From b55ae3431aedd66be04c888a3b1ec1788cd1d650 Mon Sep 17 00:00:00 2001
From: Daniel Larimer <dlarimer@invictus-innovations.com>
Date: Wed, 15 Oct 2014 17:00:49 -0400
Subject: [PATCH] adding real 128 for fixed point 64.64 math

---
 CMakeLists.txt         |   1 +
 include/fc/real128.hpp |  36 +++++++++++++
 src/real128.cpp        | 115 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 152 insertions(+)
 create mode 100644 include/fc/real128.hpp
 create mode 100644 src/real128.cpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ec8d33b..efd92be 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -92,6 +92,7 @@ option( UNITY_BUILD OFF )
 
 set( fc_sources
      src/uint128.cpp
+     src/real128.cpp
      src/variant.cpp
      src/exception.cpp
      src/variant_object.cpp
diff --git a/include/fc/real128.hpp b/include/fc/real128.hpp
new file mode 100644
index 0000000..ed8aac3
--- /dev/null
+++ b/include/fc/real128.hpp
@@ -0,0 +1,36 @@
+#include <fc/uint128.hpp>   
+
+namespace fc {
+   class variant;
+
+   /**
+    * Provides 64.64 fixed point math operations
+    * based upon base 2^64-1  
+    */
+   class real128
+   {
+      public:
+         real128( uint64_t integer = 0):fixed(integer){}
+         real128( const std::string& str );
+         operator std::string()const;
+
+         friend real128 operator * ( real128 a, const real128& b ) { a *= b; return a; }
+         friend real128 operator / ( real128 a, const real128& b ) { a /= b; return a; }
+         friend real128 operator + ( real128 a, const real128& b ) { a += b; return a; }
+         friend real128 operator - ( real128 a, const real128& b ) { a -= b; return a; }
+
+         real128& operator += ( const real128& o );
+         real128& operator -= ( const real128& o );
+         real128& operator /= ( const real128& o );
+         real128& operator *= ( const real128& o );
+
+         uint64_t to_uint64()const{ return fixed.high_bits(); }
+
+      private:
+         uint128  fixed;
+   };
+
+   void to_variant( const real128& var,  variant& vo );
+   void from_variant( const variant& var,  real128& vo );
+
+} // namespace fc
diff --git a/src/real128.cpp b/src/real128.cpp
new file mode 100644
index 0000000..a67d0a4
--- /dev/null
+++ b/src/real128.cpp
@@ -0,0 +1,115 @@
+#include <fc/real128.hpp>
+#include <fc/crypto/bigint.hpp>
+#include <fc/exception/exception.hpp>
+#include <sstream>
+
+namespace fc
+{
+   real128& real128::operator += ( const real128& o )
+   {
+      fixed += o.fixed;
+      return *this;
+   }
+   real128& real128::operator -= ( const real128& o )
+   {
+      fixed -= o.fixed;
+      return *this;
+   }
+
+   real128& real128::operator /= ( const real128& o )
+   { try {
+      FC_ASSERT( o.fixed > uint128(0), "Divide by Zero" );
+       
+      fc::bigint self(fixed);
+      fc::bigint other(o.fixed);
+      self *= fc::bigint(uint128(0,-1));
+      self /= other;
+      fixed = self;
+
+      return *this;
+   } FC_CAPTURE_AND_RETHROW( (*this)(o) ) }
+
+   real128& real128::operator *= ( const real128& o )
+   { try {
+      fc::bigint self(fixed);
+      fc::bigint other(o.fixed);
+      self *= other;
+      self /= fc::bigint(uint128(0,-1));
+      fixed = self;
+      return *this;
+   } FC_CAPTURE_AND_RETHROW( (*this)(o) ) }
+
+
+   real128::real128( const std::string& ratio_str )
+   {
+     const char* c = ratio_str.c_str();
+     int digit = *c - '0';
+     if (digit >= 0 && digit <= 9)
+     {
+       uint64_t int_part = digit;
+       ++c;
+       digit = *c - '0';
+       while (digit >= 0 && digit <= 9)
+       {
+         int_part = int_part * 10 + digit;
+         ++c;
+         digit = *c - '0';
+       }
+       fixed = fc::uint128(int_part);
+     }
+     else
+     {
+       // if the string doesn't look like "123.45" or ".45", this code isn't designed to parse it correctly
+       // in particular, we don't try to handle leading whitespace or '+'/'-' indicators at the beginning
+       assert(*c == '.');
+       fixed = fc::uint128();
+     }
+
+
+     if (*c == '.')
+     {
+       c++;
+       digit = *c - '0';
+       if (digit >= 0 && digit <= 9)
+       {
+         int64_t frac_part = digit;
+         int64_t frac_magnitude = 10;
+         ++c;
+         digit = *c - '0';
+         while (digit >= 0 && digit <= 9)
+         {
+           frac_part = frac_part * 10 + digit;
+           frac_magnitude *= 10;
+           ++c;
+           digit = *c - '0';
+         }
+         *this += real128( frac_part ) / real128( frac_magnitude );
+       }
+     }
+   }
+   real128::operator std::string()const
+   {
+      std::stringstream ss;
+      ss << to_uint64();
+      ss << '.';
+      auto frac = *this * real128( uint128(-1,0) );
+      frac += real128(1);
+
+      ss << std::string( frac.fixed ).substr(1);
+
+      auto number = ss.str();
+      while(  number.back() == '0' ) number.pop_back();
+
+      return number;
+   }
+
+   void to_variant( const real128& var,  variant& vo )
+   {
+      vo = std::string(var);
+   }
+   void from_variant( const variant& var,  real128& vo )
+   {
+     vo = real128(var.as_string());
+   }
+
+} // namespace fc