1*44431c82SRobert Mustacchi /* $OpenBSD: merge.c,v 1.10 2015/06/21 03:20:56 millert Exp $ */
2*44431c82SRobert Mustacchi /*-
3*44431c82SRobert Mustacchi * Copyright (c) 1992, 1993
4*44431c82SRobert Mustacchi * The Regents of the University of California. All rights reserved.
5*44431c82SRobert Mustacchi *
6*44431c82SRobert Mustacchi * This code is derived from software contributed to Berkeley by
7*44431c82SRobert Mustacchi * Peter McIlroy.
8*44431c82SRobert Mustacchi *
9*44431c82SRobert Mustacchi * Redistribution and use in source and binary forms, with or without
10*44431c82SRobert Mustacchi * modification, are permitted provided that the following conditions
11*44431c82SRobert Mustacchi * are met:
12*44431c82SRobert Mustacchi * 1. Redistributions of source code must retain the above copyright
13*44431c82SRobert Mustacchi * notice, this list of conditions and the following disclaimer.
14*44431c82SRobert Mustacchi * 2. Redistributions in binary form must reproduce the above copyright
15*44431c82SRobert Mustacchi * notice, this list of conditions and the following disclaimer in the
16*44431c82SRobert Mustacchi * documentation and/or other materials provided with the distribution.
17*44431c82SRobert Mustacchi * 3. Neither the name of the University nor the names of its contributors
18*44431c82SRobert Mustacchi * may be used to endorse or promote products derived from this software
19*44431c82SRobert Mustacchi * without specific prior written permission.
20*44431c82SRobert Mustacchi *
21*44431c82SRobert Mustacchi * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22*44431c82SRobert Mustacchi * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23*44431c82SRobert Mustacchi * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24*44431c82SRobert Mustacchi * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25*44431c82SRobert Mustacchi * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26*44431c82SRobert Mustacchi * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27*44431c82SRobert Mustacchi * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28*44431c82SRobert Mustacchi * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29*44431c82SRobert Mustacchi * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30*44431c82SRobert Mustacchi * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31*44431c82SRobert Mustacchi * SUCH DAMAGE.
32*44431c82SRobert Mustacchi */
33*44431c82SRobert Mustacchi
34*44431c82SRobert Mustacchi /*
35*44431c82SRobert Mustacchi * Hybrid exponential search/linear search merge sort with hybrid
36*44431c82SRobert Mustacchi * natural/pairwise first pass. Requires about .3% more comparisons
37*44431c82SRobert Mustacchi * for random data than LSMS with pairwise first pass alone.
38*44431c82SRobert Mustacchi * It works for objects as small as two bytes.
39*44431c82SRobert Mustacchi */
40*44431c82SRobert Mustacchi
41*44431c82SRobert Mustacchi #define NATURAL
42*44431c82SRobert Mustacchi #define THRESHOLD 16 /* Best choice for natural merge cut-off. */
43*44431c82SRobert Mustacchi
44*44431c82SRobert Mustacchi /* #define NATURAL to get hybrid natural merge.
45*44431c82SRobert Mustacchi * (The default is pairwise merging.)
46*44431c82SRobert Mustacchi */
47*44431c82SRobert Mustacchi
48*44431c82SRobert Mustacchi #include <sys/types.h>
49*44431c82SRobert Mustacchi
50*44431c82SRobert Mustacchi #include <errno.h>
51*44431c82SRobert Mustacchi #include <stdlib.h>
52*44431c82SRobert Mustacchi #include <string.h>
53*44431c82SRobert Mustacchi
54*44431c82SRobert Mustacchi static void setup(u_char *, u_char *, size_t, size_t, int (*)());
55*44431c82SRobert Mustacchi static void insertionsort(u_char *, size_t, size_t, int (*)());
56*44431c82SRobert Mustacchi
57*44431c82SRobert Mustacchi #define ISIZE sizeof(int)
58*44431c82SRobert Mustacchi #define PSIZE sizeof(u_char *)
59*44431c82SRobert Mustacchi #define ICOPY_LIST(src, dst, last) \
60*44431c82SRobert Mustacchi do \
61*44431c82SRobert Mustacchi *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \
62*44431c82SRobert Mustacchi while(src < last)
63*44431c82SRobert Mustacchi #define ICOPY_ELT(src, dst, i) \
64*44431c82SRobert Mustacchi do \
65*44431c82SRobert Mustacchi *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \
66*44431c82SRobert Mustacchi while (i -= ISIZE)
67*44431c82SRobert Mustacchi
68*44431c82SRobert Mustacchi #define CCOPY_LIST(src, dst, last) \
69*44431c82SRobert Mustacchi do \
70*44431c82SRobert Mustacchi *dst++ = *src++; \
71*44431c82SRobert Mustacchi while (src < last)
72*44431c82SRobert Mustacchi #define CCOPY_ELT(src, dst, i) \
73*44431c82SRobert Mustacchi do \
74*44431c82SRobert Mustacchi *dst++ = *src++; \
75*44431c82SRobert Mustacchi while (i -= 1)
76*44431c82SRobert Mustacchi
77*44431c82SRobert Mustacchi /*
78*44431c82SRobert Mustacchi * Find the next possible pointer head. (Trickery for forcing an array
79*44431c82SRobert Mustacchi * to do double duty as a linked list when objects do not align with word
80*44431c82SRobert Mustacchi * boundaries.
