-
Notifications
You must be signed in to change notification settings - Fork 2
/
smoothsort.c
227 lines (214 loc) · 6.62 KB
/
smoothsort.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
/*
* This file is part of the Sofia-SIP package
*
* Copyright (C) 2005 Nokia Corporation.
*
* Contact: Pekka Pessi <pekka.pessi@nokia.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
*/
/**@file smoothsort.c
* @brief Smoothsort implementation
*
* Smoothsort is a in-place sorting algorithm with performance of O(NlogN)
* in worst case and O(n) in best case.
*
* @sa <a href="http://www.enterag.ch/hartwig/order/smoothsort.pdf">
* "Smoothsort, an alternative for sorting in-situ", E.D. Dijkstra, EWD796a</a>,
* <http://www.enterag.ch/hartwig/order/smoothsort.pdf>.
*
* @author Pekka Pessi <Pekka.Pessi@nokia.com>
*/
#include <assert.h>
#include <stdio.h>
#include <sys/types.h>
/** Description of current stretch */
typedef struct {
size_t b, c; /** Leonardo numbers */
unsigned long long p; /** Concatenation codification */
} stretch;
/** Description of array */
typedef struct
{
void *m;
int (*less)(void *m, size_t a, size_t b);
void (*swap)(void *m, size_t a, size_t b);
} array;
static inline size_t stretch_up(stretch s[1])
{
size_t next;
s->p >>= 1;
next = s->b + s->c + 1, s->c = s->b, s->b = next;
return next;
}
static inline size_t stretch_down(stretch s[1], unsigned bit)
{
size_t next;
s->p <<= 1, s->p |= bit;
next = s->c, s->c = s->b - s->c - 1, s->b = next;
return next;
}
#if DEBUG_SMOOTHSORT
static char const *binary(unsigned long long p)
{
static char binary[65];
int i;
if (p == 0)
return "0";
binary[64] = 0;
for (i = 64; p; p >>= 1)
binary[--i] = "01"[p & 1];
return binary + i;
}
#else
#undef DEBUG
#define DEBUG(x) ((void)0)
#endif
/**
* Sift the root of the stretch.
*
* The low values are sifted up (towards index 0) from root.
*
* @param array description of array to sort
* @param r root of the stretch
* @param s description of current stretch
*/
static void sift(array const *array, size_t r, stretch s)
{
while (s.b >= 3) {
size_t r2 = r - s.b + s.c;
if (!array->less(array->m, r - 1, r2)) {
r2 = r - 1;
stretch_down(&s, 0);
}
if (array->less(array->m, r2, r))
break;
DEBUG(("\tswap(%p @%zu <=> @%zu)\n", array, r, r2));
array->swap(array->m, r, r2); r = r2;
stretch_down(&s, 0);
}
}
/** Trinkle the roots of the given stretches
*
* @param array description of array to sort
* @param r root of the stretch
* @param s description of stretches to concatenate
*/
static void trinkle(array const *array, size_t r, stretch s)
{
DEBUG(("trinkle(%p, %zu, (%u, %s))\n", array, r, s.b, binary(s.p)));
while (s.p != 0) {
size_t r2, r3;
while ((s.p & 1) == 0)
stretch_up(&s);
if (s.p == 1)
break;
r3 = r - s.b;
if (array->less(array->m, r3, r))
break;
s.p--;
if (s.b < 3) {
DEBUG(("\tswap(%p @%zu <=> @%zu b=%u)\n", array, r, r3, s.b));
array->swap(array->m, r, r3); r = r3;
continue;
}
r2 = r - s.b + s.c;
if (array->less(array->m, r2, r - 1)) {
r2 = r - 1;
stretch_down(&s, 0);
}
if (array->less(array->m, r2, r3)) {
DEBUG(("swap(%p [%zu]=[%zu])\n", array, r, r3));
array->swap(array->m, r, r3); r = r3;
continue;
}
DEBUG(("\tswap(%p @%zu <=> @%zu b=%u)\n", array, r, r2, s.b));
array->swap(array->m, r, r2); r = r2;
stretch_down(&s, 0);
break;
}
sift(array, r, s);
}
/** Trinkles the stretches when the adjacent stretches are already trusty.
*
* @param array description of array to sort
* @param r root of the stretch
* @param stretch description of stretches to trinkle
*/
static void semitrinkle(array const *array, size_t r, stretch s)
{
size_t r1 = r - s.c;
DEBUG(("semitrinkle(%p, %zu, (%u, %s))\n", array, r, s.b, binary(s.p)));
if (array->less(array->m, r, r1)) {
DEBUG(("\tswap(%p @%zu <=> @%zu b=%u)\n", array, r, r1, s.b));
array->swap(array->m, r, r1);
trinkle(array, r1, s);
}
}
/** Sort array using smoothsort.
*
* Sort @a N elements from array @a base starting with index @a r with smoothsort.
*
* @param base pointer to array
* @param r lowest index to sort
* @param N number of elements to sort
* @param less comparison function returning nonzero if m[a] < m[b]
* @param swap swapper function exchanging elements m[a] and m[b]
*/
void su_smoothsort(void *base, size_t r, size_t N,
int (*less)(void *m, size_t a, size_t b),
void (*swap)(void *m, size_t a, size_t b))
{
stretch s = { 1, 1, 1 };
size_t q;
array const array[1] = {{ base, less, swap }};
assert(less && swap);
if (base == NULL || N <= 1 || less == NULL || swap == NULL)
return;
DEBUG(("\nsmoothsort(%p, %zu)\n", array, nmemb));
for (q = 1; q != N; q++, r++, s.p++) {
DEBUG(("loop0 q=%zu, b=%u, p=%s \n", q, s.b, binary(s.p)));
if ((s.p & 7) == 3) {
sift(array, r, s), stretch_up(&s), stretch_up(&s);
}
else /* if ((s.p & 3) == 1) */ {
assert((s.p & 3) == 1);
if (q + s.c < N)
sift(array, r, s);
else
trinkle(array, r, s);
while (stretch_down(&s, 0) > 1)
/* noop */;
}
}
trinkle(array, r, s);
for (; q > 1; q--) {
s.p--;
DEBUG(("loop1 q=%zu: b=%u p=%s\n", q, s.b, binary(s.p)));
if (s.b <= 1) {
while ((s.p & 1) == 0)
stretch_up(&s);
--r;
}
else /* if b >= 3 */ {
if (s.p) semitrinkle(array, r - (s.b - s.c), s);
stretch_down(&s, 1);
semitrinkle(array, --r, s);
stretch_down(&s, 1);
}
}
}