--------------------------------------------------------------------------
                          XI format description
                   (FastTracker II Extended Instrument)
          reverse engineered by KB / The Obsessed Maniacs / Reflex
                Changed for PsyTexx by Alex Zolotov (2007)
--------------------------------------------------------------------------
C = Chars, B = Byte, W = Word, D = Double word

Pos(h) Len(h) Meaning
-------------------------------------------------------------- file header
0000   C15    "Extended Instrument: "
0015   C16    Instrument name, padded w/ spaces

002b   B01    $1a
002c   C14    Tracker name, padded w/ spaces
0040   W02    Version Number (current $0102)
              ($5050 - PsyTexx instrument)

-------------------------------------------------------------- inst header
0042   B60    Sample number for notes 1..96

00a2   W30    12 volume envelope points:
              +0 Time index for Point 1 (ticks since note)
              +2 Volume for Point 1     (00..40)
              +4 Time index for Point 2
              +6 Volume for Point 2
              [...]
00d2   W30    12 panning envelope points
              (Same structure as volume envelope)

0102   B01    Number of volume points
0103   B01    Number of panning points
0104   B01    Volume sustain point
0105   B01    Volume loop start point
0106   B01    Volume loop end point
0107   B01    Panning sustain point
0108   B01    Panning loop start point
0109   B01    Panning loop end point
010a   B01    Volume type;   b0=on, b1=sustain, b2=loop
010b   B01    Panning type;  b0=on, b1=sustain, b2=loop

010c   B01    Vibrato type
010d   B01    Vibrato sweep
010e   B01    Vibrato depth
010f   B01    Vibrato rate

0110   W02    Volume fadeout (0..fff)
0112   B16    ????? (Zeroes or extened info for PsyTexx (vol,finetune,pan,relative,flags))

0128   W02    Number of Samples

---------------------------------------------------------- sample headers

012a   D04    Sample Length
012e   D04    Sample loop start
0132   D04    Sample loop length
0136   B01    Volume
0137   B01    Finetune (signed)
0138   B01    Sample Type; b0,1=loop: 0=none 1=fwd 2=bidi
                           b4 = 16bit sample
                           b6 = two channels (stereo) [PsyTexx feature]
0139   B01    Panning
013A   B01    Relative Note (signed, 00=C-4) (call it Transpose)
013B   B01    Sample Name Length
013C   C16    Sample Name, padded w/ zeroes

And so on w/ samples 1 to x
Length: $28 bytes for each sample

------------------------------------------------------------- sample data

$012a+(number of samples)*$28 : sample data for all samples in delta values
                                (signed)

