Xoroshiro128+ PRNG implementation
https://en.wikipedia.org/wiki/Xoroshiro128%2B
#include "xoroshiro128plus.h"
uint64_t seed = 1; /* random value */
xrshr128p_state_t state;
xrshr128p_init(seed, &state);
uint64_t r = xrshr128p_next(&state);
/* SIMD version, requires x86 AVX2 extensions */
xrshr128p_avx2_state_t avx2_state;
xrshr128p_avx2_init(seed, &avx2_state);
__m256i simd_r = xrshr128p_avx2_next(&avx2_state);5 PRNGs were used to generate 128M random input values for the Pearson's chi-squared test. See test.c for more details.
Results on 1.6 GHz Intel Core i5:
speed=94.93M/s chi_test=0 rand()
speed=109.60M/s chi_test=1 xorshift128plus(&key)
speed=213.19M/s chi_test=1 avx_xorshift128plus(&simd_key)
speed=231.95M/s chi_test=1 xrshr128p_next(&state)
speed=291.28M/s chi_test=1 xrshr128p_avx2_next(&simd_state)