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#include <stddef.h> // for size_t
#include <stdlib.h> // for malloc() and free()
#include <assert.h>
#include "utils.h"
#include "cycle.h"
/* cycling iterable */
struct Cycle {
const void *base;
size_t i;
size_t memb_n;
size_t memb_size;
};
/*
* cycle_new: create a new cycle of array startinng at 'base' with memb_n
* elements each of size 'memb_size'
*/
struct Cycle *
cycle_new(const void *base, size_t memb_n, size_t memb_size)
{
assert(base != NULL);
assert(memb_n > 0);
assert(memb_size > 0);
struct Cycle *cycle = malloc(sizeof *cycle);
if (cycle == NULL) {
return NULL;
}
cycle->base = base;
cycle->i = 0;
cycle->memb_n = memb_n;
cycle->memb_size = memb_size;
return cycle;
}
/* cycle_free: free memmory used by cycle */
void
cycle_free(struct Cycle *cycle)
{
assert(cycle != NULL);
free(cycle);
}
/* cycle_index: get index of current element of cycle */
size_t
cycle_index(struct Cycle *cycle)
{
assert(cycle != NULL);
return cycle->i;
}
/* cycle_current: get current element of cycle */
const void *
cycle_current(struct Cycle *cycle)
{
assert(cycle != NULL);
return (const char *)cycle->base + cycle->memb_size*cycle->i;
}
/* cycle_next: point cycle to next element and return it */
const void *
cycle_next(struct Cycle *cycle)
{
assert(cycle != NULL);
cycle->i = (cycle->i >= cycle->memb_n-1) ? 0 : cycle->i+1;
return cycle_current(cycle);
}
/* cycle_prev: point cycle to previous elemetn and return it */
const void *
cycle_prev(struct Cycle *cycle)
{
assert(cycle != NULL);
cycle->i = (cycle->i <= 0) ? cycle->memb_n-1 : cycle->i-1;
return cycle_current(cycle);
}
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