stdlib: Restored previous qsort() implementation; the licensing is resolved.
Thanks to Gareth McCaughan for changing his code to the zlib license on our behalf!
Ryan C. Gordon
parent
2436ca200d
commit
32c70cc546
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@ -1,3 +1,28 @@
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/*
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Simple DirectMedia Layer
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Copyright (C) 1997-2016 Sam Lantinga <slouken@libsdl.org>
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#if defined(__clang_analyzer__) && !defined(SDL_DISABLE_ANALYZE_MACROS)
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#define SDL_DISABLE_ANALYZE_MACROS 1
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#endif
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#include "../SDL_internal.h"
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#include "SDL_stdinc.h"
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@ -9,208 +34,501 @@ SDL_qsort(void *base, size_t nmemb, size_t size, int (*compare) (const void *, c
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{
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qsort(base, nmemb, size, compare);
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}
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#else
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#ifdef REGTEST
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#undef REGTEST
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#ifdef assert
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#undef assert
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#endif
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#ifdef TEST
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#undef TEST
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#define assert SDL_assert
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#ifdef malloc
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#undef malloc
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#endif
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#ifndef _PDCLIB_memswp
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#define _PDCLIB_memswp( i, j, size ) char tmp; do { tmp = *i; *i++ = *j; *j++ = tmp; } while ( --size );
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#define malloc SDL_malloc
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#ifdef free
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#undef free
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#endif
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#ifndef _PDCLIB_size_t
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#define _PDCLIB_size_t size_t
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#define free SDL_free
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#ifdef memcpy
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#undef memcpy
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#endif
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#ifdef qsort
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#undef qsort
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#define memcpy SDL_memcpy
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#ifdef memmove
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#undef memmove
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#endif
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#define qsort SDL_qsort
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#define inline SDL_INLINE
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#define memmove SDL_memmove
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#ifdef qsortG
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#undef qsortG
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#endif
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#define qsortG SDL_qsort
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/*
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This code came from PDCLib, under the public domain. Specifically this:
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https://bitbucket.org/pdclib/pdclib/raw/a82b02d0c7d4ed633b97f2a7639d9a10b1c92ec8/functions/stdlib/qsort.c
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The _PDCLIB_memswp macro was from
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https://bitbucket.org/pdclib/pdclib/src/a82b02d0c7d4ed633b97f2a7639d9a10b1c92ec8/platform/posix/internals/_PDCLIB_config.h?at=default&fileviewer=file-view-default#_PDCLIB_config.h-28
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This code came from Gareth McCaughan, under the zlib license.
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Specifically this: https://www.mccaughan.org.uk/software/qsort.c-1.14
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Everything below this comment until the HAVE_QSORT #endif was from Gareth
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(any minor changes will be noted inline).
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Thank you to Gareth for relicensing this code under the zlib license for our
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benefit!
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Everything below this comment until the HAVE_QSORT #endif was from PDCLib (minor changes noted inline).
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--ryan.
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*/
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/* $Id$ */
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/* qsort( void *, size_t, size_t, int(*)( const void *, const void * ) )
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This file is part of the Public Domain C Library (PDCLib).
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Permission is granted to use, modify, and / or redistribute at will.
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/* This is a drop-in replacement for the C library's |qsort()| routine.
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*
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* It is intended for use where you know or suspect that your
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* platform's qsort is bad. If that isn't the case, then you
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* should probably use the qsort your system gives you in preference
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* to mine -- it will likely have been tested and tuned better.
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*
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* Features:
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* - Median-of-three pivoting (and more)
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* - Truncation and final polishing by a single insertion sort
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* - Early truncation when no swaps needed in pivoting step
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* - Explicit recursion, guaranteed not to overflow
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* - A few little wrinkles stolen from the GNU |qsort()|.
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* (For the avoidance of doubt, no code was stolen, only
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* broad ideas.)
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* - separate code for non-aligned / aligned / word-size objects
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*
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* Earlier releases of this code used an idiosyncratic licence
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* I wrote myself, because I'm an idiot. The code is now released
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* under the "zlib/libpng licence"; you will find the actual
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* terms in the next comment. I request (but do not require)
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* that if you make any changes beyond the name of the exported
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* routine and reasonable tweaks to the TRUNC_* and
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* PIVOT_THRESHOLD values, you modify the _ID string so as
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* to make it clear that you have changed the code.