81*44431c82SRobert Mustacchi */
82*44431c82SRobert Mustacchi /* Assumption: PSIZE is a power of 2. */
83*44431c82SRobert Mustacchi #define EVAL(p) (u_char **) \
84*44431c82SRobert Mustacchi ((u_char *)0 + \
85*44431c82SRobert Mustacchi (((u_char *)p + PSIZE - 1 - (u_char *) 0) & ~(PSIZE - 1)))
86*44431c82SRobert Mustacchi
87*44431c82SRobert Mustacchi /*
88*44431c82SRobert Mustacchi * Arguments are as for qsort.
89*44431c82SRobert Mustacchi */
90*44431c82SRobert Mustacchi int
mergesort(void * base,size_t nmemb,size_t size,int (* cmp)(const void *,const void *))91*44431c82SRobert Mustacchi mergesort(void *base, size_t nmemb, size_t size,
92*44431c82SRobert Mustacchi int (*cmp)(const void *, const void *))
93*44431c82SRobert Mustacchi {
94*44431c82SRobert Mustacchi int i, sense;
95*44431c82SRobert Mustacchi int big, iflag;
96*44431c82SRobert Mustacchi u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2;
97*44431c82SRobert Mustacchi u_char *list2, *list1, *p2, *p, *last, **p1;
98*44431c82SRobert Mustacchi
99*44431c82SRobert Mustacchi if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
100*44431c82SRobert Mustacchi errno = EINVAL;
101*44431c82SRobert Mustacchi return (-1);
102*44431c82SRobert Mustacchi }
103*44431c82SRobert Mustacchi
104*44431c82SRobert Mustacchi if (nmemb == 0)
105*44431c82SRobert Mustacchi return (0);
106*44431c82SRobert Mustacchi
107*44431c82SRobert Mustacchi /*
108*44431c82SRobert Mustacchi * XXX
109*44431c82SRobert Mustacchi * Stupid subtraction for the Cray.
110*44431c82SRobert Mustacchi */
111*44431c82SRobert Mustacchi iflag = 0;
112*44431c82SRobert Mustacchi if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
113*44431c82SRobert Mustacchi iflag = 1;
114*44431c82SRobert Mustacchi
115*44431c82SRobert Mustacchi if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
116*44431c82SRobert Mustacchi return (-1);
117*44431c82SRobert Mustacchi
118*44431c82SRobert Mustacchi list1 = base;
119*44431c82SRobert Mustacchi setup(list1, list2, nmemb, size, cmp);
120*44431c82SRobert Mustacchi last = list2 + nmemb * size;
121*44431c82SRobert Mustacchi i = big = 0;
122*44431c82SRobert Mustacchi while (*EVAL(list2) != last) {
123*44431c82SRobert Mustacchi l2 = list1;
124*44431c82SRobert Mustacchi p1 = EVAL(list1);
125*44431c82SRobert Mustacchi for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
126*44431c82SRobert Mustacchi p2 = *EVAL(p2);
127*44431c82SRobert Mustacchi f1 = l2;
128*44431c82SRobert Mustacchi f2 = l1 = list1 + (p2 - list2);
129*44431c82SRobert Mustacchi if (p2 != last)
130*44431c82SRobert Mustacchi p2 = *EVAL(p2);
131*44431c82SRobert Mustacchi l2 = list1 + (p2 - list2);
132*44431c82SRobert Mustacchi while (f1 < l1 && f2 < l2) {
133*44431c82SRobert Mustacchi if ((*cmp)(f1, f2) <= 0) {
134*44431c82SRobert Mustacchi q = f2;
135*44431c82SRobert Mustacchi b = f1, t = l1;
136*44431c82SRobert Mustacchi sense = -1;
137*44431c82SRobert Mustacchi } else {
138*44431c82SRobert Mustacchi q = f1;
139*44431c82SRobert Mustacchi b = f2, t = l2;
