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1.9 KiB

package common
import (
"bytes"
"encoding/binary"
"sort"
)
var (
Zero256 = Word256{0}
One256 = Word256{1}
)
type Word256 [32]byte
func (w Word256) String() string { return string(w[:]) }
func (w Word256) Copy() Word256 { return w }
func (w Word256) Bytes() []byte { return w[:] } // copied.
func (w Word256) Prefix(n int) []byte { return w[:n] }
func (w Word256) Postfix(n int) []byte { return w[32-n:] }
func (w Word256) IsZero() bool {
accum := byte(0)
for _, byt := range w {
accum |= byt
}
return accum == 0
}
func (w Word256) Compare(other Word256) int {
return bytes.Compare(w[:], other[:])
}
func Uint64ToWord256(i uint64) Word256 {
word := Word256{}
buf := [8]byte{}
PutUint64(buf[:], i)
word[24], word[25], word[26], word[27] = buf[7], buf[6], buf[5], buf[4]
word[28], word[29], word[30], word[31] = buf[3], buf[2], buf[1], buf[0]
return word
}
func RightPadWord256(bz []byte) (word Word256) {
copy(word[:], bz)
return
}
func LeftPadWord256(bz []byte) (word Word256) {
copy(word[32-len(bz):], bz)
return
}
func Uint64FromWord256(word Word256) uint64 {
buf := [8]byte{}
buf[0], buf[1], buf[2], buf[3] = word[31], word[30], word[29], word[28]
buf[4], buf[5], buf[6], buf[7] = word[27], word[26], word[25], word[24]
return binary.LittleEndian.Uint64(buf[:])
}
//-------------------------------------
type Tuple256 struct {
First Word256
Second Word256
}
func (tuple Tuple256) Compare(other Tuple256) int {
firstCompare := tuple.First.Compare(other.First)
if firstCompare == 0 {
return tuple.Second.Compare(other.Second)
} else {
return firstCompare
}
}
func Tuple256Split(t Tuple256) (Word256, Word256) {
return t.First, t.Second
}
type Tuple256Slice []Tuple256
func (p Tuple256Slice) Len() int { return len(p) }
func (p Tuple256Slice) Less(i, j int) bool {
return p[i].Compare(p[j]) < 0
}
func (p Tuple256Slice) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
func (p Tuple256Slice) Sort() { sort.Sort(p) }