Support median block size > 4 GB

add a 128/64 division routine so we can use a > 32 bit median block
size in calculations

1 files changed, 48 insertions, 0 deletions

diff --git a/contrib/epee/src/int-util.cpp b/contrib/epee/src/int-util.cpp
new file mode 100644
index 000000000..e9d0822e0
--- /dev/null
+++ b/contrib/epee/src/int-util.cpp
@@ -0,0 +1,48 @@
+// Copyright (c) 2019, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <boost/multiprecision/cpp_int.hpp>
+
+void div128_64(uint64_t dividend_hi, uint64_t dividend_lo, uint64_t divisor, uint64_t* quotient_hi, uint64_t *quotient_lo, uint64_t *remainder_hi, uint64_t *remainder_lo)
+{
+  typedef boost::multiprecision::uint128_t uint128_t;
+
+  uint128_t dividend = dividend_hi;
+  dividend <<= 64;
+  dividend |= dividend_lo;
+
+  uint128_t q, r;
+  divide_qr(dividend, uint128_t(divisor), q, r);
+
+  *quotient_hi = ((q >> 64) & 0xffffffffffffffffull).convert_to<uint64_t>();
+  *quotient_lo = (q & 0xffffffffffffffffull).convert_to<uint64_t>();
+  if (remainder_hi)
+    *remainder_hi = ((r >> 64) & 0xffffffffffffffffull).convert_to<uint64_t>();
+  if (remainder_lo)
+    *remainder_lo = (r & 0xffffffffffffffffull).convert_to<uint64_t>();
+}