State Manipulation

Functions
void	pcgAdvance (PcgState *rng, uint64 delta)

Detailed Description

Advanced functions for manipulating generator state.

Function Documentation

pcgAdvance()

void pcgAdvance	(	PcgState *	rng,
		uint64	delta
	)

Advances the RNG state forward (or backward) by a specified number of steps

Efficiently jumps the RNG state forward or backward without generating intermediate values. This is useful for:

• Skipping ahead in a sequence for parallel generation
• Implementing "save states" in simulations
• Jumping to specific points in a reproducible sequence

The algorithm uses O(log(delta)) time complexity based on fast exponentiation, making even very large jumps efficient.

Note: Passing a negative value (as uint64) will advance backward, effectively "jumping back" in the sequence.

Example:

PcgState rng1, rng2;
pcgSeed(&rng1, 42, 54);
pcgSeed(&rng2, 42, 54);
 
pcgAdvance(&rng2, 1000);  // Jump ahead 1000 steps
 
// rng1 and rng2 are now at different points in the same sequence
// Generate 1000 values from rng1 would bring it to rng2's state

Parameters

rng	Pointer to initialized PCG state
delta	Number of steps to advance (can be negative to go backward)