The implementation exposes an API to generate type-specific treap
implmentation and various functions to operate on it. It uses
obj_pool.h to store memory nodes in a treap.
Treaps provide a memory-efficient binary search tree structure.
Insertion/deletion/search are about as about as fast in the average
case as red-black trees and the chances of worst-case behavior are
vanishingly small, thanks to (pseudo-)randomness. That is a small
price to pay, given that treaps are much simpler to implement.
[db: Altered to reference nodes by offset from a common base pointer]
[db: Bob Jenkins' hashing implementation dropped for Knuth's]
[db: Methods unnecessary for search and insert dropped]
From: Jason Evans <jasone@xxxxxxxxxxxxx>
Signed-off-by: David Barr <david.barr@xxxxxxxxxxxx>
Signed-off-by: Ramkumar Ramachandra <artagnon@xxxxxxxxx>
---
vcs-svn/trp.h | 118 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
vcs-svn/trp.txt | 62 +++++++++++++++++++++++++++++
2 files changed, 180 insertions(+), 0 deletions(-)
create mode 100644 vcs-svn/trp.h
create mode 100644 vcs-svn/trp.txt
diff --git a/vcs-svn/trp.h b/vcs-svn/trp.h
new file mode 100644
index 0000000..c90f5c3
--- /dev/null
+++ b/vcs-svn/trp.h
@@ -0,0 +1,118 @@
+/*
+ * cpp macro implementation of treaps.
+ *
+ * Usage:
+ * #include <stdint.h>
+ * #include <trp.h>
+ * trp_gen(...)
+ */
+
+#ifndef TRP_H_
+#define TRP_H_
+
+/* Node structure. */
+struct trp_node {
+ uint32_t trpn_left;
+ uint32_t trpn_right;
+};
+
+/* Root structure. */
+struct trp_root {
+ uint32_t trp_root;
+};
+
+/* Pointer/Offset conversion */
+#define trpn_pointer(a_base, a_offset) (a_base##_pointer(a_offset))
+#define trpn_offset(a_base, a_pointer) (a_base##_offset(a_pointer))
+
+/* Left accessors. */
+#define trp_left_get(a_base, a_field, a_node) \
+ trpn_pointer(a_base, (a_node)->a_field.trpn_left)
+#define trp_left_set(a_base, a_field, a_node, a_left) \
+ (a_node)->a_field.trpn_left = trpn_offset(a_base, a_left)
+
+/* Right accessors. */
+#define trp_right_get(a_base, a_field, a_node) \
+ trpn_pointer(a_base, (a_node)->a_field.trpn_right)
+#define trp_right_set(a_base, a_field, a_node, a_right) \
+ (a_node)->a_field.trpn_right = trpn_offset(a_base, a_right)
+
+/* Priority accessors. */
+#define KNUTH_GOLDEN_RATIO_32BIT 2654435761u
+#define trp_prio_get(a_node) \
+ (KNUTH_GOLDEN_RATIO_32BIT*(uint32_t)(uintptr_t)(a_node))
+
+/* Node initializer. */
+#define trp_node_new(a_base, a_field, a_node) \
+ trp_left_set(a_base, a_field, (a_node), NULL); \
+ trp_right_set(a_base, a_field, (a_node), NULL)
+
+/* Internal utility macros. */
+#define trpn_rotate_left(a_base, a_field, a_node, r_node) \
+ do { (r_node) = trp_right_get(a_base, a_field, (a_node)); \
+ trp_right_set(a_base, a_field, (a_node), \
+ trp_left_get(a_base, a_field, (r_node))); \
+ trp_left_set(a_base, a_field, (r_node), (a_node)); } while(0)
+
+#define trpn_rotate_right(a_base, a_field, a_node, r_node) \
+ do { (r_node) = trp_left_get(a_base, a_field, (a_node)); \
+ trp_left_set(a_base, a_field, (a_node), \
+ trp_right_get(a_base, a_field, (r_node))); \
+ trp_right_set(a_base, a_field, (r_node), (a_node)); } while(0)
+
+#define trp_gen(a_attr, a_pre, a_type, a_field, a_base, a_cmp) \
+a_attr a_type *a_pre##psearch(struct trp_root *treap, a_type *key) \
+{ \
+ a_type *ret; \
+ a_type *tnode = trpn_pointer(a_base, treap->trp_root); \
+ ret = NULL; \
+ while (tnode != NULL) { \
+ int cmp = (a_cmp)(key, tnode); \
+ if (cmp < 0) \
+ tnode = trp_left_get(a_base, a_field, tnode); \
+ else if (cmp > 0) { \
