Replace scriptnum_test's normative ScriptNum implementation

Compare against the scriptnum from Bitcoin Core 0.10 instead of OpenSSL.
Closes #7086.

src/test/scriptnum10.h

@@ -0,0 +1,183 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2013 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_TEST_SCRIPTNUM10_H
+#define BITCOIN_TEST_SCRIPTNUM10_H
+
+#include <algorithm>
+#include <limits>
+#include <stdexcept>
+#include <stdint.h>
+#include <string>
+#include <vector>
+#include "assert.h"
+
+class scriptnum10_error : public std::runtime_error
+{
+public:
+    explicit scriptnum10_error(const std::string& str) : std::runtime_error(str) {}
+};
+
+class CScriptNum10
+{
+/**
+ * The ScriptNum implementation from Bitcoin Core 0.10.0, for cross-comparison.
+ */
+public:
+
+    explicit CScriptNum10(const int64_t& n)
+    {
+        m_value = n;
+    }
+
+    static const size_t nDefaultMaxNumSize = 4;
+
+    explicit CScriptNum10(const std::vector<unsigned char>& vch, bool fRequireMinimal,
+                        const size_t nMaxNumSize = nDefaultMaxNumSize)
+    {
+        if (vch.size() > nMaxNumSize) {
+            throw scriptnum10_error("script number overflow");
+        }
+        if (fRequireMinimal && vch.size() > 0) {
+            // Check that the number is encoded with the minimum possible
+            // number of bytes.
+            //
+            // If the most-significant-byte - excluding the sign bit - is zero
+            // then we're not minimal. Note how this test also rejects the
+            // negative-zero encoding, 0x80.
+            if ((vch.back() & 0x7f) == 0) {
+                // One exception: if there's more than one byte and the most
+                // significant bit of the second-most-significant-byte is set
+                // it would conflict with the sign bit. An example of this case
+                // is +-255, which encode to 0xff00 and 0xff80 respectively.
+                // (big-endian).
+                if (vch.size() <= 1 || (vch[vch.size() - 2] & 0x80) == 0) {
+                    throw scriptnum10_error("non-minimally encoded script number");
+                }
+            }
+        }
+        m_value = set_vch(vch);
+    }
+
+    inline bool operator==(const int64_t& rhs) const    { return m_value == rhs; }
+    inline bool operator!=(const int64_t& rhs) const    { return m_value != rhs; }
+    inline bool operator<=(const int64_t& rhs) const    { return m_value <= rhs; }
+    inline bool operator< (const int64_t& rhs) const    { return m_value <  rhs; }
+    inline bool operator>=(const int64_t& rhs) const    { return m_value >= rhs; }
+    inline bool operator> (const int64_t& rhs) const    { return m_value >  rhs; }
+
+    inline bool operator==(const CScriptNum10& rhs) const { return operator==(rhs.m_value); }
+    inline bool operator!=(const CScriptNum10& rhs) const { return operator!=(rhs.m_value); }
+    inline bool operator<=(const CScriptNum10& rhs) const { return operator<=(rhs.m_value); }
+    inline bool operator< (const CScriptNum10& rhs) const { return operator< (rhs.m_value); }
+    inline bool operator>=(const CScriptNum10& rhs) const { return operator>=(rhs.m_value); }
+    inline bool operator> (const CScriptNum10& rhs) const { return operator> (rhs.m_value); }
+
+    inline CScriptNum10 operator+(   const int64_t& rhs)    const { return CScriptNum10(m_value + rhs);}
+    inline CScriptNum10 operator-(   const int64_t& rhs)    const { return CScriptNum10(m_value - rhs);}
+    inline CScriptNum10 operator+(   const CScriptNum10& rhs) const { return operator+(rhs.m_value);   }
+    inline CScriptNum10 operator-(   const CScriptNum10& rhs) const { return operator-(rhs.m_value);   }
+
+    inline CScriptNum10& operator+=( const CScriptNum10& rhs)       { return operator+=(rhs.m_value);  }
+    inline CScriptNum10& operator-=( const CScriptNum10& rhs)       { return operator-=(rhs.m_value);  }
+
+    inline CScriptNum10 operator-()                         const
+    {
+        assert(m_value != std::numeric_limits<int64_t>::min());
+        return CScriptNum10(-m_value);
+    }
+
+    inline CScriptNum10& operator=( const int64_t& rhs)
+    {
+        m_value = rhs;
+        return *this;
+    }
+
+    inline CScriptNum10& operator+=( const int64_t& rhs)
+    {
+        assert(rhs == 0 || (rhs > 0 && m_value <= std::numeric_limits<int64_t>::max() - rhs) ||
+                           (rhs < 0 && m_value >= std::numeric_limits<int64_t>::min() - rhs));
+        m_value += rhs;
+        return *this;
+    }
+
+    inline CScriptNum10& operator-=( const int64_t& rhs)
+    {
+        assert(rhs == 0 || (rhs > 0 && m_value >= std::numeric_limits<int64_t>::min() + rhs) ||
+                           (rhs < 0 && m_value <= std::numeric_limits<int64_t>::max() + rhs));
+        m_value -= rhs;
+        return *this;
+    }
+
+    int getint() const
+    {
+        if (m_value > std::numeric_limits<int>::max())
+            return std::numeric_limits<int>::max();
+        else if (m_value < std::numeric_limits<int>::min())
+            return std::numeric_limits<int>::min();
+        return m_value;
+    }
+
+    std::vector<unsigned char> getvch() const
+    {
+        return serialize(m_value);
+    }
+
+    static std::vector<unsigned char> serialize(const int64_t& value)
+    {
+        if(value == 0)
+            return std::vector<unsigned char>();
+
+        std::vector<unsigned char> result;
+        const bool neg = value < 0;
+        uint64_t absvalue = neg ? -value : value;
+
+        while(absvalue)
+        {
+            result.push_back(absvalue & 0xff);
+            absvalue >>= 8;
+        }
+
+//    - If the most significant byte is >= 0x80 and the value is positive, push a
+//    new zero-byte to make the significant byte < 0x80 again.
+
+//    - If the most significant byte is >= 0x80 and the value is negative, push a
+//    new 0x80 byte that will be popped off when converting to an integral.
+
+//    - If the most significant byte is < 0x80 and the value is negative, add
+//    0x80 to it, since it will be subtracted and interpreted as a negative when
+//    converting to an integral.
+
+        if (result.back() & 0x80)
+            result.push_back(neg ? 0x80 : 0);
+        else if (neg)
+            result.back() |= 0x80;
+
+        return result;
+    }
+
+private:
+    static int64_t set_vch(const std::vector<unsigned char>& vch)
+    {
+      if (vch.empty())
+          return 0;
+
+      int64_t result = 0;
+      for (size_t i = 0; i != vch.size(); ++i)
+          result |= static_cast<int64_t>(vch[i]) << 8*i;
+
+      // If the input vector's most significant byte is 0x80, remove it from
+      // the result's msb and return a negative.
+      if (vch.back() & 0x80)
+          return -((int64_t)(result & ~(0x80ULL << (8 * (vch.size() - 1)))));
+
+      return result;
+    }
+
+    int64_t m_value;
+};
+
+
+#endif // BITCOIN_TEST_BIGNUM_H