Add generic circular buffer

Add a circular buffer implementation, to factorize multiple specific
queues implementation.
This commit is contained in:
Romain Vimont 2019-05-29 20:53:21 +02:00
parent 7475550ae8
commit b38292cd69
3 changed files with 126 additions and 0 deletions

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@ -154,6 +154,9 @@ executable('scrcpy', src,
### TESTS
tests = [
['test_cbuf', [
'tests/test_cbuf.c',
]],
['test_control_event_queue', [
'tests/test_control_event_queue.c',
'src/control_event.c'

50
app/src/cbuf.h Normal file
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@ -0,0 +1,50 @@
// generic circular buffer (bounded queue) implementation
#ifndef CBUF_H
#define CBUF_H
#include <stdbool.h>
#include <unistd.h>
// To define a circular buffer type of 20 ints:
// typedef CBUF(int, 20) my_cbuf_t;
//
// data has length CAP + 1 to distinguish empty vs full.
#define CBUF(TYPE, CAP) { \
TYPE data[(CAP) + 1]; \
size_t head; \
size_t tail; \
}
#define cbuf_size_(PCBUF) \
(sizeof((PCBUF)->data) / sizeof(*(PCBUF)->data))
#define cbuf_is_empty(PCBUF) \
((PCBUF)->head == (PCBUF)->tail)
#define cbuf_is_full(PCBUF) \
(((PCBUF)->head + 1) % cbuf_size_(PCBUF) == (PCBUF)->tail)
#define cbuf_init(PCBUF) \
(void) ((PCBUF)->head = (PCBUF)->tail = 0)
#define cbuf_push(PCBUF, ITEM) \
({ \
bool ok = !cbuf_is_full(PCBUF); \
if (ok) { \
(PCBUF)->data[(PCBUF)->head] = (ITEM); \
(PCBUF)->head = ((PCBUF)->head + 1) % cbuf_size_(PCBUF); \
} \
ok; \
}) \
#define cbuf_take(PCBUF, PITEM) \
({ \
bool ok = !cbuf_is_empty(PCBUF); \
if (ok) { \
*(PITEM) = (PCBUF)->data[(PCBUF)->tail]; \
(PCBUF)->tail = ((PCBUF)->tail + 1) % cbuf_size_(PCBUF); \
} \
ok; \
})
#endif

73
app/tests/test_cbuf.c Normal file
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@ -0,0 +1,73 @@
#include <assert.h>
#include <string.h>
#include "cbuf.h"
struct int_queue CBUF(int, 32);
static void test_cbuf_empty(void) {
struct int_queue queue;
cbuf_init(&queue);
assert(cbuf_is_empty(&queue));
bool push_ok = cbuf_push(&queue, 42);
assert(push_ok);
assert(!cbuf_is_empty(&queue));
int item;
bool take_ok = cbuf_take(&queue, &item);
assert(take_ok);
assert(cbuf_is_empty(&queue));
bool take_empty_ok = cbuf_take(&queue, &item);
assert(!take_empty_ok); // the queue is empty
}
static void test_cbuf_full(void) {
struct int_queue queue;
cbuf_init(&queue);
assert(!cbuf_is_full(&queue));
// fill the queue
for (int i = 0; i < 32; ++i) {
bool ok = cbuf_push(&queue, i);
assert(ok);
}
bool ok = cbuf_push(&queue, 42);
assert(!ok); // the queue if full
int item;
bool take_ok = cbuf_take(&queue, &item);
assert(take_ok);
assert(!cbuf_is_full(&queue));
}
static void test_cbuf_push_take(void) {
struct int_queue queue;
cbuf_init(&queue);
bool push1_ok = cbuf_push(&queue, 42);
assert(push1_ok);
bool push2_ok = cbuf_push(&queue, 35);
assert(push2_ok);
int item;
bool take1_ok = cbuf_take(&queue, &item);
assert(take1_ok);
assert(item == 42);
bool take2_ok = cbuf_take(&queue, &item);
assert(take2_ok);
assert(item == 35);
}
int main(void) {
test_cbuf_empty();
test_cbuf_full();
test_cbuf_push_take();
return 0;
}