forked from Shiloh/githaven
44 lines
1.5 KiB
Go
Vendored
44 lines
1.5 KiB
Go
Vendored
package numeric
|
|
|
|
var interleaveMagic = []uint64{
|
|
0x5555555555555555,
|
|
0x3333333333333333,
|
|
0x0F0F0F0F0F0F0F0F,
|
|
0x00FF00FF00FF00FF,
|
|
0x0000FFFF0000FFFF,
|
|
0x00000000FFFFFFFF,
|
|
0xAAAAAAAAAAAAAAAA,
|
|
}
|
|
|
|
var interleaveShift = []uint{1, 2, 4, 8, 16}
|
|
|
|
// Interleave the first 32 bits of each uint64
|
|
// apdated from org.apache.lucene.util.BitUtil
|
|
// which was adapted from:
|
|
// http://graphics.stanford.edu/~seander/bithacks.html#InterleaveBMN
|
|
func Interleave(v1, v2 uint64) uint64 {
|
|
v1 = (v1 | (v1 << interleaveShift[4])) & interleaveMagic[4]
|
|
v1 = (v1 | (v1 << interleaveShift[3])) & interleaveMagic[3]
|
|
v1 = (v1 | (v1 << interleaveShift[2])) & interleaveMagic[2]
|
|
v1 = (v1 | (v1 << interleaveShift[1])) & interleaveMagic[1]
|
|
v1 = (v1 | (v1 << interleaveShift[0])) & interleaveMagic[0]
|
|
v2 = (v2 | (v2 << interleaveShift[4])) & interleaveMagic[4]
|
|
v2 = (v2 | (v2 << interleaveShift[3])) & interleaveMagic[3]
|
|
v2 = (v2 | (v2 << interleaveShift[2])) & interleaveMagic[2]
|
|
v2 = (v2 | (v2 << interleaveShift[1])) & interleaveMagic[1]
|
|
v2 = (v2 | (v2 << interleaveShift[0])) & interleaveMagic[0]
|
|
return (v2 << 1) | v1
|
|
}
|
|
|
|
// Deinterleave the 32-bit value starting at position 0
|
|
// to get the other 32-bit value, shift it by 1 first
|
|
func Deinterleave(b uint64) uint64 {
|
|
b &= interleaveMagic[0]
|
|
b = (b ^ (b >> interleaveShift[0])) & interleaveMagic[1]
|
|
b = (b ^ (b >> interleaveShift[1])) & interleaveMagic[2]
|
|
b = (b ^ (b >> interleaveShift[2])) & interleaveMagic[3]
|
|
b = (b ^ (b >> interleaveShift[3])) & interleaveMagic[4]
|
|
b = (b ^ (b >> interleaveShift[4])) & interleaveMagic[5]
|
|
return b
|
|
}
|