1 // Copyright (c) 2009-2010 Satoshi Nakamoto
2 // Copyright (c) 2009-2015 The Bitcoin Core developers
3 // Distributed under the MIT software license, see the accompanying
4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 
6 #ifndef BITCOIN_TEST_SCRIPTNUM10_H
7 #define BITCOIN_TEST_SCRIPTNUM10_H
8 
9 #include <algorithm>
10 #include <limits>
11 #include <stdexcept>
12 #include <stdint.h>
13 #include <string>
14 #include <vector>
15 #include "assert.h"
16 
17 class scriptnum10_error : public std::runtime_error
18 {
19 public:
scriptnum10_error(const std::string & str)20     explicit scriptnum10_error(const std::string& str) : std::runtime_error(str) {}
21 };
22 
23 class CScriptNum10
24 {
25 /**
26  * The ScriptNum implementation from Bitcoin Core 0.10.0, for cross-comparison.
27  */
28 public:
29 
CScriptNum10(const int64_t & n)30     explicit CScriptNum10(const int64_t& n)
31     {
32         m_value = n;
33     }
34 
35     static const size_t nDefaultMaxNumSize = 4;
36 
37     explicit CScriptNum10(const std::vector<unsigned char>& vch, bool fRequireMinimal,
38                         const size_t nMaxNumSize = nDefaultMaxNumSize)
39     {
40         if (vch.size() > nMaxNumSize) {
41             throw scriptnum10_error("script number overflow");
42         }
43         if (fRequireMinimal && vch.size() > 0) {
44             // Check that the number is encoded with the minimum possible
45             // number of bytes.
46             //
47             // If the most-significant-byte - excluding the sign bit - is zero
48             // then we're not minimal. Note how this test also rejects the
49             // negative-zero encoding, 0x80.
50             if ((vch.back() & 0x7f) == 0) {
51                 // One exception: if there's more than one byte and the most
52                 // significant bit of the second-most-significant-byte is set
53                 // it would conflict with the sign bit. An example of this case
54                 // is +-255, which encode to 0xff00 and 0xff80 respectively.
55                 // (big-endian).
56                 if (vch.size() <= 1 || (vch[vch.size() - 2] & 0x80) == 0) {
57                     throw scriptnum10_error("non-minimally encoded script number");
58                 }
59             }
60         }
61         m_value = set_vch(vch);
62     }
63 
64     inline bool operator==(const int64_t& rhs) const    { return m_value == rhs; }
65     inline bool operator!=(const int64_t& rhs) const    { return m_value != rhs; }
66     inline bool operator<=(const int64_t& rhs) const    { return m_value <= rhs; }
67     inline bool operator< (const int64_t& rhs) const    { return m_value <  rhs; }
68     inline bool operator>=(const int64_t& rhs) const    { return m_value >= rhs; }
69     inline bool operator> (const int64_t& rhs) const    { return m_value >  rhs; }
70 
71     inline bool operator==(const CScriptNum10& rhs) const { return operator==(rhs.m_value); }
72     inline bool operator!=(const CScriptNum10& rhs) const { return operator!=(rhs.m_value); }
73     inline bool operator<=(const CScriptNum10& rhs) const { return operator<=(rhs.m_value); }
74     inline bool operator< (const CScriptNum10& rhs) const { return operator< (rhs.m_value); }
75     inline bool operator>=(const CScriptNum10& rhs) const { return operator>=(rhs.m_value); }
76     inline bool operator> (const CScriptNum10& rhs) const { return operator> (rhs.m_value); }
77 
78     inline CScriptNum10 operator+(   const int64_t& rhs)    const { return CScriptNum10(m_value + rhs);}
79     inline CScriptNum10 operator-(   const int64_t& rhs)    const { return CScriptNum10(m_value - rhs);}
80     inline CScriptNum10 operator+(   const CScriptNum10& rhs) const { return operator+(rhs.m_value);   }
81     inline CScriptNum10 operator-(   const CScriptNum10& rhs) const { return operator-(rhs.m_value);   }
82 
83     inline CScriptNum10& operator+=( const CScriptNum10& rhs)       { return operator+=(rhs.m_value);  }
84     inline CScriptNum10& operator-=( const CScriptNum10& rhs)       { return operator-=(rhs.m_value);  }
85 
86     inline CScriptNum10 operator-()                         const
87     {
88         assert(m_value != std::numeric_limits<int64_t>::min());
89         return CScriptNum10(-m_value);
90     }
91 
92     inline CScriptNum10& operator=( const int64_t& rhs)
93     {
94         m_value = rhs;
95         return *this;
96     }
97 
98     inline CScriptNum10& operator+=( const int64_t& rhs)
99     {
100         assert(rhs == 0 || (rhs > 0 && m_value <= std::numeric_limits<int64_t>::max() - rhs) ||
101                            (rhs < 0 && m_value >= std::numeric_limits<int64_t>::min() - rhs));
102         m_value += rhs;
103         return *this;
104     }
105 
106     inline CScriptNum10& operator-=( const int64_t& rhs)
107     {
108         assert(rhs == 0 || (rhs > 0 && m_value >= std::numeric_limits<int64_t>::min() + rhs) ||
109                            (rhs < 0 && m_value <= std::numeric_limits<int64_t>::max() + rhs));
110         m_value -= rhs;
111         return *this;
112     }
113 
getint()114     int getint() const
115     {
116         if (m_value > std::numeric_limits<int>::max())
117             return std::numeric_limits<int>::max();
118         else if (m_value < std::numeric_limits<int>::min())
119             return std::numeric_limits<int>::min();
120         return m_value;
121     }
122 
getvch()123     std::vector<unsigned char> getvch() const
124     {
125         return serialize(m_value);
126     }
127 
serialize(const int64_t & value)128     static std::vector<unsigned char> serialize(const int64_t& value)
129     {
130         if(value == 0)
131             return std::vector<unsigned char>();
132 
133         std::vector<unsigned char> result;
134         const bool neg = value < 0;
135         uint64_t absvalue = neg ? -value : value;
136 
137         while(absvalue)
138         {
139             result.push_back(absvalue & 0xff);
140             absvalue >>= 8;
141         }
142 
143 //    - If the most significant byte is >= 0x80 and the value is positive, push a
144 //    new zero-byte to make the significant byte < 0x80 again.
145 
146 //    - If the most significant byte is >= 0x80 and the value is negative, push a
147 //    new 0x80 byte that will be popped off when converting to an integral.
148 
149 //    - If the most significant byte is < 0x80 and the value is negative, add
150 //    0x80 to it, since it will be subtracted and interpreted as a negative when
151 //    converting to an integral.
152 
153         if (result.back() & 0x80)
154             result.push_back(neg ? 0x80 : 0);
155         else if (neg)
156             result.back() |= 0x80;
157 
158         return result;
159     }
160 
161 private:
set_vch(const std::vector<unsigned char> & vch)162     static int64_t set_vch(const std::vector<unsigned char>& vch)
163     {
164       if (vch.empty())
165           return 0;
166 
167       int64_t result = 0;
168       for (size_t i = 0; i != vch.size(); ++i)
169           result |= static_cast<int64_t>(vch[i]) << 8*i;
170 
171       // If the input vector's most significant byte is 0x80, remove it from
172       // the result's msb and return a negative.
173       if (vch.back() & 0x80)
174           return -((int64_t)(result & ~(0x80ULL << (8 * (vch.size() - 1)))));
175 
176       return result;
177     }
178 
179     int64_t m_value;
180 };
181 
182 
183 #endif // BITCOIN_TEST_BIGNUM_H
184