1 files changed, 114 insertions, 0 deletions
diff --git a/cpp/hash.c b/cpp/hash.c
new file mode 100644
index 0000000..3d340e8
--- /dev/null
+++ b/cpp/hash.c
@@ -0,0 +1,114 @@
+
+#include <stdio.h>
+#include <malloc.h>
+#include "cc.h"
+
+/*
+ * Two functions:
+ * char * set_entry(int namespace, char * name, void * value);
+ *        returns a pointer to the copy of the name;
+ *
+ * void * read_entry(int namespace, char * name);
+ *        returns the value;
+ */
+
+struct hashentry
+{
+   struct hashentry * next;
+   void * value;
+   int    namespace;
+   char	  word[1];
+};
+
+struct hashentry ** hashtable;
+int  hashsize  = 0xFF;	/* 2^X -1 */
+int  hashcount = 0;
+static int hashvalue();
+
+void *
+read_entry(namespace, word)
+int namespace;
+char * word;
+{
+   int hash_val;
+   struct hashentry * hashline;
+   if( hashtable == 0 ) return 0;
+   hash_val = hashvalue(namespace, word);
+
+   hashline = hashtable[hash_val];
+
+   for(; hashline; hashline = hashline->next)
+   {
+      if(namespace != hashline->namespace) continue;
+      if(word[0] != hashline->word[0])     continue;
+      if(strcmp(word, hashline->word) )    continue;
+      return hashline->value;
+   }
+   return 0;
+}
+
+char *
+set_entry(namespace, word, value)
+int namespace;
+char * word;
+void * value;
+{
+   int hash_val, i;
+   struct hashentry * hashline, *prev;
+   hash_val = hashvalue(namespace, word);
+
+   if( hashtable )
+   {
+      hashline = hashtable[hash_val];
+
+      for(prev=0; hashline; prev=hashline, hashline = hashline->next)
+      {
+         if(namespace != hashline->namespace) continue;
+         if(word[0] != hashline->word[0])     continue;
+         if(strcmp(word, hashline->word) )    continue;
+         if( value ) hashline->value = value;
+         else
+         {
+            if( prev == 0 ) hashtable[hash_val] = hashline->next;
+            else            prev->next = hashline->next;
+            free(hashline);
+            return 0;
+         }
+         return hashline->word;
+      }
+   }
+   if( value == 0 ) return 0;
+   if( hashtable == 0 )
+   {
+      hashtable = malloc((hashsize+1)*sizeof(char*));
+      if( hashtable == 0 ) cfatal("Out of memory");
+      for(i=0; i<=hashsize; i++) hashtable[i] = 0;
+   }
+   /* Add record */
+   hashline = malloc(sizeof(struct hashentry)+strlen(word));
+   if( hashline == 0 ) cfatal("Out of memory");
+   else
+   {
+      hashline->next  = hashtable[hash_val];
+      hashline->namespace = namespace;
+      hashline->value = value;
+      strcpy(hashline->word, word);
+      hashtable[hash_val] = hashline;
+   }
+   return hashline->word;
+}
+
+static int hashvalue(namespace, word)
+int namespace;
+char * word;
+{
+   int val = namespace;
+   char *p = word;
+
+   while(*p)
+   {
+      val = ((val<<4)^((val>>12)&0xF)^((*p++)&0xFF));
+   }
+   val &= hashsize;
+   return val;
+}