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sys/tree.h: Add parent rotations 

Add specialized rotations RB_PARENT_ROTATE_LEFT() and RB_PARENT_ROTATE_RIGHT()
which may be used if the parent node exists and the direction of the child is
known.  The specialized rotations are derived from RB_ROTATE_LEFT() and
RB_ROTATE_RIGHT() where the RB_SWAP_CHILD() was replaced by a simple
assignment.
This commit is contained in:
Sebastian Huber 2021-10-05 15:43:34 +02:00
parent ee30f991c3
commit 5f7f27c817
1 changed files with 39 additions and 4 deletions
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43
newlib/libc/include/sys/tree.h
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@ -381,6 +381,37 @@ struct { \
RB_AUGMENT(elm); \
} while (/*CONSTCOND*/ 0)
/*
* The RB_PARENT_ROTATE_LEFT() and RB_PARENT_ROTATE_RIGHT() rotations are
* specialized versions of RB_ROTATE_LEFT() and RB_ROTATE_RIGHT() which may be
* used if the parent node exists and the direction of the child element is
* known.
*/
#define RB_PARENT_ROTATE_LEFT(parent, left, tmp, field) do { \
(tmp) = RB_RIGHT(left, field); \
if ((RB_RIGHT(left, field) = RB_LEFT(tmp, field)) != NULL) { \
RB_SET_PARENT(RB_RIGHT(left, field), left, field); \
} \
RB_SET_PARENT(tmp, parent, field); \
RB_LEFT(parent, field) = (tmp); \
RB_LEFT(tmp, field) = (left); \
RB_SET_PARENT(left, tmp, field); \
RB_AUGMENT(left); \
} while (/*CONSTCOND*/ 0)
#define RB_PARENT_ROTATE_RIGHT(parent, right, tmp, field) do { \
(tmp) = RB_LEFT(right, field); \
if ((RB_LEFT(right, field) = RB_RIGHT(tmp, field)) != NULL) { \
RB_SET_PARENT(RB_LEFT(right, field), right, field); \
} \
RB_SET_PARENT(tmp, parent, field); \
RB_RIGHT(parent, field) = (tmp); \
RB_RIGHT(tmp, field) = (right); \
RB_SET_PARENT(right, tmp, field); \
RB_AUGMENT(right); \
} while (/*CONSTCOND*/ 0)
/* Generates prototypes and inline functions */
#define RB_PROTOTYPE(name, type, field, cmp) \
RB_PROTOTYPE_INTERNAL(name, type, field, cmp,)
@ -454,7 +485,8 @@ name##_RB_INSERT_COLOR(struct name *head, struct type *elm) \
continue; \
} \
if (RB_RIGHT(parent, field) == elm) { \
RB_ROTATE_LEFT(head, parent, tmp, field);\
RB_PARENT_ROTATE_LEFT(gparent, parent, \
tmp, field); \
tmp = parent; \
parent = elm; \
elm = tmp; \
@ -470,7 +502,8 @@ name##_RB_INSERT_COLOR(struct name *head, struct type *elm) \
continue; \
} \
if (RB_LEFT(parent, field) == elm) { \
RB_ROTATE_RIGHT(head, parent, tmp, field);\
RB_PARENT_ROTATE_RIGHT(gparent, parent, \
tmp, field); \
tmp = parent; \
parent = elm; \
elm = tmp; \
@ -500,7 +533,8 @@ name##_RB_REMOVE_COLOR(struct name *head, struct type *parent) \
RB_COLOR(RB_RIGHT(tmp, field), field) = RB_BLACK; \
else if (RB_ISRED(RB_LEFT(tmp, field), field)) { \
struct type *oleft; \
RB_ROTATE_RIGHT(head, tmp, oleft, field); \
RB_PARENT_ROTATE_RIGHT(parent, tmp, \
oleft, field); \
RB_COLOR(oleft, field) = RB_BLACK; \
tmp = oleft; \
} else { \
@ -525,7 +559,8 @@ name##_RB_REMOVE_COLOR(struct name *head, struct type *parent) \
RB_COLOR(RB_LEFT(tmp, field), field) = RB_BLACK; \
else if (RB_ISRED(RB_RIGHT(tmp, field), field)) { \
struct type *oright; \
RB_ROTATE_LEFT(head, tmp, oright, field); \
RB_PARENT_ROTATE_LEFT(parent, tmp, \
oright, field); \
RB_COLOR(oright, field) = RB_BLACK; \
tmp = oright; \
} else { \