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#include <assert.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include "util.h"
typedef int T;
struct ring_buffer {
size_t head, tail;
T array[8]; /* fit for your needs... */
};
void
ring_init(struct ring_buffer *rb)
{
rb->head = rb->tail = 0;
}
bool
ring_push_front(struct ring_buffer *rb, T data)
{
const size_t prev = (rb->tail + NELEM(rb->array) - 1) % NELEM(rb->array);
if ( prev == rb->head )
return false;
rb->array[prev] = data;
rb->tail = prev;
return true;
}
bool
ring_push_back(struct ring_buffer *rb, T data)
{
const size_t next = (rb->head + 1) % NELEM(rb->array);
if ( next == rb->tail )
return false;
rb->array[rb->head] = data;
rb->head = next;
return true;
}
bool
ring_pop_front(struct ring_buffer *rb, T *data)
{
if ( rb->head == rb->tail )
return false;
const size_t next = (rb->tail + 1) % NELEM(rb->array);
*data = rb->array[rb->tail];
rb->tail = next;
return true;
}
bool
ring_pop_back(struct ring_buffer *rb, T *data)
{
if ( rb->head == rb->tail )
return false;
const size_t prev = (rb->head + NELEM(rb->array) - 1) % NELEM(rb->array);
*data = rb->array[prev];
rb->head = prev;
return true;
}
void
f()
{
ERROR("");
}
void
debug_print(const char *msg, struct ring_buffer *rb)
{
printf("%s: head: %zu, tail: %zu\n", msg, rb->head, rb->tail);
}
int
main(void)
{
#if 0
struct ring_buffer rb;
ring_init(&rb);
#else
struct ring_buffer rb = { .head = 0, .tail = 0 };
#endif
assert(ring_push_back(&rb, 1) == true); // 1
assert(ring_push_back(&rb, 2) == true); // 1, 2
assert(ring_push_back(&rb, 3) == true); // 1, 2, 3
assert(ring_push_back(&rb, 4) == true); // 1, 2, 3, 4
debug_print("Stand", &rb);
assert(ring_push_front(&rb, 0) == true); // 0, 1, 2, 3, 4
assert(ring_push_front(&rb, -1) == true); // -1, 0, 1, 2, 3, 4
debug_print("Stand", &rb);
T temp;
assert(ring_pop_back(&rb, &temp) == true); // -1, 0, 1, 2, 3
assert(ring_pop_front(&rb, &temp) == true); // 0, 1, 2, 3
debug_print("Stand", &rb);
assert(ring_push_back(&rb, 4) == true); // 0, 1, 2, 3, 4
assert(ring_push_back(&rb, 5) == true); // 0, 1, 2, 3, 4, 5
assert(ring_push_back(&rb, 6) == true); // 0, 1, 2, 3, 4, 5, 6
assert(ring_push_back(&rb, 7) == false); // 0, 1, 2, 3, 4, 5, 6
assert(ring_push_front(&rb, 7) == false); // 0, 1, 2, 3, 4, 5, 6
while ( ring_pop_back(&rb, &temp) ) {
printf("temp: %d\n", temp);
}
debug_print("Stand", &rb);
return EXIT_SUCCESS;
}
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