diff options
Diffstat (limited to 'vendor/github.com/RoaringBitmap/roaring/clz_compat.go')
-rw-r--r-- | vendor/github.com/RoaringBitmap/roaring/clz_compat.go | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/vendor/github.com/RoaringBitmap/roaring/clz_compat.go b/vendor/github.com/RoaringBitmap/roaring/clz_compat.go new file mode 100644 index 0000000000..eeef4de35b --- /dev/null +++ b/vendor/github.com/RoaringBitmap/roaring/clz_compat.go @@ -0,0 +1,36 @@ +// +build !go1.9 + +package roaring + +// LeadingZeroBits returns the number of consecutive most significant zero +// bits of x. +func countLeadingZeros(i uint64) int { + if i == 0 { + return 64 + } + n := 1 + x := uint32(i >> 32) + if x == 0 { + n += 32 + x = uint32(i) + } + if (x >> 16) == 0 { + n += 16 + x <<= 16 + } + if (x >> 24) == 0 { + n += 8 + x <<= 8 + } + if x>>28 == 0 { + n += 4 + x <<= 4 + } + if x>>30 == 0 { + n += 2 + x <<= 2 + + } + n -= int(x >> 31) + return n +} |