783b20712e
On RISC-V 64-bit, GCC complains about undefined reference to 'ffs' via __builtin_ffs(). So implement a brute force way to do it. Once the toolchain has __builtin_ffs(), this can be reverted. Signed-off-by: Daniel Leung <daniel.leung@intel.com>
90 lines
1.8 KiB
C
90 lines
1.8 KiB
C
/*
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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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/**
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*
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* @brief find most significant bit set in a 32-bit word
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*
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* This routine finds the first bit set starting from the most significant bit
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* in the argument passed in and returns the index of that bit. Bits are
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* numbered starting at 1 from the least significant bit. A return value of
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* zero indicates that the value passed is zero.
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*
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* @return most significant bit set, 0 if @a op is 0
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*/
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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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/**
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*
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* @brief find least significant bit set in a 32-bit word
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*
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* This routine finds the first bit set starting from the least significant bit
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* in the argument passed in and returns the index of that bit. Bits are
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* numbered starting at 1 from the least significant bit. A return value of
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* zero indicates that the value passed is zero.
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*
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* @return least significant bit set, 0 if @a op is 0
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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().
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* Need to do this manually.
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*/
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int bit;
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if (op == 0) {
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return 0;
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}
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for (bit = 0; bit < 32; bit++) {
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if ((op & (1 << bit)) != 0) {
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return (bit + 1);
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}
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}
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/*
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* This should never happen but we need to keep
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* compiler happy.
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*/
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return 0;
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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_ */
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