From 340ee4f3e36ec37baa9748ad7107d90050b8af20 Mon Sep 17 00:00:00 2001
From: Jack Lloyd <jack@randombit.net>
Date: Wed, 5 Dec 2018 08:32:26 -0500
Subject: Remove some conditional branches from division

---
 src/lib/math/bigint/bigint.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'src/lib/math/bigint/bigint.cpp')

diff --git a/src/lib/math/bigint/bigint.cpp b/src/lib/math/bigint/bigint.cpp
index a4545e4a1..1a09a92f1 100644
--- a/src/lib/math/bigint/bigint.cpp
+++ b/src/lib/math/bigint/bigint.cpp
@@ -317,7 +317,7 @@ BigInt BigInt::operator-() const
    return x;
    }
 
-void BigInt::reduce_below(const BigInt& p, secure_vector<word>& ws)
+size_t BigInt::reduce_below(const BigInt& p, secure_vector<word>& ws)
    {
    if(p.is_negative())
       throw Invalid_Argument("BigInt::reduce_below mod must be positive");
@@ -332,14 +332,19 @@ void BigInt::reduce_below(const BigInt& p, secure_vector<word>& ws)
 
    clear_mem(ws.data(), ws.size());
 
+   size_t reductions = 0;
+
    for(;;)
       {
       word borrow = bigint_sub3(ws.data(), data(), p_words + 1, p.data(), p_words);
       if(borrow)
          break;
 
+      ++reductions;
       swap_reg(ws);
       }
+
+   return reductions;
    }
 
 /*
-- 
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