ReactOS  0.4.14-dev-384-g5b37caa
zerobytes.c
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1 /* @(#)zerobytes.c 1.2 11/07/30 Copyright Copyright 1987, 1995-2011 J. Schilling */
2 /*
3  * fill memory with null bytes
4  *
5  * Copyright (c) 1987, 1995-2011 J. Schilling
6  */
7 /*
8  * The contents of this file are subject to the terms of the
9  * Common Development and Distribution License, Version 1.0 only
10  * (the "License"). You may not use this file except in compliance
11  * with the License.
12  *
13  * See the file CDDL.Schily.txt in this distribution for details.
14  *
15  * When distributing Covered Code, include this CDDL HEADER in each
16  * file and include the License file CDDL.Schily.txt from this distribution.
17  */
18 
19 #include <schily/standard.h>
20 #include <schily/align.h>
21 #include <schily/types.h>
22 #include <schily/schily.h>
23 
24 #define DO8(a) a; a; a; a; a; a; a; a;
25 
26 /*
27  * zero(to, cnt)
28  */
29 EXPORT char *
30 zerobytes(tov, cnt)
31  void *tov;
32  ssize_t cnt;
33 {
34  register char *to = (char *)tov;
35  register ssize_t n;
36  register long lval = 0L;
37 
38  /*
39  * If we change cnt to be unsigned, check for == instead of <=
40  */
41  if ((n = cnt) <= 0)
42  return (to);
43 
44  if (n < 8 * sizeof (long)) { /* Simple may be faster... */
45  do { /* n is always > 0 */
46  *to++ = '\0';
47  } while (--n > 0);
48  return (to);
49  }
50 
51  /*
52  * Assign byte-wise until properly aligned for a long pointer.
53  */
54  while (--n >= 0 && !laligned(to)) {
55  *to++ = '\0';
56  }
57  n++;
58 
59  if (n >= (ssize_t)(8 * sizeof (long))) {
60  register ssize_t rem = n % (8 * sizeof (long));
61 
62  n /= (8 * sizeof (long));
63  {
64  register long *tol = (long *)to;
65 
66  do {
67  DO8 (*tol++ = lval);
68  } while (--n > 0);
69 
70  to = (char *)tol;
71  }
72  n = rem;
73 
74  if (n >= 8) {
75  n -= 8;
76  do {
77  DO8 (*to++ = '\0');
78  } while ((n -= 8) >= 0);
79  n += 8;
80  }
81  if (n > 0) do {
82  *to++ = '\0';
83  } while (--n > 0);
84  return (to);
85  }
86  if (n > 0) do {
87  *to++ = '\0';
88  } while (--n > 0);
89  return (to);
90 }
#define laligned(a)
Definition: align.h:19
EXPORT char * zerobytes(void *tov, ssize_t cnt)
Definition: zerobytes.c:30
GLdouble n
Definition: glext.h:7729
static const WCHAR L[]
Definition: oid.c:1250
int ssize_t
Definition: rosdhcp.h:48
#define long
Definition: qsort.c:33
#define DO8(a)
Definition: zerobytes.c:24