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score: Simplify _Watchdog_Next_first()

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This commit is contained in:
Sebastian Huber
2021-10-09 16:12:07 +02:00
parent 3f0ad2b3b7
commit a4112bd8af
1 changed files with 35 additions and 18 deletions
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53
cpukit/include/rtems/score/watchdogimpl.h
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@@ -351,33 +351,50 @@ RTEMS_INLINE_ROUTINE bool _Watchdog_Is_scheduled(
} }
/** /**
* @brief Sets the first node of the header. * @brief Sets the first watchdog of the watchdog collection to the next
* watchdog of the current first watchdog.
* *
* Sets the first node of the header to either the leftmost child node of the * This function may be used during watchdog removals, see _Watchdog_Remove()
* watchdog control node, or if not present sets it to the right child node of * and _Watchdog_Tickle().
* the watchdog control node. if both are not present, the new first node is
* the parent node of the current first node.
* *
* @param[in, out] header The watchdog header. * @param[in, out] header is the watchdog collection header.
* @param the_watchdog The watchdog control node for the operation. *
* @param first is the current first watchdog which should be removed
* afterwards.
*/ */
RTEMS_INLINE_ROUTINE void _Watchdog_Next_first( RTEMS_INLINE_ROUTINE void _Watchdog_Next_first(
Watchdog_Header *header, Watchdog_Header *header,
Watchdog_Control *the_watchdog const Watchdog_Control *first
) )
{ {
RBTree_Node *node = _RBTree_Right( &the_watchdog->Node.RBTree ); RBTree_Node *right;
if ( node != NULL ) { /*
RBTree_Node *left; * This function uses the following properties of red-black trees:
*
* 1. Every leaf (NULL) is black.
*
* 2. If a node is red, then both its children are black.
*
* 3. Every simple path from a node to a descendant leaf contains the same
* number of black nodes.
*
* The first node has no left child. So every path from the first node has
* exactly one black node (including leafs). The first node cannot have a
* non-leaf black right child. It may have a red right child. In this case
* both children must be leafs.
*/
_Assert( header->first == &first->Node.RBTree );
_Assert( _RBTree_Left( &first->Node.RBTree ) == NULL );
right = _RBTree_Right( &first->Node.RBTree );
while ( ( left = _RBTree_Left( node ) ) != NULL ) { if ( right != NULL ) {
node = left; _Assert( RB_COLOR( right, Node ) == RB_RED );
} _Assert( _RBTree_Left( right ) == NULL );
_Assert( _RBTree_Right( right ) == NULL );
header->first = node; header->first = right;
} else { } else {
header->first = _RBTree_Parent( &the_watchdog->Node.RBTree ); header->first = _RBTree_Parent( &first->Node.RBTree );
} }
} }