18c2ecf20Sopenharmony_ci/* SPDX-License-Identifier: GPL-2.0 */
28c2ecf20Sopenharmony_ci#ifndef _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_
38c2ecf20Sopenharmony_ci#define _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_
48c2ecf20Sopenharmony_ci
58c2ecf20Sopenharmony_ci#include <asm/types.h>
68c2ecf20Sopenharmony_ci#include <asm/bitsperlong.h>
78c2ecf20Sopenharmony_ci
88c2ecf20Sopenharmony_ci/**
98c2ecf20Sopenharmony_ci * __ffs - find first bit in word.
108c2ecf20Sopenharmony_ci * @word: The word to search
118c2ecf20Sopenharmony_ci *
128c2ecf20Sopenharmony_ci * Undefined if no bit exists, so code should check against 0 first.
138c2ecf20Sopenharmony_ci */
148c2ecf20Sopenharmony_cistatic __always_inline unsigned long __ffs(unsigned long word)
158c2ecf20Sopenharmony_ci{
168c2ecf20Sopenharmony_ci	int num = 0;
178c2ecf20Sopenharmony_ci
188c2ecf20Sopenharmony_ci#if __BITS_PER_LONG == 64
198c2ecf20Sopenharmony_ci	if ((word & 0xffffffff) == 0) {
208c2ecf20Sopenharmony_ci		num += 32;
218c2ecf20Sopenharmony_ci		word >>= 32;
228c2ecf20Sopenharmony_ci	}
238c2ecf20Sopenharmony_ci#endif
248c2ecf20Sopenharmony_ci	if ((word & 0xffff) == 0) {
258c2ecf20Sopenharmony_ci		num += 16;
268c2ecf20Sopenharmony_ci		word >>= 16;
278c2ecf20Sopenharmony_ci	}
288c2ecf20Sopenharmony_ci	if ((word & 0xff) == 0) {
298c2ecf20Sopenharmony_ci		num += 8;
308c2ecf20Sopenharmony_ci		word >>= 8;
318c2ecf20Sopenharmony_ci	}
328c2ecf20Sopenharmony_ci	if ((word & 0xf) == 0) {
338c2ecf20Sopenharmony_ci		num += 4;
348c2ecf20Sopenharmony_ci		word >>= 4;
358c2ecf20Sopenharmony_ci	}
368c2ecf20Sopenharmony_ci	if ((word & 0x3) == 0) {
378c2ecf20Sopenharmony_ci		num += 2;
388c2ecf20Sopenharmony_ci		word >>= 2;
398c2ecf20Sopenharmony_ci	}
408c2ecf20Sopenharmony_ci	if ((word & 0x1) == 0)
418c2ecf20Sopenharmony_ci		num += 1;
428c2ecf20Sopenharmony_ci	return num;
438c2ecf20Sopenharmony_ci}
448c2ecf20Sopenharmony_ci
458c2ecf20Sopenharmony_ci#endif /* _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ */
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