Left-leaning red-black tree data structure

Implement library functions for "left-leaning red-black trees" with
uint64_t keys.  This is meant for looking up symbols by address in the
backends that need to do so, e.g. ELF.

A good question is if there is a better way to do this, that recovers
the original symbol, but that's a future issue.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Makefile.in

@@ -59,7 +59,7 @@ X               = @EXEEXT@
 	$(NROFF) -man $< > $@
 
 #-- Begin File Lists --#
-NASM =	nasm.$(O) nasmlib.$(O) raa.$(O) saa.$(O) \
+NASM =	nasm.$(O) nasmlib.$(O) raa.$(O) saa.$(O) rbtree.$(O) \
 	float.$(O) insnsa.$(O) insnsb.$(O) \
 	assemble.$(O) labels.$(O) hashtbl.$(O) crc64.$(O) parser.$(O) \
 	outform.$(O) outlib.$(O) output/outbin.$(O) \
@@ -319,6 +319,7 @@ preproc.$(O): preproc.c compiler.h config.h hashtbl.h insnsi.h nasm.h \
  version.h
 quote.$(O): quote.c compiler.h config.h nasmlib.h quote.h
 raa.$(O): raa.c compiler.h config.h nasmlib.h raa.h
+rbtree.$(O): rbtree.c compiler.h config.h nasmlib.h rbtree.h
 regdis.$(O): regdis.c regdis.h regs.h
 regflags.$(O): regflags.c compiler.h config.h insnsi.h nasm.h nasmlib.h \
  pptok.h preproc.h regs.h tables.h version.h

Mkfiles/msvc.mak

@@ -34,7 +34,7 @@ X               = .exe
 
 #-- Begin File Lists --#
 # Edit in Makefile.in, not here!
-NASM =	nasm.$(O) nasmlib.$(O) raa.$(O) saa.$(O) \
+NASM =	nasm.$(O) nasmlib.$(O) raa.$(O) saa.$(O) rbtree.$(O) \
 	float.$(O) insnsa.$(O) insnsb.$(O) \
 	assemble.$(O) labels.$(O) hashtbl.$(O) crc64.$(O) parser.$(O) \
 	outform.$(O) outlib.$(O) output/outbin.$(O) \
@@ -252,6 +252,7 @@ preproc.$(O): preproc.c compiler.h hashtbl.h insnsi.h nasm.h nasmlib.h \
  pptok.h preproc.h quote.h regs.h stdscan.h tables.h tokens.h version.h
 quote.$(O): quote.c compiler.h nasmlib.h quote.h
 raa.$(O): raa.c compiler.h nasmlib.h raa.h
+rbtree.$(O): rbtree.c compiler.h nasmlib.h rbtree.h
 regdis.$(O): regdis.c regdis.h regs.h
 regflags.$(O): regflags.c compiler.h insnsi.h nasm.h nasmlib.h pptok.h \
  preproc.h regs.h tables.h version.h

Mkfiles/netware.mak

@@ -30,7 +30,7 @@ O = o
 
 #-- Begin File Lists --#
 # Edit in Makefile.in, not here!
-NASM =	nasm.o nasmlib.o raa.o saa.o \
+NASM =	nasm.o nasmlib.o raa.o saa.o rbtree.o \
 	float.o insnsa.o insnsb.o \
 	assemble.o labels.o hashtbl.o crc64.o parser.o \
 	outform.o outlib.o outbin.o \
@@ -194,6 +194,7 @@ preproc.o: preproc.c compiler.h config.h hashtbl.h insnsi.h nasm.h nasmlib.h \
  pptok.h preproc.h quote.h regs.h stdscan.h tables.h tokens.h version.h
 quote.o: quote.c compiler.h config.h nasmlib.h quote.h
 raa.o: raa.c compiler.h config.h nasmlib.h raa.h
+rbtree.o: rbtree.c compiler.h config.h nasmlib.h rbtree.h
 regdis.o: regdis.c regdis.h regs.h
 regflags.o: regflags.c compiler.h config.h insnsi.h nasm.h nasmlib.h pptok.h \
  preproc.h regs.h tables.h version.h

Mkfiles/openwcom.mak

@@ -46,7 +46,7 @@ X               = .exe
 # Note: wcl386 is broken if forward slashes are used as path separators.
 #-- Begin File Lists --#
 # Edit in Makefile.in, not here!
-NASM =	nasm.$(O) nasmlib.$(O) raa.$(O) saa.$(O) &
+NASM =	nasm.$(O) nasmlib.$(O) raa.$(O) saa.$(O) rbtree.$(O) &
 	float.$(O) insnsa.$(O) insnsb.$(O) &
 	assemble.$(O) labels.$(O) hashtbl.$(O) crc64.$(O) parser.$(O) &
 	outform.$(O) outlib.$(O) output\outbin.$(O) &
@@ -281,6 +281,7 @@ preproc.$(O): preproc.c compiler.h hashtbl.h insnsi.h nasm.h nasmlib.h &
  pptok.h preproc.h quote.h regs.h stdscan.h tables.h tokens.h version.h
 quote.$(O): quote.c compiler.h nasmlib.h quote.h
 raa.$(O): raa.c compiler.h nasmlib.h raa.h
+rbtree.$(O): rbtree.c compiler.h nasmlib.h rbtree.h
 regdis.$(O): regdis.c regdis.h regs.h
 regflags.$(O): regflags.c compiler.h insnsi.h nasm.h nasmlib.h pptok.h &
  preproc.h regs.h tables.h version.h

