Files
@ r25846:3dc91304dafe
Branch filter:
Location: cpp/openttd-patchpack/source/src/core/overflowsafe_type.hpp
r25846:3dc91304dafe
11.3 KiB
text/x-c++hdr
Codechange: Remove (unused) ability to specify min/max of OverflowSafeInt
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 | /*
* This file is part of OpenTTD.
* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
* OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file overflowsafe_type.hpp An overflow safe integer-like type. */
#ifndef OVERFLOWSAFE_TYPE_HPP
#define OVERFLOWSAFE_TYPE_HPP
#include "math_func.hpp"
#include <limits>
#ifdef __has_builtin
# if __has_builtin(__builtin_add_overflow) && __has_builtin(__builtin_sub_overflow) && __has_builtin(__builtin_mul_overflow)
# define HAS_OVERFLOW_BUILTINS
# endif
#endif
/**
* Overflow safe template for integers, i.e. integers that will never overflow
* you multiply the maximum value with 2, or add 2, or subtract something from
* the minimum value, etc.
* @param T the type these integers are stored with.
*/
template <class T>
class OverflowSafeInt
{
private:
static constexpr T T_MAX = std::numeric_limits<T>::max();
static constexpr T T_MIN = std::numeric_limits<T>::min();
/** The non-overflow safe backend to store the value in. */
T m_value;
public:
OverflowSafeInt() : m_value(0) { }
OverflowSafeInt(const OverflowSafeInt& other) { this->m_value = other.m_value; }
OverflowSafeInt(const int64 int_) { this->m_value = int_; }
inline OverflowSafeInt& operator = (const OverflowSafeInt& other) { this->m_value = other.m_value; return *this; }
inline OverflowSafeInt operator - () const { return OverflowSafeInt(this->m_value == T_MIN ? T_MAX : -this->m_value); }
/**
* Safe implementation of addition.
* @param other the amount to add
* @note when the addition would yield more than T_MAX, it will be T_MAX.
*/
inline OverflowSafeInt& operator += (const OverflowSafeInt& other)
{
#ifdef HAS_OVERFLOW_BUILTINS
if (unlikely(__builtin_add_overflow(this->m_value, other.m_value, &this->m_value))) {
this->m_value = (other.m_value < 0) ? T_MIN : T_MAX;
}
#else
if (this->m_value > 0 && other.m_value > 0 && (T_MAX - other.m_value) < this->m_value) {
this->m_value = T_MAX;
} else if (this->m_value < 0 && other.m_value < 0 && (this->m_value == T_MIN || other.m_value == T_MIN || ((T_MAX + this->m_value) + other.m_value < (T_MIN + T_MAX)))) {
this->m_value = T_MIN;
} else {
this->m_value += other.m_value;
}
#endif
return *this;
}
/**
* Safe implementation of subtraction.
* @param other the amount to subtract
* @note when the subtraction would yield less than T_MIN, it will be T_MIN.
*/
inline OverflowSafeInt& operator -= (const OverflowSafeInt& other)
{
#ifdef HAS_OVERFLOW_BUILTINS
if (unlikely(__builtin_sub_overflow(this->m_value, other.m_value, &this->m_value))) {
this->m_value = (other.m_value < 0) ? T_MAX : T_MIN;
}
#else
if (this->m_value > 0 && other.m_value < 0 && (T_MAX + other.m_value) < this->m_value) {
this->m_value = T_MAX;
} else if (this->m_value < 0 && other.m_value > 0 && (T_MAX + this->m_value) < (T_MIN + T_MAX) + other.m_value) {
this->m_value = T_MIN;
} else {
this->m_value -= other.m_value;
}
#endif
return *this;
}
/* Operators for addition and subtraction */
inline OverflowSafeInt operator + (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result += other; return result; }
inline OverflowSafeInt operator + (const int other) const { OverflowSafeInt result = *this; result += (int64)other; return result; }
inline OverflowSafeInt operator + (const uint other) const { OverflowSafeInt result = *this; result += (int64)other; return result; }
inline OverflowSafeInt operator - (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result -= other; return result; }
inline OverflowSafeInt operator - (const int other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; }
inline OverflowSafeInt operator - (const uint other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; }
inline OverflowSafeInt& operator ++ () { return *this += 1; }
inline OverflowSafeInt& operator -- () { return *this += -1; }
inline OverflowSafeInt operator ++ (int) { OverflowSafeInt org = *this; *this += 1; return org; }
inline OverflowSafeInt operator -- (int) { OverflowSafeInt org = *this; *this += -1; return org; }
/**
* Safe implementation of multiplication.
* @param factor the factor to multiply this with.
* @note when the multiplication would yield more than T_MAX (or less than T_MIN),
* it will be T_MAX (respectively T_MIN).
