Map Script Format
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When the game loads a map it looks at a pointer table at 0x06959C and runs a some kind of script to load the map parts.
There seem to be 1314(check) entries.
For some reason offsets are not directly read but calculated via this code: (don't ask!)
i.e. when loading map id 0 the first offset is 0x83FF05 which after the code is run turns into 0xA5FF83 (0x25FF83 ROM).
u32 Background::GetAddress()
{
u32 AdrLow = GetBytei();
u16 AdrHigh = GetWordi();
u8 push = AdrHigh & 0x7F;
AdrHigh = push ^ AdrHigh;
AdrHigh<<= 1;
AdrHigh |= 0x80;
AdrHigh |= push;
AdrHigh += (((ROMOffset|(1<<23)) & 0xFF0000) >> 8);
if( (AdrHigh & 0xFF00) >= 0xC000 )
AdrHigh &= 0xFF7F;
return (AdrHigh<<8)|AdrLow;
}
Commands
| Opcode | Argument length (byte) | Function | ||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0x00 | 2 | Run map script
| ||||||||||||||||||||||||||||||||||||
| 0x02 | 5 | Play SPC data
| ||||||||||||||||||||||||||||||||||||
| 0x08 | variable | run sub command
| ||||||||||||||||||||||||||||||||||||
| 0x10 | 4 | Load data
| ||||||||||||||||||||||||||||||||||||
| 0x20 | 7 | Load MapTile/Collision data
| ||||||||||||||||||||||||||||||||||||
| 0x40 | 6 | Set palette for map
| ||||||||||||||||||||||||||||||||||||
| 0x80 | 6 | Load Tile Data
|