comparison stitch/wrap.h @ 0:5242703e91d3 tip

Initial checkin for AIM92 aimR8.2 (last updated May 1997).

+/*
+    wrap.h
+    ======
+
+    wrap alocations with debugging information for program verifiaction.
+
+*/
+
+/*
+    The following routines "wrap" memory with a frame as it is  allocated.
+    The  information  in the frame is sufficient to check if the bounds of
+    the alloacation have been exceeded.  Part of the frame is  used  as  a
+    pointer for a linked list  which  is  also  assembled  containing  all
+    allocated  memory  chunks.  This  enables  a  call  at any time to the
+    routine "checkWrapping()" to examine all  the  frames  of  all  memory
+    allocations for corruption while an application runs.
+
+
+	Memory map of a framed allocation after "wrapping"
+
+		   +--------------+
+	   head--> | struct _head |
+		   +--------------+
+	wrapped--> |  user data   |
+		   |      .       |
+		   |      .       |
+		   |      .       |
+		   |              |
+		   +--------------+
+	   tail--> | struct _tail |
+		   +--------------+
+
+
+    On allocation the  pointer  returned  from  tyhe  system  becomes  the
+    pointer  to  in instance of the stucture "_head".  A tail structure is
+    then constructed containing a repeat of the size feild of  the  header
+    for  consistency  checking  and a pointer to the previous allocation's
+    frame.  The user receives a pointer to  the  memory  bytes  availiable
+    after  the  head  structure  and  is therefore unaware of the wrapping
+    process.  On deallocation or reallocation the framed memory is  simply
+    unwrapped  by the reverse process checking for corruption before being
+    passed to the system memory allocation routines.
+
+*/
+
+/* bits rounded up in alligning the tail structure */
+
+#define BITS_ROUND 4
+
+/* rounds up byte size specification to ensure tail structure's elements are aligned */
+
+#define ROUNDUP( _size ) ( ( _size ) + ( 1 << BITS_ROUND ) - 1 >> BITS_ROUND << BITS_ROUND )
+
+/* Calculates the size required for the wrapped allocation including frame. */
+
+#define WRAPPED_SIZE( _size ) ( ROUNDUP( sizeof ( struct _head ) ) + ROUNDUP( _size ) + sizeof( struct _tail ) )
+
+
+struct _head { char *where ; struct _head **pointing, *previous ; unsigned size ; } ;
+struct _tail { unsigned size ; } ;
+
+extern Pointer wrap( /* char   *mem, unsigned size, char where[] */ ) ;
+extern char *unwrap( /* Pointer mem, unsigned size               */ ) ;
+
+