Basic Gravis UltraSound Programming

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  GUSDOC 
 읕컴컴컴켸

                                THE OFFICAL

                 GRAVIS ULTRASOUND PROGRAMMERS ENCYCLOPEDIA

                                ( G.U.P.E )

                                  v 0.1

                            Written by Mark Dixon.

   -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

  INTRODUCTION
  ~~~~~~~~~~~~
     The Gravis Ultrasound is by far the best & easiest sound card to
   program. Why? Because the card does all the hard stuff for you, leaving
   you and the CPU to do other things! This reference will document some
   (but not all) of the Gravis Ultrasound's hardware functions, allowing
   you to play music & sound effects on your GUS.

     We will not be going into great detail as to the theory behind
   everything - if you want to get technical information then read the
   GUS SDK. We will be merely providing you with the routines necessary
   to play samples on the GUS, and a basic explanation of how they work.

     This document will NOT go into DMA transfer or MIDI specifications.
   If someone knows something about them, and would like to write some
   info on them, we would appreciate it very much.

     All source code is in Pascal (tested under Turbo Pascal v7.0, but
   should work with TP 6.0 and possibly older versions). This document
   will assume reasonable knowledge of programming, and some knowledge of
   soundcards & music.

  INITIALISATION & AUTODETECTION
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Since we are not using DMA, we only need to find the GUS's I/O port,
  which can be done from the DOS environment space, or preferably from a
  routine that will scan all possible I/O ports until it finds a GUS.

    The theory behind the detection routine is to store some values into
  GUS memory, and then read them back. If we have the I/O port correct,
  we will read back exactly what we wrote. So first, we need a routine
  that will write data to the memory of the GUS :

   Function  GUSPeek(Loc : Longint) : Byte;

   { Read a value from GUS memory }

   Var
     B : Byte;
     AddLo : Word;
     AddHi : Byte;
   Begin
     AddLo := Loc AND $FFFF;
     AddHi := LongInt(Loc AND $FF0000) SHR 16;

     Port [Base+$103] := $43;
     Portw[Base+$104] := AddLo;
     Port [Base+$103] := $44;
     Port [Base+$105] := AddHi;

     B := Port[Base+$107];
     GUSPeek := B;
   End;

   Procedure GUSPoke(Loc : Longint; B : Byte);

   { Write a value into GUS memory }

   Var
     AddLo : Word;
     AddHi : Byte;
   Begin
     AddLo := Loc AND $FFFF;
     AddHi := LongInt(Loc AND $FF0000) SHR 16;
     Port [Base+$103] := $43;
     Portw[Base+$104] := AddLo;
     Port [Base+$103] := $44;
     Port [Base+$105] := AddHi;
     Port [Base+$107] := B;
   End;

    Since the GUS can have up to 1meg of memory, we need to use a 32bit
  word to address all possible memory locations. However, the hardware of
  the GUS will only accept a 24bit word, which means we have to change
  the 32bit address into a 24bit address. The first two lines of each
  procedure does exactly that.

    The rest of the procedures simply send commands and data out through
  the GUS I/O port defined by the variable BASE (A word). So to test for
  the presence of the GUS, we simply write a routine to read/write memory
  for all possible values of BASE :

   Function GUSProbe : Boolean;

   { Returns TRUE if there is a GUS at I/O address BASE }

   Var
     B : Byte;
   Begin
     Port [Base+$103] := $4C;
     Port [Base+$105] := 0;
     GUSDelay;
     GUSDelay;
     Port [Base+$103] := $4C;
     Port [Base+$105] := 1;
     GUSPoke(0, $AA);
     GUSPoke($100, $55);
     B := GUSPeek(0);
     If B = $AA then GUSProbe := True else GUSProbe := False;
   End;

   Procedure GUSFind;

   { Search all possible I/O addresses for the GUS }

   Var
     I : Word;
   Begin
     for I := 1 to 8 do
     Begin
       Base := $200 + I*$10;
       If GUSProbe then I := 8;
     End;
     If Base < $280 then
       Write('Found your GUS at ', Base, ' ');
   End;

    The above routines will obviously need to be customised for your own
  use - for example, setting a boolean flag to TRUE if you find a GUS,
  rather than just displaying a message.

    It is also a good idea to find out exactly how much RAM is on the
  GUS, and this can be done in a similar process to the above routine.
  Since the memory can either be 256k, 512k, 768k or 1024k, all we have
  to do is to read/write values on the boundaries of these memory
  addresses. If we read the same value as we wrote, then we know exactly
  how much memory is available.

   Function  GUSFindMem : Longint;

   { Returns how much RAM is available on the GUS }

   Var
     I : Longint;
     B : Byte;
   Begin
     GUSPoke($40000, $AA);
     If GUSPeek($40000) <> $AA then I := $3FFFF
       else
     Begin
       GUSPoke($80000, $AA);
       If GUSPeek($80000) <> $AA then I := $8FFFF
         else
       Begin
         GUSPoke($C0000, $AA);
         If GUSPeek($C0000) <> $AA then I := $CFFFF
           else I := $FFFFF;
       End;
     End;
     GUSFindMem := I;
   End;

    Now that we know where the GUS is, and how much memory it has, we
  need to initialise it for output. Unfortunately, the below routine is
  slightly buggy. If you run certain programs (I discovered this after
  running Second Reality demo) that use the GUS, and then your program
  using this init routine, it will not initialise the GUS correctly.

    It appears that I am not doing everything that is necessary to
  initialise the GUS. However, I managed to correct the problem by
  either re-booting (not a brilliant solution) or running Dual Module
  Player, which seems to initialise it properly. If someone knows where
  i'm going wrong, please say so!

    Anyway, the following routine should be called after you have found
  the GUS, and before you start doing anything else with the GUS.

   Procedure GUSDelay; Assembler;

   { Pause for approx. 7 cycles. }

   ASM
     mov   dx, 0300h
     in    al, dx
     in    al, dx
     in    al, dx
     in    al, dx
     in    al, dx
     in    al, dx
     in    al, dx
   End;


   Procedure GUSReset;

   { An incomplete routine to initialise the GUS for output. }

   Begin
     port [Base+$103]   := $4C;
     port [Base+$105] := 1;
     GUSDelay;
     port [Base+$103]   := $4C;
     port [Base+$105] := 7;
     port [Base+$103]   := $0E;
     port [Base+$105] := (14 OR $0C0);
   End;

    Now you have all the routine necessary to find and initialise the
  GUS, let's see just what we can get the GUS to do!

  MAKING SOUNDS
  ~~~~~~~~~~~~~
    The GUS is unique in that it allows you to store the data to be
  played in it's onboard DRAM. To play the sample, you then tell it what
  frequency to play it at, what volume and pan position, and which sample
  to play. The GUS will then do everything in the background, it will
  interpolate the data to give an effective 44khz (or less, depending on
  how many active voices) sample. This means that an 8khz sample will
  sound better on the GUS than most other cards, since the GUS will play
  it at 44khz!

