Integration of OCCT 6.5.0 from SVN

src/TCollection/TCollection.cxx

@@ -0,0 +1,45 @@
+
+// File:	TCollection.cxx
+// Created:	Thu Jan 14 16:15:39 1993
+// Author:	Remi LEQUETTE
+//		<rle@phylox>
+
+#include <TCollection.ixx>
+
+// The array of prime numbers used as consequtive steps for 
+// size of array of buckets in the map.
+//
+// The prime numbers are used for array size with the hope that this will 
+// lead to less probablility of having the same hash codes for
+// different map items (note that all hash codes are modulo that size).
+//
+// The value of each next step is chosen to be ~2 times greater than previous.
+// Though this could be thought as too much, actually the amount of 
+// memory overhead in that case is only ~15% as compared with total size of
+// all auxiliary data structures (each map node takes ~24 bytes), 
+// and this proves to pay off in performance (see OCC13189).
+
+#define NB_PRIMES 12
+static const Standard_Integer Primes[NB_PRIMES+1] = {
+     101,
+    1009,
+    2003,
+    5003,
+   10007,
+   20011,
+   37003,
+   57037,
+   65003,
+  100019,
+  209953,   // The following are Pierpont primes taken from Wikipedia [List of prime numbers]
+  472393,
+  995329
+};  
+
+Standard_Integer TCollection::NextPrimeForMap(const Standard_Integer N)
+{
+  Standard_Integer i;
+  for (i = 0; i < NB_PRIMES; i++) 
+    if (Primes[i] > N) break;
+  return Primes[i];
+}