c1226a005e
This patch introduces the C-language equivalent of the function: unsigned long __ffs(unsigned long word); In include/asm-generic/bitops/__ffs.h This code largely copied from: include/asm-sparc/bitops.h Signed-off-by: Akinobu Mita <mita@miraclelinux.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
43 lines
729 B
C
43 lines
729 B
C
#ifndef _ASM_GENERIC_BITOPS___FFS_H_
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#define _ASM_GENERIC_BITOPS___FFS_H_
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#include <asm/types.h>
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/**
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* __ffs - find first bit in word.
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* @word: The word to search
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*
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* Undefined if no bit exists, so code should check against 0 first.
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*/
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static inline unsigned long __ffs(unsigned long word)
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{
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int num = 0;
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#if BITS_PER_LONG == 64
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if ((word & 0xffffffff) == 0) {
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num += 32;
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word >>= 32;
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}
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#endif
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if ((word & 0xffff) == 0) {
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num += 16;
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word >>= 16;
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}
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if ((word & 0xff) == 0) {
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num += 8;
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word >>= 8;
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}
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if ((word & 0xf) == 0) {
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num += 4;
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word >>= 4;
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}
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if ((word & 0x3) == 0) {
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num += 2;
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word >>= 2;
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}
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if ((word & 0x1) == 0)
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num += 1;
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return num;
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}
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#endif /* _ASM_GENERIC_BITOPS___FFS_H_ */
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