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Annotation of src/lib/libc/stdlib/qsort.c, Revision 1.19

1.19    ! lukem       1: /*     $NetBSD: qsort.c,v 1.18 2009/01/11 02:46:30 christos Exp $      */
1.5       thorpej     2:
1.1       cgd         3: /*-
1.4       mycroft     4:  * Copyright (c) 1992, 1993
                      5:  *     The Regents of the University of California.  All rights reserved.
1.1       cgd         6:  *
                      7:  * Redistribution and use in source and binary forms, with or without
                      8:  * modification, are permitted provided that the following conditions
                      9:  * are met:
                     10:  * 1. Redistributions of source code must retain the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer.
                     12:  * 2. Redistributions in binary form must reproduce the above copyright
                     13:  *    notice, this list of conditions and the following disclaimer in the
                     14:  *    documentation and/or other materials provided with the distribution.
1.13      agc        15:  * 3. Neither the name of the University nor the names of its contributors
1.1       cgd        16:  *    may be used to endorse or promote products derived from this software
                     17:  *    without specific prior written permission.
                     18:  *
                     19:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     20:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     21:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     22:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     23:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     24:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     25:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     26:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     27:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     28:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     29:  * SUCH DAMAGE.
                     30:  */
                     31:
1.8       christos   32: #include <sys/cdefs.h>
1.1       cgd        33: #if defined(LIBC_SCCS) && !defined(lint)
1.5       thorpej    34: #if 0
1.7       mikel      35: static char sccsid[] = "@(#)qsort.c    8.1 (Berkeley) 6/4/93";
1.5       thorpej    36: #else
1.19    ! lukem      37: __RCSID("$NetBSD: qsort.c,v 1.18 2009/01/11 02:46:30 christos Exp $");
1.5       thorpej    38: #endif
1.1       cgd        39: #endif /* LIBC_SCCS and not lint */
                     40:
                     41: #include <sys/types.h>
1.11      lukem      42:
                     43: #include <assert.h>
                     44: #include <errno.h>
1.1       cgd        45: #include <stdlib.h>
                     46:
1.14      perry      47: static inline char     *med3 __P((char *, char *, char *,
1.8       christos   48:     int (*)(const void *, const void *)));
1.14      perry      49: static inline void      swapfunc __P((char *, char *, size_t, int));
1.4       mycroft    50:
                     51: #define min(a, b)      (a) < (b) ? a : b
                     52:
1.1       cgd        53: /*
1.4       mycroft    54:  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
1.1       cgd        55:  */
1.4       mycroft    56: #define swapcode(TYPE, parmi, parmj, n) {              \
1.10      christos   57:        size_t i = (n) / sizeof (TYPE);                 \
                     58:        TYPE *pi = (TYPE *)(void *)(parmi);             \
                     59:        TYPE *pj = (TYPE *)(void *)(parmj);             \
1.4       mycroft    60:        do {                                            \
1.10      christos   61:                TYPE    t = *pi;                        \
1.4       mycroft    62:                *pi++ = *pj;                            \
                     63:                *pj++ = t;                              \
                     64:         } while (--i > 0);                             \
                     65: }
1.1       cgd        66:
1.4       mycroft    67: #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
                     68:        es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
1.1       cgd        69:
1.14      perry      70: static inline void
1.15      rmind      71: swapfunc(char *a, char *b, size_t n, int swaptype)
1.1       cgd        72: {
1.15      rmind      73:
1.7       mikel      74:        if (swaptype <= 1)
1.4       mycroft    75:                swapcode(long, a, b, n)
1.1       cgd        76:        else
1.4       mycroft    77:                swapcode(char, a, b, n)
1.1       cgd        78: }
                     79:
1.10      christos   80: #define swap(a, b)                                             \
                     81:        if (swaptype == 0) {                                    \
                     82:                long t = *(long *)(void *)(a);                  \
                     83:                *(long *)(void *)(a) = *(long *)(void *)(b);    \
                     84:                *(long *)(void *)(b) = t;                       \
                     85:        } else                                                  \
1.4       mycroft    86:                swapfunc(a, b, es, swaptype)
                     87:
1.10      christos   88: #define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype)
1.4       mycroft    89:
1.14      perry      90: static inline char *
1.15      rmind      91: med3(char *a, char *b, char *c,
                     92:     int (*cmp) __P((const void *, const void *)))
1.4       mycroft    93: {
1.15      rmind      94:
1.4       mycroft    95:        return cmp(a, b) < 0 ?
