SNSF Specifications version 0.03

SNSF is a PSF format for the SNES. The header of the file should begin with 'PSF' with a version byte
of 0x23. Next comes the Reserved section size, Program Section Size, and the Program CRC.

The Reserved section if filled, contains SRAM and/or Savestate data.  The layout of the reserved
section is as follows.

Offset         Size    Description
0x00000000     4       Data Type
0x00000004     4       Size of Data
0x00000008     XX      Data block.

Sram Data block
Offset         Size    Description
0x00000000     4       Offset of SRAM to load
0x00000004     XX      SRAM data.

These blocks repeat for as many data blocks that reside within the reserved section.
Currently, the defined Data types are:

0 = SRAM, Max size of 0x20000 bytes.
1 = Save State.  (Not currently used.)
2 = Save State Patch (also not currently used.)
-1 (0xFFFFFFFF) = End of reserved section.  Specify the size as 0.

If the reserved section is less than 9 bytes, you may ignore this section completely.

The program section contains a SNES rom, that has been patched to only play back music.  A good
quality rip should not be doing anything with any hardware other than the 128Kbyte ram, and the
Audio Processing Unit. Unnecessary interrupt code should be removed, and those interupts should
only have a return from interrupt instruction on them.  (RTI, 0x40)

However, the emulator should tolerate access to the other hardware, just in case.  If the rom is
converted for use on a flash cart, it should run on actual hardware.

(There is only one game so far that needs a special chip, to complete its APU loading routines.
That game is Star Ocean, and as such, that is the only special chip specifically supported right
now, due to that games memory mapping requirements.)

The Program is layed out as follows.

Offset         Size    Description
0x00000000     4       SNSF_Offset
0x00000004     4       Size of Rom.
0x00000008     XX      The Rom data itself.


The offset/size helps you to know how much rom space to allocate, but is also used for 
minisnsf/snsflibs.  Look at the official psf specs for lib loading order.  Multiple libs are 
supported.

The Maximum offset for the main snsflib file, is 0x7F00 for LoROM and 0xFF00 for HiROM.  Minisnsf files
and any addon _libN snsflib files are allowed to go past these limits.

Finally, Look at the official psf specs for info on how tags are stored.

The following reserved tags are to be implemented into the playback plugin, and faithfully followed.

_memory - Used to force the rom to be loaded either as HiROM, or as LoROM.   The possible tag settings 
are "HiROM", and "LoROM".  Precedence of forcing is emulator user settings, then minisnsf settings, then
snsflib settings.

_video - Used to force the video mode.  Possible settings are "NTSC", and "PAL".  Precedence of forcing is
also emulator user settings, then minisnsf setting, then snsflib settings.

_sramfill - Used to fill the sram with an initial value other that 0xFF by default.  (Some games might require this.)
In the event that the reserved section contains sram data, then that sram data takes precedence over the sram fill.