jtimon
10 years ago
committed by
Pieter Wuille
Pieter Wuille
6 changed files with 215 additions and 195 deletions
@ -0,0 +1,127 @@ |
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// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2013 The Bitcoin developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include "compressor.h" |
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bool CScriptCompressor::IsToKeyID(CKeyID &hash) const |
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{ |
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if (script.size() == 25 && script[0] == OP_DUP && script[1] == OP_HASH160 |
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&& script[2] == 20 && script[23] == OP_EQUALVERIFY |
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&& script[24] == OP_CHECKSIG) { |
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memcpy(&hash, &script[3], 20); |
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return true; |
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} |
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return false; |
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} |
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bool CScriptCompressor::IsToScriptID(CScriptID &hash) const |
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{ |
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if (script.size() == 23 && script[0] == OP_HASH160 && script[1] == 20 |
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&& script[22] == OP_EQUAL) { |
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memcpy(&hash, &script[2], 20); |
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return true; |
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} |
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return false; |
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} |
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bool CScriptCompressor::IsToPubKey(CPubKey &pubkey) const |
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{ |
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if (script.size() == 35 && script[0] == 33 && script[34] == OP_CHECKSIG |
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&& (script[1] == 0x02 || script[1] == 0x03)) { |
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pubkey.Set(&script[1], &script[34]); |
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return true; |
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} |
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if (script.size() == 67 && script[0] == 65 && script[66] == OP_CHECKSIG |
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&& script[1] == 0x04) { |
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pubkey.Set(&script[1], &script[66]); |
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return pubkey.IsFullyValid(); // if not fully valid, a case that would not be compressible
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} |
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return false; |
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} |
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bool CScriptCompressor::Compress(std::vector<unsigned char> &out) const |
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{ |
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CKeyID keyID; |
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if (IsToKeyID(keyID)) { |
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out.resize(21); |
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out[0] = 0x00; |
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memcpy(&out[1], &keyID, 20); |
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return true; |
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} |
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CScriptID scriptID; |
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if (IsToScriptID(scriptID)) { |
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out.resize(21); |
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out[0] = 0x01; |
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memcpy(&out[1], &scriptID, 20); |
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return true; |
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} |
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CPubKey pubkey; |
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if (IsToPubKey(pubkey)) { |
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out.resize(33); |
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memcpy(&out[1], &pubkey[1], 32); |
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if (pubkey[0] == 0x02 || pubkey[0] == 0x03) { |
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out[0] = pubkey[0]; |
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return true; |
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} else if (pubkey[0] == 0x04) { |
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out[0] = 0x04 | (pubkey[64] & 0x01); |
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return true; |
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} |
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} |
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return false; |
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} |
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unsigned int CScriptCompressor::GetSpecialSize(unsigned int nSize) const |
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{ |
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if (nSize == 0 || nSize == 1) |
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return 20; |
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if (nSize == 2 || nSize == 3 || nSize == 4 || nSize == 5) |
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return 32; |
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return 0; |
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} |
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bool CScriptCompressor::Decompress(unsigned int nSize, const std::vector<unsigned char> &in) |
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{ |
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switch(nSize) { |
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case 0x00: |
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script.resize(25); |
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script[0] = OP_DUP; |
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script[1] = OP_HASH160; |
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script[2] = 20; |
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memcpy(&script[3], &in[0], 20); |
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script[23] = OP_EQUALVERIFY; |
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script[24] = OP_CHECKSIG; |
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return true; |
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case 0x01: |
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script.resize(23); |
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script[0] = OP_HASH160; |
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script[1] = 20; |
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memcpy(&script[2], &in[0], 20); |
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script[22] = OP_EQUAL; |
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return true; |
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case 0x02: |
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case 0x03: |
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script.resize(35); |
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script[0] = 33; |
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script[1] = nSize; |
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memcpy(&script[2], &in[0], 32); |
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script[34] = OP_CHECKSIG; |
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return true; |
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case 0x04: |
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case 0x05: |
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unsigned char vch[33] = {}; |
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vch[0] = nSize - 2; |
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memcpy(&vch[1], &in[0], 32); |
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CPubKey pubkey(&vch[0], &vch[33]); |
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if (!pubkey.Decompress()) |
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return false; |
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assert(pubkey.size() == 65); |
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script.resize(67); |
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script[0] = 65; |
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memcpy(&script[1], pubkey.begin(), 65); |
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script[66] = OP_CHECKSIG; |
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return true; |
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} |
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return false; |
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} |
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@ -0,0 +1,84 @@ |
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// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2013 The Bitcoin developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef H_BITCOIN_SCRIPT_COMPRESSOR |
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#define H_BITCOIN_SCRIPT_COMPRESSOR |
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#include "script/script.h" |
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/** Compact serializer for scripts.
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* |
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* It detects common cases and encodes them much more efficiently. |
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* 3 special cases are defined: |
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* * Pay to pubkey hash (encoded as 21 bytes) |
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* * Pay to script hash (encoded as 21 bytes) |
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* * Pay to pubkey starting with 0x02, 0x03 or 0x04 (encoded as 33 bytes) |
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* |
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* Other scripts up to 121 bytes require 1 byte + script length. Above |
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* that, scripts up to 16505 bytes require 2 bytes + script length. |
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*/ |
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class CScriptCompressor |
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{ |
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private: |
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// make this static for now (there are only 6 special scripts defined)
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// this can potentially be extended together with a new nVersion for
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// transactions, in which case this value becomes dependent on nVersion
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// and nHeight of the enclosing transaction.
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static const unsigned int nSpecialScripts = 6; |
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CScript &script; |
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protected: |
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// These check for scripts for which a special case with a shorter encoding is defined.
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// They are implemented separately from the CScript test, as these test for exact byte
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// sequence correspondences, and are more strict. For example, IsToPubKey also verifies
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// whether the public key is valid (as invalid ones cannot be represented in compressed
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// form).
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bool IsToKeyID(CKeyID &hash) const; |
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bool IsToScriptID(CScriptID &hash) const; |
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bool IsToPubKey(CPubKey &pubkey) const; |
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bool Compress(std::vector<unsigned char> &out) const; |
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unsigned int GetSpecialSize(unsigned int nSize) const; |
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bool Decompress(unsigned int nSize, const std::vector<unsigned char> &out); |
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public: |
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CScriptCompressor(CScript &scriptIn) : script(scriptIn) { } |
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unsigned int GetSerializeSize(int nType, int nVersion) const { |
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std::vector<unsigned char> compr; |
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if (Compress(compr)) |
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return compr.size(); |
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unsigned int nSize = script.size() + nSpecialScripts; |
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return script.size() + VARINT(nSize).GetSerializeSize(nType, nVersion); |
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} |
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template<typename Stream> |
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void Serialize(Stream &s, int nType, int nVersion) const { |
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std::vector<unsigned char> compr; |
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if (Compress(compr)) { |
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s << CFlatData(compr); |
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return; |
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} |
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unsigned int nSize = script.size() + nSpecialScripts; |
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s << VARINT(nSize); |
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s << CFlatData(script); |
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} |
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template<typename Stream> |
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void Unserialize(Stream &s, int nType, int nVersion) { |
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unsigned int nSize = 0; |
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s >> VARINT(nSize); |
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if (nSize < nSpecialScripts) { |
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std::vector<unsigned char> vch(GetSpecialSize(nSize), 0x00); |
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s >> REF(CFlatData(vch)); |
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Decompress(nSize, vch); |
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return; |
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} |
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nSize -= nSpecialScripts; |
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script.resize(nSize); |
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s >> REF(CFlatData(script)); |
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} |
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}; |
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#endif |
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