| 1 | /* Helper macros for pointer arithmetic. |
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| 2 | Copyright (C) 2012-2024 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | The GNU C Library is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 13 | Lesser General Public License for more details. |
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| 14 | |
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| 15 | You should have received a copy of the GNU Lesser General Public |
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| 16 | License along with the GNU C Library; if not, see |
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| 17 | <https://www.gnu.org/licenses/>. */ |
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| 18 | |
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| 19 | #ifndef _LIBC_POINTER_ARITH_H |
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| 20 | #define _LIBC_POINTER_ARITH_H 1 |
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| 21 | |
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| 22 | #include <stdint.h> |
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| 23 | |
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| 24 | /* 1 if 'type' is a pointer type, 0 otherwise. */ |
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| 25 | # define __pointer_type(type) (__builtin_classify_type ((type) 0) == 5) |
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| 26 | |
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| 27 | /* intptr_t if P is true, or T if P is false. */ |
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| 28 | # define __integer_if_pointer_type_sub(T, P) \ |
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| 29 | __typeof__ (*(0 ? (__typeof__ (0 ? (T *) 0 : (void *) (P))) 0 \ |
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| 30 | : (__typeof__ (0 ? (intptr_t *) 0 : (void *) (!(P)))) 0)) |
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| 31 | |
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| 32 | /* intptr_t if EXPR has a pointer type, or the type of EXPR otherwise. */ |
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| 33 | # define __integer_if_pointer_type(expr) \ |
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| 34 | __integer_if_pointer_type_sub(__typeof__ ((__typeof__ (expr)) 0), \ |
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| 35 | __pointer_type (__typeof__ (expr))) |
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| 36 | |
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| 37 | /* Cast an integer or a pointer VAL to integer with proper type. */ |
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| 38 | # define cast_to_integer(val) ((__integer_if_pointer_type (val)) (val)) |
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| 39 | |
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| 40 | /* Cast an integer VAL to void * pointer. */ |
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| 41 | # define cast_to_pointer(val) ((void *) (uintptr_t) (val)) |
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| 42 | |
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| 43 | /* Align a value by rounding down to closest size. |
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| 44 | e.g. Using size of 4096, we get this behavior: |
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| 45 | {4095, 4096, 4097} = {0, 4096, 4096}. */ |
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| 46 | #define ALIGN_DOWN(base, size) ((base) & -((__typeof__ (base)) (size))) |
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| 47 | |
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| 48 | /* Align a value by rounding up to closest size. |
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| 49 | e.g. Using size of 4096, we get this behavior: |
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| 50 | {4095, 4096, 4097} = {4096, 4096, 8192}. |
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| 51 | |
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| 52 | Note: The size argument has side effects (expanded multiple times). */ |
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| 53 | #define ALIGN_UP(base, size) ALIGN_DOWN ((base) + (size) - 1, (size)) |
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| 54 | |
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| 55 | /* Same as ALIGN_DOWN(), but automatically casts when base is a pointer. */ |
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| 56 | #define PTR_ALIGN_DOWN(base, size) \ |
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| 57 | ((__typeof__ (base)) ALIGN_DOWN ((uintptr_t) (base), (size))) |
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| 58 | |
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| 59 | /* Same as ALIGN_UP(), but automatically casts when base is a pointer. */ |
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| 60 | #define PTR_ALIGN_UP(base, size) \ |
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| 61 | ((__typeof__ (base)) ALIGN_UP ((uintptr_t) (base), (size))) |
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| 62 | |
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| 63 | /* Check if BASE is aligned on SIZE */ |
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| 64 | #define PTR_IS_ALIGNED(base, size) \ |
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| 65 | ((((uintptr_t) (base)) & (size - 1)) == 0) |
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| 66 | |
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| 67 | /* Returns the ptrdiff_t difference between P1 and P2. */ |
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| 68 | #define PTR_DIFF(p1, p2) \ |
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| 69 | ((ptrdiff_t)((uintptr_t)(p1) - (uintptr_t)(p2))) |
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| 70 | |
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| 71 | #endif |
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| 72 | |
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