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*
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* If you find problems with this code, or find ways of
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* making it significantly faster, please let me know!
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* My e-mail address, valid as of early 2016 and for the
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* foreseeable future, is
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* gareth.mccaughan@pobox.com
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* Thanks!
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*
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* Gareth McCaughan
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*/
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/* I commented this out. --ryan. #include <stdlib.h> */
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#ifndef REGTEST
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/* This implementation is taken from Paul Edward's PDPCLIB.
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Original code is credited to Raymond Gardner, Englewood CO.
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Minor mods are credited to Paul Edwards.
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Some reformatting and simplification done by Martin Baute.
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All code is still Public Domain.
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/* Copyright (c) 1998-2016 Gareth McCaughan
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any
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* damages arising from the use of this software.
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*
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented;
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* you must not claim that you wrote the original software.
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* If you use this software in a product, an acknowledgment
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* in the product documentation would be appreciated but
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* is not required.
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*
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* 2. Altered source versions must be plainly marked as such,
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* and must not be misrepresented as being the original software.
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*
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* 3. This notice may not be removed or altered from any source
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* distribution.
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*/
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/* Wrapper for _PDCLIB_memswp protects against multiple argument evaluation. */
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static inline void memswp( char * i, char * j, size_t size )
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{
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_PDCLIB_memswp( i, j, size );
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}
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/* For small sets, insertion sort is faster than quicksort.
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T is the threshold below which insertion sort will be used.
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Must be 3 or larger.
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/* Revision history since release:
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* 1998-03-19 v1.12 First release I have any records of.
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* 2007-09-02 v1.13 Fix bug kindly reported by Dan Bodoh
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* (premature termination of recursion).
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* Add a few clarifying comments.
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* Minor improvements to debug output.
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* 2016-02-21 v1.14 Replace licence with 2-clause BSD,
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* and clarify a couple of things in
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* comments. No code changes.
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*/
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#define T 7
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/* Macros for handling the QSort stack */
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#define PREPARE_STACK char * stack[STACKSIZE]; char * * stackptr = stack
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#define PUSH( base, limit ) stackptr[0] = base; stackptr[1] = limit; stackptr += 2
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#define POP( base, limit ) stackptr -= 2; base = stackptr[0]; limit = stackptr[1]
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/* TODO: Stack usage is log2( nmemb ) (minus what T shaves off the worst case).
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Worst-case nmemb is platform dependent and should probably be
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configured through _PDCLIB_config.h.
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*/
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#define STACKSIZE 64
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void qsort( void * base, size_t nmemb, size_t size, int (*compar)( const void *, const void * ) )
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{
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char * i;
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char * j;
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_PDCLIB_size_t thresh = T * size;
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char * base_ = (char *)base;
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char * limit = base_ + nmemb * size;
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PREPARE_STACK;
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for ( ;; )
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{
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if ( (size_t)( limit - base_ ) > thresh ) /* QSort for more than T elements. */
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{
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/* We work from second to last - first will be pivot element. */
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i = base_ + size;
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j = limit - size;
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/* We swap first with middle element, then sort that with second
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and last element so that eventually first element is the median
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of the three - avoiding pathological pivots.
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TODO: Instead of middle element, chose one randomly.
