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1 office 1 /**
2 * @file balign.h
3 * @author Ambroz Bizjak <ambrop7@gmail.com>
4 *
5 * @section LICENSE
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the author nor the
15 * names of its contributors may be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
22 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
25 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
27 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * @section DESCRIPTION
30 *
31 * Integer alignment macros.
32 */
33  
34 #ifndef BADVPN_MISC_BALIGN_H
35 #define BADVPN_MISC_BALIGN_H
36  
37 #include <stddef.h>
38 #include <stdint.h>
39  
40 /**
41 * Checks if aligning x up to n would overflow.
42 */
43 static int balign_up_overflows (size_t x, size_t n)
44 {
45 size_t r = x % n;
46  
47 return (r && x > SIZE_MAX - (n - r));
48 }
49  
50 /**
51 * Aligns x up to n.
52 */
53 static size_t balign_up (size_t x, size_t n)
54 {
55 size_t r = x % n;
56 return (r ? x + (n - r) : x);
57 }
58  
59 /**
60 * Aligns x down to n.
61 */
62 static size_t balign_down (size_t x, size_t n)
63 {
64 return (x - (x % n));
65 }
66  
67 /**
68 * Calculates the quotient of a and b, rounded up.
69 */
70 static size_t bdivide_up (size_t a, size_t b)
71 {
72 size_t r = a % b;
73 return (r > 0 ? a / b + 1 : a / b);
74 }
75  
76 #endif