From: Brian Norris <banorris@uci.edu>
Date: Wed, 6 Mar 2013 02:17:49 +0000 (-0800)
Subject: ms-queue: bugfix - get_ptr() and get_count() were switched
X-Git-Tag: oopsla2013-final~32
X-Git-Url: http://demsky.eecs.uci.edu/git/?p=model-checker-benchmarks.git;a=commitdiff_plain;h=d3c94c5b4370fc71d1c12272af29b3a95178f4bd

ms-queue: bugfix - get_ptr() and get_count() were switched

I ported the implementation wrong, so that we were extracting bits from
the wrong field.
---

diff --git a/ms-queue/my_queue.c b/ms-queue/my_queue.c
index 33a6292..498fb42 100644
--- a/ms-queue/my_queue.c
+++ b/ms-queue/my_queue.c
@@ -31,8 +31,6 @@ void init_queue(queue_t *q, int num_threads)
 	tail = MAKE_POINTER(1, 0);
 	next = MAKE_POINTER(0, 0); // (NULL, 0)
 
-	atomic_init(&q->nodes[0].next, 0); // assumed inititalized in original example
-
 	atomic_store(&q->head, head);
 	atomic_store(&q->tail, tail);
 	atomic_store(&q->nodes[1].next, next);
diff --git a/ms-queue/my_queue.h b/ms-queue/my_queue.h
index 5877a68..c92e420 100644
--- a/ms-queue/my_queue.h
+++ b/ms-queue/my_queue.h
@@ -11,8 +11,8 @@ typedef atomic_ullong pointer_t;
 
 static inline void set_count(pointer *p, unsigned int val) { *p = (*p & ~COUNT_MASK) | ((pointer)val << 32); }
 static inline void set_ptr(pointer *p, unsigned int val) { *p = (*p & ~PTR_MASK) | val; }
-static inline unsigned int get_count(pointer p) { return p & PTR_MASK; }
-static inline unsigned int get_ptr(pointer p) { return (p & COUNT_MASK) >> 32; }
+static inline unsigned int get_count(pointer p) { return (p & COUNT_MASK) >> 32; }
+static inline unsigned int get_ptr(pointer p) { return p & PTR_MASK; }
 
 typedef struct node {
 	unsigned int value;