erigon-pulse/common/dbutils/helper.go

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package dbutils
// EncodeTimestamp has the property: if a < b, then Encoding(a) < Encoding(b) lexicographically
func EncodeTimestamp(timestamp uint64) []byte {
var suffix []byte
var limit uint64 = 32
for bytecount := 1; bytecount <= 8; bytecount++ {
if timestamp < limit {
suffix = make([]byte, bytecount)
b := timestamp
for i := bytecount - 1; i > 0; i-- {
suffix[i] = byte(b & 0xff)
b >>= 8
}
suffix[0] = byte(b) | (byte(bytecount) << 5) // 3 most significant bits of the first byte are bytecount
break
}
limit <<= 8
}
return suffix
}
func DecodeTimestamp(suffix []byte) (uint64, []byte) {
bytecount := int(suffix[0] >> 5)
timestamp := uint64(suffix[0] & 0x1f)
for i := 1; i < bytecount; i++ {
timestamp = (timestamp << 8) | uint64(suffix[i])
}
return timestamp, suffix[bytecount:]
}
// NextSubtree does []byte++. Returns false if overflow.
func NextSubtree(in []byte) ([]byte, bool) {
r := make([]byte, len(in))
copy(r, in)
for i := len(r) - 1; i >= 0; i-- {
if r[i] != 255 {
r[i]++
return r, true
}
r = r[:i] // make it shorter, because in tries after 11ff goes 12, but not 1200
}
return nil, false
}
// NextNibblesSubtree does []byte++. Returns false if overflow.
func NextNibblesSubtree(in []byte, out *[]byte) bool {
r := (*out)[:len(in)]
copy(r, in)
for i := len(r) - 1; i >= 0; i-- {
if r[i] != 15 { // max value of nibbles
r[i]++
*out = r
return true
}
r = r[:i] // make it shorter, because in tries after 11ff goes 12, but not 1200
}
*out = r
return false
}