Random sequence format

This feature is exclusive to Java Edition.

 

Random sequences are random number sequence generators used by loot tables and the /random (roll|value) ... command.

NBT structure

Current random sequences in a world and the random sequence settings of the world are stored in the /data/random_sequences.dat, which is a GZip-ed NBT file.

Usage

Random sequences are used by a loot table when its seed is not specified. Loot tables in containers from the world generation are not affected by random sequences (but are directly affected by the world seed).

Random sequences use the Xoroshiro128++ random number generator.

When a random sequence is called for the first time, it is created with the seed:

1. From the [Int] salt value.
2. If [Boolean] include_world_seed is true, XOR the [Int] salt with the world seed.
3. Expands it to 128 bits. The lower 64 bits are the XOR between the value and 0x6a09e667f3bcc909; The higher 64 bits is the sum of the lower 64 bits and 0x9e3779b97f4a7c15.
4. If [Boolean] include_sequence_id is true, XOR it with the MD5 of the namespaced ID of the creating random sequence.
5. The two long numbers calculated from the lower 64 bits and the higher 64 bits respectively as follows are the seed of the random sequence.

public static long mixStafford13(long v) {
	v = (v ^ v >>> 30) * 0xbf58476d1ce4e5b9L;
	v = (v ^ v >>> 27) * 0x94d049bb133111ebL;
	return v ^ v >>> 31;
}

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