manual: link lock-example1.c

doc/cprover-manual/cbmc-tutorial.md

@@ -209,35 +209,43 @@ obtained with the option `--property`.
 
 ### Unbounded Loops
 
-CBMC can also be used for programs with unbounded loops. In this case,
-CBMC is used for bug hunting only; CBMC does not attempt to find all
-bugs. The following program (lock-example.c) is an example of a program
-with a user-specified property:
+CBMC can also be used for programs with unbounded loops.  In this case, CBMC
+is used for bug hunting only; CBMC does not attempt to find all bugs.  The
+following program
+([lock-example.c](https://raw.githubusercontent.com/diffblue/cbmc/develop/doc/cprover-manual/lock-example.c))
+is an example of a program with a user-specified property:
 
 ```C
 _Bool nondet_bool();
 _Bool LOCK = 0;
 
-_Bool lock() {
-  if(nondet_bool()) {
+_Bool lock()
+{
+  if(nondet_bool())
+  {
     assert(!LOCK);
     LOCK = 1;
-    return 1; }
+    return 1;
+  }
 
   return 0;
 }
 
-void unlock() {
+void unlock()
+{
   assert(LOCK);
   LOCK = 0;
 }
 
-int main() {
+int main()
+{
   unsigned got_lock = 0;
   int times;
 
-  while(times > 0) {
-    if(lock()) {
+  while(times > 0)
+  {
+    if(lock())
+    {
       got_lock++;
       /* critical section */
     }

doc/cprover-manual/lock-example.c

@@ -0,0 +1,41 @@
+_Bool nondet_bool();
+_Bool LOCK = 0;
+
+_Bool lock()
+{
+  if(nondet_bool())
+  {
+    assert(!LOCK);
+    LOCK = 1;
+    return 1;
+  }
+
+  return 0;
+}
+
+void unlock()
+{
+  assert(LOCK);
+  LOCK = 0;
+}
+
+int main()
+{
+  unsigned got_lock = 0;
+  int times;
+
+  while(times > 0)
+  {
+    if(lock())
+    {
+      got_lock++;
+      /* critical section */
+    }
+
+    if(got_lock != 0)
+      unlock();
+
+    got_lock--;
+    times--;
+  }
+}