1 files changed, 23 insertions, 20 deletions

diff --git a/src/hash.c b/src/hash.c
index 8ec043f11..c822cb5f1 100644
--- a/src/hash.c
+++ b/src/hash.c
@@ -55,11 +55,19 @@ void sqlite3HashClear(Hash *pH){
 static unsigned int strHash(const char *z){
   unsigned int h = 0;
   unsigned char c;
-  while( (c = (unsigned char)*z++)!=0 ){     /*OPTIMIZATION-IF-TRUE*/
+  while( z[0] ){     /*OPTIMIZATION-IF-TRUE*/
     /* Knuth multiplicative hashing.  (Sorting & Searching, p. 510).
     ** 0x9e3779b1 is 2654435761 which is the closest prime number to
-    ** (2**32)*golden_ratio, where golden_ratio = (sqrt(5) - 1)/2. */
-    h += sqlite3UpperToLower[c];
+    ** (2**32)*golden_ratio, where golden_ratio = (sqrt(5) - 1)/2.
+    **
+    ** Only bits 0xdf for ASCII and bits 0xbf for EBCDIC each octet are
+    ** hashed since the omitted bits determine the upper/lower case difference.
+    */
+#ifdef SQLITE_EBCDIC
+    h += 0xbf & (unsigned char)*(z++);
+#else
+    h += 0xdf & (unsigned char)*(z++);
+#endif
     h *= 0x9e3779b1;
   }
   return h;
@@ -132,9 +140,8 @@ static int rehash(Hash *pH, unsigned int new_size){
   pH->htsize = new_size = sqlite3MallocSize(new_ht)/sizeof(struct _ht);
   memset(new_ht, 0, new_size*sizeof(struct _ht));
   for(elem=pH->first, pH->first=0; elem; elem = next_elem){
-    unsigned int h = strHash(elem->pKey) % new_size;
     next_elem = elem->next;
-    insertElement(pH, &new_ht[h], elem);
+    insertElement(pH, &new_ht[elem->h % new_size], elem);
   }
   return 1;
 }
@@ -154,21 +161,20 @@ static HashElem *findElementWithHash(
   unsigned int h;                /* The computed hash */
   static HashElem nullElement = { 0, 0, 0, 0 };
 
+  h = strHash(pKey);
   if( pH->ht ){   /*OPTIMIZATION-IF-TRUE*/
     struct _ht *pEntry;
-    h = strHash(pKey) % pH->htsize;
-    pEntry = &pH->ht[h];
+    pEntry = &pH->ht[h % pH->htsize];
     elem = pEntry->chain;
     count = pEntry->count;
   }else{
-    h = 0;
     elem = pH->first;
     count = pH->count;
   }
   if( pHash ) *pHash = h;
   while( count ){
     assert( elem!=0 );
-    if( sqlite3StrICmp(elem->pKey,pKey)==0 ){ 
+    if( h==elem->h && sqlite3StrICmp(elem->pKey,pKey)==0 ){ 
       return elem;
     }
     elem = elem->next;
@@ -180,10 +186,9 @@ static HashElem *findElementWithHash(
 /* Remove a single entry from the hash table given a pointer to that
 ** element and a hash on the element's key.
 */
-static void removeElementGivenHash(
+static void removeElement(
   Hash *pH,         /* The pH containing "elem" */
-  HashElem* elem,   /* The element to be removed from the pH */
-  unsigned int h    /* Hash value for the element */
+  HashElem *elem    /* The element to be removed from the pH */
 ){
   struct _ht *pEntry;
   if( elem->prev ){
@@ -195,7 +200,7 @@ static void removeElementGivenHash(
     elem->next->prev = elem->prev;
   }
   if( pH->ht ){
-    pEntry = &pH->ht[h];
+    pEntry = &pH->ht[elem->h % pH->htsize];
     if( pEntry->chain==elem ){
       pEntry->chain = elem->next;
     }
@@ -246,7 +251,7 @@ void *sqlite3HashInsert(Hash *pH, const char *pKey, void *data){
   if( elem->data ){
     void *old_data = elem->data;
     if( data==0 ){
-      removeElementGivenHash(pH,elem,h);
+      removeElement(pH,elem);
     }else{
       elem->data = data;
       elem->pKey = pKey;
@@ -257,14 +262,12 @@ void *sqlite3HashInsert(Hash *pH, const char *pKey, void *data){
   new_elem = (HashElem*)sqlite3Malloc( sizeof(HashElem) );
   if( new_elem==0 ) return data;
   new_elem->pKey = pKey;
+  new_elem->h = h;
   new_elem->data = data;
   pH->count++;
-  if( pH->count>=10 && pH->count > 2*pH->htsize ){
-    if( rehash(pH, pH->count*2) ){
-      assert( pH->htsize>0 );
-      h = strHash(pKey) % pH->htsize;
-    }
+  if( pH->count>=5 && pH->count > 2*pH->htsize ){
+    rehash(pH, pH->count*3);
   }
-  insertElement(pH, pH->ht ? &pH->ht[h] : 0, new_elem);
+  insertElement(pH, pH->ht ? &pH->ht[new_elem->h % pH->htsize] : 0, new_elem);
   return 0;
 }