File: msort.c

package info (click to toggle)
glibc 2.24-11+deb9u4
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 225,852 kB
  • sloc: ansic: 996,505; asm: 261,827; sh: 10,484; makefile: 9,856; cpp: 4,169; python: 3,971; perl: 2,254; awk: 1,753; pascal: 1,521; yacc: 291; sed: 80
file content (310 lines) | stat: -rw-r--r-- 7,072 bytes parent folder | download | duplicates (5)
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
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
/* An alternative to qsort, with an identical interface.
   This file is part of the GNU C Library.
   Copyright (C) 1992-2016 Free Software Foundation, Inc.
   Written by Mike Haertel, September 1988.

   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, see
   <http://www.gnu.org/licenses/>.  */

#include <alloca.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <memcopy.h>
#include <errno.h>
#include <atomic.h>

struct msort_param
{
  size_t s;
  size_t var;
  __compar_d_fn_t cmp;
  void *arg;
  char *t;
};
static void msort_with_tmp (const struct msort_param *p, void *b, size_t n);

static void
msort_with_tmp (const struct msort_param *p, void *b, size_t n)
{
  char *b1, *b2;
  size_t n1, n2;

  if (n <= 1)
    return;

  n1 = n / 2;
  n2 = n - n1;
  b1 = b;
  b2 = (char *) b + (n1 * p->s);

  msort_with_tmp (p, b1, n1);
  msort_with_tmp (p, b2, n2);

  char *tmp = p->t;
  const size_t s = p->s;
  __compar_d_fn_t cmp = p->cmp;
  void *arg = p->arg;
  switch (p->var)
    {
    case 0:
      while (n1 > 0 && n2 > 0)
	{
	  if ((*cmp) (b1, b2, arg) <= 0)
	    {
	      *(uint32_t *) tmp = *(uint32_t *) b1;
	      b1 += sizeof (uint32_t);
	      --n1;
	    }
	  else
	    {
	      *(uint32_t *) tmp = *(uint32_t *) b2;
	      b2 += sizeof (uint32_t);
	      --n2;
	    }
	  tmp += sizeof (uint32_t);
	}
      break;
    case 1:
      while (n1 > 0 && n2 > 0)
	{
	  if ((*cmp) (b1, b2, arg) <= 0)
	    {
	      *(uint64_t *) tmp = *(uint64_t *) b1;
	      b1 += sizeof (uint64_t);
	      --n1;
	    }
	  else
	    {
	      *(uint64_t *) tmp = *(uint64_t *) b2;
	      b2 += sizeof (uint64_t);
	      --n2;
	    }
	  tmp += sizeof (uint64_t);
	}
      break;
    case 2:
      while (n1 > 0 && n2 > 0)
	{
	  unsigned long *tmpl = (unsigned long *) tmp;
	  unsigned long *bl;

	  tmp += s;
	  if ((*cmp) (b1, b2, arg) <= 0)
	    {
	      bl = (unsigned long *) b1;
	      b1 += s;
	      --n1;
	    }
	  else
	    {
	      bl = (unsigned long *) b2;
	      b2 += s;
	      --n2;
	    }
	  while (tmpl < (unsigned long *) tmp)
	    *tmpl++ = *bl++;
	}
      break;
    case 3:
      while (n1 > 0 && n2 > 0)
	{
	  if ((*cmp) (*(const void **) b1, *(const void **) b2, arg) <= 0)
	    {
	      *(void **) tmp = *(void **) b1;
	      b1 += sizeof (void *);
	      --n1;
	    }
	  else
	    {
	      *(void **) tmp = *(void **) b2;
	      b2 += sizeof (void *);
	      --n2;
	    }
	  tmp += sizeof (void *);
	}
      break;
    default:
      while (n1 > 0 && n2 > 0)
	{
	  if ((*cmp) (b1, b2, arg) <= 0)
	    {
	      tmp = (char *) __mempcpy (tmp, b1, s);
	      b1 += s;
	      --n1;
	    }
	  else
	    {
	      tmp = (char *) __mempcpy (tmp, b2, s);
	      b2 += s;
	      --n2;
	    }
	}
      break;
    }

  if (n1 > 0)
    memcpy (tmp, b1, n1 * s);
  memcpy (b, p->t, (n - n2) * s);
}


void
__qsort_r (void *b, size_t n, size_t s, __compar_d_fn_t cmp, void *arg)
{
  size_t size = n * s;
  char *tmp = NULL;
  struct msort_param p;

