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XOR-Shift RNG

The XOR-shift generator is a very lightweight random number generator based on XOR shifts. See the Wikipedia article on Xorshift generators for more information.

Constructor​

// #1 - use a random seed based on time-of-day
// NOTE: this will create variation between runs and between platforms.
XORShiftRNG::XORShiftRNG();

// #2 - use explicitly defined seed
XORShiftRNG::XORShiftRNG(unsigned int seed);

Create a new XORShift random number generator.

Parameters​

  • returns None

generateNextInt32​

int32_t generateNextInt32();

Generate the next signed 32-bit integer.

Parameters​

  • returns (int32_t) The next signed 32-bit integer.

generateNextInt64​

int64_t generateNextInt64();

Generate the next signed 64-bit integer.

Parameters​

  • returns (int64_t) The next signed 64-bit integer.

generateNextUInt32​

uint32_t generateNextUInt32();

Generate the next unsigned 32-bit integer.

Parameters​

  • returns (uint32_t) The next unsigned 32-bit integer.

generateNextUInt64​

uint64_t generateNextUInt64();

Generate the next unsigned 64-bit integer.

Parameters​

  • returns (uint64_t) The next unsigned 64-bit integer

nextUniform​

double  nextUniform();

Generate the next double within the range [0,1).

Parameters​

  • returns (double) The next double within the range [0,1).

seed​

void seed(uint64_t newSeed);

Re-seed the random number generator.

Parameters​

  • newSeed (uint64_t) A seed.
  • returns None

Examples​

Example 1: generateNextInt32()​

SST::RNG::XORShiftRNG* rng = new SST::RNG::XORShiftRNG(11);

int rndNumber;
rndNumber = (int)(rng->generateNextInt32());
rndNumber = (rndNumber & 0x0000FFFF) ^ ((rndNumber & 0xFFFF0000) >> 16);
rndNumber = abs((int)(rndNumber % 3));

Example 2: generateNextUInt32()​

SST::RNG::XORShiftRNG randomGenerator = new SST::RNG::XORShiftRNG(11);

int rndNumber;
int index = randomGenerator.generateNextUInt32() % (numWays-1);

Example 3: generateNextUInt64()​

SST::RNG::XORShiftRNG rng = new SST::RNG::XORShiftRNG(11);

uint64_t selectA = (rng.generateNextUInt64() % pageCount);
uint64_t selectB = (rng.generateNextUInt64() % pageCount);
#include <sst/core/rng/xorshift.h>