/* this routine allocates read buffers and generates stripe maps for the
* regions of the array from the start of the stripe to the start of the
* access, and from the end of the access to the end of the stripe. It also
* computes and returns the number of DAG nodes needed to read all this data.
* Note that this routine does the wrong thing if the access is fully
* contained within one stripe unit, so we RF_ASSERT against this case at the
* start.
*
* layoutPtr - in: layout information
* asmap - in: access stripe map
* dag_h - in: header of the dag to create
* new_asm_h - in: ptr to array of 2 headers. to be filled in
* nRodNodes - out: num nodes to be generated to read unaccessed data
* sosBuffer, eosBuffer - out: pointers to newly allocated buffer
*/