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42 lines
654 B
42 lines
654 B
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef _ASM_GENERIC_BITOPS_FFS_H_ |
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#define _ASM_GENERIC_BITOPS_FFS_H_ |
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/** |
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* ffs - find first bit set |
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* @x: the word to search |
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* |
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* This is defined the same way as |
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* the libc and compiler builtin ffs routines, therefore |
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* differs in spirit from the above ffz (man ffs). |
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*/ |
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static inline int ffs(int x) |
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{ |
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int r = 1; |
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if (!x) |
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return 0; |
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if (!(x & 0xffff)) { |
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x >>= 16; |
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r += 16; |
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} |
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if (!(x & 0xff)) { |
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x >>= 8; |
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r += 8; |
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} |
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if (!(x & 0xf)) { |
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x >>= 4; |
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r += 4; |
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} |
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if (!(x & 3)) { |
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x >>= 2; |
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r += 2; |
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} |
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if (!(x & 1)) { |
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x >>= 1; |
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r += 1; |
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} |
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return r; |
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} |
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#endif /* _ASM_GENERIC_BITOPS_FFS_H_ */
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