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*/
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memswp( ( ( ( (size_t)( limit - base_ ) ) / size ) / 2 ) * size + base_, base_, size );
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if ( compar( i, j ) > 0 ) memswp( i, j, size );
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if ( compar( base_, j ) > 0 ) memswp( base_, j, size );
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if ( compar( i, base_ ) > 0 ) memswp( i, base_, size );
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/* Now we have the median for pivot element, entering main Quicksort. */
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for ( ;; )
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{
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do
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{
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/* move i right until *i >= pivot */
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i += size;
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} while ( compar( i, base_ ) < 0 );
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do
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{
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/* move j left until *j <= pivot */
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j -= size;
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} while ( compar( j, base_ ) > 0 );
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if ( i > j )
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{
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/* break loop if pointers crossed */
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break;
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}
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/* else swap elements, keep scanning */
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memswp( i, j, size );
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}
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/* move pivot into correct place */
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memswp( base_, j, size );
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/* larger subfile base / limit to stack, sort smaller */
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if ( j - base_ > limit - i )
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{
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/* left is larger */
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PUSH( base_, j );
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base_ = i;
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}
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else
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{
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/* right is larger */
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PUSH( i, limit );
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limit = j;
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}
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}
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else /* insertion sort for less than T elements */
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{
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for ( j = base_, i = j + size; i < limit; j = i, i += size )
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{
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for ( ; compar( j, j + size ) > 0; j -= size )
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{
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memswp( j, j + size, size );
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if ( j == base_ )
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{
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break;
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}
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}
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}
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if ( stackptr != stack ) /* if any entries on stack */
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{
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POP( base_, limit );
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}
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else /* else stack empty, done */
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{
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break;
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}
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}
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}
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}
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#endif
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#ifdef TEST
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#include <_PDCLIB_test.h>
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/* BEGIN SDL CHANGE ... commented this out with an #if 0 block. --ryan. */
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#if 0
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#include <assert.h>
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#include <stdlib.h>
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#include <string.h>
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#include <limits.h>
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static int compare( const void * left, const void * right )
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{
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return *( (unsigned char *)left ) - *( (unsigned char *)right );
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#define DEBUG_QSORT
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static char _ID[]="<qsort.c gjm 1.14 2016-02-21>";
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#endif
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/* END SDL CHANGE ... commented this out with an #if 0 block. --ryan. */
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/* How many bytes are there per word? (Must be a power of 2,
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* and must in fact equal sizeof(int).)
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*/
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#define WORD_BYTES sizeof(int)
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/* How big does our stack need to be? Answer: one entry per
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* bit in a |size_t|.
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*/
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#define STACK_SIZE (8*sizeof(size_t))
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/* Different situations have slightly different requirements,
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* and we make life epsilon easier by using different truncation
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* points for the three different cases.
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* So far, I have tuned TRUNC_words and guessed that the same
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* value might work well for the other two cases. Of course
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* what works well on my machine might work badly on yours.
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*/
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#define TRUNC_nonaligned 12
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#define TRUNC_aligned 12
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#define TRUNC_words 12*WORD_BYTES /* nb different meaning */
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/* We use a simple pivoting algorithm for shortish sub-arrays
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* and a more complicated one for larger ones. The threshold
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* is PIVOT_THRESHOLD.
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*/
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#define PIVOT_THRESHOLD 40
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typedef struct { char * first; char * last; } stack_entry;
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#define pushLeft {stack[stacktop].first=ffirst;stack[stacktop++].last=last;}
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#define pushRight {stack[stacktop].first=first;stack[stacktop++].last=llast;}
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#define doLeft {first=ffirst;llast=last;continue;}
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#define doRight {ffirst=first;last=llast;continue;}
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#define pop {if (--stacktop<0) break;\
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first=ffirst=stack[stacktop].first;\
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last=llast=stack[stacktop].last;\
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continue;}
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/* Some comments on the implementation.
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* 1. When we finish partitioning the array into "low"
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* and "high", we forget entirely about short subarrays,
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* because they'll be done later by insertion sort.
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* Doing lots of little insertion sorts might be a win
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* on large datasets for locality-of-reference reasons,
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* but it makes the code much nastier and increases
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* bookkeeping overhead.
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* 2. We always save the shorter and get to work on the
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* longer. This guarantees that every time we push
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* an item onto the stack its size is <= 1/2 of that
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* of its parent; so the stack can't need more than
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* log_2(max-array-size) entries.
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* 3. We choose a pivot by looking at the first, last
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* and middle elements. We arrange them into order
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* because it's easy to do that in conjunction with
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* choosing the pivot, and it makes things a little
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* easier in the partitioning step. Anyway, the pivot
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* is the middle of these three. It's still possible
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* to construct datasets where the algorithm takes
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* time of order n^2, but it simply never happens in
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* practice.
