Implement Bech32m encoding/decoding

src/bech32.h

@@ -1,4 +1,4 @@
-// Copyright (c) 2017 Pieter Wuille
+// Copyright (c) 2017, 2021 Pieter Wuille
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -7,7 +7,7 @@
 // separator character (1), and a base32 data section, the last
 // 6 characters of which are a checksum.
 //
-// For more information, see BIP 173.
+// For more information, see BIP 173 and BIP 350.
 
 #ifndef BITCOIN_BECH32_H
 #define BITCOIN_BECH32_H
@@ -19,11 +19,29 @@
 namespace bech32
 {
 
-/** Encode a Bech32 string. If hrp contains uppercase characters, this will cause an assertion error. */
-std::string Encode(const std::string& hrp, const std::vector<uint8_t>& values);
+enum class Encoding {
+    INVALID, //!< Failed decoding
 
-/** Decode a Bech32 string. Returns (hrp, data). Empty hrp means failure. */
-std::pair<std::string, std::vector<uint8_t>> Decode(const std::string& str);
+    BECH32,  //!< Bech32 encoding as defined in BIP173
+    BECH32M, //!< Bech32m encoding as defined in BIP350
+};
+
+/** Encode a Bech32 or Bech32m string. If hrp contains uppercase characters, this will cause an
+ *  assertion error. Encoding must be one of BECH32 or BECH32M. */
+std::string Encode(Encoding encoding, const std::string& hrp, const std::vector<uint8_t>& values);
+
+struct DecodeResult
+{
+    Encoding encoding;         //!< What encoding was detected in the result; Encoding::INVALID if failed.
+    std::string hrp;           //!< The human readable part
+    std::vector<uint8_t> data; //!< The payload (excluding checksum)
+
+    DecodeResult() : encoding(Encoding::INVALID) {}
+    DecodeResult(Encoding enc, std::string&& h, std::vector<uint8_t>&& d) : encoding(enc), hrp(std::move(h)), data(std::move(d)) {}
+};
+
+/** Decode a Bech32 string. */
+DecodeResult Decode(const std::string& str);
 
 } // namespace bech32