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replace heap sort with smoothsort implementation by Valentin Ochs

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Smoothsort is an adaptive variant of heapsort. This version was
written by Valentin Ochs (apo) specifically for inclusion in musl. I
worked with him to get it working in O(1) memory usage even with giant
array element widths, and to optimize it heavily for size and speed.
It's still roughly 4 times as large as the old heap sort
implementation, but roughly 20 times faster given an almost-sorted
array of 1M elements (20 being the base-2 log of 1M), i.e. it really
does reduce O(n log n) to O(n) in the mostly-sorted case. It's still
somewhat slower than glibc's Introsort for random input, but now
considerably faster than glibc when the input is already sorted, or
mostly sorted.
This commit is contained in:
Rich Felker 2011-04-27 13:27:04 -04:00
commit 22263709ed
2 changed files with 197 additions and 32 deletions
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COPYRIGHT
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@ -19,6 +19,10 @@ The implementation of DES for crypt (src/misc/crypt.c) is Copyright ©
1994 David Burren. It is licensed under a BSD license compatible with
the GNU LGPL.
The smoothsort implementation (src/stdlib/qsort.c) is Copyright © 2011
Valentin Ochs and is licensed under an MIT-style license compatible
with the GNU LGPL.
The x86_64 port was written by Nicholas J. Kain. See individual files
for their copyright status.