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* 3' Newsflash: On further investigation I find that
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* it's easy to construct datasets where median-of-3
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* simply isn't good enough. So on large-ish subarrays
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* we do a more sophisticated pivoting: we take three
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* sets of 3 elements, find their medians, and then
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* take the median of those.
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* 4. We copy the pivot element to a separate place
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* because that way we can always do our comparisons
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* directly against a pointer to that separate place,
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* and don't have to wonder "did we move the pivot
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* element?". This makes the inner loop better.
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* 5. It's possible to make the pivoting even more
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* reliable by looking at more candidates when n
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* is larger. (Taking this to its logical conclusion
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* results in a variant of quicksort that doesn't
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* have that n^2 worst case.) However, the overhead
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* from the extra bookkeeping means that it's just
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* not worth while.
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* 6. This is pretty clean and portable code. Here are
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* all the potential portability pitfalls and problems
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* I know of:
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* - In one place (the insertion sort) I construct
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* a pointer that points just past the end of the
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* supplied array, and assume that (a) it won't
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* compare equal to any pointer within the array,
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* and (b) it will compare equal to a pointer
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* obtained by stepping off the end of the array.
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* These might fail on some segmented architectures.
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* - I assume that there are 8 bits in a |char| when
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* computing the size of stack needed. This would
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* fail on machines with 9-bit or 16-bit bytes.
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* - I assume that if |((int)base&(sizeof(int)-1))==0|
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* and |(size&(sizeof(int)-1))==0| then it's safe to
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* get at array elements via |int*|s, and that if
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* actually |size==sizeof(int)| as well then it's
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* safe to treat the elements as |int|s. This might
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* fail on systems that convert pointers to integers
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* in non-standard ways.
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* - I assume that |8*sizeof(size_t)<=INT_MAX|. This
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* would be false on a machine with 8-bit |char|s,
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* 16-bit |int|s and 4096-bit |size_t|s. :-)
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*/
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/* The recursion logic is the same in each case.
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* We keep chopping up until we reach subarrays of size
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* strictly less than Trunc; we leave these unsorted. */
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#define Recurse(Trunc) \
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{ size_t l=last-ffirst,r=llast-first; \
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if (l<Trunc) { \
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if (r>=Trunc) doRight \
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else pop \
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} \
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else if (l<=r) { pushLeft; doRight } \
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else if (r>=Trunc) { pushRight; doLeft }\
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else doLeft \
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}
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int main( void )
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{
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char presort[] = { "shreicnyjqpvozxmbt" };
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char sorted1[] = { "bcehijmnopqrstvxyz" };
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char sorted2[] = { "bticjqnyozpvreshxm" };
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char s[19];
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strcpy( s, presort );
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qsort( s, 18, 1, compare );
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TESTCASE( strcmp( s, sorted1 ) == 0 );
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strcpy( s, presort );
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qsort( s, 9, 2, compare );
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TESTCASE( strcmp( s, sorted2 ) == 0 );
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strcpy( s, presort );
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qsort( s, 1, 1, compare );
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TESTCASE( strcmp( s, presort ) == 0 );
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#if defined(REGTEST) && (__BSD_VISIBLE || __APPLE__)
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puts( "qsort.c: Skipping test #4 for BSD as it goes into endless loop here." );
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#else
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qsort( s, 100, 0, compare );
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TESTCASE( strcmp( s, presort ) == 0 );
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#endif
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return TEST_RESULTS;
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/* and so is the pivoting logic (note: last is inclusive): */
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#define Pivot(swapper,sz) \
|
||||
if (last-first>PIVOT_THRESHOLD*sz) mid=pivot_big(first,mid,last,sz,compare);\
|
||||
else { \
|
||||
if (compare(first,mid)<0) { \
|
||||
if (compare(mid,last)>0) { \
|
||||
swapper(mid,last); \
|
||||
if (compare(first,mid)>0) swapper(first,mid);\
|
||||
} \
|
||||
} \
|
||||
else { \
|
||||
if (compare(mid,last)>0) swapper(first,last)\
|
||||
else { \
|
||||
swapper(first,mid); \
|
||||
if (compare(mid,last)>0) swapper(mid,last);\
|
||||
} \
|
||||
} \
|
||||
first+=sz; last-=sz; \
|
||||
}
|
||||
|
||||
#ifdef DEBUG_QSORT
|
||||
#include <stdio.h>
|
||||
#endif
|
||||
|
||||
/* and so is the partitioning logic: */
|
||||
#define Partition(swapper,sz) { \
|
||||
do { \
|
||||
while (compare(first,pivot)<0) first+=sz; \
|
||||
while (compare(pivot,last)<0) last-=sz; \
|
||||
if (first<last) { \
|
||||
swapper(first,last); \
|
||||
first+=sz; last-=sz; } \
|
||||
else if (first==last) { first+=sz; last-=sz; break; }\
|
||||
} while (first<=last); \
|
||||
}
|
||||
|
||||
/* and so is the pre-insertion-sort operation of putting
|
||||
* the smallest element into place as a sentinel.
