+/* align addr on a size boundary - adjust address up/down if needed */
+#define _ALIGN_UP(addr,size) (((addr)+((size)-1))&(~((size)-1)))
+#define _ALIGN_DOWN(addr,size) ((addr)&(~((size)-1)))
+
+/* align addr on a size boundary - adjust address up if needed */
+#define _ALIGN(addr,size) _ALIGN_UP(addr,size)
+
+/* to align the pointer to the (next) page boundary */
+#define PAGE_ALIGN(addr) _ALIGN(addr, PAGE_SIZE)
+
+