    The GUS also has 32 seperate digital channels (that are mixed by a
  processor on the GUS) which all have their own individual samples,
  frequencies, volumes and panning positions. For some reason, however,
  the GUS can only maintain 44khz output with 16 channels - the more
  channels, the lower the playback rate (which basically means, lower
  quality). If you are using all 32 channels (unlikely), then playback is
  reduced to 22khz.

    Since you allready know how to store samples in the GUS dram (simply
  use the GUSPoke routine to store the bytes) we will now look at various
  routines to change the way the gus plays a sample. The first routine we
  will look at will set the volume of an individual channel :

   Procedure GUSSetVolume( Voi : Byte; Vol : Word);

   { Set the volume of channel VOI to Vol, a 16bit logarithmic scale
     volume value -  0 is off, $ffff is full volume, $e0000 is half
     volume, etc }

   Begin
     Port [Base+$102] := Voi;
     Port [Base+$102] := Voi;
     Port [Base+$102] := Voi;
     Port [Base+$103] := 9;
     Portw[Base+$104] := Vol;  { 0-0ffffh, log scale not linear }
   End;

    The volume (and pan position & frequency) can be changed at ANY time
  regardless of weather the GUS is allready playing the sample or not.
  This means that to fade out a sample, you simply make several calls to
  the GUSSetVolume routine with exponentially (to account for the
  logarithmic scale) decreasing values.

    The next two routines will set the pan position (from 0 to 15, 0
    being left, 15 right and 7 middle) and the frequency respectively :

   Procedure GUSSetBalance( V, B : Byte);
   Begin
     Port [Base+$102] := V;
     Port [Base+$102] := V;
     Port [Base+$102] := V;
     Port [Base+$103] := $C;
     Port [Base+$105] := B;
   End;

   Procedure GUSSetFreq( V : Byte; F : Word);
   Begin
     Port [Base+$102] := V;
     Port [Base+$102] := V;
     Port [Base+$102] := V;
     Port [Base+$103] := 1;
     Portw[Base+$104] := F;
   End;

    I'm not sure the the value F in the set frequency procedure. The GUS
  SDK claims that it is the exact frequency at which the sample should be
  played.

    When playing a sample, it is necessary to set the volume, position
  and frequency BEFORE playing the sample. In order to start playing a
  sample, you need to tell the GUS where abouts in memory the sample is
  stored, and how big the sample is  :


   Procedure GUSPlayVoice( V, Mode : Byte;VBegin, VStart, VEnd : Longint);

   { This routine tells the GUS to play a sample commencing at VBegin,
     starting at location VStart, and stopping at VEnd }

   Var
     GUS_Register : Word;
   Begin
     Port [Base+$102] := V;
     Port [Base+$102] := V;
     Port [Base+$103] := $0A;
     Portw[Base+$104] := (VBegin SHR 7) AND 8191;
     Port [Base+$103] := $0B;
     Portw[Base+$104] := (VBegin AND $127) SHL 8;
     Port [Base+$103] := $02;
     Portw[Base+$104] := (VStart SHR 7) AND 8191;
     Port [Base+$103] := $03;
     Portw[Base+$104] := (VStart AND $127) SHL 8;
     Port [Base+$103] := $04;
     Portw[Base+$104] := ((VEnd)   SHR 7) AND 8191;
     Port [Base+$103] := $05;
     Portw[Base+$104] := ((VEnd)   AND $127) SHL 8;
     Port [Base+$103] := $0;
     Port [Base+$105] := Mode;

     { The below part isn't mentioned as necessary, but the card won't
       play anything without it! }

     Port[Base] := 1;
     Port[Base+$103] := $4C;
     Port[Base+$105] := 3;
   end;

    There are a few important things to note about this routine. Firstly,
  the value VEnd refers to the location in memory, not the length of the
  sample. So if the sample commenced at location 1000, and was 5000 bytes
  long, the VEnd would be 6000 if you wanted the sample to play to the
  end. VBegin and VStart are two weird values, one of them defines the
  start of the sample, and the other defines where abouts to actually
  start playing. I'm not sure why both are needed, since I have allways
  set them to the same value.

