Splash animation

The WonderSwan Color upgraded the internal EEPROM from 128 bytes to 2 kilobytes; most of the additional space is utilized to allow for branding consoles in the form of unique, custom splash animations on console startup.

Format

Offset	Length	Contents
$85	1	Must be $00
$86	1	Size; 0 = ends at <= $3FF, 1 = ends at <= $7FF
$87	1	First frame
$88	1	Last frame
$89	1	Sprite count
$8A	1	Palette flags
$8B	1	Tile count
$8C	2	Palette location - $80
$8E	2	Tile data location - $80
$90	2	Tilemap location - $80
$92	2	Screen offset (Horizontal)
$94	2	Screen offset (Vertical)
$96	1	Tilemap width
$97	1	Tilemap height
$98	2	VBlank IRQ handler offset
$9A	2	VBlank IRQ handler segment, must be $0600
$9C	1	Owner name X (horizontal)
$9D	1	Owner name Y (horizontal)
$9E	1	Owner name X (vertical)
$9F	1	Owner name Y (vertical)
$A0	2	Padding, unused
$A2	2	Sound wavetable location - $80
$A4	2	Sound channel 1 data offset - $80
$A6	2	Sound channel 2 data offset - $80
$A8	2	Sound channel 3 data offset - $80
$AA	2	Sound channel 4 data offset - $80
$AC	10	SwanCrystal TFT LCD configuration
$B6	10	Padding, unused
$C0	...	Arbitrary data - palettes, tilemaps, etc.

Palette flags

7  bit  0
---- ----
b..p pppp
|  +-++++- Palette count (0-16)
+--------- Tile/palette bits per pixel:
             0 = 1 bit per pixel
             1 = 2 bits per pixel

VBlank IRQ handler

A custom splash animation must provide a valid VBlank IRQ handler, with the following rules:

• The segment must be 0x0600; the offset is provided relative to $80, as with other data offsets.
• The code must end with a retf opcode, or equivalent.

Horizontal/Vertical orientation handling

The splash animation loader will automatically rotate the tile data and tilemap when booting a cartridge whose header declares vertical orientation as its startup orientation.

Sound channel data format

TODO