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e78b8e4cf3
* Otherwise overflow checks result in divide by 0. * If denominator is 0, let the divide by 0 exception throw. * Move mulDiv out of STAmount
81 lines
2.6 KiB
C++
81 lines
2.6 KiB
C++
//------------------------------------------------------------------------------
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/*
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This file is part of rippled: https://github.com/ripple/rippled
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Copyright (c) 2012-2015 Ripple Labs Inc.
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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//==============================================================================
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#ifndef RIPPLE_BASICS_MULDIV_H_INCLUDED
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#define RIPPLE_BASICS_MULDIV_H_INCLUDED
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#include <cstdint>
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#include <type_traits>
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#include <utility>
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namespace ripple
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{
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/** Return value*mul/div accurately.
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Computes the result of the multiplication and division in
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a single step, avoiding overflow and retaining precision.
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Throws:
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None
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Returns:
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`std::pair`:
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`first` is `false` if the calculation overflows,
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`true` if the calculation is safe.
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`second` is the result of the calculation if
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`first` is `false`, max value of `uint64_t`
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if `true`.
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*/
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std::pair<bool, std::uint64_t>
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mulDiv(std::uint64_t value, std::uint64_t mul, std::uint64_t div);
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/** Return value*mul/div accurately.
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Computes the result of the multiplication and division in
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a single step, avoiding overflow and retaining precision.
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Throws:
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std::overflow_error
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*/
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std::uint64_t
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mulDivThrow(std::uint64_t value, std::uint64_t mul, std::uint64_t div);
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template <class T1, class T2,
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class = std::enable_if_t <
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std::is_integral<T1>::value &&
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std::is_unsigned<T1>::value &&
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sizeof(T1) <= sizeof(std::uint64_t) >,
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class = std::enable_if_t <
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std::is_integral<T2>::value &&
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std::is_unsigned<T2>::value &&
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sizeof(T2) <= sizeof(std::uint64_t) >
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>
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void lowestTerms(T1& a, T2& b)
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{
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std::uint64_t x = a, y = b;
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while (y != 0)
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{
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auto t = x % y;
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x = y;
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y = t;
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}
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a /= x;
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b /= x;
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}
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} // ripple
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#endif
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