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Source code

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

typedef unsigned char u8;
typedef unsigned int u32;
typedef unsigned long u64;
typedef size_t usize;
typedef ssize_t isize;

typedef u32 T;

struct Iter
{
    T *start;
    T *end;
};

inline T *iter_nth(struct Iter *iter, usize n) {
    usize size = sizeof(T);
    usize diff = iter->end - iter->start;
    usize len = diff / size;

if (n >= len) {
        // This iterator is now empty.
        iter->start = iter->end;
        return NULL;
    }
    iter->start += n;
    T *old = iter->start;
    iter->start += 1;
    return old;
}

inline T *iter_next(struct Iter *iter) {
    if (iter->end == iter->start) {
        return NULL;
    } else {
        T *old = iter->start;
        iter->start += 1;
        return old;
    }
}

struct Skip {
    struct Iter iter;
    usize n;
};

__attribute__((always_inline)) static T *skip_next(struct Skip *sk) {
    if (sk->n == 0) {
        return iter_next(&sk->iter);
    } else {
        usize old_n = sk->n;
        sk->n = 0;
        return iter_nth(&sk->iter, old_n);
    }
}

inline T *skip_nth(struct Skip *sk, usize n) {
    // Can't just add n + sk->n due to overflow.
    if (sk->n > 0) {
        usize to_skip = sk->n;
        sk->n = 0;
        // nth(n) skips n+1
        return iter_nth(&sk->iter, to_skip - 1);
    }
    return iter_nth(&sk->iter, n);
}

void clippy_suggestion(u32 odd[32]) {
    odd[0] = 0xedb88320;
    struct Skip sk = {
        .iter = {
            .start = odd,
            .end = odd + 32,
        },
        .n = 1,
    };
    for (usize i = 1; ; ++i) {
        T *ptr = skip_next(&sk);
        if (ptr == NULL) {
            break;
        }
        *ptr = 1 << i;
    }
}