Mkfiles/owlinux.mak

@@ -57,7 +57,7 @@ X               = .exe
 
 #-- Begin File Lists --#
 # Edit in Makefile.in, not here!
-NASM =	nasm.$(O) nasmlib.$(O) raa.$(O) saa.$(O) \
+NASM =	nasm.$(O) nasmlib.$(O) raa.$(O) saa.$(O) rbtree.$(O) \
 	float.$(O) insnsa.$(O) insnsb.$(O) \
 	assemble.$(O) labels.$(O) hashtbl.$(O) crc64.$(O) parser.$(O) \
 	outform.$(O) outlib.$(O) output/outbin.$(O) \
@@ -291,6 +291,7 @@ preproc.$(O): preproc.c compiler.h hashtbl.h insnsi.h nasm.h nasmlib.h \
  pptok.h preproc.h quote.h regs.h stdscan.h tables.h tokens.h version.h
 quote.$(O): quote.c compiler.h nasmlib.h quote.h
 raa.$(O): raa.c compiler.h nasmlib.h raa.h
+rbtree.$(O): rbtree.c compiler.h nasmlib.h rbtree.h
 regdis.$(O): regdis.c regdis.h regs.h
 regflags.$(O): regflags.c compiler.h insnsi.h nasm.h nasmlib.h pptok.h \
  preproc.h regs.h tables.h version.h

rbtree.c

@@ -0,0 +1,100 @@
+/*
+ * rbtree.c
+ *
+ * Simple implementation of a left-leaning red-black tree with 64-bit
+ * integer keys.  The search operation will return the highest node <=
+ * the key; only search, insert, and full-tree deletion is supported,
+ * but additional standard llrbtree operations can be coded up at will.
+ *
+ * See http://www.cs.princeton.edu/~rs/talks/LLRB/RedBlack.pdf for
+ * information about left-leaning red-black trees.
+ */
+
+#include "rbtree.h"
+#include "nasmlib.h"
+
+const struct rbtree *rb_search(const struct rbtree *tree, uint64_t key)
+{
+    const struct rbtree *best = NULL;
+
+    while (tree) {
+	if (tree->key == key)
+	    return tree;
+	else if (tree->key > key)
+	    tree = tree->left;
+	else {
+	    best = tree;
+	    tree = tree->right;
+	}
+    }
+    return best;
+}
+
+static bool is_red(struct rbtree *h)
+{
+    return h && h->red;
+}
+
+static struct rbtree *rotate_left(struct rbtree *h)
+{
+    struct rbtree *x = h->right;
+    h->right = x->left;
+    x->left = h;
+    x->red = x->left->red;
+    x->left->red = true;
+    return x;
+}
+
+static struct rbtree *rotate_right(struct rbtree *h)
+{
+    struct rbtree *x = h->left;
+    h->left = x->right;
+    x->right = h;
+    x->red = x->right->red;
+    x->right->red = true;
+    return x;
+}
+
+static void color_flip(struct rbtree *h)
+{
+    h->red = !h->red;
+    h->left->red = !h->left->red;
+    h->right->red = !h->right->red;
+}
+
+struct rbtree *rb_insert(struct rbtree *tree, uint64_t key, void *data)
+{
+    if (!tree) {
+	struct rbtree *node = nasm_malloc(sizeof *node);
+    
+	node->key   = key;
+	node->data  = data;
+	node->red   = true;
+	return node;
+    }
+
+    if (is_red(tree->left) && is_red(tree->right))
+	color_flip(tree);
+
+    if (key < tree->key)
+	tree->left = rb_insert(tree->left, key, data);
+    else
+	tree->right = rb_insert(tree->right, key, data);
+
+    if (is_red(tree->right))
+	tree = rotate_left(tree);
+
+    if (is_red(tree->left) && is_red(tree->left->left))
+	tree = rotate_right(tree);
+
+    return tree;
+}
+
+void rb_free(struct rbtree *tree)
+{
+    if (tree) {
+	rb_free(tree->left);
+	rb_free(tree->right);
+	nasm_free(tree);
+    }
+}

rbtree.h

@@ -0,0 +1,18 @@
+#ifndef NASM_RBTREE_H
+#define NASM_RBTREE_H
+
+#include "compiler.h"
+#include <inttypes.h>
+
+struct rbtree {
+    uint64_t key;
+    void *data;
+    struct rbtree *left, *right;
+    bool red;
+};
+
+struct rbtree *rb_insert(struct rbtree *, uint64_t, void *);
+const struct rbtree *rb_search(const struct rbtree *, uint64_t);
+void rb_free(struct rbtree *);
+
+#endif /* NASM_RBTREE_H */