140*44431c82SRobert Mustacchi sense = 0;
141*44431c82SRobert Mustacchi }
142*44431c82SRobert Mustacchi if (!big) { /* here i = 0 */
143*44431c82SRobert Mustacchi while ((b += size) < t && cmp(q, b) >sense)
144*44431c82SRobert Mustacchi if (++i == 6) {
145*44431c82SRobert Mustacchi big = 1;
146*44431c82SRobert Mustacchi goto EXPONENTIAL;
147*44431c82SRobert Mustacchi }
148*44431c82SRobert Mustacchi } else {
149*44431c82SRobert Mustacchi EXPONENTIAL: for (i = size; ; i <<= 1)
150*44431c82SRobert Mustacchi if ((p = (b + i)) >= t) {
151*44431c82SRobert Mustacchi if ((p = t - size) > b &&
152*44431c82SRobert Mustacchi (*cmp)(q, p) <= sense)
153*44431c82SRobert Mustacchi t = p;
154*44431c82SRobert Mustacchi else
155*44431c82SRobert Mustacchi b = p;
156*44431c82SRobert Mustacchi break;
157*44431c82SRobert Mustacchi } else if ((*cmp)(q, p) <= sense) {
158*44431c82SRobert Mustacchi t = p;
159*44431c82SRobert Mustacchi if (i == size)
160*44431c82SRobert Mustacchi big = 0;
161*44431c82SRobert Mustacchi goto FASTCASE;
162*44431c82SRobert Mustacchi } else
163*44431c82SRobert Mustacchi b = p;
164*44431c82SRobert Mustacchi while (t > b+size) {
165*44431c82SRobert Mustacchi i = (((t - b) / size) >> 1) * size;
166*44431c82SRobert Mustacchi if ((*cmp)(q, p = b + i) <= sense)
167*44431c82SRobert Mustacchi t = p;
168*44431c82SRobert Mustacchi else
169*44431c82SRobert Mustacchi b = p;
170*44431c82SRobert Mustacchi }
171*44431c82SRobert Mustacchi goto COPY;
172*44431c82SRobert Mustacchi FASTCASE: while (i > size)
173*44431c82SRobert Mustacchi if ((*cmp)(q,
174*44431c82SRobert Mustacchi p = b + (i >>= 1)) <= sense)
175*44431c82SRobert Mustacchi t = p;
176*44431c82SRobert Mustacchi else
177*44431c82SRobert Mustacchi b = p;
178*44431c82SRobert Mustacchi COPY: b = t;
179*44431c82SRobert Mustacchi }
180*44431c82SRobert Mustacchi i = size;
181*44431c82SRobert Mustacchi if (q == f1) {
182*44431c82SRobert Mustacchi if (iflag) {
183*44431c82SRobert Mustacchi ICOPY_LIST(f2, tp2, b);
184*44431c82SRobert Mustacchi ICOPY_ELT(f1, tp2, i);
185*44431c82SRobert Mustacchi } else {
186*44431c82SRobert Mustacchi CCOPY_LIST(f2, tp2, b);
187*44431c82SRobert Mustacchi CCOPY_ELT(f1, tp2, i);
188*44431c82SRobert Mustacchi }
189*44431c82SRobert Mustacchi } else {
190*44431c82SRobert Mustacchi if (iflag) {
191*44431c82SRobert Mustacchi ICOPY_LIST(f1, tp2, b);
192*44431c82SRobert Mustacchi ICOPY_ELT(f2, tp2, i);
193*44431c82SRobert Mustacchi } else {
194*44431c82SRobert Mustacchi CCOPY_LIST(f1, tp2, b);
195*44431c82SRobert Mustacchi CCOPY_ELT(f2, tp2, i);
196*44431c82SRobert Mustacchi }
197*44431c82SRobert Mustacchi }
198*44431c82SRobert Mustacchi }
199*44431c82SRobert Mustacchi if (f2 < l2) {
200*44431c82SRobert Mustacchi if (iflag)
201*44431c82SRobert Mustacchi ICOPY_LIST(f2, tp2, l2);
202*44431c82SRobert Mustacchi else
203*44431c82SRobert Mustacchi CCOPY_LIST(f2, tp2, l2);
204*44431c82SRobert Mustacchi } else if (f1 < l1) {
205*44431c82SRobert Mustacchi if (iflag)
206*44431c82SRobert Mustacchi ICOPY_LIST(f1, tp2, l1);
