mirror of
https://github.com/danog/libtgvoip.git
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5caaaafa42
I'm now using the entire audio processing module from WebRTC as opposed to individual DSP algorithms pulled from there before. Seems to work better this way.
177 lines
6.5 KiB
C++
177 lines
6.5 KiB
C++
/*
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* Copyright 2016 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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// This file defines six constexpr functions:
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//
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// rtc::SafeEq // ==
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// rtc::SafeNe // !=
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// rtc::SafeLt // <
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// rtc::SafeLe // <=
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// rtc::SafeGt // >
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// rtc::SafeGe // >=
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//
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// They each accept two arguments of arbitrary types, and in almost all cases,
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// they simply call the appropriate comparison operator. However, if both
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// arguments are integers, they don't compare them using C++'s quirky rules,
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// but instead adhere to the true mathematical definitions. It is as if the
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// arguments were first converted to infinite-range signed integers, and then
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// compared, although of course nothing expensive like that actually takes
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// place. In practice, for signed/signed and unsigned/unsigned comparisons and
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// some mixed-signed comparisons with a compile-time constant, the overhead is
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// zero; in the remaining cases, it is just a few machine instructions (no
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// branches).
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#ifndef RTC_BASE_NUMERICS_SAFE_COMPARE_H_
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#define RTC_BASE_NUMERICS_SAFE_COMPARE_H_
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#include <stddef.h>
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#include <stdint.h>
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#include <type_traits>
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#include <utility>
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#include "rtc_base/type_traits.h"
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namespace rtc {
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namespace safe_cmp_impl {
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template <size_t N>
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struct LargerIntImpl : std::false_type {};
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template <>
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struct LargerIntImpl<sizeof(int8_t)> : std::true_type {
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using type = int16_t;
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};
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template <>
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struct LargerIntImpl<sizeof(int16_t)> : std::true_type {
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using type = int32_t;
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};
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template <>
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struct LargerIntImpl<sizeof(int32_t)> : std::true_type {
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using type = int64_t;
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};
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// LargerInt<T1, T2>::value is true iff there's a signed type that's larger
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// than T1 (and no larger than the larger of T2 and int*, for performance
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// reasons); and if there is such a type, LargerInt<T1, T2>::type is an alias
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// for it.
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template <typename T1, typename T2>
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struct LargerInt
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: LargerIntImpl<sizeof(T1) < sizeof(T2) || sizeof(T1) < sizeof(int*)
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? sizeof(T1)
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: 0> {};
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template <typename T>
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constexpr typename std::make_unsigned<T>::type MakeUnsigned(T a) {
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return static_cast<typename std::make_unsigned<T>::type>(a);
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}
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// Overload for when both T1 and T2 have the same signedness.
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template <typename Op,
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typename T1,
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typename T2,
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typename std::enable_if<std::is_signed<T1>::value ==
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std::is_signed<T2>::value>::type* = nullptr>
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constexpr bool Cmp(T1 a, T2 b) {
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return Op::Op(a, b);
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}
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// Overload for signed - unsigned comparison that can be promoted to a bigger
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// signed type.
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template <typename Op,
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typename T1,
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typename T2,
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typename std::enable_if<std::is_signed<T1>::value &&
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std::is_unsigned<T2>::value &&
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LargerInt<T2, T1>::value>::type* = nullptr>
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constexpr bool Cmp(T1 a, T2 b) {
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return Op::Op(a, static_cast<typename LargerInt<T2, T1>::type>(b));
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}
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// Overload for unsigned - signed comparison that can be promoted to a bigger
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// signed type.
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template <typename Op,
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typename T1,
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typename T2,
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typename std::enable_if<std::is_unsigned<T1>::value &&
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std::is_signed<T2>::value &&
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LargerInt<T1, T2>::value>::type* = nullptr>
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constexpr bool Cmp(T1 a, T2 b) {
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return Op::Op(static_cast<typename LargerInt<T1, T2>::type>(a), b);
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}
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// Overload for signed - unsigned comparison that can't be promoted to a bigger
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// signed type.
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template <typename Op,
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typename T1,
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typename T2,
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typename std::enable_if<std::is_signed<T1>::value &&
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std::is_unsigned<T2>::value &&
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!LargerInt<T2, T1>::value>::type* = nullptr>
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constexpr bool Cmp(T1 a, T2 b) {
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return a < 0 ? Op::Op(-1, 0) : Op::Op(safe_cmp_impl::MakeUnsigned(a), b);
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}
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// Overload for unsigned - signed comparison that can't be promoted to a bigger
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// signed type.
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template <typename Op,
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typename T1,
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typename T2,
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typename std::enable_if<std::is_unsigned<T1>::value &&
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std::is_signed<T2>::value &&
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!LargerInt<T1, T2>::value>::type* = nullptr>
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constexpr bool Cmp(T1 a, T2 b) {
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return b < 0 ? Op::Op(0, -1) : Op::Op(a, safe_cmp_impl::MakeUnsigned(b));
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}
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#define RTC_SAFECMP_MAKE_OP(name, op) \
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struct name { \
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template <typename T1, typename T2> \
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static constexpr bool Op(T1 a, T2 b) { \
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return a op b; \
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} \
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};
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RTC_SAFECMP_MAKE_OP(EqOp, ==)
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RTC_SAFECMP_MAKE_OP(NeOp, !=)
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RTC_SAFECMP_MAKE_OP(LtOp, <)
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RTC_SAFECMP_MAKE_OP(LeOp, <=)
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RTC_SAFECMP_MAKE_OP(GtOp, >)
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RTC_SAFECMP_MAKE_OP(GeOp, >=)
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#undef RTC_SAFECMP_MAKE_OP
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} // namespace safe_cmp_impl
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#define RTC_SAFECMP_MAKE_FUN(name) \
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template <typename T1, typename T2> \
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constexpr \
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typename std::enable_if<IsIntlike<T1>::value && IsIntlike<T2>::value, \
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bool>::type Safe##name(T1 a, T2 b) { \
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/* Unary plus here turns enums into real integral types. */ \
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return safe_cmp_impl::Cmp<safe_cmp_impl::name##Op>(+a, +b); \
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} \
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template <typename T1, typename T2> \
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constexpr \
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typename std::enable_if<!IsIntlike<T1>::value || !IsIntlike<T2>::value, \
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bool>::type Safe##name(const T1& a, \
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const T2& b) { \
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return safe_cmp_impl::name##Op::Op(a, b); \
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}
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RTC_SAFECMP_MAKE_FUN(Eq)
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RTC_SAFECMP_MAKE_FUN(Ne)
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RTC_SAFECMP_MAKE_FUN(Lt)
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RTC_SAFECMP_MAKE_FUN(Le)
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RTC_SAFECMP_MAKE_FUN(Gt)
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RTC_SAFECMP_MAKE_FUN(Ge)
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#undef RTC_SAFECMP_MAKE_FUN
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} // namespace rtc
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#endif // RTC_BASE_NUMERICS_SAFE_COMPARE_H_
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