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64 lines
2.5 KiB
C
64 lines
2.5 KiB
C
/* Helper macros for pointer arithmetic.
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Copyright (C) 2012-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _LIBC_POINTER_ARITH_H
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#define _LIBC_POINTER_ARITH_H 1
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#include <stdint.h>
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/* 1 if 'type' is a pointer type, 0 otherwise. */
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# define __pointer_type(type) (__builtin_classify_type ((type) 0) == 5)
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/* intptr_t if P is true, or T if P is false. */
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# define __integer_if_pointer_type_sub(T, P) \
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__typeof__ (*(0 ? (__typeof__ (0 ? (T *) 0 : (void *) (P))) 0 \
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: (__typeof__ (0 ? (intptr_t *) 0 : (void *) (!(P)))) 0))
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/* intptr_t if EXPR has a pointer type, or the type of EXPR otherwise. */
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# define __integer_if_pointer_type(expr) \
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__integer_if_pointer_type_sub(__typeof__ ((__typeof__ (expr)) 0), \
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__pointer_type (__typeof__ (expr)))
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/* Cast an integer or a pointer VAL to integer with proper type. */
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# define cast_to_integer(val) ((__integer_if_pointer_type (val)) (val))
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/* Cast an integer VAL to void * pointer. */
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# define cast_to_pointer(val) ((void *) (uintptr_t) (val))
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/* Align a value by rounding down to closest size.
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e.g. Using size of 4096, we get this behavior:
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{4095, 4096, 4097} = {0, 4096, 4096}. */
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#define ALIGN_DOWN(base, size) ((base) & -((__typeof__ (base)) (size)))
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/* Align a value by rounding up to closest size.
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e.g. Using size of 4096, we get this behavior:
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{4095, 4096, 4097} = {4096, 4096, 8192}.
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Note: The size argument has side effects (expanded multiple times). */
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#define ALIGN_UP(base, size) ALIGN_DOWN ((base) + (size) - 1, (size))
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/* Same as ALIGN_DOWN(), but automatically casts when base is a pointer. */
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#define PTR_ALIGN_DOWN(base, size) \
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((__typeof__ (base)) ALIGN_DOWN ((uintptr_t) (base), (size)))
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/* Same as ALIGN_UP(), but automatically casts when base is a pointer. */
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#define PTR_ALIGN_UP(base, size) \
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((__typeof__ (base)) ALIGN_UP ((uintptr_t) (base), (size)))
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#endif
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