51 lines
1.5 KiB
C
51 lines
1.5 KiB
C
#ifndef _ASM_GENERIC_BITOPS_HWEIGHT_H_
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#define _ASM_GENERIC_BITOPS_HWEIGHT_H_
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#include <asm/types.h>
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/*
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* hweightN: returns the hamming weight (i.e. the number
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* of bits set) of a N-bit word
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*/
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static inline unsigned int hweight32(unsigned int w)
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{
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unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
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res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
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res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
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res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
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return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
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}
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static inline unsigned int hweight16(unsigned int w)
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{
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unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555);
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res = (res & 0x3333) + ((res >> 2) & 0x3333);
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res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F);
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return (res & 0x00FF) + ((res >> 8) & 0x00FF);
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}
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static inline unsigned int hweight8(unsigned int w)
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{
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unsigned int res = (w & 0x55) + ((w >> 1) & 0x55);
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res = (res & 0x33) + ((res >> 2) & 0x33);
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return (res & 0x0F) + ((res >> 4) & 0x0F);
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}
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static inline unsigned long hweight64(__u64 w)
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{
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#if BITS_PER_LONG == 32
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return hweight32((unsigned int)(w >> 32)) +
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hweight32((unsigned int)w);
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#elif BITS_PER_LONG == 64
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__u64 res = w - ((w >> 1) & 0x5555555555555555ul);
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res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
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res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
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res = res + (res >> 8);
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res = res + (res >> 16);
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return (res + (res >> 32)) & 0x00000000000000FFul;
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#endif
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}
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#endif /* _ASM_GENERIC_BITOPS_HWEIGHT_H_ */
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