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| -rw-r--r-- | include/utils.h | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/include/utils.h b/include/utils.h index 15b2e393..45cb5a70 100644 --- a/include/utils.h +++ b/include/utils.h @@ -76,6 +76,43 @@ (void) (&_max1 == &_max2); \ _max1 > _max2 ? _max1 : _max2; }) + +/** + * fls - find last (most-significant) bit set + * @x: the word to search + * + * This is defined the same way as ffs. + * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32. + */ +static inline int 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; +} + extern void __memory_allocation_error(const char *filename, uint32_t line) __noreturn; #define memory_allocation_error() \ |