forked from KarypisLab/GKlib
-
Notifications
You must be signed in to change notification settings - Fork 0
/
gk_mksort.h
271 lines (256 loc) · 10 KB
/
gk_mksort.h
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
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
/*!
\file gk_mksort.h
\brief Templates for the qsort routine
\date Started 3/28/07
\author George
\version\verbatim $Id: gk_mksort.h 21051 2017-05-25 04:36:14Z karypis $ \endverbatim
*/
#ifndef _GK_MKSORT_H_
#define _GK_MKSORT_H_
/* Adopted from GNU glibc by Mjt.
* See stdlib/qsort.c in glibc */
/* Copyright (C) 1991, 1992, 1996, 1997, 1999 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Written by Douglas C. Schmidt ([email protected]).
The GNU C 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.
The GNU C 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 the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/* in-line qsort implementation. Differs from traditional qsort() routine
* in that it is a macro, not a function, and instead of passing an address
* of a comparision routine to the function, it is possible to inline
* comparision routine, thus speed up sorting alot.
*
* Usage:
* #include "iqsort.h"
* #define islt(a,b) (strcmp((*a),(*b))<0)
* char *arr[];
* int n;
* GKQSORT(char*, arr, n, islt);
*
* The "prototype" and 4 arguments are:
* GKQSORT(TYPE,BASE,NELT,ISLT)
* 1) type of each element, TYPE,
* 2) address of the beginning of the array, of type TYPE*,
* 3) number of elements in the array, and
* 4) comparision routine.
* Array pointer and number of elements are referenced only once.
* This is similar to a call
* qsort(BASE,NELT,sizeof(TYPE),ISLT)
* with the difference in last parameter.
* Note the islt macro/routine (it receives pointers to two elements):
* the only condition of interest is whenever one element is less than
* another, no other conditions (greather than, equal to etc) are tested.
* So, for example, to define integer sort, use:
* #define islt(a,b) ((*a)<(*b))
* GKQSORT(int, arr, n, islt)
*
* The macro could be used to implement a sorting function (see examples
* below), or to implement the sorting algorithm inline. That is, either
* create a sorting function and use it whenever you want to sort something,
* or use GKQSORT() macro directly instead a call to such routine. Note that
* the macro expands to quite some code (compiled size of int qsort on x86
* is about 700..800 bytes).
*
* Using this macro directly it isn't possible to implement traditional
* qsort() routine, because the macro assumes sizeof(element) == sizeof(TYPE),
* while qsort() allows element size to be different.
*
* Several ready-to-use examples:
*
* Sorting array of integers:
* void int_qsort(int *arr, unsigned n) {
* #define int_lt(a,b) ((*a)<(*b))
* GKQSORT(int, arr, n, int_lt);
* }
*
* Sorting array of string pointers:
* void str_qsort(char *arr[], unsigned n) {
* #define str_lt(a,b) (strcmp((*a),(*b)) < 0)
* GKQSORT(char*, arr, n, str_lt);
* }
*
* Sorting array of structures:
*
* struct elt {
* int key;
* ...
* };
* void elt_qsort(struct elt *arr, unsigned n) {
* #define elt_lt(a,b) ((a)->key < (b)->key)
* GKQSORT(struct elt, arr, n, elt_lt);
* }
*
* And so on.
*/
/* Swap two items pointed to by A and B using temporary buffer t. */
#define _GKQSORT_SWAP(a, b, t) ((void)((t = *a), (*a = *b), (*b = t)))
/* Discontinue quicksort algorithm when partition gets below this size. */
#define _GKQSORT_MAX_THRESH 8
/* The next 4 #defines implement a very fast in-line stack abstraction. */
#define _GKQSORT_STACK_SIZE (8 * sizeof(size_t))
#define _GKQSORT_PUSH(top, low, high) (((top->_lo = (low)), (top->_hi = (high)), ++top))
#define _GKQSORT_POP(low, high, top) ((--top, (low = top->_lo), (high = top->_hi)))
#define _GKQSORT_STACK_NOT_EMPTY (_stack < _top)
/* The main code starts here... */
#define GK_MKQSORT(GKQSORT_TYPE,GKQSORT_BASE,GKQSORT_NELT,GKQSORT_LT) \
{ \
GKQSORT_TYPE *const _base = (GKQSORT_BASE); \
const size_t _elems = (GKQSORT_NELT); \
GKQSORT_TYPE _hold; \
\
if (_elems < 1) \
return; \
\