                     96:               (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
                     97:               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
1.1       cgd        98: }
                     99:
1.4       mycroft   100: void
1.15      rmind     101: qsort(void *a, size_t n, size_t es,
                    102:     int (*cmp) __P((const void *, const void *)))
1.4       mycroft   103: {
                    104:        char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
1.15      rmind     105:        size_t d, r;
                    106:        int swaptype, swap_cnt, cmp_result;
1.11      lukem     107:
                    108:        _DIAGASSERT(a != NULL);
                    109:        _DIAGASSERT(cmp != NULL);
1.1       cgd       110:
1.4       mycroft   111: loop:  SWAPINIT(a, es);
                    112:        swap_cnt = 0;
                    113:        if (n < 7) {
1.7       mikel     114:                for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
1.4       mycroft   115:                        for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
                    116:                             pl -= es)
                    117:                                swap(pl, pl - es);
                    118:                return;
                    119:        }
1.7       mikel     120:        pm = (char *) a + (n / 2) * es;
1.4       mycroft   121:        if (n > 7) {
1.7       mikel     122:                pl = (char *) a;
                    123:                pn = (char *) a + (n - 1) * es;
1.4       mycroft   124:                if (n > 40) {
                    125:                        d = (n / 8) * es;
                    126:                        pl = med3(pl, pl + d, pl + 2 * d, cmp);
                    127:                        pm = med3(pm - d, pm, pm + d, cmp);
                    128:                        pn = med3(pn - 2 * d, pn - d, pn, cmp);
1.1       cgd       129:                }
1.4       mycroft   130:                pm = med3(pl, pm, pn, cmp);
1.1       cgd       131:        }
1.4       mycroft   132:        swap(a, pm);
1.7       mikel     133:        pa = pb = (char *) a + es;
1.1       cgd       134:
1.7       mikel     135:        pc = pd = (char *) a + (n - 1) * es;
1.4       mycroft   136:        for (;;) {
1.15      rmind     137:                while (pb <= pc && (cmp_result = cmp(pb, a)) <= 0) {
                    138:                        if (cmp_result == 0) {
1.4       mycroft   139:                                swap_cnt = 1;
                    140:                                swap(pa, pb);
                    141:                                pa += es;
1.1       cgd       142:                        }
1.4       mycroft   143:                        pb += es;
                    144:                }
1.15      rmind     145:                while (pb <= pc && (cmp_result = cmp(pc, a)) >= 0) {
                    146:                        if (cmp_result == 0) {
1.4       mycroft   147:                                swap_cnt = 1;
                    148:                                swap(pc, pd);
                    149:                                pd -= es;
1.1       cgd       150:                        }
1.4       mycroft   151:                        pc -= es;
1.1       cgd       152:                }
1.4       mycroft   153:                if (pb > pc)
1.1       cgd       154:                        break;
1.4       mycroft   155:                swap(pb, pc);
                    156:                swap_cnt = 1;
                    157:                pb += es;
                    158:                pc -= es;
1.1       cgd       159:        }
1.4       mycroft   160:        if (swap_cnt == 0) {  /* Switch to insertion sort */
1.7       mikel     161:                for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
1.4       mycroft   162:                        for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
                    163:                             pl -= es)
                    164:                                swap(pl, pl - es);
1.1       cgd       165:                return;
                    166:        }
                    167:
1.7       mikel     168:        pn = (char *) a + n * es;
                    169:        r = min(pa - (char *) a, pb - pa);
1.4       mycroft   170:        vecswap(a, pb - r, r);
1.19    ! lukem     171:        r = min((size_t)(pd - pc), pn - pd - es);
1.4       mycroft   172:        vecswap(pb, pn - r, r);
                    173:        if ((r = pb - pa) > es)
                    174:                qsort(a, r / es, es, cmp);
                    175:        if ((r = pd - pc) > es) {
                    176:                /* Iterate rather than recurse to save stack space */
                    177:                a = pn - r;
                    178:                n = r / es;
                    179:                goto loop;
1.1       cgd       180:        }
1.4       mycroft   181: /*             qsort(pn - r, r / es, es, cmp);*/
1.1       cgd       182: }

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