rtems: Constify rtems_task_wake_when()

Add a parameter to _TOD_Validate() to disable the validation of the
ticks member.

There are two reasons for this change.  Firstly, in
rtems_task_wake_when() was a double check for time_buffer == NULL (one
in rtems_task_wake_when() and one in _TOD_Validate()).  Secondly, the
ticks member is ignored by rtems_task_wake_when().  This was done with a
write of zero to the ticks member and thus a modification of the
user-provided structure.  Now the structure is no longer modified.
Using a mask parameter is quite efficient. You just have to load an
immediate value and there are no additional branches in _TOD_Validate().

Close #4406.

2 files changed, 21 insertions, 6 deletions

diff --git a/cpukit/include/rtems/rtems/clockimpl.h b/cpukit/include/rtems/rtems/clockimpl.h
index 8ec4f0f6e3..404b8234ee 100644
--- a/cpukit/include/rtems/rtems/clockimpl.h
+++ b/cpukit/include/rtems/rtems/clockimpl.h
@@ -35,19 +35,34 @@ extern "C" {
  */
 
 /**
- * @brief TOD Validate
+ * @brief Using this constant for the ticks mask disables the validation of the
+ *   ticks member in _TOD_Validate().
+ */
+#define TOD_DISABLE_TICKS_VALIDATION 0
+
+/**
+ * @brief Using this constant for the ticks mask enables the validation of the
+ *   ticks member in _TOD_Validate().
+ */
+#define TOD_ENABLE_TICKS_VALIDATION UINT32_MAX
+
+/**
+ * @brief Validates the time of day.
  *
- * This support function tests whether @a the_tod references
- * a valid time of day.
+ * @param the_tod is the reference to the time of day structure to validate or
+ *   NULL.
  *
- * @param the_tod A reference to the time of day structure to validate.
+ * @param ticks_mask is the mask for the ticks member of the time of day.  Use
+ *   #TOD_ENABLE_TICKS_VALIDATION to validate the ticks member.  Use
+ *   #TOD_DISABLE_TICKS_VALIDATION to skip the validation of the ticks member.
  *
  * @retval RTEMS_SUCCESSFUL @a the_tod references a valid time of day.
  * @retval RTEMS_INVALID_CLOCK @a the_tod references an invalid time of day.
  * @retval RTEMS_INVALID_ADDRESS @a the_tod reference is @c NULL.
  */
 rtems_status_code _TOD_Validate(
-  const rtems_time_of_day *the_tod
+  const rtems_time_of_day *the_tod,
+  uint32_t                 ticks_mask
 );
 
 /**
diff --git a/cpukit/include/rtems/rtems/tasks.h b/cpukit/include/rtems/rtems/tasks.h
index be95768d4a..8b5912bcf9 100644
--- a/cpukit/include/rtems/rtems/tasks.h
+++ b/cpukit/include/rtems/rtems/tasks.h
@@ -2071,7 +2071,7 @@ rtems_status_code rtems_task_wake_after( rtems_interval ticks );
  *   occur.
  * @endparblock
  */
-rtems_status_code rtems_task_wake_when( rtems_time_of_day *time_buffer );
+rtems_status_code rtems_task_wake_when( const rtems_time_of_day *time_buffer );
 
 /* Generated from spec:/rtems/task/if/get-scheduler */