/* Don't declare two variables of type GKQSORT_TYPE in a single \
* statement: eg `TYPE a, b;', in case if TYPE is a pointer, \
* expands to `type* a, b;' wich isn't what we want. \
*/ \
\
if (_elems > _GKQSORT_MAX_THRESH) { \
GKQSORT_TYPE *_lo = _base; \
GKQSORT_TYPE *_hi = _lo + _elems - 1; \
struct { \
GKQSORT_TYPE *_hi; GKQSORT_TYPE *_lo; \
} _stack[_GKQSORT_STACK_SIZE], *_top = _stack + 1; \
\
while (_GKQSORT_STACK_NOT_EMPTY) { \
GKQSORT_TYPE *_left_ptr; GKQSORT_TYPE *_right_ptr; \
\
/* Select median value from among LO, MID, and HI. Rearrange \
LO and HI so the three values are sorted. This lowers the \
probability of picking a pathological pivot value and \
skips a comparison for both the LEFT_PTR and RIGHT_PTR in \
the while loops. */ \
\
GKQSORT_TYPE *_mid = _lo + ((_hi - _lo) >> 1); \
\
if (GKQSORT_LT (_mid, _lo)) \
_GKQSORT_SWAP (_mid, _lo, _hold); \
if (GKQSORT_LT (_hi, _mid)) \
_GKQSORT_SWAP (_mid, _hi, _hold); \
else \
goto _jump_over; \
if (GKQSORT_LT (_mid, _lo)) \
_GKQSORT_SWAP (_mid, _lo, _hold); \
_jump_over:; \
\
_left_ptr = _lo + 1; \
_right_ptr = _hi - 1; \
\
/* Here's the famous ``collapse the walls'' section of quicksort. \
Gotta like those tight inner loops! They are the main reason \
that this algorithm runs much faster than others. */ \
do { \
while (GKQSORT_LT (_left_ptr, _mid)) \
++_left_ptr; \
\
while (GKQSORT_LT (_mid, _right_ptr)) \
--_right_ptr; \
\
if (_left_ptr < _right_ptr) { \
_GKQSORT_SWAP (_left_ptr, _right_ptr, _hold); \
if (_mid == _left_ptr) \
_mid = _right_ptr; \
else if (_mid == _right_ptr) \
_mid = _left_ptr; \
++_left_ptr; \
--_right_ptr; \
} \
else if (_left_ptr == _right_ptr) { \
++_left_ptr; \
--_right_ptr; \
break; \
} \
} while (_left_ptr <= _right_ptr); \
\
/* Set up pointers for next iteration. First determine whether \
left and right partitions are below the threshold size. If so, \
ignore one or both. Otherwise, push the larger partition's \
bounds on the stack and continue sorting the smaller one. */ \
\
if (_right_ptr - _lo <= _GKQSORT_MAX_THRESH) { \
if (_hi - _left_ptr <= _GKQSORT_MAX_THRESH) \
/* Ignore both small partitions. */ \
_GKQSORT_POP (_lo, _hi, _top); \
else \
/* Ignore small left partition. */ \
_lo = _left_ptr; \
} \
else if (_hi - _left_ptr <= _GKQSORT_MAX_THRESH) \
/* Ignore small right partition. */ \
_hi = _right_ptr; \
else if (_right_ptr - _lo > _hi - _left_ptr) { \
/* Push larger left partition indices. */ \
_GKQSORT_PUSH (_top, _lo, _right_ptr); \
_lo = _left_ptr; \
} \
else { \
/* Push larger right partition indices. */ \
_GKQSORT_PUSH (_top, _left_ptr, _hi); \
_hi = _right_ptr; \
} \
} \
} \
\
/* Once the BASE array is partially sorted by quicksort the rest \
is completely sorted using insertion sort, since this is efficient \
for partitions below MAX_THRESH size. BASE points to the \
beginning of the array to sort, and END_PTR points at the very \
last element in the array (*not* one beyond it!). */ \
\
{ \
GKQSORT_TYPE *const _end_ptr = _base + _elems - 1; \
GKQSORT_TYPE *_tmp_ptr = _base; \
register GKQSORT_TYPE *_run_ptr; \
GKQSORT_TYPE *_thresh; \
\
_thresh = _base + _GKQSORT_MAX_THRESH; \
if (_thresh > _end_ptr) \
_thresh = _end_ptr; \
\
/* Find smallest element in first threshold and place it at the \
array's beginning. This is the smallest array element, \
and the operation speeds up insertion sort's inner loop. */ \
\
for (_run_ptr = _tmp_ptr + 1; _run_ptr <= _thresh; ++_run_ptr) \
if (GKQSORT_LT (_run_ptr, _tmp_ptr)) \
_tmp_ptr = _run_ptr; \
\
if (_tmp_ptr != _base) \
_GKQSORT_SWAP (_tmp_ptr, _base, _hold); \
\
/* Insertion sort, running from left-hand-side \
* up to right-hand-side. */ \
\
_run_ptr = _base + 1; \
while (++_run_ptr <= _end_ptr) { \
_tmp_ptr = _run_ptr - 1; \
while (GKQSORT_LT (_run_ptr, _tmp_ptr)) \
--_tmp_ptr; \
\
++_tmp_ptr; \
if (_tmp_ptr != _run_ptr) { \
GKQSORT_TYPE *_trav = _run_ptr + 1; \
while (--_trav >= _run_ptr) { \
GKQSORT_TYPE *_hi; GKQSORT_TYPE *_lo; \
_hold = *_trav; \
\
for (_hi = _lo = _trav; --_lo >= _tmp_ptr; _hi = _lo) \
*_hi = *_lo; \
*_hi = _hold; \
} \
} \
} \
} \
\
}
#endif