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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/linux/bitops.h | |
download | kernel_samsung_espresso10-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip kernel_samsung_espresso10-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz kernel_samsung_espresso10-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.bz2 |
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'include/linux/bitops.h')
-rw-r--r-- | include/linux/bitops.h | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h new file mode 100644 index 0000000..cb3c3ef --- /dev/null +++ b/include/linux/bitops.h @@ -0,0 +1,159 @@ +#ifndef _LINUX_BITOPS_H +#define _LINUX_BITOPS_H +#include <asm/types.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; +} + +/* + * fls: find last bit set. + */ + +static __inline__ int generic_fls(int x) +{ + int r = 32; + + if (!x) + return 0; + if (!(x & 0xffff0000u)) { + x <<= 16; + r -= 16; + } + if (!(x & 0xff000000u)) { + x <<= 8; + r -= 8; + } + if (!(x & 0xf0000000u)) { + x <<= 4; + r -= 4; + } + if (!(x & 0xc0000000u)) { + x <<= 2; + r -= 2; + } + if (!(x & 0x80000000u)) { + x <<= 1; + r -= 1; + } + return r; +} + +/* + * Include this here because some architectures need generic_ffs/fls in + * scope + */ +#include <asm/bitops.h> + +static __inline__ int get_bitmask_order(unsigned int count) +{ + int order; + + order = fls(count); + return order; /* We could be slightly more clever with -1 here... */ +} + +/* + * 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); +} + +static inline unsigned long generic_hweight64(__u64 w) +{ +#if BITS_PER_LONG < 64 + return generic_hweight32((unsigned int)(w >> 32)) + + generic_hweight32((unsigned int)w); +#else + u64 res; + res = (w & 0x5555555555555555ul) + ((w >> 1) & 0x5555555555555555ul); + res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); + res = (res & 0x0F0F0F0F0F0F0F0Ful) + ((res >> 4) & 0x0F0F0F0F0F0F0F0Ful); + res = (res & 0x00FF00FF00FF00FFul) + ((res >> 8) & 0x00FF00FF00FF00FFul); + res = (res & 0x0000FFFF0000FFFFul) + ((res >> 16) & 0x0000FFFF0000FFFFul); + return (res & 0x00000000FFFFFFFFul) + ((res >> 32) & 0x00000000FFFFFFFFul); +#endif +} + +static inline unsigned long hweight_long(unsigned long w) +{ + return sizeof(w) == 4 ? generic_hweight32(w) : generic_hweight64(w); +} + +/* + * rol32 - rotate a 32-bit value left + * + * @word: value to rotate + * @shift: bits to roll + */ +static inline __u32 rol32(__u32 word, unsigned int shift) +{ + return (word << shift) | (word >> (32 - shift)); +} + +/* + * ror32 - rotate a 32-bit value right + * + * @word: value to rotate + * @shift: bits to roll + */ +static inline __u32 ror32(__u32 word, unsigned int shift) +{ + return (word >> shift) | (word << (32 - shift)); +} + +#endif |