207*44431c82SRobert Mustacchi else
208*44431c82SRobert Mustacchi CCOPY_LIST(f1, tp2, l1);
209*44431c82SRobert Mustacchi }
210*44431c82SRobert Mustacchi *p1 = l2;
211*44431c82SRobert Mustacchi }
212*44431c82SRobert Mustacchi tp2 = list1; /* swap list1, list2 */
213*44431c82SRobert Mustacchi list1 = list2;
214*44431c82SRobert Mustacchi list2 = tp2;
215*44431c82SRobert Mustacchi last = list2 + nmemb*size;
216*44431c82SRobert Mustacchi }
217*44431c82SRobert Mustacchi if (base == list2) {
218*44431c82SRobert Mustacchi memmove(list2, list1, nmemb*size);
219*44431c82SRobert Mustacchi list2 = list1;
220*44431c82SRobert Mustacchi }
221*44431c82SRobert Mustacchi free(list2);
222*44431c82SRobert Mustacchi return (0);
223*44431c82SRobert Mustacchi }
224*44431c82SRobert Mustacchi
225*44431c82SRobert Mustacchi #define swap(a, b) { \
226*44431c82SRobert Mustacchi s = b; \
227*44431c82SRobert Mustacchi i = size; \
228*44431c82SRobert Mustacchi do { \
229*44431c82SRobert Mustacchi tmp = *a; *a++ = *s; *s++ = tmp; \
230*44431c82SRobert Mustacchi } while (--i); \
231*44431c82SRobert Mustacchi a -= size; \
232*44431c82SRobert Mustacchi }
233*44431c82SRobert Mustacchi #define reverse(bot, top) { \
234*44431c82SRobert Mustacchi s = top; \
235*44431c82SRobert Mustacchi do { \
236*44431c82SRobert Mustacchi i = size; \
237*44431c82SRobert Mustacchi do { \
238*44431c82SRobert Mustacchi tmp = *bot; *bot++ = *s; *s++ = tmp; \
239*44431c82SRobert Mustacchi } while (--i); \
240*44431c82SRobert Mustacchi s -= size2; \
241*44431c82SRobert Mustacchi } while(bot < s); \
242*44431c82SRobert Mustacchi }
243*44431c82SRobert Mustacchi
244*44431c82SRobert Mustacchi /*
245*44431c82SRobert Mustacchi * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of
246*44431c82SRobert Mustacchi * increasing order, list2 in a corresponding linked list. Checks for runs
247*44431c82SRobert Mustacchi * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL
248*44431c82SRobert Mustacchi * is defined. Otherwise simple pairwise merging is used.)
249*44431c82SRobert Mustacchi */
250*44431c82SRobert Mustacchi void
setup(u_char * list1,u_char * list2,size_t n,size_t size,int (* cmp)(const void *,const void *))251*44431c82SRobert Mustacchi setup(u_char *list1, u_char *list2, size_t n, size_t size,
252*44431c82SRobert Mustacchi int (*cmp)(const void *, const void *))
253*44431c82SRobert Mustacchi {
254*44431c82SRobert Mustacchi int i, length, size2, sense;
255*44431c82SRobert Mustacchi u_char tmp, *f1, *f2, *s, *l2, *last, *p2;
256*44431c82SRobert Mustacchi
257*44431c82SRobert Mustacchi size2 = size*2;
258*44431c82SRobert Mustacchi if (n <= 5) {
259*44431c82SRobert Mustacchi insertionsort(list1, n, size, cmp);
260*44431c82SRobert Mustacchi *EVAL(list2) = (u_char*) list2 + n*size;
261*44431c82SRobert Mustacchi return;
262*44431c82SRobert Mustacchi }
263*44431c82SRobert Mustacchi /*
264*44431c82SRobert Mustacchi * Avoid running pointers out of bounds; limit n to evens
265*44431c82SRobert Mustacchi * for simplicity.
