Fix qsort code for swapping elements with a size of 64KiB or more.

This code did not previously work properly, because the X register value was overwritten within the loop. This could result in incorrect behavior such as hanging or data corruption when using qsort with element sizes >= 64KiB.
2023-02-14 18:43:40 -06:00 · 2023-02-14 18:43:40 -06:00 · 60d49c7dc3
parent 74de206058
commit 60d49c7dc3
1 changed files with 4 additions and 2 deletions
--- a/stdlib.asm
+++ b/stdlib.asm
@ -830,8 +830,9 @@ r        equ   7                        right entry
 swap     tsc                            set up addressing
         phd
         tcd
-         ldx   lsize+2                  move 64K chunks
+         lda   lsize+2                  move 64K chunks
         beq   sw2
+         sta   banks
         ldy   #0
 sw1      lda   [l],Y
         tax
@ -844,7 +845,7 @@ sw1      lda   [l],Y
         bne   sw1
         inc   l+2
         inc   r+2
-         dex
+         dec   banks
         bne   sw1
 sw2      lda   lsize                    if there are an odd number of bytes then
         lsr   A
@ -893,6 +894,7 @@ sw6      pld
 ;
 lsize    entry
         ds    4                        local copy of size
+banks    ds    2                        number of whole banks to swap
         end

 ****************************************************************