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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);*/ |
| } |