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# rpmdb/merge.c

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    00001 /*@-mustmod -sizeoftype @*/
    00002 /*-
    00003  * Copyright (c) 1992, 1993
    00004  *      The Regents of the University of California.  All rights reserved.
    00005  *
    00006  * This code is derived from software contributed to Berkeley by
    00007  * Peter McIlroy.
    00008  *
    00009  * Redistribution and use in source and binary forms, with or without
    00010  * modification, are permitted provided that the following conditions
    00011  * are met:
    00012  * 1. Redistributions of source code must retain the above copyright
    00013  *    notice, this list of conditions and the following disclaimer.
    00014  * 2. Redistributions in binary form must reproduce the above copyright
    00015  *    notice, this list of conditions and the following disclaimer in the
    00016  *    documentation and/or other materials provided with the distribution.
    00017  * 3. All advertising materials mentioning features or use of this software
    00018  *    must display the following acknowledgement:
    00019  *      This product includes software developed by the University of
    00020  *      California, Berkeley and its contributors.
    00021  * 4. Neither the name of the University nor the names of its contributors
    00022  *    may be used to endorse or promote products derived from this software
    00023  *    without specific prior written permission.
    00024  *
    00025  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
    00026  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    00027  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    00028  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
    00029  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
    00030  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
    00031  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    00032  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    00033  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
    00034  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    00035  * SUCH DAMAGE.
    00036  */
    00037
    00038 #if defined(LIBC_SCCS) && !defined(lint)
    00039 static char sccsid[] = "@(#)merge.c     8.2 (Berkeley) 2/14/94";
    00040 #endif /* LIBC_SCCS and not lint */
    00041
    00042 /*
    00043  * Hybrid exponential search/linear search merge sort with hybrid
    00044  * natural/pairwise first pass.  Requires about .3% more comparisons
    00045  * for random data than LSMS with pairwise first pass alone.
    00046  * It works for objects as small as two bytes.
    00047  */
    00048
    00049 #define NATURAL
    00050 #define THRESHOLD 16    /* Best choice for natural merge cut-off. */
    00051
    00052 /* #define NATURAL to get hybrid natural merge.
    00053  * (The default is pairwise merging.)
    00054  */
    00055
    00056 #include "system.h"
    00057
    00058 #include "rpmdb.h"
    00059
    00060 #include "debug.h"
    00061
    00062 #define ISIZE sizeof(int)
    00063 #define PSIZE sizeof(unsigned char *)
    00064 #define ICOPY_LIST(src, dst, last)                              \
    00065         do                                                      \
    00066         *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE;    \
    00067         while(src < last)
    00068 #define ICOPY_ELT(src, dst, i)                                  \
    00069         do                                                      \
    00070         *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE;  \
    00071         while (i -= ISIZE)
    00072
    00073 #define CCOPY_LIST(src, dst, last)              \
    00074         do                                      \
    00075                 *dst++ = *src++;                \
    00076         while (src < last)
    00077 #define CCOPY_ELT(src, dst, i)                  \
    00078         do                                      \
    00079                 *dst++ = *src++;                \
    00080         while (i -= 1)
    00081
    00082 /*
    00083  * Find the next possible pointer head.  (Trickery for forcing an array
    00084  * to do double duty as a linked list when objects do not align with word
    00085  * boundaries.
    00086  */
    00087 /* Assumption: PSIZE is a power of 2. */
    00088 #define EVAL(p) (unsigned char **)                                      \
    00089     ((unsigned char *)0 +                                               \
    00090         (((unsigned char *)p + PSIZE - 1 - (unsigned char *) 0) & ~(PSIZE - 1)))
    00091
    00092 #define swap(a, b) {                                    \
    00093                 s = b;                                  \
    00094                 i = (int) size;                         \
    00095                 do {                                    \
    00096                         tmp = *a; *a++ = *s; *s++ = tmp; \
    00097                 } while (--i);                          \
    00098                 a -= size;                              \
    00099         }
    00100 #define reverse(bot, top) {                             \
    00101         s = top;                                        \
    00102         do {                                            \
    00103                 i = (int) size;                         \
    00104                 do {                                    \
    00105                         tmp = *bot; *bot++ = *s; *s++ = tmp; \
    00106                 } while (--i);                          \
    00107                 s -= size2;                             \
    00108         } while(bot < s);                               \
    00109 }
    00110
    00111 /*
    00112  * This is to avoid out-of-bounds addresses in sorting the
    00113  * last 4 elements.
