Juravis — The NodeJS Mod Patching Tool

cxdf (compact cross differentiation format) was developed for JuraviS in order to streamline a compact and effective format for modifying game files based on their original counterparts. This format aims to give an alternative to including copyrighted data into patch files.

All values are stored in Little-Endian.

1. Identifier [2 bytes]
   • String J5 or [0x4A,0x35]
2. Version [1 byte]
   • Current Version: 0x01
3. Settings [1 byte]
   • 00001000: Resize on filesize mismatch
   • 00000111: New filesize byte count
4. Filesize [0-7 bytes, unsigned]
5. Patch Instructions [varies, multiple]

1. Header [1 byte]
   • 11110000: Instruction ID
   • 00001000:
     • 0 = Seek (absolute jump to offset)
     • 1 = Hop (relative jump from current offset)
   • 00000111: Seek/Hop offset byte count
2. Seek/Hop Offset [0-7 bytes, unsigned]
3. Instruction Data [varies]

Writes a single byte with the given value to the current offset of the modification buffer.

1. Byte Value [1 byte]

Writes a single byte repeating for a given length to the current offset of the modification buffer.

1. Repeat count [1 byte, unsigned]
   • 1-256
2. Byte Value [1 byte]

Same as above; long version;

1. Repeat count [2 bytes, unsigned]
   • 1-65536
2. Byte Value [1 byte]

Writes a buffer of bytes to the current offset of the modification buffer.

1. Buffer length [1 byte, unsigned]
   • 1-256
2. Buffer [1-256 bytes]

Same as above; long version;

1. Buffer length [2 bytes, unsigned]
   • 1-65536
2. Buffer [1-65536 bytes]

Writes a buffer of bytes repeating a number of times to the current offset of the modification buffer.

1. Repeat count [1 byte, unsigned]
   • 1-256
2. Buffer length [1 byte, unsigned]
   • 1-256
3. Buffer [1-256 bytes]

Same as above; long version;

1. Repeat count [2 bytes, unsigned]
   • 1-65536
2. Buffer length [1 byte, unsigned]
   • 1-256
3. Buffer [1-256 bytes]

Copies a buffer of bytes from the unmodified buffer back to the current position in the modification buffer.

1. Parameters
   • 10000000:
     • 0 = Absolute Offset (unsigned)
     • 1 = Relative Offset (signed)
   • 00111000: Offset byte size
   • 00000111: Copy length byte size
2. Offset [0-7 bytes, unsigned or signed, see first parameter]
3. Copy length [0-7 bytes, unsigned]
   • Read value is +1 (examples: 0x00 → 1, 0xFF → 256)