|
||||
* Doing this makes the inner loop nicer. I got this
|
||||
* idea from the GNU implementation of qsort().
|
||||
* We find the smallest element from the first |nmemb|,
|
||||
* or the first |limit|, whichever is smaller;
|
||||
* therefore we must have ensured that the globally smallest
|
||||
* element is in the first |limit|.
|
||||
*/
|
||||
#define PreInsertion(swapper,limit,sz) \
|
||||
first=base; \
|
||||
last=first + ((nmemb>limit ? limit : nmemb)-1)*sz;\
|
||||
while (last!=base) { \
|
||||
if (compare(first,last)>0) first=last; \
|
||||
last-=sz; } \
|
||||
if (first!=base) swapper(first,(char*)base);
|
||||
|
||||
/* and so is the insertion sort, in the first two cases: */
|
||||
#define Insertion(swapper) \
|
||||
last=((char*)base)+nmemb*size; \
|
||||
for (first=((char*)base)+size;first!=last;first+=size) { \
|
||||
char *test; \
|
||||
/* Find the right place for |first|. \
|
||||
* My apologies for var reuse. */ \
|
||||
for (test=first-size;compare(test,first)>0;test-=size) ; \
|
||||
test+=size; \
|
||||
if (test!=first) { \
|
||||
/* Shift everything in [test,first) \
|
||||
* up by one, and place |first| \
|
||||
* where |test| is. */ \
|
||||
memcpy(pivot,first,size); \
|
||||
memmove(test+size,test,first-test); \
|
||||
memcpy(test,pivot,size); \
|
||||
} \
|
||||
}
|
||||
|
||||
#define SWAP_nonaligned(a,b) { \
|
||||
register char *aa=(a),*bb=(b); \
|
||||
register size_t sz=size; \
|
||||
do { register char t=*aa; *aa++=*bb; *bb++=t; } while (--sz); }
|
||||
|
||||
#define SWAP_aligned(a,b) { \
|
||||
register int *aa=(int*)(a),*bb=(int*)(b); \
|
||||
register size_t sz=size; \
|
||||
do { register int t=*aa;*aa++=*bb; *bb++=t; } while (sz-=WORD_BYTES); }
|
||||
|
||||
#define SWAP_words(a,b) { \
|
||||
register int t=*((int*)a); *((int*)a)=*((int*)b); *((int*)b)=t; }
|
||||
|
||||
/* ---------------------------------------------------------------------- */
|
||||
|
||||
static char * pivot_big(char *first, char *mid, char *last, size_t size,
|
||||
int compare(const void *, const void *)) {
|
||||
int d=(((last-first)/size)>>3)*size;
|
||||
#ifdef DEBUG_QSORT
|
||||
fprintf(stderr, "pivot_big: first=%p last=%p size=%lu n=%lu\n", first, (unsigned long)last, size, (unsigned long)((last-first+1)/size));
|
||||
#endif
|
||||
char *m1,*m2,*m3;
|
||||
{ char *a=first, *b=first+d, *c=first+2*d;
|
||||
#ifdef DEBUG_QSORT
|
||||
fprintf(stderr,"< %d %d %d @ %p %p %p\n",*(int*)a,*(int*)b,*(int*)c, a,b,c);
|
||||
#endif
|
||||
m1 = compare(a,b)<0 ?
