- This function will play a MIDI file directly to the computers external speakers

  ; ----------------------------------------------
  ; PlayMidi
  ;
  ; Inputs: ax == sequence in midi to play (default to 0)
  ;
  ; Outputs:ax == 1 for successful play, 0 for failure
  ;
  ; Input/Output: sound from the FM synthesis
  ;
  ; Purpose: uses the installed midpak drivers on user interrupt 66h
  ; to play a midi sequence
  ;
  ; Written by: Nathan Hamstra
  ; -----------------------------------------------

• StopMidi -- This function will stop the MIDI file playing from the computer

  ; ----------------------------------------------
  ; StopMidi
  ;
  ; Inputs: None
  ;
  ; Outputs: None
  ;
  ; Input/Output: Nothing
  ;
  ; Purpose: uses another midipak interrupt call to stop the music
  ;
  ; Written by: Nathan Hamstra
  ; -----------------------------------------------

• RegisterMidi -- This function will read the file from memory and then register it with midpak.

  ; ----------------------------------------------
  ; RegisterMidi
  ;
  ; Inputs: ax == index in wavtable array of file to register ;
  ; Outputs: None
  ;
  ; Input/Output: Nothing
  ;
  ; Purpose: Reads the midifile into memory, then registers it with
  ; midpak
  ;
  ; Written by: Nathan Hamstra
  ; -----------------------------------------------

Sound Structures

Below all the data structures that are used in the sound routines are going to be described.

• WaveHdr -- This is the format of the WAV file headers.

  WaveHdr STRUC ; Format of wave file header   format db 'RIFF'   filelen dd ?   wavefmt db 'WAVEfmt_'   fmt_len dd ?   fmt_tag dw ?   channel dw ?   samples dd ?   bytesps dd ?   bkalign dw ?   bitsps dw ?   data db 'data'   datalen dd ? WaveHdr Ends

Sound Variables

Below all the variables that will be used in the sound routines will be described.

• SBuf_Page -- Used to store the page of the sound when needed
• SBuf_Offset -- Used to store the offset of the sound when needed
• SBuf_Length -- The length of the SoundBlaster Buffer
• FileHandle -- Use to store the file handle name
• FinalBufferSize -- The final size of the buffer
• NeedReFill -- A boolean variable
• LoadBuf -- An easiear way to access the header STRUC
• FileNO -- Will store the handle
• WAVLength -- The length of the WAV file
• WAVFile0 -- This will be used to store the offset of all of the WAV files to be used (for testing)
• WAVFile1 -- This will be used to store the offset of all of the WAV files to be used (for testing)
• WAVFile2 -- This will be used to store the offset of all of the WAV files to be used (for testing)
• WAVFile3 -- This will be used to store the offset of all of the WAV files to be used (for testing)
• WAVTable -- This will be a Jump Table to actually access the WAV files.
• IntCounter -- Keeps track of how many times the interrupt has been called
• NeedRefill -- Keeps track of how many times the interrupt has been called
• MidiFile0 -- This will store the filename of a midi file.
• MidiFile1 -- This will store the filename of a midi file.
• MidiFile2 -- This will store the filename of a midi file.
• MidiTable -- A Table of offsets to the MIDI FileNames
• MidiLengthTable -- A Table of MIDI filelengths
• MidiLength

Sound Segment

Below the segments that the will be used in the sound routines will be described.

• SoundSeg -- This is the segment that will be used in the sound programming

  	SoundSeg SEGMENT PUBLIC
  	sndbuf DB 2048 DUP (10, 20, 50, 80, 90, 80, 50, 20)
  	SoundSeg ENDS

• MidiSeg -- This is the segment that will be used in playing the MIDI file

  	MidiSeg
  	midibuf db 32*32*32*2 dup(?)
  	MidiSeg ENDS