time-to-botec/C/xorshift-scratchpad/xorshift-struct.c

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#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
struct xorshift32_state {
uint32_t a;
};
uint32_t xorshift32(struct xorshift32_state *state)
{
/* Algorithm "xor" from p. 4 of Marsaglia, "Xorshift RNGs" */
uint32_t x = state->a;
x ^= x << 13;
x ^= x >> 17;
x ^= x << 5;
return state->a = x;
}
float rand_xorshift32(struct xorshift32_state *state){
return (float) xorshift32(state) / (float) UINT32_MAX;
}
int main(){
struct xorshift32_state** states = malloc(sizeof(struct xorshift32_state*) * 4);
for(int i=0; i<4;i++){
states[i] = malloc(sizeof(struct xorshift32_state));
states[i]->a = (uint32_t) i + 1;
}
for(int i=0; i<1000000000; i++){
uint32_t x = xorshift32(states[0]);
float y = rand_xorshift32(states[1]);
// printf("%u\n", x);
// printf("%f\n", y);
}
for(int i=0; i<4;i++){
free(states[i]);
}
free(states);
return 0;
}