1.1 --- a/DynArray.h	Mon Sep 03 15:09:32 2012 -0700
     1.2 +++ b/DynArray.h	Fri Mar 08 05:37:45 2013 -0800
     1.3 @@ -12,16 +12,44 @@
     1.4  #include "PR_impl/Services_Offered_by_PR/Memory_Handling/vmalloc.h"
     1.5  
     1.6  
     1.7 -   //A dynamic array is same as any other array, but add a DynArrayInfo next
     1.8 -   // to it.  Accesses and updates of array indexes are done normally, it's
     1.9 -   // only when add a new element into array that use the extra info.
    1.10 -   // An add can cause the pointer to the normal array to change..  so must
    1.11 -   // be protected to single VP at a time.
    1.12 +
    1.13 +/*WARNING: Passing a DynArray as a param is dangerous if add to the DynArray
    1.14 + * inside the function called!   After adding or other operation that might
    1.15 + * change the size, must re-read the addr of the chunk of memory that is the
    1.16 + * array, via the DynArrayInfo.
    1.17 + *Here's why: An array variable is a location, either on the stack
    1.18 + * or in a field of a struct, whose contents is an addr.  That addr is of the
    1.19 + * first location of a chunk of locations.  The DynArray works by changing
    1.20 + * the chunk of locations, then modifying the contents of the original 
    1.21 + * array variable.  It overwrites the addr of the old chunk of locations
    1.22 + * with the addr of the new chunk.
    1.23 + *But when the array variable is passed as a parameter, such as 
    1.24 + * in this: "foo( myDynArray )", then there are now two locations that hold
    1.25 + * the addr of the same chunk of locations.  So when a call is made that
    1.26 + * adds to the DynArray, and inside the DynArray expands, it only updates
    1.27 + * the original location with  the new addr.  Hence, the function will begin
    1.28 + * overwriting memory past the end of the old chunk, because it still has 
    1.29 + * the pointer to the old chunk of locations.
    1.30 + *
    1.31 + *A dynamic array is accessed same as any other array.  However, must use
    1.32 + * dyn array calls, defined in here, in order to add or increase the size.
    1.33 + * Must re-read the original array variable after any size-changing calls.
    1.34 + *To pass a DynArray as a parameter to a function, can only pass the 
    1.35 + * DynArrayInfo, then inside the function, to read the addr of the first 
    1.36 + * location in the chunk of locations that is the array, do this:
    1.37 + * "localArrayCopy = *(myDynArrayInfo->addrOfPtrToArray).  After that, can 
    1.38 + * treat localArrayCopy as a normal array, as long as don't make any calls
    1.39 + * that add or otherwise could increase the size of the array.  If do make
    1.40 + * such a call, then re-copy the array via the above.  Can then use the
    1.41 + * copy up until another add to the array.
    1.42 + * 
    1.43 + */
    1.44  typedef struct
    1.45   {
    1.46 -   void ***addrOfPtrToArray; //addr of array of ptrs == triple *
    1.47 -   int32   numInArray;
    1.48 -   int32   sizeOfArray;
    1.49 +   void ***addrOfPtrToArray; //addr of var that is array of ptrs == triple *
    1.50 +   int32   numInArray;  //num entries added
    1.51 +   int32   sizeOfArray; //num elems alloc'd
    1.52 +   int32   sizeOfElem;  //num bytes in one elem of array -- used in 2nd version
    1.53   }
    1.54  PrivDynArrayInfo;
    1.55