mirror of https://github.com/OpenTTD/OpenTTD.git
150 lines
10 KiB
C++
150 lines
10 KiB
C++
/* $Id$ */
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/** @file overflowsafe_type.hpp An overflow safe integer-like type. */
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#ifndef OVERFLOWSAFE_TYPE_HPP
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#define OVERFLOWSAFE_TYPE_HPP
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#include "math_func.hpp"
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/**
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* Overflow safe template for integers, i.e. integers that will never overflow
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* you multiply the maximum value with 2, or add 2, or substract somethng from
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* the minimum value, etc.
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* @param T the type these integers are stored with.
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* @param T_MAX the maximum value for the integers.
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* @param T_MIN the minimum value for the integers.
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*/
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template <class T, T T_MAX, T T_MIN>
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class OverflowSafeInt
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{
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private:
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/** The non-overflow safe backend to store the value in. */
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T m_value;
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public:
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OverflowSafeInt() : m_value(0) { }
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OverflowSafeInt(const OverflowSafeInt& other) { this->m_value = other.m_value; }
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OverflowSafeInt(const int64 int_) { this->m_value = int_; }
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FORCEINLINE OverflowSafeInt& operator = (const OverflowSafeInt& other) { this->m_value = other.m_value; return *this; }
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FORCEINLINE OverflowSafeInt operator - () const { return OverflowSafeInt(-this->m_value); }
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/**
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* Safe implementation of addition.
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* @param other the amount to add
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* @note when the addition would yield more than T_MAX (or less than T_MIN),
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* it will be T_MAX (respectively T_MIN).
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*/
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FORCEINLINE OverflowSafeInt& operator += (const OverflowSafeInt& other)
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{
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if ((T_MAX - abs(other.m_value)) < abs(this->m_value) &&
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(this->m_value < 0) == (other.m_value < 0)) {
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this->m_value = (this->m_value < 0) ? T_MIN : T_MAX ;
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} else {
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this->m_value += other.m_value;
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}
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return *this;
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}
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/* Operators for addition and substraction */
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FORCEINLINE OverflowSafeInt operator + (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result += other; return result; }
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FORCEINLINE OverflowSafeInt operator + (const int other) const { OverflowSafeInt result = *this; result += (int64)other; return result; }
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FORCEINLINE OverflowSafeInt operator + (const uint other) const { OverflowSafeInt result = *this; result += (int64)other; return result; }
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FORCEINLINE OverflowSafeInt& operator -= (const OverflowSafeInt& other) { return *this += (-other); }
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FORCEINLINE OverflowSafeInt operator - (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result -= other; return result; }
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FORCEINLINE OverflowSafeInt operator - (const int other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; }
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FORCEINLINE OverflowSafeInt operator - (const uint other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; }
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FORCEINLINE OverflowSafeInt& operator ++ () { return *this += 1; }
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FORCEINLINE OverflowSafeInt& operator -- () { return *this += -1; }
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FORCEINLINE OverflowSafeInt operator ++ (int) { OverflowSafeInt org = *this; *this += 1; return org; }
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FORCEINLINE OverflowSafeInt operator -- (int) { OverflowSafeInt org = *this; *this += -1; return org; }
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/**
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* Safe implementation of multiplication.
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* @param factor the factor to multiply this with.
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* @note when the multiplication would yield more than T_MAX (or less than T_MIN),
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* it will be T_MAX (respectively T_MIN).
