73 lines
1.4 KiB
C
73 lines
1.4 KiB
C
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#ifndef _LINUX_BITOPS_H
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#define _LINUX_BITOPS_H
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/*
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* ffs: find first bit set. 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 generic_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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/*
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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 generic_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 generic_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 generic_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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#include <asm/bitops.h>
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#endif
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