ucos2.patch

This patch fixes a bug present when passing the OS_TASK_OPT_STK_CLR
option to OSTaskCreateExt().  The original code would overwrite an
additional byte before the stack and leave the last byte untouched.

The Dynamic C 10.72E release includes the patched OS_TASK.C file, but
the uC/OS-II source isn't included in the Open Source GitHub code
repository.  If your Dynamic C installation is based on 10.72D or
earlier, you will need to manually apply this fix using `patch`:

    patch -p1 --forward < ucos2.patch

Include the command-line option "--dry-run" to test the patch.  The
"--forward" option ignores the patch if already applied.

--- a/Lib/Rabbit4000/UCOS2/OS_TASK.C	2016-03-03 16:23:12 -0700
+++ b/Lib/Rabbit4000/UCOS2/OS_TASK.C	2019-06-11 17:09:04 -0700
@@ -479,7 +479,9 @@
         if (opt & OS_TASK_OPT_STK_CHK) {          // See if stack checking has been enabled
             if (opt & OS_TASK_OPT_STK_CLR) {      // See if stack needs to be cleared
                                                   // Yes, fill the stack with zeros
-                _f_memset((void __far *)(PhysAddr - stk_size), 0, stk_size);
+                // PhysAddr is the last address of the stack (e.g., ...FF), so it's
+                // necessary to add 1 to get to the starting address of the stack.
+                _f_memset((void __far *)(PhysAddr - stk_size + 1), 0, stk_size);
             }
         }