How to fix custom song glitches on emlators.

Gi Nattak and I have been trying to understand why some custom song glitches on emulators (and real hardware) except zsnes. The reason is simple: the instruments data overflow sometimes in the SPC-700 RAM in part of the RAM where it doesn't belong to. This will happen when your instruments use too much space total in memory. The reason why the glitch doesn't appear in zsnes is because zsnes runs the SMP (audio CPU) completely out of sync with the CPU.

With some testing, Gi Nattak found that the total of blocks (9 bytes each) used by all samples in one song must not exceed 3746. You can see how much blocks an instrument use in FF3usME.

For quick reference, here's the size of the original samples:

Code:

## size name
-------------------------
01 0337 FF6 Spanish Guitar
02 0129 FF6 Electric Bass
03 0489 FF6 Pan Flute
04 0554 FF6 Sitar
05 0663 FF6 Cello
06 0573 FF6 Choir
07 0123 FF6 Flute
08 0237 FF6 Clarinet
09 0379 FF6 Unusual Synth (Atma)
0A 0169 FF6 Oboe
0B 0116 FF6 Rock Organ
0C 0785 FF6 Piano
0D 1046 FF6 Strings
0E 0120 FF6 Trumpet
0F 0081 FF6 Hi Hat Closed
10 0900 FF6 Shadow's picked string
11 0537 FF6 Hi Hat Open
12 0477 FF6 Crash Cymbal
13 0375 FF6 Breath (like Narshe)
14 0250 FF6 Snare
15 0212 FF6 Snapping fingers
16 0400 FF6 Timpani
17 0750 FF6 Conga Drum
18 0197 FF6 Floor Bass
19 0178 FF6 Picked String
1A 0262 FF6 Trombone
1B 0106 FF6 Harp
1C 0146 FF6 Bass Guitar
1D 0108 FF6 Picked String?
1E 0444 FF6 Distortion Guitar
1F 0139 FF6 Ocarina
20 0350 FF6 Marimba
21 0500 FF6 Snare (hard hit)
22 0137 FF6 Kick
23 0050 FF6 Cow Bell
24 0605 FF6 Tubular Bell
25 0389 FF6 Church Organ
26 0192 FF6 Woot
27 0359 FF6 Synth
28 0313 FF6 More Synth
29 0222 FF6 Even More Synth
2A 0098 FF6 Snapping Fingers
2B 0081 FF6 ?? Synth
2C 0492 FF6 Contrabass
2D 0412 FF6 Maracas
2E 0334 FF6 Conga Drum
2F 0243 FF6 Shaker
30 0281 FF6 Wood Block
31 0485 FF6 Bright Piano
32 0373 FF6 Acoustic Guitar
33 0351 FF6 Bagpipe
34 0367 FF6 Pan Flute
35 0292 FF6 Violin
36 0143 FF6 Bottle Blow
37 0625 FF6 Tambourine
38 0414 FF6 Male Voice
39 0496 FF6 Low Male Voice
3A 0344 FF6 Female Voice
3B 0299 FF6 Pipe Organ
3C 0460 FF6 Metal Bang
3D 0450 FF6 Metal Clank
3E 0195 FF6 Xylophone
3F 0717 FF6 Crowd Noise