From 382adcc93c54792507018a21aedda6e58a22f8f8 Mon Sep 17 00:00:00 2001
From: Edward Hennis <ximinez@users.noreply.github.com>
Date: Fri, 10 Jul 2015 17:47:47 -0400
Subject: [PATCH] Move mulDiv and lowestTerms to STAmount.cpp

---
 src/ripple/core/impl/LoadFeeTrack.cpp | 35 ---------------------------
 src/ripple/protocol/STAmount.h        | 21 ++++++++++++++++
 src/ripple/protocol/impl/STAmount.cpp | 20 +++++++++++++++
 3 files changed, 41 insertions(+), 35 deletions(-)

diff --git a/src/ripple/core/impl/LoadFeeTrack.cpp b/src/ripple/core/impl/LoadFeeTrack.cpp
index 3131f551ae..7235e6fe5b 100644
--- a/src/ripple/core/impl/LoadFeeTrack.cpp
+++ b/src/ripple/core/impl/LoadFeeTrack.cpp
@@ -25,41 +25,6 @@
 
 namespace ripple {
 
-template <class T1, class T2>
-void lowestTerms(T1& a,  T2& b)
-{
-    std::uint64_t x = a, y = b;
-    while (y != 0)
-    {
-        auto t = x % y;
-        x = y;
-        y = t;
-    }
-    a /= x;
-    b /= x;
-}
-
-// TODO REMOVE!
-static
-std::uint64_t
-mulDiv(std::uint64_t value, std::uint64_t mul, std::uint64_t div)
-{
-    lowestTerms(value, div);
-    lowestTerms(mul, div);
-
-    if (value < mul)
-        std::swap(value, mul);
-    const auto max = std::numeric_limits<std::uint64_t>::max();
-    if (value > max / mul)
-    {
-        value /= div;
-        if (value > max / mul)
-            throw std::overflow_error("mulDiv");
-        return value * mul;
-    }
-    return value * mul / div;
-}
-
 // Scale from fee units to millionths of a ripple
 std::uint64_t
 LoadFeeTrack::scaleFeeBase (std::uint64_t fee, std::uint64_t baseFee,
diff --git a/src/ripple/protocol/STAmount.h b/src/ripple/protocol/STAmount.h
index adb2249c71..27a3921d1e 100644
--- a/src/ripple/protocol/STAmount.h
+++ b/src/ripple/protocol/STAmount.h
@@ -400,6 +400,27 @@ inline bool isXRP(STAmount const& amount)
     return isXRP (amount.issue().currency);
 }
 
+/**
+    A utility function to compute (value)*(mul)/(div) while avoiding
+    overflow but keeping precision.
+*/
+std::uint64_t
+mulDiv(std::uint64_t value, std::uint64_t mul, std::uint64_t div);
+
+template <class T1, class T2>
+void lowestTerms(T1& a,  T2& b)
+{
+    std::uint64_t x = a, y = b;
+    while (y != 0)
+    {
+        auto t = x % y;
+        x = y;
+        y = t;
+    }
+    a /= x;
+    b /= x;
+}
+
 } // ripple
 
 #endif
diff --git a/src/ripple/protocol/impl/STAmount.cpp b/src/ripple/protocol/impl/STAmount.cpp
index 3ecc9abe8b..d818923219 100644
--- a/src/ripple/protocol/impl/STAmount.cpp
+++ b/src/ripple/protocol/impl/STAmount.cpp
@@ -1257,4 +1257,24 @@ divRound (STAmount const& num, STAmount const& den,
     return STAmount (issue, amount, offset, resultNegative);
 }
 
+// compute (value)*(mul)/(div) - avoid overflow but keep precision
+std::uint64_t
+mulDiv(std::uint64_t value, std::uint64_t mul, std::uint64_t div)
+{
+    lowestTerms(value, div);
+    lowestTerms(mul, div);
+
+    if (value < mul)
+        std::swap(value, mul);
+    const auto max = std::numeric_limits<std::uint64_t>::max();
+    if (value > max / mul)
+    {
+        value /= div;
+        if (value > max / mul)
+            throw std::overflow_error("mulDiv");
+        return value * mul;
+    }
+    return value * mul / div;
+}
+
 } // ripple