    Now that the gus is buisy playing a sample, the CPU is totally free
  to be doing other things. We might, for example, want to spy on the gus
  and see where it is currently up to in playing the sample :

   Function VoicePos( V : Byte) : Longint;
   Var
     P : Longint;
     Temp0, Temp1 : Word;
   Begin
     Port [Base+$102] := V;
     Port [Base+$102] := V;
     Port [Base+$102] := V;
     Port [Base+$103] := $8A;
     Temp0 := Portw[Base+$104];
     Port [Base+$103] := $8B;
     Temp1 := Portw[Base+$104];
     VoicePos := (Temp0 SHL 7)+ (Temp1 SHR 8);
   End;

    This routine will return the memory location that the channel V is
  currently playing. If the GUS has reached the end of the sample, then
  the returned value will be VEnd. If you want to see what BYTE value is
  currently being played (for visual output of the sample's waveform),
  then you simply PEEK the location pointed to by this routine.

    Finally, we might want to stop playing the sample before it has
  reached it's end - the following routine will halt the playback on
  channel V.

   Procedure GUSStopVoice( V : Byte);
   Var
     Temp : Byte;
   Begin
     Port [Base+$102] := V;
     Port [Base+$102] := V;
     Port [Base+$102] := V;
     Port [Base+$103] := $80;
     Temp := Port[Base+$105];
     Port [Base+$103] := 0;
     Port [Base+$105] := (Temp AND $df) OR 3;
     GUSDelay;
     Port [Base+$103] := 0;
     Port [Base+$105] := (Temp AND $df) OR 3;
   End;

  SPECIAL EFFECTS
  ~~~~~~~~~~~~~~~
    There are a few extra features of the GUS that are worthy of mention,
  the main one being hardware controlled sample looping. The GUS has a
  control byte for each of the 32 channels. This control byte consists of
  8 flags that effect the way the sample is played, as follows :
   ( The table is taken directly from the GUS Software Developers Kit )

            =================================
            | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
            =================================
              |   |   |   |   |   |   |   |
              |   |   |   |   |   |   |   +---- Voice Stopped
              |   |   |   |   |   |   +-------- Stop Voice
              |   |   |   |   |   +------------ 16 bit data
              |   |   |   |   +---------------- Loop enable
              |   |   |   +-------------------- Bi-directional loop enable
              |   |   +------------------------ Wave table IRQ
              |   +---------------------------- Direction of movement
              +-------------------------------- IRQ pending
         (*)Bit 0 = 1 : Voice is stopped. This gets set by hitting the end
                    address (not looping) or by setting bit 1 in this reg.
            Bit 1 = 1 : Stop Voice. Manually force voice to stop.
            Bit 2 = 1 : 16 bit wave data, 0 = 8 bit data
            Bit 3 = 1 : Loop to begin address when it hits the end address.
            Bit 4 = 1 : Bi-directional looping enabled
            Bit 5 = 1 : Enable wavetable IRQ. Generate an irq when the voice
                        hits the end address. Will generate irq even if looping
                        is enabled.
         (*)Bit 6 = 1 - Decreasing addresses, 0 = increasing addresses. It is
                        self-modifying because it might shift directions when
                        it hits one of the loop boundaries and looping is enabled.
         (*)Bit 7 = 1 - Wavetable IRQ pending. If IRQ's are enabled and
                        looping is NOT enabled, an IRQ will be constantly
                        generated until voice is stopped. This means that
                        you may get more than 1 IRQ if it isn't handled
                        properly.

   Procedure GUSVoiceControl( V, B : Byte);
   Begin
     Port [Base+$102] := V;
     Port [Base+$102] := V;
     Port [Base+$103] := $0;
     Port [Base+$105] := B;
   End;

    The above routine will set the Voice Control byte for the channel
  defined in V. For example, if you want channel 1 to play the sample in
  a continuous loop, you would use the procedure like this :

     GUSVoiceControl( 1, $F );  { Bit 3 ON = $F }

  CONCLUSION
  ~~~~~~~~~~

    The above routines are all that is necessary to get the GUS to start
  playing music. To prove this, I have included my 669 player & source
  code in the package as a practical example. The GUSUnit contains all
  the routines discussed above. I won't go into the theory of the 669
  player, but it is a good starting point if you want to learn about
  modplayers. The player is contained within the archive 669UNIT.ARJ

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  README 
 읕컴컴컴켸

   GUS669 Unit  v0.2b
   Copyright 1994 Mark Dixon.
   (aka C.D. of Silicon Logic)

   LEGAL STUFF
   ~~~~~~~~~~~
   I'd like to avoid this, but it has to be done. Basically, if anything
   in this archive causes any kind of damage, I cannot be held
   responsable - USE AT YOUR OWN RISK.

   In adition, since I spent long hours working on this project, and
   attempting to decode the GUS SDK, I would appreciate it if people
   didn't rip off my work. Give me credit for what I have done, and if
   your planning to use my routines for commercial purposes, talk to me
   first, or you might find yourself on the wrong side of a legal battle.
   (Hey, let's sound tough while i'm at it, I have lawyer's in the
   family, so it's not gonna cost me much to sue someone. And don't
   criticise my spelling! :)

   BORING STUFF
   ~~~~~~~~~~~~
   Well, if your the sort of person who likes to ignore all the rubishy
   bits that go into a README text file, then you'd better stop now and
   go and try out the source code!

