libclamav/qsort.c
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 /*-
  * 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.
  * 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.
  */
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 #if HAVE_CONFIG_H
 #include "clamav-config.h"
 #endif
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 #include <stdlib.h>
 
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 #include "clamav.h"
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 #include "platform.h"
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 #include "others.h"
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 static inline char *med3(char *, char *, char *, int (*)(const void *, const void *));
 static inline char *med3_r(void *, char *, char *, char *, int (*)(const void *, const void *, const void *));
 static inline void swapfunc(char *, char *, int, int);
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 /*
  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  */
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 #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);                      \
     }
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 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
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                                            es % sizeof(long)                 \
                                        ? 2                                   \
                                        : es == sizeof(long) ? 0 : 1;
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 static inline void
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     swapfunc(a, b, n, swaptype) char *a,
     *b;
 int n, swaptype;
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 {
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     if (swaptype <= 1)
         swapcode(long, a, b, n) else swapcode(char, a, b, n)
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 }
 
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 #define swap(a, b)                   \
     if (swaptype == 0) {             \
         long t       = *(long *)(a); \
         *(long *)(a) = *(long *)(b); \
         *(long *)(b) = t;            \
     } else                           \
         swapfunc(a, b, es, swaptype)
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 #define vecswap(a, b, n) \
     if ((n) > 0) swapfunc(a, b, n, swaptype)
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 #define CMP1(a, b) ((int)(*((uint32_t *)(a)) - *((uint32_t *)(b))))
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 #define CMP(a, b) (cmp ? (cmp(a, b)) : CMP1(a, b))
 #define CMP_R(arg, a, b) (cmp ? (cmp(arg, a, b)) : CMP1(a, b))
 #define MED3(a, b, c, d) (d ? (med3(a, b, c, d)) : (CMP1(a, b) < 0 ? (CMP1(b, c) < 0 ? (b) : (CMP1(a, c) < 0 ? (c) : (a))) : (CMP1(b, c) > 0 ? (b) : (CMP1(a, c) < 0 ? (a) : (c)))))
 #define MED3_R(arg, a, b, c, d) (d ? (med3_r(arg, a, b, c, d)) : (CMP1(a, b) < 0 ? (CMP1(b, c) < 0 ? (b) : (CMP1(a, c) < 0 ? (c) : (a))) : (CMP1(b, c) > 0 ? (b) : (CMP1(a, c) < 0 ? (a) : (c)))))
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 static inline char *
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     med3(a, b, c, cmp) char *a,
     *b, *c;
 int (*cmp)(const void *, const void *);
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 {
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     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));
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 }
 
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 static inline char *
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     med3_r(arg, a, b, c, cmp) void *arg;
 char *a, *b, *c;
 int (*cmp)(const void *, const void *, const void *);
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 {
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     return CMP_R(arg, a, b) < 0 ? (CMP_R(arg, b, c) < 0 ? b : (CMP_R(arg, a, c) < 0 ? c : a))
                                 : (CMP_R(arg, b, c) > 0 ? b : (CMP_R(arg, a, c) < 0 ? a : c));
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 }
 
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 void cli_qsort(void *a, size_t n, size_t es, int (*cmp)(const void *, const void *))
 {
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     char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
     int d, r, swaptype, swap_cnt;
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 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;
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     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;
     }
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     pn = (char *)a + n * es;
     r  = MIN(pa - (char *)a, pb - pa);
     vecswap(a, pb - r, r);
     r = MIN((size_t)(pd - pc), (size_t)(pn - pd - es));
     vecswap(pb, pn - r, r);
     if ((size_t)(r = pb - pa) > es)
         cli_qsort(a, r / es, es, cmp);
     if ((size_t)(r = pd - pc) > es) {
         /* Iterate rather than recurse to save stack space */
         a = pn - r;
         n = r / es;
         goto loop;
     }
     /*		cli_qsort(pn - r, r / es, es, cmp);*/
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 }
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 void cli_qsort_r(void *a, size_t n, size_t es, int (*cmp)(const void *, const void *, const void *), void *arg)
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 {
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     char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
     int d, r, swaptype, swap_cnt;
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 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_R(arg, 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_R(arg, pl, pl + d, pl + 2 * d, cmp);
             pm = MED3_R(arg, pm - d, pm, pm + d, cmp);
             pn = MED3_R(arg, pn - 2 * d, pn - d, pn, cmp);
         }
         pm = MED3_R(arg, pl, pm, pn, cmp);
     }
     swap(a, pm);
     pa = pb = (char *)a + es;
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     pc = pd = (char *)a + (n - 1) * es;
     for (;;) {
         while (pb <= pc && (r = CMP_R(arg, pb, a)) <= 0) {
             if (r == 0) {
                 swap_cnt = 1;
                 swap(pa, pb);
                 pa += es;
             }
             pb += es;
         }
         while (pb <= pc && (r = CMP_R(arg, 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_R(arg, pl - es, pl) > 0;
                  pl -= es)
                 swap(pl, pl - es);
         return;
     }
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     pn = (char *)a + n * es;
     r  = MIN(pa - (char *)a, pb - pa);
     vecswap(a, pb - r, r);
     r = MIN((size_t)(pd - pc), (size_t)(pn - pd - es));
     vecswap(pb, pn - r, r);
     if ((size_t)(r = pb - pa) > es)
         cli_qsort_r(a, r / es, es, cmp, arg);
     if ((size_t)(r = pd - pc) > es) {
         /* Iterate rather than recurse to save stack space */
         a = pn - r;
         n = r / es;
         goto loop;
     }
     /*		cli_qsort_r(pn - r, r / es, es, cmp);*/
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 }