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simplify xorshift implementation; struct not needed.

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NunoSempere 2023-06-03 03:42:30 -06:00
parent a2e1a48d82
commit 131ea138ae
2 changed files with 10 additions and 15 deletions
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C/scratchpad/xorshift
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C/scratchpad/xorshift.c
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@ -2,34 +2,29 @@
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
struct xorshift32_state { uint32_t xorshift32(uint32_t* state)
uint32_t a;
};
uint32_t xorshift32(struct xorshift32_state *state)
{ {
/* Algorithm "xor" from p. 4 of Marsaglia, "Xorshift RNGs" */ /* Algorithm "xor" from p. 4 of Marsaglia, "Xorshift RNGs" */
uint32_t x = state->a; uint32_t x = *state;
x ^= x << 13; x ^= x << 13;
x ^= x >> 17; x ^= x >> 17;
x ^= x << 5; x ^= x << 5;
return state->a = x; return *state = x;
} }
int main(){ int main(){
struct xorshift32_state** state = malloc(sizeof(struct xorshift32_state*) * 4); uint32_t** states = malloc(4 * sizeof(uint32_t*));
for(int i=0; i<4;i++){ for(int i=0; i<4;i++){
state[i] = malloc(sizeof(struct xorshift32_state)); states[i] = malloc(sizeof(uint32_t));
state[i]->a = (uint32_t) i + 1; *states[i] = i + 1;
} }
printf("%i\n", xorshift32(state[0])); printf("%i\n", xorshift32(states[0]));
printf("%i\n", xorshift32(state[0])); printf("%i\n", xorshift32(states[1]));
for(int i=0; i<4;i++){ for(int i=0; i<4;i++){
free(state[i]); free(states[i]);
} }
free(state); free(states);
return 0; return 0;
} }