|
||||
(compare(b,c)<0 ? b : (compare(a,c)<0 ? c : a))
|
||||
: (compare(a,c)<0 ? a : (compare(b,c)<0 ? c : b));
|
||||
}
|
||||
{ char *a=mid-d, *b=mid, *c=mid+d;
|
||||
#ifdef DEBUG_QSORT
|
||||
fprintf(stderr,". %d %d %d @ %p %p %p\n",*(int*)a,*(int*)b,*(int*)c, a,b,c);
|
||||
#endif
|
||||
m2 = compare(a,b)<0 ?
|
||||
(compare(b,c)<0 ? b : (compare(a,c)<0 ? c : a))
|
||||
: (compare(a,c)<0 ? a : (compare(b,c)<0 ? c : b));
|
||||
}
|
||||
{ char *a=last-2*d, *b=last-d, *c=last;
|
||||
#ifdef DEBUG_QSORT
|
||||
fprintf(stderr,"> %d %d %d @ %p %p %p\n",*(int*)a,*(int*)b,*(int*)c, a,b,c);
|
||||
#endif
|
||||
m3 = compare(a,b)<0 ?
|
||||
(compare(b,c)<0 ? b : (compare(a,c)<0 ? c : a))
|
||||
: (compare(a,c)<0 ? a : (compare(b,c)<0 ? c : b));
|
||||
}
|
||||
#ifdef DEBUG_QSORT
|
||||
fprintf(stderr,"-> %d %d %d @ %p %p %p\n",*(int*)m1,*(int*)m2,*(int*)m3, m1,m2,m3);
|
||||
#endif
|
||||
return compare(m1,m2)<0 ?
|
||||
(compare(m2,m3)<0 ? m2 : (compare(m1,m3)<0 ? m3 : m1))
|
||||
: (compare(m1,m3)<0 ? m1 : (compare(m2,m3)<0 ? m3 : m2));
|
||||
}
|
||||
|
||||
/* ---------------------------------------------------------------------- */
|
||||
|
||||
static void qsort_nonaligned(void *base, size_t nmemb, size_t size,
|
||||
int (*compare)(const void *, const void *)) {
|
||||
|
||||
stack_entry stack[STACK_SIZE];
|
||||
int stacktop=0;
|
||||
char *first,*last;
|
||||
char *pivot=malloc(size);
|
||||
size_t trunc=TRUNC_nonaligned*size;
|
||||
assert(pivot!=0);
|
||||
|
||||
first=(char*)base; last=first+(nmemb-1)*size;
|
||||
|
||||
if (last-first>=trunc) {
|
||||
char *ffirst=first, *llast=last;
|
||||
while (1) {
|
||||
/* Select pivot */
|
||||
{ char * mid=first+size*((last-first)/size >> 1);
|
||||
Pivot(SWAP_nonaligned,size);
|
||||
memcpy(pivot,mid,size);
|
||||
}
|
||||
/* Partition. */
|
||||
Partition(SWAP_nonaligned,size);
|
||||
/* Prepare to recurse/iterate. */
|
||||
Recurse(trunc)
|
||||
}
|
||||
}
|
||||
PreInsertion(SWAP_nonaligned,TRUNC_nonaligned-1,size);
|
||||
Insertion(SWAP_nonaligned);
|
||||
free(pivot);
|
||||
}
|
||||
|
||||
static void qsort_aligned(void *base, size_t nmemb, size_t size,
|
||||
int (*compare)(const void *, const void *)) {
|
||||
|
||||
stack_entry stack[STACK_SIZE];
|
||||
int stacktop=0;
|
||||
char *first,*last;
|
||||
char *pivot=malloc(size);
|
||||
size_t trunc=TRUNC_aligned*size;
|
||||
assert(pivot!=0);
|
||||
|
||||
first=(char*)base; last=first+(nmemb-1)*size;
|
||||
|
||||
if (last-first>=trunc) {
|
||||
char *ffirst=first,*llast=last;
|
||||
while (1) {
|
||||
/* Select pivot */
|
||||
{ char * mid=first+size*((last-first)/size >> 1);
|
||||
Pivot(SWAP_aligned,size);
|
||||
memcpy(pivot,mid,size);
