add btAlignPointer template and use it in serializer/allocator

this should fix Issue 559

src/LinearMath/btAlignedAllocator.cpp

@@ -58,16 +58,18 @@ static inline void btAlignedFreeDefault(void *ptr)
 	free(ptr);
 }
 #else
+
+
+
+
+
 static inline void *btAlignedAllocDefault(size_t size, int alignment)
 {
   void *ret;
   char *real;
-  unsigned long offset;
-
   real = (char *)sAllocFunc(size + sizeof(void *) + (alignment-1));
   if (real) {
-    offset = (alignment - (unsigned long)(real + sizeof(void *))) & (alignment-1);
-    ret = (void *)((real + sizeof(void *)) + offset);
+	ret = btAlignPointer(real + sizeof(void *),alignment);
     *((void **)(ret)-1) = (void *)(real);
   } else {
     ret = (void *)(real);
@@ -110,7 +112,6 @@ void*   btAlignedAllocInternal  (size_t size, int alignment,int line,char* filen
 {
  void *ret;
  char *real;
- unsigned long offset;
 
  gTotalBytesAlignedAllocs += size;
  gNumAlignedAllocs++;
@@ -118,9 +119,7 @@ void*   btAlignedAllocInternal  (size_t size, int alignment,int line,char* filen
  
  real = (char *)sAllocFunc(size + 2*sizeof(void *) + (alignment-1));
  if (real) {
-   offset = (alignment - (unsigned long)(real + 2*sizeof(void *))) &
-(alignment-1);
-   ret = (void *)((real + 2*sizeof(void *)) + offset);
+   ret = (void*) btAlignPointer((real + 2*sizeof(void *), alignment);
    *((void **)(ret)-1) = (void *)(real);
        *((int*)(ret)-2) = size;
 

src/LinearMath/btScalar.h

@@ -519,4 +519,21 @@ struct btTypedObject
 		return m_objectType;
 	}
 };
+
+
+///align a pointer to the provided alignment, upwards
+template <typename T>T* btAlignPointer(T* unalignedPtr, size_t alignment)
+{
+        union
+        {
+                T* ptr;
+                size_t integer;
+        };
+        const size_t bit_mask = ~(alignment - 1);
+        ptr = unalignedPtr;
+		integer += alignment-1;
+        integer &= bit_mask;
+        return ptr;
+}
+
 #endif //BT_SCALAR_H

src/LinearMath/btSerializer.h

@@ -246,15 +246,7 @@ protected:
 				while (*cp)cp++;
 				cp++;
 			}
-			{
-				nr= (long)cp;
-			//	long mask=3;
-				nr= ((nr+3)&~3)-nr;
-				while (nr--)
-				{
-					cp++;
-				}
-			}
+			cp = btAlignPointer(cp,4);
 
 			/*
 				TYPE (4 bytes)
@@ -281,15 +273,7 @@ protected:
 				cp++;
 			}
 
-		{
-				nr= (long)cp;
-			//	long mask=3;
-				nr= ((nr+3)&~3)-nr;
-				while (nr--)
-				{
-					cp++;
-				}
-			}
+			cp = btAlignPointer(cp,4);
 
 
 			/*