Zephyr API Documentation
4.0.99
A Scalable Open Source RTOS
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ffs.h
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/*
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* Copyright (c) 2015, Wind River Systems, Inc.
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* Copyright (c) 2017, Oticon A/S
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef ZEPHYR_INCLUDE_ARCH_COMMON_FFS_H_
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#define ZEPHYR_INCLUDE_ARCH_COMMON_FFS_H_
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#ifndef _ASMLANGUAGE
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#include <
zephyr/types.h
>
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#ifdef __cplusplus
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extern
"C"
{
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#endif
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static
ALWAYS_INLINE
unsigned
int
find_msb_set
(
uint32_t
op)
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{
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if
(op == 0) {
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return
0;
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}
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return
32 - __builtin_clz(op);
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}
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static
ALWAYS_INLINE
unsigned
int
find_lsb_set
(
uint32_t
op)
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{
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#ifdef CONFIG_TOOLCHAIN_HAS_BUILTIN_FFS
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return
__builtin_ffs(op);
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#else
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/*
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* Toolchain does not have __builtin_ffs(). Leverage find_lsb_set()
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* by first clearing all but the lowest set bit.
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*/
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op = op ^ (op & (op - 1));
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return
find_msb_set
(op);
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#endif
/* CONFIG_TOOLCHAIN_HAS_BUILTIN_FFS */
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}
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#ifdef __cplusplus
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}
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#endif
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#endif
/* _ASMLANGUAGE */
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#endif
/* ZEPHYR_INCLUDE_ARCH_COMMON_FFS_H_ */
find_msb_set
static ALWAYS_INLINE unsigned int find_msb_set(uint32_t op)
find most significant bit set in a 32-bit word
Definition
ffs.h:31
find_lsb_set
static ALWAYS_INLINE unsigned int find_lsb_set(uint32_t op)
find least significant bit set in a 32-bit word
Definition
ffs.h:53
ALWAYS_INLINE
#define ALWAYS_INLINE
Definition
common.h:129
types.h
uint32_t
__UINT32_TYPE__ uint32_t
Definition
stdint.h:90
zephyr
arch
common
ffs.h
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