X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/20eb516fdebd2fb901e6a09ffa7e741cfb8e3a83..7292c4c6e2b50cc43f17507745ff6c3e2d0057f3:/sym.c

diff --git a/sym.c b/sym.c
index 4e11fba..3aea8c7 100644
--- a/sym.c
+++ b/sym.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: sym.c,v 1.11 2000/06/17 10:37:39 mdw Exp $
+ * $Id: sym.c,v 1.13 2001/01/25 21:14:49 mdw Exp $
  *
  * Symbol table management
  *
@@ -30,6 +30,15 @@
 /*----- Revision history --------------------------------------------------*
  *
  * $Log: sym.c,v $
+ * Revision 1.13  2001/01/25 21:14:49  mdw
+ * Always add a terminating null, and don't count it in the length.
+ *
+ * Revision 1.12  2001/01/20 11:49:37  mdw
+ * Export tuning parameters from header file, for the benefit of other
+ * hashtable implementations.  Change the storage of symbol names: store
+ * the name after the allocated symbol block in all cases.  This replaces
+ * the previous complicated and slightly wasteful arrangement.
+ *
  * Revision 1.11  2000/06/17 10:37:39  mdw
  * Add support for arena management.
  *
@@ -85,27 +94,6 @@
 #include "sub.h"
 #include "sym.h"
 
-/*----- Tuning parameters -------------------------------------------------*/
-
-/* --- Initial hash table size --- *
- *
- * This is the initial @mask@ value.  It must be of the form %$2^n - 1$%,
- * so that it can be used to mask of the bottom bits of a hash value.
- */
-
-#define SYM_INITSZ 64			/* Size of a new hash table */
-
-/* --- Maximum load factor --- *
- *
- * This parameter controls how much the table has to be loaded before the
- * table is extended.  The number of elements %$n$%, the number of bins %$b$%
- * and the limit %$l$% satisfy the relation %$n < bl$%; if a new item is
- * added to the table and this relation is found to be false, the table is
- * doubled in size.
- */
-
-#define SYM_LIMIT(n) ((n) * 2)		/* Load factor for growing table */
-
 /*----- Main code ---------------------------------------------------------*/
 
 /* --- @sym_create@ --- *
@@ -145,8 +133,6 @@ void sym_destroy(sym_table *t)
     SYM_NEXT(&i, p);
     if (!p)
       break;
-    if (p->len > SYM_BUFSZ)
-      subarena_free(t->s, p->name.p, p->len);
     x_free(t->t.a, p);
   }
   hash_destroy(&t->t);
@@ -192,7 +178,7 @@ void *sym_find(sym_table *t, const char *n, long l, size_t sz, unsigned *f)
 
   /* --- Find the correct bin --- */
 
-  len = l < 0 ? strlen(n) + 1 : l;
+  len = l < 0 ? strlen(n) : l;
   CRC32(hash, 0, n, len);
   bin = HASH_BIN(&t->t, hash);
 
@@ -224,21 +210,18 @@ void *sym_find(sym_table *t, const char *n, long l, size_t sz, unsigned *f)
   if (f) *f = 0;
   if (!sz) return (0);
 
-  /* --- Create a new symbol block and initialize it --- */
+  /* --- Create a new symbol block and initialize it --- *
+   *
+   * The name is attached to the end of the symbol block.
+   */
 
-  q = x_alloc(t->t.a, sz);
+  q = x_alloc(t->t.a, sz + len + 1);
   q->b.next = *bin;
   q->b.hash = hash;
+  q->name = (char *)q + sz;
+  memcpy(q->name, n, len);
+  q->name[len] = 0;
   q->len = len;
-  if (n) {
-    if (len <= SYM_BUFSZ)
-      memcpy(q->name.b, n, len);
-    else {
-      q->name.p = subarena_alloc(t->s, len);
-      memcpy(q->name.p, n, len);
-    }
-  }
-
   *bin = &q->b;
 
   /* --- Consider growing the array --- */
@@ -246,7 +229,7 @@ void *sym_find(sym_table *t, const char *n, long l, size_t sz, unsigned *f)
   if (t->load)
     t->load--;
   if (!t->load && hash_extend(&t->t))
-    t->load = SYM_LIMIT(t->t.mask / 2 + 1);
+    t->load = SYM_LIMIT(t->t.mask + 1);
 
   /* --- Finished that, so return the new symbol block --- */
 
@@ -269,8 +252,6 @@ void sym_remove(sym_table *t, void *p)
 {
   sym_base *q = p;
   hash_remove(&t->t, &q->b);
-  if (q->len > SYM_BUFSZ)
-    subarena_free(t->s, q->name.p, q->len);
   xfree(q);
   t->load++;
 }