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wdenk 2000-08-21 15:05:47 +00:00
parent 40c855574c
commit b15cbc0be0
11 changed files with 1145 additions and 0 deletions
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72
include/linux/bitops.h Normal file
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#ifndef _LINUX_BITOPS_H
#define _LINUX_BITOPS_H
/*
* ffs: find first bit set. This is defined the same way as
* the libc and compiler builtin ffs routines, therefore
* differs in spirit from the above ffz (man ffs).
*/
static inline int generic_ffs(int x)
{
int r = 1;
if (!x)
return 0;
if (!(x & 0xffff)) {
x >>= 16;
r += 16;
}
if (!(x & 0xff)) {
x >>= 8;
r += 8;
}
if (!(x & 0xf)) {
x >>= 4;
r += 4;
}
if (!(x & 3)) {
x >>= 2;
r += 2;
}
if (!(x & 1)) {
x >>= 1;
r += 1;
}
return r;
}
/*
* hweightN: returns the hamming weight (i.e. the number
* of bits set) of a N-bit word
*/
static inline unsigned int generic_hweight32(unsigned int w)
{
unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
}
static inline unsigned int generic_hweight16(unsigned int w)
{
unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555);
res = (res & 0x3333) + ((res >> 2) & 0x3333);
res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F);
return (res & 0x00FF) + ((res >> 8) & 0x00FF);
}
static inline unsigned int generic_hweight8(unsigned int w)
{
unsigned int res = (w & 0x55) + ((w >> 1) & 0x55);
res = (res & 0x33) + ((res >> 2) & 0x33);
return (res & 0x0F) + ((res >> 4) & 0x0F);
}
#include <asm/bitops.h>
#endif