1/* Helper macros for pointer arithmetic.
 2   Copyright (C) 2012-2025 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/* Check if BASE is aligned on SIZE  */
64#define PTR_IS_ALIGNED(base, size) \
65  ((((uintptr_t) (base)) & (size - 1)) == 0)
66
67/* Returns the ptrdiff_t difference between P1 and P2.  */
68#define PTR_DIFF(p1, p2) \
69  ((ptrdiff_t)((uintptr_t)(p1) - (uintptr_t)(p2)))
70
71#endif