   Basically, this readme isn't going to say much more than what the
   source code is, and then go dribling on for five pages about
   absolutely nothing.

   SOURCE CODE! DID SOMEONE SAY - SOURCE CODE!! - ????
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   Yes, that's right, free with every download of this wonderful archive
   comes the complete Pascal source code to a 669 module player for the
   GUS. I'd have included my MOD player, but I haven't been able to get
   all the MOD commands working, so you'll just have to make do with a
   669 player :)

   Feel free to make use of this source code for any non-commercial
   purposes you might be able to think of - and mention my name while
   your at it! Since the source code is here, people are bound to modify
   it for their personal uses. If you do this, I would very much like to
   see your modifications - so that I can include them in the next
   release of the player.

   Well, I don't want to bore you anymore, and it's getting late (not!)
   so i'd better let you go and play around with the source code :)

   SILICON LOGIC
   ~~~~~~~~~~~~~
   What ever happened to Silicon Logic? Well, after being killed off over
   in Perth, a major revival is underway here in Canberra, with a more
   commercial view - more on that later.

   For those of you who have never heard of Silicon Logic, then you're
   either not Australian, or not into the ausie demo scene. But then,
   that covers about 99.999999999999% of the world population :)

   GREETINGS
   ~~~~~~~~~
   I've allways wanted to dribble some thanks, so here goes.

    Thanks go to...

     Darren Lyon    - Who got me into this programming lark in the first
                      place. Finally wrote myself a mod player :)
     Tran           - Your source code really helped!
     Kitsune        - Love those mods, keep up the good work!

     ... and Advanced Gravis, for making the best sound card ever.

    Greetings to...

     FiRE members   - I'll probably never join you guys, but good luck
                      anyway!
     UNiQUE         - How's the board going?
     CRaSH          - Still ripping other peoples source code?
     Old SL members - Thanks for the support, good luck with your new
                      group!
     Oliver White   - G'day... just thought i'd say hi, since you so
                      kindly beta tested the player for me.
     Murray Head    - Rick Price sux! :-) SoundBlaster sux too! :-)
     Perth people   - I'm coming back... someday!

     THE PICK / MINNOW   -  Hey, give me a call sometime, long time no
                            talk...

   INTERESTED IN A DEMO GROUP IN CANBERRA?
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   If there is anyone interested in joining a demo / coding group in
   Canberra (ACT), then drop me a line.

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  GUSUNIT.PAS
 읕컴컴컴컴컴켸

 Unit  GUSUnit;

 {
   GUS DigiUnit  v1.0
   Copyright 1994 Mark Dixon.

   This product is "Learnware".

   All contents of this archive, including source and executables, are the
   intellectual property of the author, Mark Dixon. Use of this product for
   commercial programs, or commercial gain in ANY way, is illegal. Private
   use, or non-commercial use (such as demos, PD games, etc) is allowed,
   provided you give credit to the author for these routines.

   Feel free to make any modifications to these routines, but I would
   appreciate it if you sent me these modifications, so that I can include
   them in the next version of the Gus669 Unit.

   If you wish to use these routines for commercial purposes, then you will
   need a special agreement. Please contact me, Mark Dixon, and we can work
   something out.

   What's "Learnware"? Well, I think I just made it up actually. What i'm
   getting at is that the source code is provided for LEARNING purposes only.
   I'd get really angry if someone ripped off my work and tried to make out
   that they wrote a mod player.

   As of this release (Gus699 Unit), the Gus DigiUnit has moved to version
   1.0, and left the beta stage. I feel these routines are fairly sound,
   and I haven't made any changes to them in weeks.

   Notice the complete absence of comments here? Well, that's partially
   the fault of Gravis and their SDK, since it was so hard to follow, I
   was more worried about getting it working than commenting it. No offense
   to Gravis though, since they created this wonderful card! :-) It helps
   a lot if you have the SDK as a reference when you read this code,
   otherwise you might as well not bother reading it.

 }

 INTERFACE

 Procedure GUSPoke(Loc : Longint; B : Byte);
 Function  GUSPeek(Loc : Longint) : Byte;
 Procedure GUSSetFreq( V : Byte; F : Word);
 Procedure GUSSetBalance( V, B : Byte);
 Procedure GUSSetVolume( Voi : Byte; Vol : Word);
 Procedure GUSPlayVoice( V, Mode : Byte;VBegin, VStart, VEnd : Longint);
 Procedure GUSVoiceControl( V, B : Byte);
 Procedure GUSReset;
 Function VoicePos( V : Byte) : Longint;

 Const
   Base : Word = $200;
   Mode : Byte = 0;

 IMPLEMENTATION

 Uses Crt;

 Function Hex( W : Word) : String;
 Var
   I, J : Word;
   S : String;
   C : Char;
 Const
   H : Array[0..15] of Char = ('0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F');
 Begin
   S := '';
   S := S + H[(W DIV $1000) MOD 16];
   S := S + H[(W DIV $100 ) MOD 16];
   S := S + H[(W DIV $10  ) MOD 16];
   S := S + H[(W DIV $1   ) MOD 16];
   Hex := S+'h';
 End;

 Procedure GUSDelay; Assembler;
 ASM
   mov   dx, 0300h
   in    al, dx
   in    al, dx
   in    al, dx
   in    al, dx
   in    al, dx
   in    al, dx
   in    al, dx
 End;

