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9090848d | 1 | /* Helper macros for pointer arithmetic. |
04277e02 | 2 | Copyright (C) 2012-2019 Free Software Foundation, Inc. |
9090848d ZW |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
16 | License along with the GNU C Library; if not, see | |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
9090848d ZW |
18 | |
19 | #ifndef _LIBC_POINTER_ARITH_H | |
20 | #define _LIBC_POINTER_ARITH_H 1 | |
21 | ||
22 | #include <stdint.h> | |
23 | ||
24 | /* 1 if 'type' is a pointer type, 0 otherwise. */ | |
25 | # define __pointer_type(type) (__builtin_classify_type ((type) 0) == 5) | |
26 | ||
27 | /* intptr_t if P is true, or T if P is false. */ | |
28 | # define __integer_if_pointer_type_sub(T, P) \ | |
29 | __typeof__ (*(0 ? (__typeof__ (0 ? (T *) 0 : (void *) (P))) 0 \ | |
30 | : (__typeof__ (0 ? (intptr_t *) 0 : (void *) (!(P)))) 0)) | |
31 | ||
32 | /* intptr_t if EXPR has a pointer type, or the type of EXPR otherwise. */ | |
33 | # define __integer_if_pointer_type(expr) \ | |
34 | __integer_if_pointer_type_sub(__typeof__ ((__typeof__ (expr)) 0), \ | |
35 | __pointer_type (__typeof__ (expr))) | |
36 | ||
37 | /* Cast an integer or a pointer VAL to integer with proper type. */ | |
38 | # define cast_to_integer(val) ((__integer_if_pointer_type (val)) (val)) | |
39 | ||
40 | /* Align a value by rounding down to closest size. | |
41 | e.g. Using size of 4096, we get this behavior: | |
42 | {4095, 4096, 4097} = {0, 4096, 4096}. */ | |
43 | #define ALIGN_DOWN(base, size) ((base) & -((__typeof__ (base)) (size))) | |
44 | ||
45 | /* Align a value by rounding up to closest size. | |
46 | e.g. Using size of 4096, we get this behavior: | |
47 | {4095, 4096, 4097} = {4096, 4096, 8192}. | |
48 | ||
49 | Note: The size argument has side effects (expanded multiple times). */ | |
50 | #define ALIGN_UP(base, size) ALIGN_DOWN ((base) + (size) - 1, (size)) | |
51 | ||
52 | /* Same as ALIGN_DOWN(), but automatically casts when base is a pointer. */ | |
53 | #define PTR_ALIGN_DOWN(base, size) \ | |
54 | ((__typeof__ (base)) ALIGN_DOWN ((uintptr_t) (base), (size))) | |
55 | ||
56 | /* Same as ALIGN_UP(), but automatically casts when base is a pointer. */ | |
57 | #define PTR_ALIGN_UP(base, size) \ | |
58 | ((__typeof__ (base)) ALIGN_UP ((uintptr_t) (base), (size))) | |
59 | ||
60 | #endif |