266*44431c82SRobert Mustacchi */
267*44431c82SRobert Mustacchi i = 4 + (n & 1);
268*44431c82SRobert Mustacchi insertionsort(list1 + (n - i) * size, i, size, cmp);
269*44431c82SRobert Mustacchi last = list1 + size * (n - i);
270*44431c82SRobert Mustacchi *EVAL(list2 + (last - list1)) = list2 + n * size;
271*44431c82SRobert Mustacchi
272*44431c82SRobert Mustacchi #ifdef NATURAL
273*44431c82SRobert Mustacchi p2 = list2;
274*44431c82SRobert Mustacchi f1 = list1;
275*44431c82SRobert Mustacchi sense = (cmp(f1, f1 + size) > 0);
276*44431c82SRobert Mustacchi for (; f1 < last; sense = !sense) {
277*44431c82SRobert Mustacchi length = 2;
278*44431c82SRobert Mustacchi /* Find pairs with same sense. */
279*44431c82SRobert Mustacchi for (f2 = f1 + size2; f2 < last; f2 += size2) {
280*44431c82SRobert Mustacchi if ((cmp(f2, f2+ size) > 0) != sense)
281*44431c82SRobert Mustacchi break;
282*44431c82SRobert Mustacchi length += 2;
283*44431c82SRobert Mustacchi }
284*44431c82SRobert Mustacchi if (length < THRESHOLD) { /* Pairwise merge */
285*44431c82SRobert Mustacchi do {
286*44431c82SRobert Mustacchi p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
287*44431c82SRobert Mustacchi if (sense > 0)
288*44431c82SRobert Mustacchi swap (f1, f1 + size);
289*44431c82SRobert Mustacchi } while ((f1 += size2) < f2);
290*44431c82SRobert Mustacchi } else { /* Natural merge */
291*44431c82SRobert Mustacchi l2 = f2;
292*44431c82SRobert Mustacchi for (f2 = f1 + size2; f2 < l2; f2 += size2) {
293*44431c82SRobert Mustacchi if ((cmp(f2-size, f2) > 0) != sense) {
294*44431c82SRobert Mustacchi p2 = *EVAL(p2) = f2 - list1 + list2;
295*44431c82SRobert Mustacchi if (sense > 0)
296*44431c82SRobert Mustacchi reverse(f1, f2-size);
297*44431c82SRobert Mustacchi f1 = f2;
298*44431c82SRobert Mustacchi }
299*44431c82SRobert Mustacchi }
300*44431c82SRobert Mustacchi if (sense > 0)
301*44431c82SRobert Mustacchi reverse (f1, f2-size);
302*44431c82SRobert Mustacchi f1 = f2;
303*44431c82SRobert Mustacchi if (f2 < last || cmp(f2 - size, f2) > 0)
304*44431c82SRobert Mustacchi p2 = *EVAL(p2) = f2 - list1 + list2;
305*44431c82SRobert Mustacchi else
306*44431c82SRobert Mustacchi p2 = *EVAL(p2) = list2 + n*size;
307*44431c82SRobert Mustacchi }
308*44431c82SRobert Mustacchi }
309*44431c82SRobert Mustacchi #else /* pairwise merge only. */
310*44431c82SRobert Mustacchi for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
311*44431c82SRobert Mustacchi p2 = *EVAL(p2) = p2 + size2;
312*44431c82SRobert Mustacchi if (cmp (f1, f1 + size) > 0)
313*44431c82SRobert Mustacchi swap(f1, f1 + size);
314*44431c82SRobert Mustacchi }
315*44431c82SRobert Mustacchi #endif /* NATURAL */
316*44431c82SRobert Mustacchi }
317*44431c82SRobert Mustacchi
318*44431c82SRobert Mustacchi /*
319*44431c82SRobert Mustacchi * This is to avoid out-of-bounds addresses in sorting the
320*44431c82SRobert Mustacchi * last 4 elements.
321*44431c82SRobert Mustacchi */
322*44431c82SRobert Mustacchi static void
insertionsort(u_char * a,size_t n,size_t size,int (* cmp)(const void *,const void *))323*44431c82SRobert Mustacchi insertionsort(u_char *a, size_t n, size_t size,
324*44431c82SRobert Mustacchi int (*cmp)(const void *, const void *))
325*44431c82SRobert Mustacchi {
326*44431c82SRobert Mustacchi u_char *ai, *s, *t, *u, tmp;
327*44431c82SRobert Mustacchi int i;
328*44431c82SRobert Mustacchi
329*44431c82SRobert Mustacchi for (ai = a+size; --n >= 1; ai += size)
330*44431c82SRobert Mustacchi for (t = ai; t > a; t -= size) {
331*44431c82SRobert Mustacchi u = t - size;
332*44431c82SRobert Mustacchi if (cmp(u, t) <= 0)
333*44431c82SRobert Mustacchi break;
334*44431c82SRobert Mustacchi swap(u, t);
335*44431c82SRobert Mustacchi }
336*44431c82SRobert Mustacchi }
337