4c0b7f290e
Chain parameters from Lethean C++ source. Base58 address encoding with Keccak-256 checksum. CryptoNote varint. LWMA difficulty skeleton. Co-Authored-By: Charon <charon@lethean.io>
75 lines
2.3 KiB
Go
75 lines
2.3 KiB
Go
// Copyright (c) 2017-2026 Lethean (https://lt.hn)
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//
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// Licensed under the European Union Public Licence (EUPL) version 1.2.
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// You may obtain a copy of the licence at:
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//
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// https://joinup.ec.europa.eu/software/page/eupl/licence-eupl
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//
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// SPDX-License-Identifier: EUPL-1.2
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// Package wire provides binary serialisation primitives for the CryptoNote
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// wire protocol. All encoding is consensus-critical and must be bit-identical
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// to the C++ reference implementation.
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package wire
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import (
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"errors"
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)
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// MaxVarintLen is the maximum number of bytes a CryptoNote varint can occupy.
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// A uint64 requires at most 10 bytes of 7-bit encoding (64 bits / 7 = ~9.14,
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// so values above 2^63-1 need a 10th byte).
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const MaxVarintLen = 10
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// ErrVarintOverflow is returned when a varint exceeds the maximum allowed
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// length of 10 bytes.
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var ErrVarintOverflow = errors.New("wire: varint overflow (exceeds 10 bytes)")
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// ErrVarintEmpty is returned when attempting to decode a varint from an
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// empty byte slice.
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var ErrVarintEmpty = errors.New("wire: cannot decode varint from empty data")
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// EncodeVarint encodes a uint64 value as a CryptoNote variable-length integer.
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//
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// The encoding uses 7 bits per byte, with the most significant bit (MSB) set
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// to 1 to indicate that more bytes follow. This is the same scheme as protobuf
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// varints but limited to 9 bytes maximum for uint64 values.
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func EncodeVarint(v uint64) []byte {
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if v == 0 {
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return []byte{0x00}
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}
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var buf [MaxVarintLen]byte
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n := 0
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for v > 0 {
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buf[n] = byte(v & 0x7f)
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v >>= 7
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if v > 0 {
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buf[n] |= 0x80
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}
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n++
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}
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return append([]byte(nil), buf[:n]...)
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}
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// DecodeVarint decodes a CryptoNote variable-length integer from the given
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// byte slice. It returns the decoded value, the number of bytes consumed,
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// and any error encountered.
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func DecodeVarint(data []byte) (uint64, int, error) {
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if len(data) == 0 {
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return 0, 0, ErrVarintEmpty
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}
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var v uint64
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for i := 0; i < len(data) && i < MaxVarintLen; i++ {
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v |= uint64(data[i]&0x7f) << (7 * uint(i))
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if data[i]&0x80 == 0 {
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return v, i + 1, nil
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}
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}
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// If we read MaxVarintLen bytes and the last one still has the
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// continuation bit set, or if we ran out of data with the continuation
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// bit still set, that is an overflow.
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if len(data) >= MaxVarintLen {
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return 0, 0, ErrVarintOverflow
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}
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return 0, 0, ErrVarintOverflow
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}
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