    00114  */
    00115 static void
    00116 insertionsort(unsigned char *a, size_t n, size_t size,
    00117                 int (*cmp) (const void *, const void *))
    00118         /*@modifies *a @*/
    00119 {
    00120         u_char *ai, *s, *t, *u, tmp;
    00121         int i;
    00122
    00123         for (ai = a+size; --n >= 1; ai += size)
    00124                 for (t = ai; t > a; t -= size) {
    00125                         u = t - size;
    00126                         if (cmp(u, t) <= 0)
    00127                                 /*@innerbreak@*/ break;
    00128                         swap(u, t);
    00129                 }
    00130 }
    00131
    00132 /*
    00133  * Optional hybrid natural/pairwise first pass.  Eats up list1 in runs of
    00134  * increasing order, list2 in a corresponding linked list.  Checks for runs
    00135  * when THRESHOLD/2 pairs compare with same sense.  (Only used when NATURAL
    00136  * is defined.  Otherwise simple pairwise merging is used.)
    00137  */
    00138 static void
    00139 setup(unsigned char *list1, /*@out@*/ unsigned char *list2,
    00140                 size_t n, size_t size, int (*cmp) (const void *, const void *))
    00141         /*@modifies list1, list2 @*/
    00142 {
    00143         int i, length, size2, sense;
    00144         unsigned char *f1, *f2, *s, *l2, *last, *p2, tmp;
    00145
    00146         size2 = size*2;
    00147         if (n <= 5) {
    00148                 insertionsort(list1, n, size, cmp);
    00149                 *EVAL(list2) = (unsigned char*) list2 + n*size;
    00150                 return;
    00151         }
    00152         /*
    00153          * Avoid running pointers out of bounds; limit n to evens
    00154          * for simplicity.
    00155          */
    00156         i = (int)(4 + (n & 1));
    00157         insertionsort(list1 + (n - i) * size, i, size, cmp);
    00158         last = list1 + size * (n - i);
    00159         *EVAL(list2 + (last - list1)) = list2 + n * size;
    00160
    00161 #ifdef NATURAL
    00162         p2 = list2;
    00163         f1 = list1;
    00164         sense = (cmp(f1, f1 + size) > 0);
    00165         for (; f1 < last; sense = !sense) {
    00166                 length = 2;
    00167                                         /* Find pairs with same sense. */
    00168                 for (f2 = f1 + size2; f2 < last; f2 += size2) {
    00169                         if ((cmp(f2, f2+ size) > 0) != sense)
    00170                                 /*@innerbreak@*/ break;
    00171                         length += 2;
    00172                 }
    00173                 if (length < THRESHOLD) {               /* Pairwise merge */
    00174                         do {
    00175                                 p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
    00176                                 if (sense > 0)
    00177                                         swap (f1, f1 + size);
    00178                         } while ((f1 += size2) < f2);
    00179                 } else {                                /* Natural merge */
    00180                         l2 = f2;
    00181                         for (f2 = f1 + size2; f2 < l2; f2 += size2) {
    00182                                 if ((cmp(f2-size, f2) > 0) != sense) {
    00183                                         p2 = *EVAL(p2) = f2 - list1 + list2;
    00184                                         if (sense > 0)
    00185                                                 reverse(f1, f2-size);
    00186                                         f1 = f2;
    00187                                 }
    00188                         }
    00189                         if (sense > 0)
    00190                                 reverse (f1, f2-size);
    00191                         f1 = f2;
    00192                         if (f2 < last || cmp(f2 - size, f2) > 0)
    00193                                 p2 = *EVAL(p2) = f2 - list1 + list2;
    00194                         else
    00195                                 p2 = *EVAL(p2) = list2 + n*size;
    00196                 }
    00197         }
    00198 #else           /* pairwise merge only. */
    00199         for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
    00200                 p2 = *EVAL(p2) = p2 + size2;
    00201                 if (cmp (f1, f1 + size) > 0)
    00202                         swap(f1, f1 + size);
    00203         }
    00204 #endif /* NATURAL */
    00205 }
    00206
    00207 /*
    00208  * Arguments are as for qsort.
    00209  */
    00210 int
    00211 rpm_mergesort(void *base, size_t nmemb, size_t size,
    00212                 int (*cmp) (const void *, const void *))
    00213 {
    00214         register int i, sense;
    00215         int big, iflag;
    00216         register unsigned char *f1, *f2, *t, *b, *q, *l1, *l2;
    00217         /*@dependent@*/
    00218         register unsigned char *tp2;
    00219         /*@owned@*/
    00220         unsigned char *list2;
    00221         /*@dependent@*/
    00222         unsigned char *list1;
    00223         unsigned char *p2, *p, *last, **p1;
    00224
    00225         if (size < PSIZE / 2) {         /* Pointers must fit into 2 * size. */
    00226                 errno = EINVAL;
    00227                 return (-1);
    00228         }
    00229
    00230         if (nmemb == 0)
    00231                 return (0);
    00232
    00233         /*
    00234          * XXX
    00235          * Stupid subtraction for the Cray.
