The player 5.0A
Created by Jarno Paananen (Guru/Sahara Surfers) (1993)
Analysed by Asle / ReDoX (asle@mygale.org)

Source:
 - Own converted MODs with the packer (sent by Gryzor !)

Note: Arg !, such a note packing method !. Pfff ... it took me almost 10 hours
     to write (and debug) a depacker !. God, how can he use such a mess ?!?.
     Anyway, I'm not sure if it's the best crunching rate yet, but it certainly
     is good :). Somehow, I guess he did better with the P60A and P61A ...
     I'll tell you when I begin them :). I know, however, that it's possible
     to do yet a bit better ! (I did :).

Offset    size (byte)    Comment
------    -----------    -------
  0           2          (Smp_Addy) Address of the sample data
                         
  2           1          (NOP) number of pattern saved

  3           1          (NOS) Number of sample (only the first 6 lower bits !)
                         if bit 7 is set to 1, ALL the samples are delta.

      ***************************************
      * the following is repeated NOS times *
      * with 6 bytes description for 1 smp  *
******************************************************
                                                     *
  4            2         Sample size (/2)            *
  6            1         finetune (0->F)             *
  7            1         volume (0->40h)             *
  8            2         Loop Start / 2              *
                                                     *
******************************************************

Note: The player removes what's beside the sample loop, so, it saves
     only the start address. If there's no loop, this value is $FFFF.
Note: if the sample size is > $FF00 (this case is impossible under ptk !),
     you have to NOT this sample size and you'll get the number of sample
     you have to repeat (the datas are the same). The first possible value
     is 00 !.


NOS*6+4      NOP*8       track table. Each pattern contains 4 tracks
                         and here is the address of the four track per
                         patterns. The first address is $0000.

NOS*6+4        ?         Pattern table. Each value is (*2). This table ends
+NOP*8                   with $FF.

NOS*6+4                  Tracks datas.
+NOP*8                   (Pat_Size is the size of the pattern list)
+Pat_Size                Each track contains 64 notes. The size is
                         between 4 and 256 bytes.


Note description:

case 1: (flag bit set to 0)

   - flag bit set to 0
  /
 |        Sample
 |        Number
 |        /   \
 |       |     |
 0000-0000  0000-0000  0000-0000
  |      |       |  |  |       |
   \    /         \/    \     /
  relative      effect   effect
    note                 value
   number



case 2: (flag byte set to 1)

   - flag byte set to 1
  /
 |        Sample
 |        Number                    value
 |        /   \                    /     \
 |       |     |                  |       |
 0000-0000  0000-0000  0000-0000  0000-0000
  |      |       |  |  |       |
   \    /         \/    \     /
  relative      effect   effect
    note                 value
   number


Note: 'value' is signed. if 'value' is < 80h, then follow 'value' empty rows.
     if 'value' is > 7Fh, then the current note is repeated 100h-'value' times



case 3: (flag byte set to 1)

   - flag byte set to 1
  /
 |              
 |            lines
 |           /     \
 |          |       |
 0000-0000  0000-0000  0000-0000  0000-0000
 |       |             |                  |
  \     /               \                /
    $80                  number of bytes


Note: Yop, that's the main packing goody ... . Well, if the first byte is $80,
     the second is the number of lines we'll have to repeat, and the last
     two bytes (a word in this case) is the number of bytes to go back to
     reach the starting point where to read our lines. Err, substract the
     number of byte to the current file pointer position (meaning after having
     read these 4 bytes) !.
      IMPORTANT!: while repeating notes, if you encounter the case 2 (empty
     rows or one line repeated), IT COUNTS ONLY FOR ONE LINE, whatever the
     number of empty/repeat row you'll have to do !!!. so much easier ... grrr.



sample number:
 The last bit of the sample number is also the first of the relative
note number. It's entirely possible considering the fact that the notes
are *2 ... so this bit is never used by the note. 


effect:

 * Effects with volume slide (5,6,A) are signed. AFF -> A10  A01 -> A01.
 * Arpeggio effect number is 8h in this format.
 * If the effect is a pattern break/jump, the track ends !.


relative note number (P50A):

C-1 to B-1 : 02,04,06,08,0a,0c,0e,10,12,14,16,18
C-2 to B-2 : 1a,1c,1e,20,22,24,26,28,2a,2c,2e,30
C-3 to B-3 : 32,34,36,38,3a,3c,3e,40,42,44,46,48

becomes (PTK):

C-1 to B-1 : 856,808,762,720,678,640,604,570,538,508,480,453
C-2 to B-2 : 428,404,381,360,339,320,302,285,269,254,240,226
C-3 to B-3 : 214,202,190,180,170,160,151,143,135,127,120,113


Information: When you encounter the effect command D or B (pattern break/jump),
            the track data ends, as stated upward. What's important, is that
            ALL the other tracks of THIS pattern have the same number of row
            as the one which ends with the break/jump. As an exemple,
            if track 0 has a pattern break at line 2, the 3 other tracks
            have ONLY 3 rows !.


 Follow Sample datas

Note: As described in the sample headers, all the samples are not always
     saved !. Refer up there to get the point :).

Note: If the samples are delta, use the following formula ...

  'new' and 'old' are both unsigned bytes
  'Sample_Data' is a table of signed bytes
  +-------------------------------------+
  |old=Sample_Data[0]                   |
  |                                     |
  |for i=1 to Sample_Size               |
  |  new = old - Sample_Data[i]         |
  |  Sample_Data[i] = new               |
  |  old = new                          |
  +-------------------------------------+