|
||||
}
|
||||
/* Partition. */
|
||||
Partition(SWAP_aligned,size);
|
||||
/* Prepare to recurse/iterate. */
|
||||
Recurse(trunc)
|
||||
}
|
||||
}
|
||||
PreInsertion(SWAP_aligned,TRUNC_aligned-1,size);
|
||||
Insertion(SWAP_aligned);
|
||||
free(pivot);
|
||||
}
|
||||
|
||||
static void qsort_words(void *base, size_t nmemb,
|
||||
int (*compare)(const void *, const void *)) {
|
||||
|
||||
stack_entry stack[STACK_SIZE];
|
||||
int stacktop=0;
|
||||
char *first,*last;
|
||||
char *pivot=malloc(WORD_BYTES);
|
||||
assert(pivot!=0);
|
||||
|
||||
first=(char*)base; last=first+(nmemb-1)*WORD_BYTES;
|
||||
|
||||
if (last-first>=TRUNC_words) {
|
||||
char *ffirst=first, *llast=last;
|
||||
while (1) {
|
||||
#ifdef DEBUG_QSORT
|
||||
fprintf(stderr,"Doing %d:%d: ",
|
||||
(first-(char*)base)/WORD_BYTES,
|
||||
(last-(char*)base)/WORD_BYTES);
|
||||
#endif
|
||||
/* Select pivot */
|
||||
{ char * mid=first+WORD_BYTES*((last-first) / (2*WORD_BYTES));
|
||||
Pivot(SWAP_words,WORD_BYTES);
|
||||
*(int*)pivot=*(int*)mid;
|
||||
#ifdef DEBUG_QSORT
|
||||
fprintf(stderr,"pivot = %p = #%lu = %d\n", mid, (unsigned long)(((int*)mid)-((int*)base)), *(int*)mid);
|
||||
#endif
|
||||
}
|
||||
/* Partition. */
|
||||
Partition(SWAP_words,WORD_BYTES);
|
||||
#ifdef DEBUG_QSORT
|
||||
fprintf(stderr, "after partitioning first=#%lu last=#%lu\n", (first-(char*)base)/4lu, (last-(char*)base)/4lu);
|
||||
#endif
|
||||
/* Prepare to recurse/iterate. */
|
||||
Recurse(TRUNC_words)
|
||||
}
|
||||
}
|
||||
PreInsertion(SWAP_words,(TRUNC_words/WORD_BYTES)-1,WORD_BYTES);
|
||||
/* Now do insertion sort. */
|
||||
last=((char*)base)+nmemb*WORD_BYTES;
|
||||
for (first=((char*)base)+WORD_BYTES;first!=last;first+=WORD_BYTES) {
|
||||
/* Find the right place for |first|. My apologies for var reuse */
|
||||
int *pl=(int*)(first-WORD_BYTES),*pr=(int*)first;
|
||||
*(int*)pivot=*(int*)first;
|
||||
for (;compare(pl,pivot)>0;pr=pl,--pl) {
|
||||
*pr=*pl; }
|
||||
if (pr!=(int*)first) *pr=*(int*)pivot;
|
||||
}
|
||||
free(pivot);
|
||||
}
|
||||
|
||||
/* ---------------------------------------------------------------------- */
|
||||
|
||||
extern void qsortG(void *base, size_t nmemb, size_t size,
|
||||
int (*compare)(const void *, const void *)) {
|
||||
|
||||
if (nmemb<=1) return;
|
||||
if (((int)base|size)&(WORD_BYTES-1))
|
||||
qsort_nonaligned(base,nmemb,size,compare);
|
||||
else if (size!=WORD_BYTES)
|
||||
qsort_aligned(base,nmemb,size,compare);
|
||||
else
|
||||
qsort_words(base,nmemb,compare);
|
||||
}
|
||||
|
||||
|
||||
#endif /* HAVE_QSORT */
|
||||
|
||||
/* vi: set ts=4 sw=4 expandtab: */
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue