C Program Preprocessor for Masscomp Array Processor

[Allan Chang]

          As a software engineering project, we are working on a
     C program preprocesor to enable programmers to take advan-
     tage of the computing power of the Masscomp Arrary Processor
     (AP-501).

          Use of the existing Array  Processor  Run-Time  Library
     requires  very detailed and laborious management by the pro-
     grammer. It is entirely the user's responsibility  to  allo-
     cate  and  free  the temporary array storage associated with
     array processor operations. Among the  notable  deficiencies
     of the library from the user's standpoint are a lack of rou-
     tines for managing the memory of the AP-501 and for sequenc-
     ing  vectors  that are too large to fit in the available AP-
     501  memory  space.  Also,  the  cryptic   subroutine   call
     sequences  necessary  to  perform useful operations are gen-
     erally unreadable.

          The preprocessor under development  will provide  means
     of accessing the array processor from within the C language 
     at a level of abstraction in conformity with the rest of C.
     At the present stage, we do not aim at recognizing portions 
     of code where it is appropriate to replace conventional
     element-by-element operations with vector operations, e.g.,
     eliminating loops.  Rather, we assume user's responsibility
     to write program segments  that explicitly require use
     of the array processor.  In terms of  data  structures,  the
     goal  is to have arrays appear to the user as elemental data
     structures that can be manipulated much as they  can  be  in
     APL.  Other  important  tasks  for  the  project  will  be 
     management  of  the AP-501  memory and  sequencing  of large
     vectors through the processor.

          The project will be developed with  the  following  two
     long-range goals: extension of  the preprocessor  to provide
     output for Fortran or other compilers, and a simple software
     simulation   of  the array  processor on machines not other-
     wise having that capability. It is one of our goals to fit
     into an existing syntax or usage framework if such exists.

          We would appreciate any information on existing similar
     systems (or publications) that would provide guidelines for 
     our work. We would welcome any concrete suggestions on syntax
     of array operation statements for the C language. At the 
     initial design stage, any enlightening information will be a
     big help, and will be thankfully so acknowledged. 

          
          If you can provide help, please contact
           
                    Robert Weir, Project Director
                    Department of Computer Science
                    UNC at Chapel Hill
                    Chapel Hill, NC 27514

             or at (919)-962-5698