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package bitops
// msb32 returns the number of bits required to store the value x
func msb32(x uint32) int {
pos := 32
temp := x >> 16
if temp != 0 {
pos -= 16
x = temp
}
temp = x >> 8
if temp != 0 {
pos -= 8
x = temp
}
temp = x >> 4
if temp != 0 {
pos -= 4
x = temp
}
temp = x >> 2
if temp != 0 {
pos -= 2
x = temp
}
temp = x >> 1
if temp != 0 {
return pos - 2
}
return int(uint32(pos) - x)
}
// msb64 returns the number of bits required to store the value x
func msb64(n uint64) int {
if n <= 0 {
return -1
}
var r, v uint
if n >= 1<<32 {
r += 32
v = uint(n >> 32)
} else {
v = uint(n)
}
if v >= 1<<16 {
r += 16
v >>= 16
}
if v >= 1<<8 {
r += 8
v >>= 8
}
if v >= 1<<4 {
r += 4
v >>= 4
}
if v >= 1<<2 {
r += 2
v >>= 2
}
r += v >> 1
return int(r)
}
func ZigZagEncode64(x int64) uint64 {
return uint64(uint64(x<<1) ^ uint64((int64(x) >> 63)))
}
func ZigZagDecode64(v uint64) int64 {
return int64((v >> 1) ^ uint64((int64(v&1)<<63)>>63))
}
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