 Function VoicePos( V : Byte) : Longint;
 Var
   P : Longint;
   I, Temp0, Temp1 : Word;
 Begin
   Port [Base+$102] := V;
   Port [Base+$103] := $8A;
   Temp0 := Portw[Base+$104];
   Port [Base+$103] := $8B;
   Temp1 := Portw[Base+$104];
   VoicePos := (Temp0 SHL 7)+ (Temp1 SHR 8);
   For I := 1 to 10 do GusDelay;
 End;

 Function  GUSPeek(Loc : Longint) : Byte;
 Var
   B : Byte;
   AddLo : Word;
   AddHi : Byte;
 Begin
   AddLo := Loc AND $FFFF;
   AddHi := LongInt(Loc AND $FF0000) SHR 16;

   Port [Base+$103] := $43;
   Portw[Base+$104] := AddLo;
   Port [Base+$103] := $44;
   Port [Base+$105] := AddHi;

   B := Port[Base+$107];
   GUSPeek := B;
 End;

 Procedure GUSPoke(Loc : Longint; B : Byte);
 Var
   AddLo : Word;
   AddHi : Byte;
 Begin
   AddLo := Loc AND $FFFF;
   AddHi := LongInt(Loc AND $FF0000) SHR 16;
 {  Write('POKE  HI :', AddHi:5, '  LO : ', AddLo:5, '    ');}
   Port [Base+$103] := $43;
   Portw[Base+$104] := AddLo;
   Port [Base+$103] := $44;
   Port [Base+$105] := AddHi;
   Port [Base+$107] := B;
 {  Writeln(B:3);}
 End;

 Function GUSProbe : Boolean;
 Var
   B : Byte;
 Begin
   Port [Base+$103] := $4C;
   Port [Base+$105] := 0;
   GUSDelay;
   GUSDelay;
   Port [Base+$103] := $4C;
   Port [Base+$105] := 1;
   GUSPoke(0, $AA);
   GUSPoke($100, $55);
   B := GUSPeek(0);
 {  Port [Base+$103] := $4C;
   Port [Base+$105] := 0;}
   { Above bit disabled since it appears to prevent the GUS from accessing
     it's memory correctly.. in some bizare way.... }

   If B = $AA then GUSProbe := True else GUSProbe := False;
 End;

 Procedure GUSFind;
 Var
   I : Word;
 Begin
   for I := 1 to 8 do
   Begin
     Base := $200 + I*$10;
     If GUSProbe then I := 8;
   End;
   If Base < $280 then
     Write('Found your GUS at ', Hex(Base), ' ');
 End;

 Function  GUSFindMem : Longint;
 { Returns how much RAM is available on the GUS }
 Var
   I : Longint;
   B : Byte;
 Begin
   GUSPoke($40000, $AA);
   If GUSPeek($40000) <> $AA then I := $3FFFF
     else
   Begin
     GUSPoke($80000, $AA);
     If GUSPeek($80000) <> $AA then I := $8FFFF
       else
     Begin
       GUSPoke($C0000, $AA);
       If GUSPeek($C0000) <> $AA then I := $CFFFF
         else I := $FFFFF;
     End;
   End;
   GUSFindMem := I;
 End;

 Procedure GUSSetFreq( V : Byte; F : Word);
 Begin
   Port [Base+$102] := V;
   Port [Base+$102] := V;
   Port [Base+$102] := V;
   Port [Base+$103] := 1;
   Portw[Base+$104] := (F { DIV 19}); { actual frequency / 19.0579083837 }
 End;

 Procedure GUSVoiceControl( V, B : Byte);
 Begin
   Port [Base+$102] := V;
   Port [Base+$102] := V;
   Port [Base+$103] := $0;
   Port [Base+$105] := B;
 End;

 Procedure GUSSetBalance( V, B : Byte);
 Begin
   Port [Base+$102] := V;
   Port [Base+$102] := V;
   Port [Base+$102] := V;
   Port [Base+$103] := $C;
   Port [Base+$105] := B;
 End;

 Procedure GUSSetVolume( Voi : Byte; Vol : Word);
 Begin
   Port [Base+$102] := Voi;
   Port [Base+$102] := Voi;
   Port [Base+$102] := Voi;
   Port [Base+$103] := 9;
   Portw[Base+$104] := Vol;  { 0-0ffffh, log ... not linear }
 End;

 Procedure GUSSetLoopMode( V : Byte);
 Var
   Temp : Byte;
 Begin
   Port [Base+$102] := V;
   Port [Base+$102] := V;
   Port [Base+$102] := V;
   Port [Base+$103] := $80;
   Temp := Port[Base+$105];
   Port [Base+$103] := 0;
   Port [Base+$105] := (Temp AND $E7) OR Mode;
 End;

 Procedure GUSStopVoice( V : Byte);
 Var
   Temp : Byte;
 Begin
   Port [Base+$102] := V;
   Port [Base+$102] := V;
   Port [Base+$102] := V;
   Port [Base+$103] := $80;
   Temp := Port[Base+$105];
   Port [Base+$103] := 0;
   Port [Base+$105] := (Temp AND $df) OR 3;
   GUSDelay;
   Port [Base+$103] := 0;
   Port [Base+$105] := (Temp AND $df) OR 3;
 End;

