Initial source commit

gamma256/gameSource/HashTable.h

@@ -0,0 +1,133 @@
+template <class Type> 
+class HashTable {
+    
+    public:
+        
+        HashTable( int inSize );
+        
+        ~HashTable();
+        
+        Type lookup( int inKeyA, int inKeyB, char *outFound );
+        
+        void insert( int inKeyA, int inKeyB, Type inItem );
+        
+        // flush all entries from table
+        void clear();
+        
+        
+    private:
+        int mSize;
+        
+        Type *mTable;
+        char *mSetFlags;
+
+        int *mKeysA;
+        int *mKeysB;
+        
+        int mHitCount;
+        int mMissCount;
+
+        int computeHash( int inKeyA, int inKeyB );
+        
+    };
+
+
+
+// Wow... never new that template function implementations must be in the
+// same file as the declaration
+
+
+template <class Type> 
+HashTable<Type>::HashTable( int inSize )
+        : mSize( inSize ),
+          mTable( new Type[ inSize ] ),
+          mSetFlags( new char[ inSize ] ),
+          mKeysA( new int[ inSize ] ),
+          mKeysB( new int[ inSize ] ),
+          mHitCount( 0 ),
+          mMissCount( 0 ) {
+    
+
+    clear();
+        
+    }
+
+
+
+#include <stdio.h>
+
+        
+template <class Type> 
+HashTable<Type>::~HashTable() {
+    delete [] mTable;
+    delete [] mSetFlags;
+    delete [] mKeysA;
+    delete [] mKeysB;
+
+    printf( "%d hits, %d misses, %f hit ratio\n", 
+            mHitCount, mMissCount, 
+            mHitCount / (double)( mHitCount + mMissCount ) );
+    }
+
+
+
+template <class Type> 
+inline int HashTable<Type>::computeHash( int inKeyA, int inKeyB ) {
+    
+    int hashKey = ( inKeyA * 734727 + inKeyB * 263474 ) % mSize;
+    if( hashKey < 0 ) {
+        hashKey += mSize;
+        }
+    return hashKey;
+    }
+
+
+        
+template <class Type> 
+Type HashTable<Type>::lookup( int inKeyA, int inKeyB, char *outFound ) {
+    
+    int hashKey = computeHash( inKeyA, inKeyB );
+    
+    if( mSetFlags[ hashKey ]
+        &&
+        mKeysA[ hashKey ] == inKeyA
+        &&
+        mKeysB[ hashKey ] == inKeyB ) {
+    
+        // hit
+        mHitCount ++;
+        
+        *outFound = true;
+        }
+    else {
+        // miss
+        mMissCount ++;
+        
+        *outFound = false;
+        }
+    
+    return mTable[ hashKey ];
+    }
+
+
+
+template <class Type> 
+void HashTable<Type>::insert( int inKeyA, int inKeyB, Type inItem ) {
+    
+    int hashKey = computeHash( inKeyA, inKeyB );
+
+    mSetFlags[ hashKey ] = true;
+    mKeysA[ hashKey ] = inKeyA;
+    mKeysB[ hashKey ] = inKeyB;
+    mTable[ hashKey ] = inItem;
+    }
+
+
+
+template <class Type> 
+void HashTable<Type>::clear() {
+    
+    for( int i=0; i<mSize; i++ ) {
+        mSetFlags[i] = false;
+        }
+    }