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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [search/] [qsort.c] - Rev 301
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/* FUNCTION <<qsort>>---sort an array INDEX qsort ANSI_SYNOPSIS #include <stdlib.h> void qsort(void *<[base]>, size_t <[nmemb]>, size_t <[size]>, int (*<[compar]>)(const void *, const void *) ); TRAD_SYNOPSIS #include <stdlib.h> qsort(<[base]>, <[nmemb]>, <[size]>, <[compar]> ) char *<[base]>; size_t <[nmemb]>; size_t <[size]>; int (*<[compar]>)(); DESCRIPTION <<qsort>> sorts an array (beginning at <[base]>) of <[nmemb]> objects. <[size]> describes the size of each element of the array. You must supply a pointer to a comparison function, using the argument shown as <[compar]>. (This permits sorting objects of unknown properties.) Define the comparison function to accept two arguments, each a pointer to an element of the array starting at <[base]>. The result of <<(*<[compar]>)>> must be negative if the first argument is less than the second, zero if the two arguments match, and positive if the first argument is greater than the second (where ``less than'' and ``greater than'' refer to whatever arbitrary ordering is appropriate). The array is sorted in place; that is, when <<qsort>> returns, the array elements beginning at <[base]> have been reordered. RETURNS <<qsort>> does not return a result. PORTABILITY <<qsort>> is required by ANSI (without specifying the sorting algorithm). */ /*- * 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. */ #include <_ansi.h> #include <stdlib.h> #ifndef __GNUC__ #define inline #endif static inline char *med3 _PARAMS((char *, char *, char *, int (*)())); static inline void swapfunc _PARAMS((char *, char *, int, int)); #define min(a, b) (a) < (b) ? a : b /* * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". */ #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, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; static inline void _DEFUN(swapfunc, (a, b, n, swaptype), char *a _AND char *b _AND int n _AND int swaptype) { if(swaptype <= 1) swapcode(long, a, b, n) else swapcode(char, a, b, n) } #define swap(a, b) \ if (swaptype == 0) { \ long t = *(long *)(a); \ *(long *)(a) = *(long *)(b); \ *(long *)(b) = t; \ } else \ swapfunc(a, b, es, swaptype) #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) static inline char * _DEFUN(med3, (a, b, c, cmp), char *a _AND char *b _AND char *c _AND int (*cmp)()) { return cmp(a, b) < 0 ? (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); } void _DEFUN(qsort, (a, n, es, cmp), void *a _AND size_t n _AND size_t es _AND int (*cmp)()) { char *pa, *pb, *pc, *pd, *pl, *pm, *pn; int d, r, swaptype, swap_cnt; loop: SWAPINIT(a, es); swap_cnt = 0; if (n < 7) { for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; pl -= es) swap(pl, pl - es); return; } pm = (char *) a + (n / 2) * es; if (n > 7) { pl = a; pn = (char *) a + (n - 1) * es; if (n > 40) { d = (n / 8) * es; pl = med3(pl, pl + d, pl + 2 * d, cmp); pm = med3(pm - d, pm, pm + d, cmp); pn = med3(pn - 2 * d, pn - d, pn, cmp); } pm = med3(pl, pm, pn, cmp); } swap(a, pm); pa = pb = (char *) a + es; pc = pd = (char *) a + (n - 1) * es; for (;;) { while (pb <= pc && (r = cmp(pb, a)) <= 0) { if (r == 0) { swap_cnt = 1; swap(pa, pb); pa += es; } pb += es; } while (pb <= pc && (r = cmp(pc, a)) >= 0) { if (r == 0) { swap_cnt = 1; swap(pc, pd); pd -= es; } pc -= es; } if (pb > pc) break; swap(pb, pc); swap_cnt = 1; pb += es; pc -= es; } if (swap_cnt == 0) { /* Switch to insertion sort */ for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; pl -= es) swap(pl, pl - es); return; } pn = (char *) a + n * es; r = min(pa - (char *)a, pb - pa); vecswap(a, pb - r, r); r = min(pd - pc, pn - pd - es); vecswap(pb, pn - r, r); if ((r = pb - pa) > es) qsort(a, r / es, es, cmp); if ((r = pd - pc) > es) { /* Iterate rather than recurse to save stack space */ a = pn - r; n = r / es; goto loop; } /* qsort(pn - r, r / es, es, cmp);*/ }
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