 Procedure GUSPlayVoice( V, Mode : Byte;VBegin, VStart, VEnd : Longint);
 Var
   GUS_Register : Word;
 Begin
   Port [Base+$102] := V;
   Port [Base+$102] := V;
   Port [Base+$103] := $0A;
   Portw[Base+$104] := (VBegin SHR 7) AND 8191;
   Port [Base+$103] := $0B;
   Portw[Base+$104] := (VBegin AND $127) SHL 8;
   Port [Base+$103] := $02;
   Portw[Base+$104] := (VStart SHR 7) AND 8191;
   Port [Base+$103] := $03;
   Portw[Base+$104] := (VStart AND $127) SHL 8;
   Port [Base+$103] := $04;
   Portw[Base+$104] := ((VEnd)   SHR 7) AND 8191;
   Port [Base+$103] := $05;
   Portw[Base+$104] := ((VEnd)   AND $127) SHL 8;
   Port [Base+$103] := $0;
   Port [Base+$105] := Mode;

   { The below part isn't mentioned as necessary, but the card won't
     play anything without it! }

   Port[Base] := 1;
   Port[Base+$103] := $4C;
   Port[Base+$105] := 3;

 end;

 Procedure GUSReset;
 Begin
   port [Base+$103]   := $4C;
   port [Base+$105] := 1;
   GUSDelay;
   port [Base+$103]   := $4C;
   port [Base+$105] := 7;
   port [Base+$103]   := $0E;
   port [Base+$105] := (14 OR $0C0);
 End;

 Var
   I : Longint;
   F : File;
   Buf : Array[1..20000] of Byte;
   S : Word;

 Begin
   Clrscr;
   Writeln('GUS DigiUnit V1.0');
   Writeln('Copyright 1994 Mark Dixon.');
   Writeln;
   GUSFind;
   Writeln('with ', GUSFindMem, ' bytes onboard.');
   Writeln;
   GUSReset;
 End.

 旼컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴
  GUS669.PAS 
 읕컴컴컴컴컴켸

 UNIT Gus669;

 {
   GUS669 Unit  v0.2b
   Copyright 1994 Mark Dixon.

   This product is "Learnware".

   All contents of this archive, including source and executables, are the
   intellectual property of the author, Mark Dixon. Use of this product for
   commercial programs, or commercial gain in ANY way, is illegal. Private
   use, or non-commercial use (such as demos, PD games, etc) is allowed,
   provided you give credit to the author for these routines.

   Feel free to make any modifications to these routines, but I would
   appreciate it if you sent me these modifications, so that I can include
   them in the next version of the Gus669 Unit.

   If you wish to use these routines for commercial purposes, then you will
   need a special agreement. Please contact me, Mark Dixon, and we can work
   something out.

   What's "Learnware"? Well, I think I just made it up actually. What i'm
   getting at is that the source code is provided for LEARNING purposes only.
   I'd get really angry if someone ripped off my work and tried to make out
   that they wrote a mod player.

   Beta version? Yes, since the product is still slightly unstable, I feel
   it is right to keep it under beta status until I find and fix a few
   bugs.

   FEATURES
     - Only works with the GUS!
     - 8 channel, 669 music format.
     - That's about it really.
     - Oh, 100% Pascal high level source code = NO ASSEMBLER!
       (So if you want to learn about how to write your own MOD player, this
        should make it easier for you)
     - Tested & compiled with Turbo Pascal v7.0

   BUGS
     - Not yet, give me a chance!
       (If you find any, I would very much appreciate it if you could take
        the time to notify me)
     - Doesn't sound right with some modules, advice anyone??
     - Could do with some better I/O handling routines when loading the
       669 to give better feedback to the user about what went wrong
       if the module didn't load.

  You can contact me at any of the following :

  FidoNet  : Mark Dixon  3:620/243
  ItnerNet : markd@cairo.anu.edu.au         ( prefered )
             d9404616@karajan.anu.edu.au    ( might not work for mail :) )
             sdixonmj@cc.curtin.edu.au      ( Don't use this one often )
             sdixonmj01@cc.curtin.edu.au    ( Might not exist any more,
                                              that's how often it's used! )
             I collect internet accounts.... :)

  If you happen to live in the Australian Capital Territory, you can
  call me on  231-2000, but at respectable hours please.

  "Want more comments? Write em!"
  Sorry, I just had to quote that. I'm not in the mood for writing lots
  of comments just yet. The main reason for writing it in Pascal is so
  that it would be easy to understand. Comments may (or may not) come later
  on.

  Okay, enough of me dribbling, here's the source your after!

 }

 Interface

 Procedure Load669(N : String);
 Procedure PlayMusic;
 Procedure StopMusic;

 Type
   { This is so that we can keep a record of what each channel is
     currently doing, so that we can inc/dec the Frequency or volume,
     or pan left/right, etc }
   Channel_Type    = Record
                       Vol : Word;
                       Freq : Word;
                       Pan : Byte;
                     End;

 Var
   Channels : Array[1..8] of Channel_Type;
   Flags : Array[0..15] of Byte;
   { Programmer flags. This will be explained when it is fully implemented. }

 Const
   Loaded : Boolean = False;    { Is a module loaded? }
   Playing : Boolean = False;   { Is a module playing? }
   WaitState : Boolean = False; { Set to TRUE whenever a new note is played }
                                { Helpful for timing in with the player }

 Const
   NumChannels = 8;

   { Thanks to Tran for releasing the Hell demo source code, from which
     I managed to find these very helpfull volume and frequency value
     tables, without which this player would not have worked! }

   voltbl : Array[0..15] of Byte =
                      (  $004,$0a0,$0b0,$0c0,$0c8,$0d0,$0d8,$0e0,
                         $0e4,$0e8,$0ec,$0f1,$0f4,$0f6,$0fa,$0ff);
   freqtbl : Array[1..60] of Word = (
                         56,59,62,66,70,74,79,83,88,94,99,105,
                         112,118,125,133,141,149,158,167,177,188,199,211,
                         224,237,251,266,282,299,317,335,355,377,399,423,
                         448,475,503,532,564,598,634,671,711,754,798,846,
                         896,950,1006,1065,1129,1197,1268,1343,1423,1508,1597,1692 );