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*/
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FORCEINLINE OverflowSafeInt& operator *= (const int factor)
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{
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if (factor != 0 && (T_MAX / abs(factor)) < abs(this->m_value)) {
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this->m_value = ((this->m_value < 0) == (factor < 0)) ? T_MAX : T_MIN ;
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} else {
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this->m_value *= factor ;
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}
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return *this;
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}
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/* Operators for multiplication */
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FORCEINLINE OverflowSafeInt operator * (const int64 factor) const { OverflowSafeInt result = *this; result *= factor; return result; }
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FORCEINLINE OverflowSafeInt operator * (const int factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
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FORCEINLINE OverflowSafeInt operator * (const uint factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
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FORCEINLINE OverflowSafeInt operator * (const uint16 factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
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FORCEINLINE OverflowSafeInt operator * (const byte factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
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/* Operators for division */
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FORCEINLINE OverflowSafeInt& operator /= (const int divisor) { this->m_value /= divisor; return *this; }
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FORCEINLINE OverflowSafeInt operator / (const OverflowSafeInt& divisor) const { OverflowSafeInt result = *this; result /= divisor.m_value; return result; }
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FORCEINLINE OverflowSafeInt operator / (const int divisor) const { OverflowSafeInt result = *this; result /= divisor; return result; }
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FORCEINLINE OverflowSafeInt operator / (const uint divisor) const { OverflowSafeInt result = *this; result /= (int)divisor; return result; }
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/* Operators for modulo */
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FORCEINLINE OverflowSafeInt& operator %= (const int divisor) { this->m_value %= divisor; return *this; }
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FORCEINLINE OverflowSafeInt operator % (const int divisor) const { OverflowSafeInt result = *this; result %= divisor; return result; }
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/* Operators for shifting */
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FORCEINLINE OverflowSafeInt& operator <<= (const int shift) { this->m_value <<= shift; return *this; }
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FORCEINLINE OverflowSafeInt operator << (const int shift) const { OverflowSafeInt result = *this; result <<= shift; return result; }
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FORCEINLINE OverflowSafeInt& operator >>= (const int shift) { this->m_value >>= shift; return *this; }
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FORCEINLINE OverflowSafeInt operator >> (const int shift) const { OverflowSafeInt result = *this; result >>= shift; return result; }
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/* Operators for (in)equality when comparing overflow safe ints */
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FORCEINLINE bool operator == (const OverflowSafeInt& other) const { return this->m_value == other.m_value; }
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FORCEINLINE bool operator != (const OverflowSafeInt& other) const { return !(*this == other); }
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FORCEINLINE bool operator > (const OverflowSafeInt& other) const { return this->m_value > other.m_value; }
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FORCEINLINE bool operator >= (const OverflowSafeInt& other) const { return this->m_value >= other.m_value; }
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FORCEINLINE bool operator < (const OverflowSafeInt& other) const { return !(*this >= other); }
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FORCEINLINE bool operator <= (const OverflowSafeInt& other) const { return !(*this > other); }
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/* Operators for (in)equality when comparing non-overflow safe ints */
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FORCEINLINE bool operator == (const int other) const { return this->m_value == other; }
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FORCEINLINE bool operator != (const int other) const { return !(*this == other); }
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FORCEINLINE bool operator > (const int other) const { return this->m_value > other; }
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FORCEINLINE bool operator >= (const int other) const { return this->m_value >= other; }
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FORCEINLINE bool operator < (const int other) const { return !(*this >= other); }
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FORCEINLINE bool operator <= (const int other) const { return !(*this > other); }
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FORCEINLINE operator int64 () const { return this->m_value; }
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};
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/* Sometimes we got int64 operator OverflowSafeInt instead of vice versa. Handle that properly */
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator + (int64 a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return b + a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator - (int64 a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return -b + a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator * (int64 a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return b * a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator / (int64 a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return (OverflowSafeInt<T, T_MAX, T_MIN>)a / (int)b; }
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/* Sometimes we got int operator OverflowSafeInt instead of vice versa. Handle that properly */
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator + (int a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return b + a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator - (int a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return -b + a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator * (int a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return b * a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator / (int a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return (OverflowSafeInt<T, T_MAX, T_MIN>)a / (int)b; }
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/* Sometimes we got uint operator OverflowSafeInt instead of vice versa. Handle that properly */
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator + (uint a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return b + a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator - (uint a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return -b + a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator * (uint a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return b * a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator / (uint a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return (OverflowSafeInt<T, T_MAX, T_MIN>)a / (int)b; }
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/* Sometimes we got byte operator OverflowSafeInt instead of vice versa. Handle that properly */
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator + (byte a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return b + a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator - (byte a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return -b + a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator * (byte a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return b * a; }
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template <class T, int64 T_MAX, int64 T_MIN> FORCEINLINE OverflowSafeInt<T, T_MAX, T_MIN> operator / (byte a, OverflowSafeInt<T, T_MAX, T_MIN> b) { return (OverflowSafeInt<T, T_MAX, T_MIN>)a / (int)b; }
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typedef OverflowSafeInt<int64, INT64_MAX, INT64_MIN> OverflowSafeInt64;
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#endif /* OVERFLOWSAFE_TYPE_HPP */
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