  /* For large object sizes use indirect sorting.  */
  if (s > 32)
    size = 2 * n * sizeof (void *) + s;

  if (size < 1024)
    /* The temporary array is small, so put it on the stack.  */
    p.t = __alloca (size);
  else
    {
      /* We should avoid allocating too much memory since this might
	 have to be backed up by swap space.  */
      static long int phys_pages;
      static int pagesize;

      if (pagesize == 0)
	{
	  phys_pages = __sysconf (_SC_PHYS_PAGES);

	  if (phys_pages == -1)
	    /* Error while determining the memory size.  So let's
	       assume there is enough memory.  Otherwise the
	       implementer should provide a complete implementation of
	       the `sysconf' function.  */
	    phys_pages = (long int) (~0ul >> 1);

	  /* The following determines that we will never use more than
	     a quarter of the physical memory.  */
	  phys_pages /= 4;

	  /* Make sure phys_pages is written to memory.  */
	  atomic_write_barrier ();

	  pagesize = __sysconf (_SC_PAGESIZE);
	}

      /* Just a comment here.  We cannot compute
	   phys_pages * pagesize
	   and compare the needed amount of memory against this value.
	   The problem is that some systems might have more physical
	   memory then can be represented with a `size_t' value (when
	   measured in bytes.  */

      /* If the memory requirements are too high don't allocate memory.  */
      if (size / pagesize > (size_t) phys_pages)
	{
	  _quicksort (b, n, s, cmp, arg);
	  return;
	}

      /* It's somewhat large, so malloc it.  */
      int save = errno;
      tmp = malloc (size);
      __set_errno (save);
      if (tmp == NULL)
	{
	  /* Couldn't get space, so use the slower algorithm
	     that doesn't need a temporary array.  */
	  _quicksort (b, n, s, cmp, arg);
	  return;
	}
      p.t = tmp;
    }

  p.s = s;
  p.var = 4;
  p.cmp = cmp;
  p.arg = arg;

  if (s > 32)
    {
      /* Indirect sorting.  */
      char *ip = (char *) b;
      void **tp = (void **) (p.t + n * sizeof (void *));
      void **t = tp;
      void *tmp_storage = (void *) (tp + n);

      while ((void *) t < tmp_storage)
	{
	  *t++ = ip;
	  ip += s;
	}
      p.s = sizeof (void *);
      p.var = 3;
      msort_with_tmp (&p, p.t + n * sizeof (void *), n);

      /* tp[0] .. tp[n - 1] is now sorted, copy around entries of
	 the original array.  Knuth vol. 3 (2nd ed.) exercise 5.2-10.  */
      char *kp;
      size_t i;
      for (i = 0, ip = (char *) b; i < n; i++, ip += s)
	if ((kp = tp[i]) != ip)
	  {
	    size_t j = i;
	    char *jp = ip;
	    memcpy (tmp_storage, ip, s);

	    do
	      {
		size_t k = (kp - (char *) b) / s;
		tp[j] = jp;
		memcpy (jp, kp, s);
		j = k;
		jp = kp;
		kp = tp[k];
	      }
	    while (kp != ip);

	    tp[j] = jp;
	    memcpy (jp, tmp_storage, s);
	  }
    }
  else
    {
      if ((s & (sizeof (uint32_t) - 1)) == 0
	  && ((char *) b - (char *) 0) % __alignof__ (uint32_t) == 0)
	{
	  if (s == sizeof (uint32_t))
	    p.var = 0;
	  else if (s == sizeof (uint64_t)
		   && ((char *) b - (char *) 0) % __alignof__ (uint64_t) == 0)
	    p.var = 1;
	  else if ((s & (sizeof (unsigned long) - 1)) == 0
		   && ((char *) b - (char *) 0)
		      % __alignof__ (unsigned long) == 0)
	    p.var = 2;
	}
      msort_with_tmp (&p, b, n);
    }
  free (tmp);
}
libc_hidden_def (__qsort_r)
weak_alias (__qsort_r, qsort_r)


void
qsort (void *b, size_t n, size_t s, __compar_fn_t cmp)
{
  return __qsort_r (b, n, s, (__compar_d_fn_t) cmp, NULL);
}
libc_hidden_def (qsort)