 Type
   Header_669_Type = Record
                       Marker      : Word;
                       Title       : Array[1..108] of Char;
                       NOS,                     { No of Samples  0 - 64 }
                       NOP         : Byte;      { No of Patterns 0 - 128 }
                       LoopOrder   : Byte;
                       Order       : Array[0..127] of Byte;
                       Tempo       : Array[0..127] of Byte;
                       Break       : Array[0..127] of Byte;
                     End;
   Sample_Type     = Record
                       FileName  : Array[1..13] of Char;
                       Length    : Longint;
                       LoopStart : Longint;
                       LoopLen   : Longint;
                     End;
   Sample_Pointer  = ^Sample_Type;
   Note_Type       = Record
                       Info,  { <- Don't worry about this little bit here }
                       Note,
                       Sample,
                       Volume,
                       Command,
                       Data    : Byte;
                     End;
   Event_Type      = Array[1..8] of Note_Type;
   Pattern_Type    = Array[0..63] of Event_Type;
   Pattern_Pointer = ^Pattern_Type;

 Var
   Header : Header_669_Type;
   Samples : Array[0..64] of Sample_Pointer;
   Patterns : Array[0..128] of Pattern_Pointer;
   GusTable : Array[0..64] of Longint;
   GusPos : Longint;
   Speed : Byte;
   Count : Word;
   OldTimer : Procedure;
   CurrentPat, CurrentEvent : Byte;

 Implementation

 Uses Dos, Crt, GUSUnit;

 Procedure Load669(N : String);
 Var
   F : File;
   I, J, K : Byte;
   T : Array[1..8,1..3] of Byte;

   Procedure LoadSample(No, Size : Longint);
   Var
     Buf : Array[1..1024] of Byte;
     I : Longint;
     J, K : Integer;
   Begin
     GusTable[No] := GusPos;

     I := Size;
     While I > 1024 do
     Begin
       BlockRead(F, Buf, SizeOf(Buf), J);
       For K := 1 to J do GusPoke(GusPos+K-1, Buf[K] XOR 127);
       Dec(I, J);
       Inc(GusPos, J);
     End;
     BlockRead(F, Buf, I, J);
     For K := 1 to J do GusPoke(GusPos+K-1, Buf[K] XOR 127);
     Inc(GusPos, J);
   End;

 Begin
   {$I-}
   Assign(F, N);
   Reset(F, 1);
   BlockRead(F, Header, SizeOf(Header));
   If Header.Marker = $6669 then
   Begin
     For I := 1 to Header.NOS do
     Begin
       New(Samples[I-1]);
       BlockRead(F, Samples[I-1]^, SizeOf(Samples[I-1]^));
     End;

     For I := 0 to Header.NOP-1 do
     Begin
       New(Patterns[I]);
       For J := 0 to 63 do
       Begin
         BlockRead(F, T, SizeOf(T));
         For K := 1 to 8 do
         Begin
           Patterns[I]^[J,K].Info    := t[K,1];
           Patterns[I]^[J,K].Note    := ( t[K,1] shr 2);
           Patterns[I]^[J,K].Sample  := ((t[K,1] AND 3) SHL 4) +  (t[K,2] SHR 4);
           Patterns[I]^[J,K].Volume  := ( t[K,2] AND 15);
           Patterns[I]^[J,K].Command := ( t[K,3] shr 4);
           Patterns[I]^[J,K].Data    := ( t[K,3] AND 15);
         End;
       End;
     End;

     For I := 1 to Header.NOS do
       LoadSample(I-1, Samples[I-1]^.Length);
   End;

   Close(F);
   {$I+}
   If (IOResult <> 0) OR (Header.Marker <> $6669) then
     Loaded := False else Loaded := True;

 End;

 Procedure UpDateNotes;
 Var
   I : Word;
   Inst : Byte;
   Note : Word;
 Begin
   WaitState := True;
   For I := 1 to NumChannels do
   With Patterns[Header.Order[CurrentPat]]^[CurrentEvent, I] do

   For I := 1 to NumChannels do
   If (Patterns[Header.Order[CurrentPat]]^[CurrentEvent, I].Info < $FE) then
   Begin
     Inst := Patterns[Header.Order[CurrentPat]]^[CurrentEvent, I].Sample;
     Note := Patterns[Header.Order[CurrentPat]]^[CurrentEvent, I].Note;
     Channels[I].Freq := FreqTbl[Note];
 {    Channels[I].Pan  := (1-(I AND 1)) * 15;}
     Channels[I].Vol  := $100*VolTbl[Patterns[Header.Order[CurrentPat]]^[CurrentEvent, I].Volume];
 {    Write(Note:3,Inst:3,' -');}

     GUSSetVolume    (I, 0);
     GUSVoiceControl (I, 1);
     GUSSetBalance   (I, Channels[I].Pan);
     GusSetFreq      ( I, Channels[I].Freq);
 {    GUSPlayVoice    ( I, 0, GusTable[Inst],
                             GusTable[Inst],
                             GusTable[Inst]+Samples[Inst]^.Length  );}

