Clarify intention between comparison to zero and the shift operation

Paul Thompson · Paul Thompson · commit 712b47f3c122 · 2018-03-04T12:44:21.000-08:00
Building with (GNU Tools for Arm Embedded Processors 7-2017-q4-major) 7.2.1 20170904 gives this warning

../events/equeue/equeue.c: In function 'equeue_incid':
../events/equeue/equeue.c:40:17: warning: '&lt;&lt;' in boolean context, did you mean '&lt;' ? [-Wint-in-bool-context]
     if (!(e-&gt;id &lt;&lt; q-&gt;npw2)) {
diff --git a/events/equeue/equeue.c b/events/equeue/equeue.c
@@ -37,7 +37,7 @@ static inline int equeue_clampdiff(unsigned a, unsigned b) {
 // Increment the unique id in an event, hiding the event from cancel
 static inline void equeue_incid(equeue_t *q, struct equeue_event *e) {
     e->id += 1;
-    if (!(e->id << q->npw2)) {
+    if (0 == (e->id << q->npw2)) {
         e->id = 1;
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -37,7 +37,7 @@ static inline int equeue_clampdiff(unsigned a, unsigned b) {`
`37`	`37`	`// Increment the unique id in an event, hiding the event from cancel`
`38`	`38`	`static inline void equeue_incid(equeue_t q, struct equeue_event e) {`
`39`	`39`	`e->id += 1;`
`40`		`- if (!(e->id << q->npw2)) {`
	`40`	`+ if (0 == (e->id << q->npw2)) {`
`41`	`41`	`e->id = 1;`
`42`	`42`	`}`
`43`	`43`	`}`