random-ops-3

#include <stdio.h>
#include <stdlib.h>

typedef struct RandomGenerator {
    struct RandomOperations *ops;
    int seed;
    int a;
    int c;
    int m;
} RandomGenerator;

typedef struct RandomOperations {
    void (*destroy)(RandomGenerator *);
    int (*next)(RandomGenerator *);
} RandomOperations;

int next(RandomGenerator *rr) {
    int res = (rr->a * rr->seed + rr->c) % rr->m;
    rr->seed = res;
    return res;
}

void destroy(RandomGenerator *rr) {
    free(rr->ops);
    free(rr);
}

RandomGenerator *random_create(int seed) {
    RandomGenerator *rr = (RandomGenerator *)malloc(sizeof(RandomGenerator));
    rr->ops = (RandomOperations *)malloc(sizeof(RandomOperations));
    rr->ops->next = &next;
    rr->ops->destroy = &destroy;
    rr->seed = seed;
    rr->a = 1103515245;
    rr->c = 12345;
    rr->m = 1 << 31;
    return rr;
}

int main(void) {
    RandomGenerator *rr = random_create(1234);
    for (int j = 0; j < 100; ++j) {
        printf("%d\n", rr->ops->next(rr));
    }
    rr->ops->destroy(rr);
    return 0;
}