XMS Sound Bank

Unit: SNDBANK

XMS-based sound library for Sound Blaster (stores sounds in extended memory).

Types

type
  TSoundInfo = record
    Name: String[12];
    XMSHandle: Word;
    XMSOffset: LongInt;
    Size: Word;
    SampleRate: Word;
    Loaded: Boolean;
  end;

  TSoundBank = object
    Sounds: array[0..31] of TSoundInfo;
    Count: Integer;
    SoundBankInitialized: Boolean;
    { ... internal fields ... }

    function Init: Boolean;
    function LoadSound(const FileName: string): Integer;  { Returns sound ID }
    function PlaySound(SoundID: Integer): Boolean;
    procedure StopSound;
    procedure Done;
  end;

Example

uses SBDSP, SndBank, Keyboard;

const
  MaxSounds = 32;

var
  Bank: TSoundBank;
  ExplosionID, LaserID: Integer;

begin
  { Initialize Sound Blaster }
  if not ResetDSP(2, 5, 1, 0) then Halt(1);

  { Initialize sound bank }
  if not Bank.Init then
  begin
    WriteLn('XMS not available! Load HIMEM.SYS');
    Halt(1);
  end;

  { Load sounds at startup (stored in XMS) }
  ExplosionID := Bank.LoadSound('DATA\EXPLODE.VOC');
  LaserID := Bank.LoadSound('DATA\LASER.VOC');

  if ExplosionID < 0 then
    WriteLn('Failed to load explosion!');

  { Game loop }
  InitKeyboard;
  while Running do
  begin
    { Play on demand (fast XMS transfer) }
    if IsKeyPressed(Key_Space) then
      Bank.PlaySound(LaserID);

    if IsKeyPressed(Key_E) then
      Bank.PlaySound(ExplosionID);

    if IsKeyPressed(Key_Escape) then
      Running := False;

    ClearKeyPressed;
  end;

  { Cleanup }
  DoneKeyboard;
  Bank.Done;          { Free XMS memory }
  UninstallHandler;   { SBDSP cleanup }
end.

Methods

Init

function Init: Boolean;

Initializes sound bank and checks for XMS driver.

Returns: True if XMS available, False otherwise.

LoadSound

function LoadSound(const FileName: string): Integer;

Loads VOC file into XMS extended memory.

Returns: Sound ID (0-31) on success, -1 on error.

PlaySound

function PlaySound(SoundID: Integer): Boolean;

Plays sound by transferring from XMS to DMA buffer.

Returns: True on success, False on error.

Behavior:

• Stops any currently playing sound

• Allocates DMA-safe buffer (64KB boundary aligned)

• Transfers from XMS to conventional memory

• Starts Sound Blaster playback

StopSound

procedure StopSound;

Stops currently playing sound immediately.

Done

procedure Done;

Frees all XMS blocks and DMA buffers. MUST call before exit.

With HSC Music

uses SBDSP, SndBank, PlayHSC;

var
  Bank: TSoundBank;
  Music: HSC_obj;

begin
  ResetDSP(2, 5, 1, 0);

  { Start music }
  Music.Init(0);
  Music.LoadFile('THEME.HSC');
  Music.Start;

  { Sound effects work with music }
  Bank.Init;
  ExplosionID := Bank.LoadSound('EXPLODE.VOC');
  Bank.PlaySound(ExplosionID);

  { IMPORTANT: Don't wait in tight loop! }
  { while Playing do ; }  { DON'T - causes freeze }

  { Cleanup }
  Bank.Done;
  Music.Done;
  UninstallHandler;
end.

Critical Notes

1. XMS required - Load HIMEM.SYS in CONFIG.SYS

2. ResetDSP first - Initialize SBDSP before Bank.Init

3. Don’t wait with HSC - Never use while Playing loop when music active

4. Call Bank.Done - Before UninstallHandler

5. Max 32 sounds - Up to ~64KB each

Memory Usage

• Conventional memory: ~8KB (largest sound + overhead)

• XMS extended memory: All sound data stored above 1MB

• DMA-safe buffer: Automatically handles 64KB page boundaries

Requirements

• HIMEM.SYS loaded (provides XMS driver)

• Sound Blaster at port $220, IRQ 5, DMA 1

• VOC files (Type 1 sound data blocks)

Notes

• Minimal conventional memory usage (sounds in XMS)

• Fast XMS transfer (~1-2ms)

• Only one sound plays at a time (single DMA channel)

• Compatible with HSC music (different interrupts)