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serialize.go
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serialize.go
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package cell
import (
"encoding/binary"
"encoding/hex"
"errors"
"hash/crc32"
"math"
)
var ErrTooBigValue = errors.New("too big value")
var ErrNegative = errors.New("value should be non negative")
var ErrRefCannotBeNil = errors.New("ref cannot be nil")
var ErrSmallSlice = errors.New("too small slice for this size")
var ErrTooBigSize = errors.New("too big size")
var ErrTooMuchRefs = errors.New("too much refs")
var ErrNotFit1023 = errors.New("cell data size should fit into 1023 bits")
var ErrNoMoreRefs = errors.New("no more refs exists")
var ErrAddressTypeNotSupported = errors.New("address type is not supported")
func (c *Cell) ToBOC() []byte {
return c.ToBOCWithFlags(true)
}
func (c *Cell) ToBOCWithFlags(withCRC bool) []byte {
// recursively go through cells, build hash index and store unique in slice
orderCells := flattenIndex([]*Cell{c})
// bytes needed to store num of cells
cellSizeBits := math.Log2(float64(len(orderCells)) + 1)
cellSizeBytes := byte(math.Ceil(cellSizeBits / 8))
var payload []byte
for i := 0; i < len(orderCells); i++ {
// serialize each cell
payload = append(payload, orderCells[i].serialize(uint(cellSizeBytes), false)...)
}
// bytes needed to store len of payload
sizeBits := math.Log2(float64(len(payload)) + 1)
sizeBytes := byte(math.Ceil(sizeBits / 8))
// has_idx 1bit, hash_crc32 1bit, has_cache_bits 1bit, flags 2bit, size_bytes 3 bit
flags := byte(0b0_0_0_00_000)
if withCRC {
flags |= 0b0_1_0_00_000
}
flags |= cellSizeBytes
var data []byte
data = append(data, bocMagic...)
data = append(data, flags)
// bytes needed to store size
data = append(data, sizeBytes)
// cells num
data = append(data, dynamicIntBytes(uint64(calcCells(c)), uint(cellSizeBytes))...)
// roots num (only 1 supported for now)
data = append(data, dynamicIntBytes(1, uint(cellSizeBytes))...)
// complete BOCs = 0
data = append(data, dynamicIntBytes(0, uint(cellSizeBytes))...)
// len of data
data = append(data, dynamicIntBytes(uint64(len(payload)), uint(sizeBytes))...)
// root should have index 0
data = append(data, dynamicIntBytes(0, uint(cellSizeBytes))...)
data = append(data, payload...)
if withCRC {
checksum := make([]byte, 4)
binary.LittleEndian.PutUint32(checksum, crc32.Checksum(data, crc32.MakeTable(crc32.Castagnoli)))
data = append(data, checksum...)
}
return data
}
func calcCells(cell *Cell) int {
m := map[string]*Cell{}
// calc unique cells
uniqCells(m, cell)
return len(m)
}
func uniqCells(m map[string]*Cell, cell *Cell) {
m[hex.EncodeToString(cell.Hash())] = cell
for _, ref := range cell.refs {
uniqCells(m, ref)
}
}
func flattenIndex(roots []*Cell) []*Cell {
var indexed []*Cell
var offset int
hashIndex := map[string]int{}
var doIndex func([]*Cell) []*Cell
doIndex = func(cells []*Cell) []*Cell {
var next [][]*Cell
for _, c := range cells {
h := hex.EncodeToString(c.Hash())
id, ok := hashIndex[h]
if !ok {
id = offset
offset++
hashIndex[h] = id
indexed = append(indexed, c)
if len(c.refs) > 0 {
next = append(next, c.refs)
}
} else { // if we already have such cell, we need to move it forward in order.
// move to end
indexed = append(indexed, indexed[id])
// remove from old position
indexed = append(indexed[:id], indexed[id+1:]...)
// reindex
for i, ci := range indexed {
// TODO: optimize
th := hex.EncodeToString(ci.Hash())
hashIndex[th] = i
}
}
}
for _, n := range next {
doIndex(n)
}
// return ordered cells to write to boc
return indexed
}
doIndex(roots)
// we need to do it this way because we can have same cells but 2 diff object pointers
var indexSetter func(node *Cell)
indexSetter = func(node *Cell) {
node.index = hashIndex[hex.EncodeToString(node.Hash())]
for _, ref := range node.refs {
indexSetter(ref)
}
}
for _, root := range roots {
indexSetter(root)
}
return indexed
}
func (c *Cell) serialize(refIndexSzBytes uint, isHash bool) []byte {
// copy
payload := append([]byte{}, c.BeginParse().MustLoadSlice(c.bitsSz)...)
unusedBits := 8 - (c.bitsSz % 8)
if unusedBits != 8 {
// we need to set bit at the end if not whole byte was used
payload[len(payload)-1] += 1 << (unusedBits - 1)
}
data := append(c.descriptors(), payload...)
if !isHash {
for _, ref := range c.refs {
data = append(data, dynamicIntBytes(uint64(ref.index), refIndexSzBytes)...)
}
} else {
for _, ref := range c.refs {
data = append(data, make([]byte, 2)...)
binary.BigEndian.PutUint16(data[len(data)-2:], uint16(ref.maxDepth(0)))
}
for _, ref := range c.refs {
data = append(data, ref.Hash()...)
}
}
return data
}
// calc how deep is the cell (how long children tree)
func (c *Cell) maxDepth(start int) int {
d := start
for _, cc := range c.refs {
if x := cc.maxDepth(start + 1); x > d {
d = x
}
}
return d
}
func (c *Cell) descriptors() []byte {
ceilBytes := c.bitsSz / 8
if c.bitsSz%8 != 0 {
ceilBytes++
}
// calc size
ln := ceilBytes + c.bitsSz/8
specBit := byte(0)
if c.special {
specBit = 8
}
return []byte{byte(len(c.refs)) + specBit + c.level*32, byte(ln)}
}
func dynamicIntBytes(val uint64, sz uint) []byte {
data := make([]byte, 8)
binary.BigEndian.PutUint64(data, val)
return data[8-sz:]
}