1package merkletree
 2
 3import (
 4	"math/big"
 5
 6	"github.com/iden3/go-iden3-crypto/poseidon"
 7)
 8
 9// HashElems performs a poseidon hash over the array of ElemBytes, currently we
10// are using 2 elements.  Uses poseidon.Hash to be compatible with the circom
11// circuits implementations.
12func HashElems(elems ...*big.Int) (*Hash, error) {
13	poseidonHash, err := poseidon.Hash(elems)
14	if err != nil {
15		return nil, err
16	}
17	return NewHashFromBigInt(poseidonHash), nil
18}
19
20// HashElemsKey performs a poseidon hash over the array of ElemBytes, currently
21// we are using 2 elements.
22func HashElemsKey(key *big.Int, elems ...*big.Int) (*Hash, error) {
23	if key == nil {
24		key = new(big.Int).SetInt64(0)
25	}
26	bi := make([]*big.Int, 3)
27	copy(bi[:], elems)
28	bi[2] = key
29	poseidonHash, err := poseidon.Hash(bi)
30	if err != nil {
31		return nil, err
32	}
33	return NewHashFromBigInt(poseidonHash), nil
34}
35
36// SetBitBigEndian sets the bit n in the bitmap to 1, in Big Endian.
37func SetBitBigEndian(bitmap []byte, n uint) {
38	bitmap[uint(len(bitmap))-n/8-1] |= 1 << (n % 8)
39}
40
41// TestBit tests whether the bit n in bitmap is 1.
42func TestBit(bitmap []byte, n uint) bool {
43	return bitmap[n/8]&(1<<(n%8)) != 0
44}
45
46// TestBitBigEndian tests whether the bit n in bitmap is 1, in Big Endian.
47func TestBitBigEndian(bitmap []byte, n uint) bool {
48	return bitmap[uint(len(bitmap))-n/8-1]&(1<<(n%8)) != 0
49}
50
51// SwapEndianness swaps the order of the bytes in the slice.
52func SwapEndianness(b []byte) []byte {
53	o := make([]byte, len(b))
54	for i := range b {
55		o[len(b)-1-i] = b[i]
56	}
57	return o
58}