| 1 |
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| 2 | #ifndef _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_
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| 3 | #define _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_
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| 4 |
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| 5 | #include <asm/types.h>
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| 6 | #include <asm/bitsperlong.h>
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| 7 |
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| 8 | |
| 9 | * __ffs - find first bit in word.
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| 10 | * @word: The word to search
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| 11 | *
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| 12 | * Undefined if no bit exists, so code should check against 0 first.
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| 13 |
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| 14 | static __always_inline unsigned int __ffs(unsigned long word)
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| 15 | {
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| 16 | unsigned int num = 0;
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| 17 |
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| 18 | #if __BITS_PER_LONG == 64
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| 19 | if ((word & 0xffffffff) == 0) {
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| 20 | num += 32;
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| 21 | word >>= 32;
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| 22 | }
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| 23 | #endif
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| 24 | if ((word & 0xffff) == 0) {
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| 25 | num += 16;
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| 26 | word >>= 16;
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| 27 | }
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| 28 | if ((word & 0xff) == 0) {
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| 29 | num += 8;
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| 30 | word >>= 8;
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| 31 | }
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| 32 | if ((word & 0xf) == 0) {
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| 33 | num += 4;
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| 34 | word >>= 4;
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| 35 | }
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| 36 | if ((word & 0x3) == 0) {
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| 37 | num += 2;
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| 38 | word >>= 2;
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| 39 | }
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| 40 | if ((word & 0x1) == 0)
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| 41 | num += 1;
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| 42 | return num;
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| 43 | }
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| 44 |
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| 45 | #endif
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