+ ret = tnode; \
+ tnode = trp_right_get(a_base, a_field, tnode); \
+ } else { \
+ ret = tnode; \
+ break; \
+ } \
+ } \
+ return (ret); \
+} \
+a_attr a_type *a_pre##insert_recurse(a_type *cur_node, a_type *ins_node) \
+{ \
+ if (cur_node == NULL) \
+ return (ins_node); \
+ else { \
+ a_type *ret; \
+ int cmp = a_cmp(ins_node, cur_node); \
+ if (cmp < 0) { \
+ a_type *left = a_pre##insert_recurse( \
+ trp_left_get(a_base, a_field, cur_node), ins_node); \
+ trp_left_set(a_base, a_field, cur_node, left); \
+ if (trp_prio_get(left) < trp_prio_get(cur_node)) \
+ trpn_rotate_right(a_base, a_field, cur_node, ret); \
+ else \
+ ret = cur_node; \
+ } else { \
+ a_type *right = a_pre##insert_recurse( \
+ trp_right_get(a_base, a_field, cur_node), ins_node); \
+ trp_right_set(a_base, a_field, cur_node, right); \
+ if (trp_prio_get(right) < trp_prio_get(cur_node)) \
+ trpn_rotate_left(a_base, a_field, cur_node, ret); \
+ else \
+ ret = cur_node; \
+ } \
+ return (ret); \
+ } \
+} \
+a_attr void a_pre##insert(struct trp_root *treap, a_type *node) \
+{ \
+ trp_node_new(a_base, a_field, node); \
+ treap->trp_root = trpn_offset(a_base, a_pre##insert_recurse( \
+ trpn_pointer(a_base, treap->trp_root), \
+ node)); \
+}
+
+#endif
diff --git a/vcs-svn/trp.txt b/vcs-svn/trp.txt
new file mode 100644
index 0000000..7cf9b40
--- /dev/null
+++ b/vcs-svn/trp.txt
@@ -0,1 +1,61 @@
+TODO: Update this documentation to match the changes to trp.h
+
+The trp_gen() macro generates a type-specific treap implementation,
+based on the above cpp macros.
+
+Arguments:
+
+ a_attr : Function attribute for generated functions (ex: static).
+ a_pre : Prefix for generated functions (ex: treap_).
+ a_t_type : Type for treap data structure (ex: treap_t).
+ a_type : Type for treap node data structure (ex: treap_node_t).
+ a_field : Name of treap node linkage (ex: treap_link).
+ a_base : Expression for the base pointer from which nodes are offset.
+ a_cmp : Node comparison function name, with the following prototype:
+ int (a_cmp *)(a_type *a_node, a_type *a_other);
+ ^^^^^^
+ or a_key
+ Interpretation of comparision function return values:
+ -1 : a_node < a_other
+ 0 : a_node == a_other
+ 1 : a_node > a_other
+ In all cases, the a_node or a_key macro argument is the first
+ argument to the comparison function, which makes it possible
+ to write comparison functions that treat the first argument
+ specially.
+
+Assuming the following setup:
+
+ typedef struct ex_node_s ex_node_t;
+ struct ex_node_s {
+ trp_node(ex_node_t) ex_link;
+ };
+ typedef trp(ex_node_t) ex_t;
+ static ex_node_t ex_base[MAX_NODES];
+ trp_gen(static, ex_, ex_t, ex_node_t, ex_link, ex_base, ex_cmp)
+
+The following API is generated:
+
+ static void
+ ex_new(ex_t *treap);
+ Description: Initialize a treap structure.
+ Args:
+ treap: Pointer to an uninitialized treap object.
+
+ static ex_node_t *
+ ex_psearch(ex_t *treap, ex_node_t *key);
+ Description: Search for node that matches key. If no match is found,
+ return what would be key's successor/predecessor, were
+ key in treap.
+ Args:
+ treap: Pointer to a initialized treap object.
+ key : Search key.
+ Ret: Node in treap that matches key, or if no match, hypothetical
+ node's successor/predecessor (NULL if no successor/predecessor).
+
+ static void
+ ex_insert(ex_t *treap, ex_node_t *node);
+ Description: Insert node into treap.
+ Args:
+ treap: Pointer to a initialized treap object.
+ node : Node to be inserted into treap.
--
1.7.1
--
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