RCarry2.cpp

#include <string.h>
#include "RCarry2.h"

static const unsigned long int mask_lo = 0x00ffffffUL;  /* 2^24 - 1 */
static const unsigned long int mask_hi = ~0x00ffffffUL;
static const unsigned long int two24 = 16777216;        /* 2^24 */

RCarry2::RCarry2(int32_t seed)
{
	/* This is the initialization algorithm of F. James, widely in use
	for RANLUX. */
	for (int i = 0; i < 24; i++)
	{
		unsigned long int k = seed / 53668;
		seed = 40014 * (seed - k * 53668) - k * 12211;
		if (seed < 0)
		{
			seed += 2147483563;
		}
		state0.u[i] = seed % two24;
	}

	state0.i = 23;
	state0.j = 9;

	if (state0.u[23] & mask_hi)
		state0.carry = 1;
	else
		state0.carry = 0;

	memcpy(&state1, &state0, sizeof(state0));
}

uint32_t RCarry2::increment(rcarry2_state_t * state)
{
	unsigned int i = state->i;
	unsigned int j = state->j;
	long int unew = state->u[j] - state->u[i] - state->carry;

	if (unew & mask_hi)
	{
		state->carry = 1;
		unew &= mask_lo;
	}
	else
		state->carry = 0;

	state->u[i] = unew;

	if (i == 0)
		i = 23;
	else
		i--;

	state->i = i;

	if (j == 0)
		j = 23;
	else
		j--;

	state->j = j;

	return unew;
}

int32_t RCarry2::get() //46.9 ticks
{
	if (pass == 0)
	{
		pass = (increment(&state1) & 31) + 1;
	}
	unsigned long int r = increment(&state0);

	n++;

	if (n == pass)
	{
		unsigned int skip = (increment(&state1) & 31) + 1;
		n = 0;
		for (unsigned int i = 0; i < skip; i++)
			increment(&state0);
		pass = 0;
	}

	return r;
}

RCarry2.h

#pragma once
#include <stdint.h>

class RCarry2
{
private:
	typedef struct
	{
		unsigned int i;
		unsigned int j;
		unsigned int carry;
		unsigned long int u[24];
	}
	rcarry2_state_t;

	int n = 0;
	int pass = 0;
	rcarry2_state_t state0, state1;
	uint32_t increment(rcarry2_state_t * state);
public:
	RCarry2(int32_t seed);
	int32_t get();
};