Array Manipulation Functions for C02

This library contains functions for handling non-string arrays. It is 
maintained separately from string.h so that it can be included only 
when needed, in order to reduce program size.

Arrays may be declared with up to 256 elements, but only lengths of up
to 255 characters may be passed to the array handling functions.

Usage: at the beginning of the program use the directives

  #include <memory.h02>
  
The following functions are defined:

  memdst(&d);         Sets array d as the destination array for subsequent
                      memchr(). memcmp(), strcpy(), and memset() calls.

                      This function is not part of the standard C and 
                      C++ string libraries. It is needed because of the 
                      parameter passing limitations of C02.

                      Note: Aliased to the setdst() routine which sets 
                      variables dstlo and dsthi as a pointer to the array.

  memset(c, n);       Fills first n bytes of the destination array set 
                      by a a prior memdst() call with character c.
                      
                      Note: dstlo and dsthi are left pointing to the
                      destination array.

  memclr(n, &s);      Memory Clear: Fills first n bytes of array s with 
                      the byte $00. 

                      Note: Calls memdst(&d) and memset(n,$00), leaving
                      dstlo and dsthi pointing to s.

  p = memchr(c, n);   Searches for character c in the first n bytes of the
                      destination array set by a a prior memdst() call. 
                      
                      Returns position of first occurance of character 
                      in array, or 255 if character was not found or a 
                      length of 0 was specified.

                      Note: dstlo and dsthi are left pointing to the
                      destination array.

  c = memcmp(n, &s);  Compares up to n bytes of source array s against the 
                      destination array set by a prior memdst() call.
                       
                      Returns 255 if destination < source, 0 if 
                      destination = source, and 1 if destination > source.

                      These results can be evaluated using the C02 
                      unary comparator ! or the test-operators :+ or :-.
                  
                      Note: dstlo and dsthi are left pointing to the
                      destination array.
                                    
  memcpy(n, &s);      Copies n bytes of source array s into destination 
                      array set by prior memdst() call. Data in the
                      destination array starting at position n is left
                      undisturbed.
                     
                      Note: dstlo and dsthi are left pointing to the
                      destination array.

  memswp(n, &s);      Swaps n bytes of source array s with destination 
                      array set by prior memdst() call. Data in both
                      arrays starting at position n is left undisturbed.
                       
                      Note: dstlo and dsthi are left pointing to the
                      destination array.

Note: This library expects the following functions to be defined

  setdst(&s);         Set destination string pointer
  setsrc(&s);         Set source string pointer and initialize index

along with the zero page pairs
  
  strlo, strhi        Source String Pointer 
  dstlo, dsthi        Destination String Pointer

and the memory locations

  temp0, temp1        Temporary storage