Utility Functions for C02 Library Functions

This module contains miscellaneous functions that aren't suited for
inclusion in any of the existing modules.

The contents of this module are subject to change, as any of the 
functions may be deprecated or moved to other modules in the future.

At the beginning of the program use the directives

  #include <stddef.h02>
  #include <util.h02>

The following functions are defined:

  addzpw(z,&n);         Adds the 16 bit value &n to the zero page word 
                        with address z.

                        Note: Stores the zero page address in temp3.

  adddst(&n);           Adds the 16 bit value &n to the destination 
                        pointer.
  
                        Note: Calls the addzpw function, passing dstlo
                        as the first argument.

  addsrc(&n);           Adds the 16 bit value &n to the source pointer.
  
                        Note: Calls the addzpw function, passing srclo
                        as the first argument.

Note: This library expects the following to be defined:

the zero page variables

  srclo,srchi:          Source pointer
  dstlo,dsthi:          Destination pointer

and the transient variables
  
  temp0                 Temporary storage (Accumulator)
  temp1                 Temporary storage (X-Index/LSB)
  temp2                 Temporary storage (Y-Index/MSB)
  temp3                 Temporary storage (Zero Page Address)