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score: Add _RBTree_Opposite_direction.

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Add a red-black tree helper method to ease obtaining the direction opposite
to the current direction. Useful for manipulating and traversing an rbtree.
This commit is contained in:
Gedare Bloom
2012-03-04 11:42:08 -05:00
parent a52be5ec40
commit 41d33b9030
2 changed files with 18 additions and 8 deletions
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16
cpukit/score/inline/rtems/score/rbtree.inl
View File

@@ -31,6 +31,16 @@
* @{
*/
/**
* @brief Get the direction opposite to @a the_dir
*/
RTEMS_INLINE_ROUTINE RBTree_Direction _RBTree_Opposite_direction(
RBTree_Direction the_dir
)
{
return (!the_dir);
}
/** @brief Set off rbtree
*
* This function sets the parent and child fields of the @a node to NULL
@@ -435,10 +445,10 @@ RTEMS_INLINE_ROUTINE void _RBTree_Rotate(
{
RBTree_Node *c;
if (the_node == NULL) return;
if (the_node->child[(1-dir)] == NULL) return;
if (the_node->child[_RBTree_Opposite_direction(dir)] == NULL) return;
c = the_node->child[(1-dir)];
the_node->child[(1-dir)] = c->child[dir];
c = the_node->child[_RBTree_Opposite_direction(dir)];
the_node->child[_RBTree_Opposite_direction(dir)] = c->child[dir];
if (c->child[dir])
c->child[dir]->parent = the_node;

10
cpukit/score/src/rbtreeextract.c
View File

@@ -50,7 +50,7 @@ static void _RBTree_Extract_validate_unprotected(
sibling->color = RBT_BLACK;
dir = the_node != parent->child[0];
_RBTree_Rotate(parent, dir);
sibling = parent->child[!dir];
sibling = parent->child[_RBTree_Opposite_direction(dir)];
}
/* sibling is black, see if both of its children are also black. */
@@ -72,15 +72,15 @@ static void _RBTree_Extract_validate_unprotected(
* Then switch the sibling and parent colors, and rotate through parent.
*/
dir = the_node != parent->child[0];
if (!_RBTree_Is_red(sibling->child[!dir])) {
if (!_RBTree_Is_red(sibling->child[_RBTree_Opposite_direction(dir)])) {
sibling->color = RBT_RED;
sibling->child[dir]->color = RBT_BLACK;
_RBTree_Rotate(sibling, !dir);
sibling = parent->child[!dir];
_RBTree_Rotate(sibling, _RBTree_Opposite_direction(dir));
sibling = parent->child[_RBTree_Opposite_direction(dir)];
}
sibling->color = parent->color;
parent->color = RBT_BLACK;
sibling->child[!dir]->color = RBT_BLACK;
sibling->child[_RBTree_Opposite_direction(dir)]->color = RBT_BLACK;
_RBTree_Rotate(parent, dir);
break; /* done */
}