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.

This code below is used to convert the ROM to a RAM address.

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;
}

Map script #0

This map script is used to select a song to be played by the 08 FC command

Commands

Opcode Argument length (byte) Function
0x00 2 Run map script
Offset Length (Byte) Name
0 2 Map ID


0x02 5 Play SPC data
Offset Length (Byte) Name
0 1 Unknown
1 1 Track ID
2 3 SPC data Offset


0x04 5 Load background using 2Bit format. Only used by map ID 0x106.
Offset Length (Byte) Name
0 3 Offset
3 1 Unknown
4 1 Layer
0x08 variable Run sub command
Opcode Argument length (byte) Function
0xF8 1 Return from sub function
0xF9 2 Call map script
0xFA 2 Push map script address
0xFC 2 Calls map script #0 which then plays the selected song id
0xFD 4 Call map script when flag is true
0xFE 2 Return from script
0xFF 0 End of script
0x10 4 Load map data
Offset Length (Byte) Name
0 1 0x01 - Map layer 0

0x02 - Map layer 1

1 3 Address
0x20 7 Load collision data or tile maps
Offset Length (Byte) Name
0 1 Seek
1 1 Size
2 1 Offset
3 1 Layer ID
0x80 set 0x80 clear
Collision data Map tiles
4 3 Address


0x40 6 Load palette
Offset Length (Byte) Name
0 1 Pal index
1 1 Pal size
2 1 Pal offset
3 3 Address


0x80 9 Load tile data
Offset Length (Byte) Name
0 1 Seek
1 1 Size
2 1 Tile mode
3 3 Address
6 2 Bank
7 1 Unknown
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