FF8/FileFormat JSM

By myst6re.

Contents

Fields Scripts

Offset	Size	Data
0	1 byte	Count of door entity
1	1 byte	Count of walkmesh line entity
2	1 byte	Count of background entity
3	1 byte	Count of other entity
4	2 bytes	Offset section 1
6	2 bytes	Offset script data
8	offsetSection1 - 8 = nbEntity * 2	Entry point of each entity
offsetSection1	offsetScriptData - offsetSection1	Entry point of each script
offsetScriptData	varies	Script Data

Entry point of each entity

Each entry is 2 bytes with:

  scriptCount = entryPointEntity & 0x7F;
  label = entryPointEntity >> 7;

The entry points are sorted in order of execution (I guess), not in the order in which entities appear in the file.

When sorting entities, it will be always in that order:

1. Lines
2. Doors
3. Backgrounds
4. Other

To know what type of an entity, so we were just use their count.

Entry point of each script

Each entry is 2 bytes with:

  position = (entryPointScript & 0x7FFF)*4;
  flag = entryPointScript >> 15;

The position is relative to offsetScriptData. The meaning of the flag is unknown, it appear always and only with door, location and background entities. Last entry point is relative EOF

Script Data

Each opcode is 4 bytes.

Opcode List