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--- base:quicksort_16-bit_elements [2016-08-18 12:20] – litwr2
+++ base:quicksort_16-bit_elements [2016-08-30 22:28] – a fix for an array address >= $8000 litwr2
@@ Line 2: / Line 2: @@
 by Vladimir Lidovski aka litwr, 13 Aug 2016 (with help of BigEd)
-It is well known that the best, the fastest sort routine is Quicksort.  It is very odd that it is not implemented for 6502 for all of 42 years, from 1975 to 2016.  The main problem is in the stack depending nature of Quicksort and the stack limit of 256 bytes of 6502 architecture.  It is solvable.
+It is well known that the best, the fastest sort routine is Quicksort.  It is very odd that its implementations for 6502 for all of 42 years (from 1975 to 2016) have a bit blurred and unofficial status.  The main problem is in the stack depending nature of Quicksort and the stack limit of 256 bytes of 6502 architecture.  It is solvable.
 The next Pascal code was translated to 6502 assembler.
@@ Line 61: / Line 61: @@
           tya
           adc i2hi
-          lsr
+          ror
           sta zp1hi
           ror zp1lo
@@ Line 277: / Line 277: @@
           tya
           adc i2hi
-          lsr
+          ror
           sta zp1hi
           ror zp1lo
@@ Line 404: / Line 404: @@
 It is required to put the proper constants after //quicksort// label.  This makes the invocation code more complex in the general case.
+The other published 6502 Quicksort is at [[http://www.vcfed.org/forum/showthread.php?4687-QuickSort-in-6502-assembler|Vintage Computer Federation]]