 {    Write(Samples[Inst]^.LoopLen:5);}
     If Samples[Inst]^.LoopLen < 1048575 then
     Begin
     GUSPlayVoice    ( I, 8, GusTable[Inst],
                             GusTable[Inst]+Samples[Inst]^.LoopStart,
                             GusTable[Inst]+Samples[Inst]^.LoopLen  );
     End
       Else
     Begin
     GUSPlayVoice    ( I, 0, GusTable[Inst],
                             GusTable[Inst],
                             GusTable[Inst]+Samples[Inst]^.Length  );
     End;

   End;

 {  Writeln;}

   For I := 1 to NumChannels do
     If (Patterns[Header.Order[CurrentPat]]^[CurrentEvent, I].Info < $FF) then
       GUSSetVolume (I, $100*VolTbl[Patterns[Header.Order[CurrentPat]]^[CurrentEvent, I].Volume]);

   For I := 1 to NumChannels do
   With Patterns[Header.Order[CurrentPat]]^[CurrentEvent, I] do
   Case Command of
     5 : Speed := Data;
     3 : Begin
           Channels[I].Freq := Channels[I].Freq + 10;
           GUSSetFreq(I, Channels[I].Freq);
         End;
     8 : Inc(Flags[Data]);
     6 : Case Data of
           0 : If Channels[I].Pan > 0 then
               Begin
                 Dec(Channels[I].Pan);
                 GusSetBalance(I, Channels[I].Pan);
               End;
           1 : If Channels[I].Pan < 15 then
               Begin
                 Inc(Channels[I].Pan);
                 GusSetBalance(I, Channels[I].Pan);
               End;
         End;
   End;

   Inc(CurrentEvent);
   If CurrentEvent > Header.Break[CurrentPat] then Begin CurrentEvent := 0; Inc(CurrentPat) End;
   If Header.Order[CurrentPat] > (Header.NOP) then Begin CurrentEvent := 0; CurrentPat := 0; End;

 End;

 Procedure UpDateEffects;
 Var
   I : Word;
 Begin
   For I := 1 to 4 do
   With Patterns[Header.Order[CurrentPat]]^[CurrentEvent, I] do
   Begin
     Case Command of
       0 : Begin
             Inc(Channels[I].Freq, Data);
             GusSetFreq(I, Channels[I].Freq);
           End;
       1 : Begin
             Dec(Channels[I].Freq, Data);
             GusSetFreq(I, Channels[I].Freq);
           End;
     End;
   End;
 End;

 { $ F+,S-,W-}
 Procedure ModInterrupt; Interrupt;
 Begin
   Inc(Count);
   If Count = Speed then
   Begin
     UpDateNotes;
     Count := 0;
   End;
   UpDateEffects;
   If (Count MOD 27) = 1 then
   Begin
     inline ($9C);
     OldTimer;
   End;
   Port[$20] := $20;
 End;
 { $ F-,S+}

 Procedure TimerSpeedup(Speed : Word);
 Begin
   Port[$43] := $36;
   Port[$40] := Lo(Speed);
   Port[$40] := Hi(Speed);
 end;

 Procedure PlayMusic;
 Begin
   If Loaded then
   Begin
     TimerSpeedUp( (1192755 DIV 32));
     GetIntVec($8, Addr(OldTimer));
     SetIntVec($8, Addr(ModInterrupt));
     Speed := Header.Tempo[0];
     Playing := True;
   End
   { If the module is not loaded, then the Playing flag will not be set,
     so your program should check the playing flag just after calling
     PlayMusic to see if everything was okay. }
 End;

 Procedure StopMusic;
 Var
   I : Byte;
 Begin
   If Playing then
   Begin
     SetIntVec($8, Addr(OldTimer));
     For I := 1 to NumChannels do GusSetVolume(I, 0);
   End;
   TimerSpeedUp($FFFF);
 End;

 Procedure Init;
 Var
   I : Byte;
 Begin
   GusPos := 1;
   Count := 0;
   Speed := 6;
   CurrentPat := 0;
   CurrentEvent := 0;
   For I := 1 to NumChannels do Channels[I].Pan  := (1-(I AND 1)) * 15;
   For I := 1 to NumChannels do GUSVoiceControl(I, 1);
   For I := 0 to 15 do Flags[I] := 0;
 End;

 Var
   I, J : Byte;

 Begin
   Init;
   Writeln('GUS669 Unit V0.2b');
   Writeln('Copyright 1994 Mark Dixon.');
   Writeln;
 End.

 旼컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴
  PLAY669.PAS 
 읕컴컴컴컴컴컴

 Program Testout_Gus669_Unit;

 Uses Crt, GUS669;

 Begin

   If ParamCount > 0 then Load669(Paramstr(1))
     else
   Begin
     Writeln;
     Writeln('Please specify the name of the 669 module you wish to play');
     Writeln('from the command line.');
     Writeln;
     Writeln('eg :    Play669  Hardwired.669 ');
     Writeln;
     Halt(1);
   End;
   PlayMusic;
   If Playing then
   Begin
     Writeln('Playing ', ParamStr(1) );
     Writeln('Press any key to stop and return to DOS.');
     Repeat
     Until Keypressed
   End
     else
   Begin
     Writeln;
     Writeln('Couldn''t load or play the module for some reason!');
     Writeln;
     Writeln('Please check your GUS is working correctly, and that you have');
     Writeln('correctly specified the 669 filename.');
     Writeln;
   End;
   StopMusic;
 End.

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Date this article was posted to GameDev.net: 7/16/1999
(Note that this date does not necessarily correspond to the date the article was written)

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