SAP file divides into two parts. First part (in text format) describes
player/music type. Second part (in binary format) contains player and music
data formed into Atari Binary File Format. This format has two bytes header
FF,FF. Next two bytes tell loader, where to load data, and next two bytes
describes where the data end.
Init data block ($02E2,$02E3) is not supported.

A little example:

FF FF 00 20 05 20 01 42 A3 04 D5
\___/ \_________/ \____________/
  A        B            C

A - Binary file header identification (always FF FF)
B - Load addres (StartAddr, EndAddr in LO,HI order - $2000 to $2005)
C - Data (that will be loaded from StartAddr)

This example will load values 01,42,A3,04,D5 into memory from $2000 to $2005.


Player Description format (first part of .sap file)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This description (in text format) is loaded line per line. Each line contains
command with parameters. Other lines which are not recognized are treated as
comment lines. Right now only these commands are supported:

   TYPE      - player type
   PLAYER    - address of player part which will be executed in 1/50 sec
               intervals
   MUSIC     - address with data
   INIT      - address of player part which will init player
   SONGS     - number of songs
   DEFSONG   - first song which will be played when .sap will be loaded
   FASTPLAY  - number of lines between each call of playing routine (312 by
               default, which is one screen - 1/50 of sec.). For example for
               double-speed tune put here the value 156 (312/2). 99% of tunes
               are single-speed which means that you don't have to define the
               FASTPLAY variable for them. Works for player TYPE "B".

commands PLAYER, MUSIC, INIT contain addresses in hexadecimal format:

PLAYER A000
PLAYER 1234
MUSIC  F400

commands SONGS, DEFSONG contain decimal numbers:

SONGS 10
DEFSONG 9

command TYPE contains single character which describes player type. Right now
only the following characters are supported:

TYPE C
TYPE B
TYPE M
TYPE S
TYPE D
TYPE R

TYPE C - player from CMC (Chaos Music Composer). In this case, also these
         commands must appear: PLAYER, MUSIC, SONGS, and DEFSONG. Player will
         be initialized as follows:

         lda #$70
         ldx #<MUSIC
         ldy #>MUSIC
         jsr PLAYER+3
         lda #$00
         ldx #DEFSONG
         jsr PLAYER+3

         in 1/50 intervals will be executed:

         jsr PLAYER+6

TYPE M - player from ???????? (this player was used by composers like Adam
         Gilmore, David Whittaker, etc). In this case, also these commands
         must appear: PLAYER, INIT, SONGS, and DEFSONG. Player will be
         initialized as follows:

         lda #DEFSONG
         jsr INIT

         in 1/50 intervals will be executed:

         jsr PLAYER

TYPE B - any player. In this case, also these commands must appear: PLAYER,
         INIT, SONGS, and DEFSONG. Player will be initialized as follows:

         lda #DEFSONG
         jsr INIT

         in 1/50 intervals will be executed:

         jsr PLAYER

         TYPE B is right now exactly the same like TYPE M but this
         distinguish is for future SAP releases.

TYPE S - SoftSynth. Like type "C", this type is temporary, and is used only
         for special type of songs, that were composed using program
         SoftSynth.
TYPE D - Digital. In SAP file with this type, must be also defined commands
         "INIT" and "PLAYER". "PLAYER" (like in type "B") sets address of
         procedure that will be called in 1/50s intervals and (like in type
         "B") must end with RTS opcode. INIT this time is a bit different. It
         sets address of procedure that will be called (with number of song
         in register A) to initialize program, but it can't end with RTS. It
         should start playing digis in endless loop. In SAP player there are
         emulated two ANTIC registers $D40A and $D40B that can help playing
         samples. D40B register increases its contents each two screen lines.
         D40A holds CPU till the end of actually created line. SAP emulates
         Atari in PAL with disabled screen. It means that we have 312 PAL
         lines, while each lines has 105 CPU cycles and 9 cycles of memory
         refresh (114 cycles per line).

Planned features:
TYPE R - Registers. In this type, binary part is not an Atari binary file.
         This part contains values that will be directly written to Pokey
         registers ($D200-$D208) in 1/50s intervals.
TIME xx:xx - song duration

How to create .SAP file
~~~~~~~~~~~~~~~~~~~~~~~
First of all we need to rip music from a game or a demo and save it in atari
binary file. Next we can create text file with commands (described above),
then we can make .sap file by linking thwse two files. We can do that using
DOS command "copy", e.g.:

copy /b music.txt+music.bin music.sap

The file is done now!
If you didn't find that song in ASMA, feel free to send it to pg@pinknet.cz
with all needed information (see ASMA.TXT for details). The song should be 
included in the nearest ASMA update.
