1/* Helper macros for pointer arithmetic.
2 Copyright (C) 2012-2021 Free Software Foundation, Inc.
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
17 <https://www.gnu.org/licenses/>. */
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/* Cast an integer VAL to void * pointer. */
41# define cast_to_pointer(val) ((void *) (uintptr_t) (val))
42
43/* Align a value by rounding down to closest size.
44 e.g. Using size of 4096, we get this behavior:
45 {4095, 4096, 4097} = {0, 4096, 4096}. */
46#define ALIGN_DOWN(base, size) ((base) & -((__typeof__ (base)) (size)))
47
48/* Align a value by rounding up to closest size.
49 e.g. Using size of 4096, we get this behavior:
50 {4095, 4096, 4097} = {4096, 4096, 8192}.
51
52 Note: The size argument has side effects (expanded multiple times). */
53#define ALIGN_UP(base, size) ALIGN_DOWN ((base) + (size) - 1, (size))
54
55/* Same as ALIGN_DOWN(), but automatically casts when base is a pointer. */
56#define PTR_ALIGN_DOWN(base, size) \
57 ((__typeof__ (base)) ALIGN_DOWN ((uintptr_t) (base), (size)))
58
59/* Same as ALIGN_UP(), but automatically casts when base is a pointer. */
60#define PTR_ALIGN_UP(base, size) \
61 ((__typeof__ (base)) ALIGN_UP ((uintptr_t) (base), (size)))
62
63#endif
64