    00236          */
    00237         iflag = 0;
    00238         if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
    00239                 iflag = 1;
    00240
    00241         if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
    00242                 return (-1);
    00243
    00244         list1 = base;
    00245         setup(list1, list2, nmemb, size, cmp);
    00246         last = list2 + nmemb * size;
    00247         i = big = 0;
    00248         while (*EVAL(list2) != last) {
    00249             l2 = list1;
    00250             p1 = EVAL(list1);
    00251             for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
    00252                 p2 = *EVAL(p2);
    00253                 f1 = l2;
    00254                 f2 = l1 = list1 + (p2 - list2);
    00255                 if (p2 != last)
    00256                         p2 = *EVAL(p2);
    00257                 l2 = list1 + (p2 - list2);
    00258                 while (f1 < l1 && f2 < l2) {
    00259                         if ((*cmp)(f1, f2) <= 0) {
    00260                                 q = f2;
    00261                                 b = f1, t = l1;
    00262                                 sense = -1;
    00263                         } else {
    00264                                 q = f1;
    00265                                 b = f2, t = l2;
    00266                                 sense = 0;
    00267                         }
    00268                         if (!big) {     /* here i = 0 */
    00269                                 while ((b += size) < t && cmp(q, b) >sense)
    00270                                         if (++i == 6) {
    00271                                                 big = 1;
    00272                                                 goto EXPONENTIAL;
    00273                                         }
    00274                         } else {
    00275 /*@-shiftimplementation@*/
    00276 EXPONENTIAL:                    for (i = (int) size; ; i <<= 1)
    00277                                         if ((p = (b + i)) >= t) {
    00278                                                 if ((p = t - size) > b &&
    00279                                                     (*cmp)(q, p) <= sense)
    00280                                                         t = p;
    00281                                                 else
    00282                                                         b = p;
    00283                                                 /*@innerbreak@*/ break;
    00284                                         } else if ((*cmp)(q, p) <= sense) {
    00285                                                 t = p;
    00286                                                 if (i == (int) size)
    00287                                                         big = 0;
    00288                                                 goto FASTCASE;
    00289                                         } else
    00290                                                 b = p;
    00291                                 /*@-infloopsuncon@*/
    00292                                 while (t > b+size) {
    00293                                         i = (int) ((((t - b) / size) >> 1) * size);
    00294                                         if ((*cmp)(q, p = b + i) <= sense)
    00295                                                 t = p;
    00296                                         else
    00297                                                 b = p;
    00298                                 }
    00299                                 goto COPY;
    00300 FASTCASE:                       while (i > (int) size)
    00301                                         if ((*cmp)(q,
    00302                                                 p = b + (i >>= 1)) <= sense)
    00303                                                 t = p;
    00304                                         else
    00305                                                 b = p;
    00306                                 /*@=infloopsuncon@*/
    00307 /*@=shiftimplementation@*/
    00308 COPY:                           b = t;
    00309                         }
    00310                         i = (int) size;
    00311                         if (q == f1) {
    00312                                 if (iflag) {
    00313                                         ICOPY_LIST(f2, tp2, b);
    00314                                         ICOPY_ELT(f1, tp2, i);
    00315                                 } else {
    00316                                         CCOPY_LIST(f2, tp2, b);
    00317                                         CCOPY_ELT(f1, tp2, i);
    00318                                 }
    00319                         } else {
    00320                                 if (iflag) {
    00321                                         ICOPY_LIST(f1, tp2, b);
    00322                                         ICOPY_ELT(f2, tp2, i);
    00323                                 } else {
    00324                                         CCOPY_LIST(f1, tp2, b);
    00325                                         CCOPY_ELT(f2, tp2, i);
    00326                                 }
    00327                         }
    00328                 }
    00329                 if (f2 < l2) {
    00330                         if (iflag)
    00331                                 ICOPY_LIST(f2, tp2, l2);
    00332                         else
    00333                                 CCOPY_LIST(f2, tp2, l2);
    00334                 } else if (f1 < l1) {
    00335                         if (iflag)
    00336                                 ICOPY_LIST(f1, tp2, l1);
    00337                         else
    00338                                 CCOPY_LIST(f1, tp2, l1);
    00339                 }
    00340                 *p1 = l2;
    00341             }
    00342 /*@-dependenttrans@*/
    00343             tp2 = list1;        /* swap list1, list2 */
    00344             list1 = list2;
    00345             list2 = tp2;
    00346 /*@=dependenttrans@*/
    00347             last = list2 + nmemb*size;
    00348         }
    00349         if (base == list2) {
    00350                 memmove(list2, list1, nmemb*size);
    00351                 list2 = list1;
    00352         }
    00353 /*@-usereleased@*/
    00354         free(list2);
    00355 /*@=usereleased@*/
    00356         return (0);
    00357 }
    00358 /*@=mustmod =sizeoftype @*/