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table.c

@@ -0,0 +1,240 @@
+/*	$OpenBSD: table.c,v 1.5 1999/01/10 17:55:03 millert Exp $	*/
+
+/*
+ * dynamic hashed associative table for commands and variables
+ */
+
+#include "sh.h"
+
+#define	INIT_TBLS	8	/* initial table size (power of 2) */
+
+static void     texpand     ARGS((struct table *tp, int nsize));
+static int      tnamecmp    ARGS((void *p1, void *p2));
+
+
+unsigned int
+hash(n)
+	register const char * n;
+{
+	register unsigned int h = 0;
+
+	while (*n != '\0')
+		h = 2*h + *n++;
+	return h * 32821;	/* scatter bits */
+}
+
+void
+tinit(tp, ap, tsize)
+	register struct table *tp;
+	register Area *ap;
+	int tsize;
+{
+	tp->areap = ap;
+	tp->tbls = NULL;
+	tp->size = tp->nfree = 0;
+	if (tsize)
+		texpand(tp, tsize);
+}
+
+static void
+texpand(tp, nsize)
+	register struct table *tp;
+	int nsize;
+{
+	register int i;
+	register struct tbl *tblp, **p;
+	register struct tbl **ntblp, **otblp = tp->tbls;
+	int osize = tp->size;
+
+	ntblp = (struct tbl**) alloc(sizeofN(struct tbl *, nsize), tp->areap);
+	for (i = 0; i < nsize; i++)
+		ntblp[i] = NULL;
+	tp->size = nsize;
+	tp->nfree = 8*nsize/10;	/* table can get 80% full */
+	tp->tbls = ntblp;
+	if (otblp == NULL)
+		return;
+	for (i = 0; i < osize; i++)
+		if ((tblp = otblp[i]) != NULL) {
+			if ((tblp->flag&DEFINED)) {
+				for (p = &ntblp[hash(tblp->name)
+					  & (tp->size-1)];
+				     *p != NULL; p--)
+					if (p == ntblp) /* wrap */
+						p += tp->size;
+				*p = tblp;
+				tp->nfree--;
+			} else if (!(tblp->flag & FINUSE)) {
+				afree((void*)tblp, tp->areap);
+			}
+		}
+	afree((void*)otblp, tp->areap);
+}
+
+struct tbl *
+tsearch(tp, n, h)
+	register struct table *tp;	/* table */
+	register const char *n;		/* name to enter */
+	unsigned int h;			/* hash(n) */
+{
+	register struct tbl **pp, *p;
+
+	if (tp->size == 0)
+		return NULL;
+
+	/* search for name in hashed table */
+	for (pp = &tp->tbls[h & (tp->size-1)]; (p = *pp) != NULL; pp--) {
+		if (*p->name == *n && strcmp(p->name, n) == 0
+		    && (p->flag&DEFINED))
+			return p;
+		if (pp == tp->tbls) /* wrap */
+			pp += tp->size;
+	}
+
+	return NULL;
+}
+
+struct tbl *
+tenter(tp, n, h)
+	register struct table *tp;	/* table */
+	register const char *n;		/* name to enter */
+	unsigned int h;			/* hash(n) */
+{
+	register struct tbl **pp, *p;
+	register int len;
+
+	if (tp->size == 0)
+		texpand(tp, INIT_TBLS);
+  Search:
+	/* search for name in hashed table */
+	for (pp = &tp->tbls[h & (tp->size-1)]; (p = *pp) != NULL; pp--) {
+		if (*p->name == *n && strcmp(p->name, n) == 0)
+			return p; 	/* found */
+		if (pp == tp->tbls) /* wrap */
+			pp += tp->size;
+	}
+
+	if (tp->nfree <= 0) {	/* too full */
+		texpand(tp, 2*tp->size);
+		goto Search;
+	}
+
+	/* create new tbl entry */
+	len = strlen(n) + 1;
+	p = (struct tbl *) alloc(offsetof(struct tbl, name[0]) + len,
+				 tp->areap);
+	p->flag = 0;
+	p->type = 0;
+	p->areap = tp->areap;
+	p->u2.field = 0;
+	p->u.array = (struct tbl *)0;
+	memcpy(p->name, n, len);
+
+	/* enter in tp->tbls */
+	tp->nfree--;
+	*pp = p;
+	return p;
+}
+
+void
+tdelete(p)
+	register struct tbl *p;
+{
+	p->flag = 0;
+}
+
+void
+twalk(ts, tp)
+	struct tstate *ts;
+	struct table *tp;
+{
+	ts->left = tp->size;
+	ts->next = tp->tbls;
+}
+
+struct tbl *
+tnext(ts)
+	struct tstate *ts;
+{
+	while (--ts->left >= 0) {
+		struct tbl *p = *ts->next++;
+		if (p != NULL && (p->flag&DEFINED))
+			return p;
+	}
+	return NULL;
+}
+
+static int
+tnamecmp(p1, p2)
+	void *p1, *p2;
+{
+	return strcmp(((struct tbl *)p1)->name, ((struct tbl *)p2)->name);
+}
+
+struct tbl **
+tsort(tp)
+	register struct table *tp;
+{
+	register int i;
+	register struct tbl **p, **sp, **dp;
+
+	p = (struct tbl **)alloc(sizeofN(struct tbl *, tp->size+1), ATEMP);
+	sp = tp->tbls;		/* source */
+	dp = p;			/* dest */
+	for (i = 0; i < tp->size; i++)
+		if ((*dp = *sp++) != NULL && (((*dp)->flag&DEFINED) ||
+					      ((*dp)->flag&ARRAY)))
+			dp++;
+	i = dp - p;
+	qsortp((void**)p, (size_t)i, tnamecmp);
+	p[i] = NULL;
+	return p;
+}
+
+#ifdef PERF_DEBUG /* performance debugging */
+
+void tprintinfo ARGS((struct table *tp));
+
+void
+tprintinfo(tp)
+	struct table *tp;
+{
+	struct tbl *te;
+	char *n;
+	unsigned int h;
+	int ncmp;
+	int totncmp = 0, maxncmp = 0;
+	int nentries = 0;
+	struct tstate ts;
+
+	shellf("table size %d, nfree %d\n", tp->size, tp->nfree);
+	shellf("    Ncmp name\n");
+	twalk(&ts, tp);
+	while ((te = tnext(&ts))) {
+		register struct tbl **pp, *p;
+
+		h = hash(n = te->name);
+		ncmp = 0;
+
+		/* taken from tsearch() and added counter */
+		for (pp = &tp->tbls[h & (tp->size-1)]; (p = *pp); pp--) {
+			ncmp++;
+			if (*p->name == *n && strcmp(p->name, n) == 0
+			    && (p->flag&DEFINED))
+				break; /* return p; */
+			if (pp == tp->tbls) /* wrap */
+				pp += tp->size;
+		}
+		shellf("    %4d %s\n", ncmp, n);
+		totncmp += ncmp;
+		nentries++;
+		if (ncmp > maxncmp)
+			maxncmp = ncmp;
+	}
+	if (nentries)
+		shellf("  %d entries, worst ncmp %d, avg ncmp %d.%02d\n",
+			nentries, maxncmp,
+			totncmp / nentries,
+			(totncmp % nentries) * 100 / nentries);
+}
+#endif /* PERF_DEBUG */