Some VOC processing code I wrote in the 90's

xvoc.pas

{
Name            : X/VOC 1.00a
Purpose         : Sound Blaster interface routines
Date            : 29th May 94
Time            : 19:18
}

unit XVoc;

interface

const

  {VOC Block types}

  MaxBlocks    = 8;

  vbTerminator = 0;
  vbVoiceData  = 1;
  vbVoiceCont  = 2;
  vbSilence    = 3;
  vbMarker     = 4;
  vbText       = 5;
  vbRepeat     = 6;
  vbUntil      = 7;
  vbExtended   = 8;

  VOCBlock : array[0..8] of string[10] =
    ('Terminator',
     'VoiceData ',
     'VoiceCont ',
     'Silence   ',
     'Marker    ',
     'Text      ',
     'Repeat    ',
     'Until     ',
     'Extended  ');

  MaxPacks = 3;

  ptNone        = 0;
  pt4bit        = 1;
  pt26bit       = 2;
  pt2bit        = 3;

  PackStr : array[0..3] of string[8] =
    ('None    ',
     '4-bits  ',
     '2.6-bits',
     '2-bits  ');

type

  TVOCHeader = record
    Desc     : array[1..19] of char;
    EOF      : byte;
    DataOffs : word;
    Version  : word;
    Checksum : word; {version+checksum must be equal to 1234h}
  end;

  PVOCBlock = ^TVOCBlock;
  TVOCBlock = object
    Len       : word;
    Temp      : byte;
  end;

  PVoiceData = ^TVoiceData;
  TVoiceData = object(TVOCBlock)
    KHz        : byte;
    Pack       : byte; {voice length=len-2}
    Data       : record end;
  end;

  PVoiceCont = ^TVoiceCont;
  TVoiceCont = object(TVOCBlock)
    Data     : record end;
  end;

  PSilence = ^TSilence;
  TSilence = object(TVOCBlock)
    Period   : word;
    KHz      : byte;
  end;

  PMarker = ^TMarker;
  TMarker = object(TVOCBlock)
    Marker : word;
  end;

  PRepeat = ^TRepeat;
  TRepeat = object(TVOCBlock)
    Count : word;
  end;

  PUntil = ^TUntil;
  TUntil = TVOCHeader;

  PExtVoice = ^TExtVoice;
  TExtVoice = object(TVOCBlock)
    XKHz    : word;
    Pack    : byte;
    Mode    : byte;
  end;

function ValidVOCHdr(var H:TVOCHeader):boolean;
function TC2KHz(tc:byte):word;

implementation

function TC2Khz;
begin
  TC2KHz := (tc-256)*1000000;
end;

function ValidVOCHdr;assembler;
asm
  les  di,H
  mov  dx,word ptr es:[di].TVOCHeader.Version
  mov  bx,word ptr es:[di].TVOCHeader.CheckSum
  mov  cx,1234h
  add  dx,bx
  xor  al,al
  cmp  dx,cx
  je   @Exit
  inc  al
@Exit:
end;

end.