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11 November 2008, 21:19

(Or perhaps just me being stupid.)

I've been trying to understand why I can't get this quicksort routine to work, it was originally a part of the "howtocode" series of articles (that you can find for instance here: http://www.mways.co.uk/amiga/howtocode/text/vectors.php

In that version, the quicksort routine is incomplete, i've got my example here: http://www.itsahit.com/ola/qsort/qsort.s

What I'm trying to do - is to sort my coordinates (Rotcoords) with respect to Z. The coords are arranged in a linked-list, formed as per description in the qsort rout (at least the way I interpreted them).

dc.w nextpointer2, x1, y1, z1
dc.w nextpointer3, x2, y2, z2
.
.

After the sorting is done; I should have the pointer to the element with the largest Z-factor in d0 and just follow the next pointer to go down the list... but... no.. It seems like the re-ordering of the list makes it stuck in an infinite loop, so that the next pointer is points to the same element again. And that really puzzles me, since the routine is wide spread (and old) and I can't really imagine it being incorrect, or?

"dumplist" just moves the z-factor of element1 into d1, second into d2.. to d7. An easier way of debugging is to hex-view the result (in asmone: h (a0) )

I'd appreciate if someone could shed some light on this..

11 November 2008, 21:19	#1
rbw Posts: n/a	Weird quicksort routine (Or perhaps just me being stupid.) I've been trying to understand why I can't get this quicksort routine to work, it was originally a part of the "howtocode" series of articles (that you can find for instance here: http://www.mways.co.uk/amiga/howtocode/text/vectors.php In that version, the quicksort routine is incomplete, i've got my example here: http://www.itsahit.com/ola/qsort/qsort.s What I'm trying to do - is to sort my coordinates (Rotcoords) with respect to Z. The coords are arranged in a linked-list, formed as per description in the qsort rout (at least the way I interpreted them). dc.w nextpointer2, x1, y1, z1 dc.w nextpointer3, x2, y2, z2 . . After the sorting is done; I should have the pointer to the element with the largest Z-factor in d0 and just follow the next pointer to go down the list... but... no.. It seems like the re-ordering of the list makes it stuck in an infinite loop, so that the next pointer is points to the same element again. And that really puzzles me, since the routine is wide spread (and old) and I can't really imagine it being incorrect, or? "dumplist" just moves the z-factor of element1 into d1, second into d2.. to d7. An easier way of debugging is to hex-view the result (in asmone: h (a0) ) I'd appreciate if someone could shed some light on this..