Subject: [Boost-commit] svn:boost r65474 - sandbox/chrono/boost/ratio
From: vicente.botet_at_[hidden]
Date: 2010-09-20 00:34:15
Author: viboes
Date: 2010-09-20 00:34:11 EDT (Mon, 20 Sep 2010)
New Revision: 65474
URL: http://svn.boost.org/trac/boost/changeset/65474
Log:
Fix ratio_less overflow taken from llvm/libcxx/include/ratio
Text files modified:
sandbox/chrono/boost/ratio/ratio.hpp | 68 ++++++++++++++++++---------------------
1 files changed, 31 insertions(+), 37 deletions(-)
Modified: sandbox/chrono/boost/ratio/ratio.hpp
==============================================================================
--- sandbox/chrono/boost/ratio/ratio.hpp (original)
+++ sandbox/chrono/boost/ratio/ratio.hpp 2010-09-20 00:34:11 EDT (Mon, 20 Sep 2010)
@@ -27,6 +27,16 @@
Anthony Williams.
*/
+// The way overflow is managed for ratio_less is taken from llvm/libcxx/include/ratio
+//===---------------------------- ratio -----------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
#ifndef BOOST_RATIO_RATIO__HPP
#define BOOST_RATIO_RATIO_HPP
@@ -505,57 +515,41 @@
namespace detail
{
- // Protect against overflow, and still get the right answer as much as possible.
- // This just demonstrates for fun how far you can push things without hitting
- // overflow. The obvious and simple implementation is conforming.
-
- template <class R1, class R2, bool ok1, bool ok2>
- struct ratio_less3 // true, true and false, false
- {
- static const bool value = ll_mul<R1::num,
- R2::den>::value < ll_mul<R2::num, R1::den>::value;
- };
-
- template <class R1, class R2>
- struct ratio_less3<R1, R2, true, false>
- {
- static const bool value = true;
- };
- template <class R1, class R2>
- struct ratio_less3<R1, R2, false, true>
+ template <class R1, class R2, bool Odd = false,
+ intmax_t Q1 = R1::num / R1::den, intmax_t M1 = R1::num % R1::den,
+ intmax_t Q2 = R2::num / R2::den, intmax_t M2 = R2::num % R2::den>
+ struct ratio_less1
{
- static const bool value = false;
+ static const bool value = Odd ? Q2 < Q1 : Q1 < Q2;
};
- template <class R1, class R2, bool = (R1::num < R1::den == R2::num < R2::den) >
- struct ratio_less2 // N1 < D1 == N2 < D2
+ template <class R1, class R2, bool Odd, intmax_t Q>
+ struct ratio_less1<R1, R2, Odd, Q, 0, Q, 0>
{
- static const intmax_t max = -((1LL << (sizeof(intmax_t) * CHAR_BIT - 1)) + 1);
- static const bool ok1 = R1::num <= max / R2::den;
- static const bool ok2 = R2::num <= max / R1::den;
- static const bool value = ratio_less3<R1, R2, ok1, ok2>::value;
+ static const bool value = false;
};
- template <class R1, class R2>
- struct ratio_less2<R1, R2, false> // N1 < D1 != N2 < D2
+ template <class R1, class R2, bool Odd, intmax_t Q, intmax_t M2>
+ struct ratio_less1<R1, R2, Odd, Q, 0, Q, M2>
{
- static const bool value = R1::num < R1::den;
+ static const bool value = !Odd;
};
- template <class R1, class R2, bool = (R1::num < R1::den == R2::num < R2::den) >
- struct ratio_less1 // N1 < D1 == N2 < D2
+ template <class R1, class R2, bool Odd, intmax_t Q, intmax_t M1>
+ struct ratio_less1<R1, R2, Odd, Q, M1, Q, 0>
{
- static const bool value = ratio_less2<ratio<R1::num, R2::num>,
- ratio<R1::den, R2::den> >::value;
+ static const bool value = Odd;
};
- template <class R1, class R2>
- struct ratio_less1<R1, R2, false> // N1 < D1 != N2 < D2
+ template <class R1, class R2, bool Odd, intmax_t Q, intmax_t M1,
+ intmax_t M2>
+ struct ratio_less1<R1, R2, Odd, Q, M1, Q, M2>
{
- static const bool value = R1::num < R1::den;
- };
-
+ static const bool value = ratio_less1<ratio<R1::den, M1>,
+ ratio<R2::den, M2>, !Odd>::value;
+ };
+
template <class R1, class R2, intmax_t S1 = static_sign<R1::num>::value,
intmax_t S2 = static_sign<R2::num>::value>
struct ratio_less