QSort(31.0)	  ARP Programmers Manual	   QSort(31.0)



     FUNCTION
	  QSort	- Quickly sort whatever	you want.

     SYNOPSIS
	  stkerr = QSort( ptr, region_size, byte_size, user_func)
	    d0		  a0	      d0	  d1	     a1

     FUNCTION
	  QSort	is an implementation of	Hoares sorting algorithm.  It
	  uses a constant amount of stack no matter what the size of
	  the data.

     INPUTS
	  baseptr   - pointer to the start of a	memory region to be
		  sorted

	  region_size -	size of	region to be sorted, in	number of
		  elements (not	bytes!)

	  byte_size - size of a	single element,	in bytes.

	  user_function	- function to be provided by caller, which
		  compares two elements	from the set to	be sorted.
		  QSort	will call the user function like so:
		  return = user_function(el1, el2)
		   d0		   a0	 a1

		  Your function	must return the	following in D0:

		  if (el1 < el2) return	< 0
		  if (el1 > el2) return	> 0
		  if (el1 == el2) return = 0

		  You must save	all registers except a0, a1, d0, d1.
		  (See below for an example of a C calling sequence)

		  QSort	will also pass A5 to you unchanged.  You can use
		  this register	to point to pass information to	your
		  comparison routine.

     RETURNS
	  stkerr - -1 if everything is cool, 0 if there	was an
		  internal recursion stack overflow (not too likely).

     EXAMPLE:
	  Here is an example of	a calling sequence from	C, which is to
	  sort an array	of pointers to strings:
	  char **names;
	  long numEls;
	  extern    Cmp();

	  if (QSort(names, numELs, 4L, Cmp))



     Page 1					     (printed 2/22/88)






     QSort(31.0)	  ARP Programmers Manual	   QSort(31.0)



	       do whatever
	       else
	       STACK_ERROR()

	  the Cmp function would look like this:

	  Cmp()
	  {
	  {
	  #asm
	      public	 _geta4
	      movem.l d2-d3/a4/a6,-(sp)	; save important registers
	      movem.l a0/a1,-(sp)	; push args
	      bsr     _geta4
	      bsr     _cmp	   ; call real compare function
	      addq.l  #8,sp	   ; clean up args
	      movem.l (sp)+,d2-d3/a4/a6	; restore registers
	  #endasm
	  }
	  }

	  The cmp function called by the above is a normal C
	  function, it can be whatever you like.  Here is a sample
	  one:

	  cmp(s1,s2)
	  char **s1, **s2;
	  {
	       return strcmp(*a, *b);
	  }

     BUGS
	  None known.

     AUTHOR
	  SDB



















     Page 2					     (printed 2/22/88)