/**************************************************************************** * libc/stdlib/lib_qsort.c * * Copyright (C) 2007, 2009, 2011 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * Leveraged from: * * Copyright (c) 1992, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ #define min(a, b) (a) < (b) ? a : b #define swapcode(TYPE, parmi, parmj, n) \ { \ long i = (n) / sizeof (TYPE); \ register TYPE *pi = (TYPE *)(parmi); \ register TYPE *pj = (TYPE *)(parmj); \ do { \ register TYPE t = *pi; \ *pi++ = *pj; \ *pj++ = t; \ } while (--i > 0); \ } #define SWAPINIT(a, width) \ swaptype = ((FAR char *)a - (FAR char *)0) % sizeof(long) || \ width % sizeof(long) ? 2 : width == sizeof(long)? 0 : 1; #define swap(a, b) \ if (swaptype == 0) \ { \ long t = *(long *)(a); \ *(long *)(a) = *(long *)(b); \ *(long *)(b) = t; \ } \ else \ { \ swapfunc(a, b, width, swaptype); \ } #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) /**************************************************************************** * Private Function Prototypes ****************************************************************************/ static inline void swapfunc(FAR char *a, FAR char *b, int n, int swaptype); static inline FAR char *med3(FAR char *a, FAR char *b, FAR char *c, CODE int (*compar)(FAR const void *, FAR const void *)); /**************************************************************************** * Private Functions ****************************************************************************/ static inline void swapfunc(FAR char *a, FAR char *b, int n, int swaptype) { if (swaptype <= 1) { swapcode(long, a, b, n) } else { swapcode(char, a, b, n) } } static inline FAR char *med3(FAR char *a, FAR char *b, FAR char *c, CODE int (*compar)(FAR const void *, FAR const void *)) { return compar(a, b) < 0 ? (compar(b, c) < 0 ? b : (compar(a, c) < 0 ? c : a)) : (compar(b, c) > 0 ? b : (compar(a, c) < 0 ? a : c)); } /**************************************************************************** * Public Function ****************************************************************************/ /**************************************************************************** * Name: qsort * * Description: * The qsort() function will sort an array of 'nel' objects, the initial * element of which is pointed to by 'base'. The size of each object, in * bytes, is specified by the 'width" argument. If the 'nel' argument has * the value zero, the comparison function pointed to by 'compar' will not * be called and no rearrangement will take place. * * The application will ensure that the comparison function pointed to by * 'compar' does not alter the contents of the array. The implementation * may reorder elements of the array between calls to the comparison * function, but will not alter the contents of any individual element. * * When the same objects (consisting of 'width" bytes, irrespective of * their current positions in the array) are passed more than once to * the comparison function, the results will be consistent with one * another. That is, they will define a total ordering on the array. * * The contents of the array will be sorted in ascending order according * to a comparison function. The 'compar' argument is a pointer to the * comparison function, which is called with two arguments that point to * the elements being compared. The application will ensure that the * function returns an integer less than, equal to, or greater than 0, * if the first argument is considered respectively less than, equal to, * or greater than the second. If two members compare as equal, their * order in the sorted array is unspecified. * * (Based on description from OpenGroup.org). * * Returned Value: * The qsort() function will not return a value. * * Notes from the original BSD version: * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". * ****************************************************************************/ void qsort(FAR void *base, size_t nel, size_t width, CODE int(*compar)(FAR const void *, FAR const void *)) { FAR char *pa; FAR char *pb; FAR char *pc; FAR char *pd; FAR char *pl; FAR char *pm; FAR char *pn; int swaptype; int swap_cnt; int d; int r; loop: SWAPINIT(base, width); swap_cnt = 0; if (nel < 7) { for (pm = (FAR char *)base + width; pm < (FAR char *)base + nel * width; pm += width) { for (pl = pm; pl > (FAR char *)base && compar(pl - width, pl) > 0; pl -= width) { swap(pl, pl - width); } } return; } pm = (FAR char *)base + (nel / 2) * width; if (nel > 7) { pl = base; pn = (FAR char *)base + (nel - 1) * width; if (nel > 40) { d = (nel / 8) * width; pl = med3(pl, pl + d, pl + 2 * d, compar); pm = med3(pm - d, pm, pm + d, compar); pn = med3(pn - 2 * d, pn - d, pn, compar); } pm = med3(pl, pm, pn, compar); } swap(base, pm); pa = pb = (FAR char *)base + width; pc = pd = (FAR char *)base + (nel - 1) * width; for (; ; ) { while (pb <= pc && (r = compar(pb, base)) <= 0) { if (r == 0) { swap_cnt = 1; swap(pa, pb); pa += width; } pb += width; } while (pb <= pc && (r = compar(pc, base)) >= 0) { if (r == 0) { swap_cnt = 1; swap(pc, pd); pd -= width; } pc -= width; } if (pb > pc) { break; } swap(pb, pc); swap_cnt = 1; pb += width; pc -= width; } if (swap_cnt == 0) { /* Switch to insertion sort */ for (pm = (FAR char *)base + width; pm < (FAR char *)base + nel * width; pm += width) { for (pl = pm; pl > (FAR char *)base && compar(pl - width, pl) > 0; pl -= width) { swap(pl, pl - width); } } return; } pn = (FAR char *)base + nel * width; r = min(pa - (FAR char *)base, pb - pa); vecswap(base, pb - r, r); r = min(pd - pc, pn - pd - width); vecswap(pb, pn - r, r); if ((r = pb - pa) > width) { qsort(base, r / width, width, compar); } if ((r = pd - pc) > width) { /* Iterate rather than recurse to save stack space */ base = pn - r; nel = r / width; goto loop; } }