*/
inline OverflowSafeInt& operator *= (const int factor)
{
#ifdef HAS_OVERFLOW_BUILTINS
bool is_result_positive = (this->m_value < 0) == (factor < 0); // -ve * -ve == +ve
if (unlikely(__builtin_mul_overflow(this->m_value, factor, &this->m_value))) {
this->m_value = is_result_positive ? T_MAX : T_MIN;
}
#else
if (factor == -1) {
this->m_value = (this->m_value == T_MIN) ? T_MAX : -this->m_value;
} else if (factor > 0 && this->m_value > 0 && (T_MAX / factor) < this->m_value) {
this->m_value = T_MAX;
} else if (factor > 0 && this->m_value < 0 && (T_MIN / factor) > this->m_value) {
this->m_value = T_MIN;
} else if (factor < 0 && this->m_value > 0 && (T_MIN / factor) < this->m_value) {
this->m_value = T_MIN;
} else if (factor < 0 && this->m_value < 0 && (T_MAX / factor) > this->m_value) {
this->m_value = T_MAX;
} else {
this->m_value *= factor;
}
#endif
return *this;
}
/* Operators for multiplication */
inline OverflowSafeInt operator * (const int64 factor) const { OverflowSafeInt result = *this; result *= factor; return result; }
inline OverflowSafeInt operator * (const int factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
inline OverflowSafeInt operator * (const uint factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
inline OverflowSafeInt operator * (const uint16 factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
inline OverflowSafeInt operator * (const byte factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
/* Operators for division */
inline OverflowSafeInt& operator /= (const int64 divisor) { this->m_value /= divisor; return *this; }
inline OverflowSafeInt operator / (const OverflowSafeInt& divisor) const { OverflowSafeInt result = *this; result /= divisor.m_value; return result; }
inline OverflowSafeInt operator / (const int divisor) const { OverflowSafeInt result = *this; result /= divisor; return result; }
inline OverflowSafeInt operator / (const uint divisor) const { OverflowSafeInt result = *this; result /= (int)divisor; return result; }
/* Operators for modulo */
inline OverflowSafeInt& operator %= (const int divisor) { this->m_value %= divisor; return *this; }
inline OverflowSafeInt operator % (const int divisor) const { OverflowSafeInt result = *this; result %= divisor; return result; }
/* Operators for shifting */
inline OverflowSafeInt& operator <<= (const int shift) { this->m_value <<= shift; return *this; }
inline OverflowSafeInt operator << (const int shift) const { OverflowSafeInt result = *this; result <<= shift; return result; }
inline OverflowSafeInt& operator >>= (const int shift) { this->m_value >>= shift; return *this; }
inline OverflowSafeInt operator >> (const int shift) const { OverflowSafeInt result = *this; result >>= shift; return result; }
/* Operators for (in)equality when comparing overflow safe ints */
inline bool operator == (const OverflowSafeInt& other) const { return this->m_value == other.m_value; }
inline bool operator != (const OverflowSafeInt& other) const { return !(*this == other); }
inline bool operator > (const OverflowSafeInt& other) const { return this->m_value > other.m_value; }
inline bool operator >= (const OverflowSafeInt& other) const { return this->m_value >= other.m_value; }
inline bool operator < (const OverflowSafeInt& other) const { return !(*this >= other); }
inline bool operator <= (const OverflowSafeInt& other) const { return !(*this > other); }
/* Operators for (in)equality when comparing non-overflow safe ints */
inline bool operator == (const int other) const { return this->m_value == other; }
inline bool operator != (const int other) const { return !(*this == other); }
inline bool operator > (const int other) const { return this->m_value > other; }
inline bool operator >= (const int other) const { return this->m_value >= other; }
inline bool operator < (const int other) const { return !(*this >= other); }
inline bool operator <= (const int other) const { return !(*this > other); }
inline operator int64 () const { return this->m_value; }
};
/* Sometimes we got int64 operator OverflowSafeInt instead of vice versa. Handle that properly */
template <class T> inline OverflowSafeInt<T> operator + (int64 a, OverflowSafeInt<T> b) { return b + a; }
template <class T> inline OverflowSafeInt<T> operator - (int64 a, OverflowSafeInt<T> b) { return -b + a; }
template <class T> inline OverflowSafeInt<T> operator * (int64 a, OverflowSafeInt<T> b) { return b * a; }
template <class T> inline OverflowSafeInt<T> operator / (int64 a, OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }
/* Sometimes we got int operator OverflowSafeInt instead of vice versa. Handle that properly */
template <class T> inline OverflowSafeInt<T> operator + (int a, OverflowSafeInt<T> b) { return b + a; }
template <class T> inline OverflowSafeInt<T> operator - (int a, OverflowSafeInt<T> b) { return -b + a; }
template <class T> inline OverflowSafeInt<T> operator * (int a, OverflowSafeInt<T> b) { return b * a; }
template <class T> inline OverflowSafeInt<T> operator / (int a, OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }
/* Sometimes we got uint operator OverflowSafeInt instead of vice versa. Handle that properly */
template <class T> inline OverflowSafeInt<T> operator + (uint a, OverflowSafeInt<T> b) { return b + a; }
template <class T> inline OverflowSafeInt<T> operator - (uint a, OverflowSafeInt<T> b) { return -b + a; }
template <class T> inline OverflowSafeInt<T> operator * (uint a, OverflowSafeInt<T> b) { return b * a; }
template <class T> inline OverflowSafeInt<T> operator / (uint a, OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }
/* Sometimes we got byte operator OverflowSafeInt instead of vice versa. Handle that properly */
template <class T> inline OverflowSafeInt<T> operator + (byte a, OverflowSafeInt<T> b) { return b + (uint)a; }
template <class T> inline OverflowSafeInt<T> operator - (byte a, OverflowSafeInt<T> b) { return -b + (uint)a; }
template <class T> inline OverflowSafeInt<T> operator * (byte a, OverflowSafeInt<T> b) { return b * (uint)a; }
template <class T> inline OverflowSafeInt<T> operator / (byte a, OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }
typedef OverflowSafeInt<int64> OverflowSafeInt64;
typedef OverflowSafeInt<int32> OverflowSafeInt32;
#undef HAS_OVERFLOW_BUILTINS
#endif /* OVERFLOWSAFE_TYPE_HPP */
|