popFront causing more memory to be used

[bearophile]

> This is becoming a "fixed size circular queue". But maybe a 
> modulus is faster than a branch here.

I have tried, and it's slower both in D and C. I don't know why.


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

uint64_t hFib(const uint32_t k, const uint32_t n) {
     uint64_t *nums = calloc(k + 1, sizeof(uint64_t));
     if (nums == NULL)
         exit(1);

     uint32_t iter = k;
     nums[k] = 1;
     uint64_t total = 1;
     for (uint32_t i = k; i < n + 1; i++) {
         const uint32_t iter_next = (iter + 1 > k) ? 0 : (iter + 
1);
         total += nums[iter] - nums[iter_next];
         nums[iter_next] = total % 100000000LLU;
         iter = iter_next;
     }

     return nums[iter];
}

int main() {
     printf("%llu\n", hFib(100, 10000));
     printf("%llu\n", hFib(1594323, 9765625));
     return 0;
}


Runtime of this C version: about 240 ms.

Bye,
bearophile