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Diffstat (limited to 'src/core')
| -rw-r--r-- | src/core/overflowsafe_type.hpp | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/src/core/overflowsafe_type.hpp b/src/core/overflowsafe_type.hpp new file mode 100644 index 000000000..632e261a6 --- /dev/null +++ b/src/core/overflowsafe_type.hpp @@ -0,0 +1,147 @@ +/* $Id$ */ + +/** @file overflowsafe_type.hpp An overflow safe integer-like type. */ + +#ifndef OVERFLOWSAFE_TYPE_HPP +#define OVERFLOWSAFE_TYPE_HPP + +/** + * Overflow safe template for integers, i.e. integers that will never overflow + * you multiply the maximum value with 2, or add 2, or substract somethng from + * the minimum value, etc. + * @param T the type these integers are stored with. + * @param T_MAX the maximum value for the integers. + * @param T_MIN the minimum value for the integers. + */ +template <class T, T T_MAX, T T_MIN> +class OverflowSafeInt +{ +private: + /** 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_; } + + FORCEINLINE OverflowSafeInt& operator = (const OverflowSafeInt& other) { this->m_value = other.m_value; return *this; } + + FORCEINLINE OverflowSafeInt operator - () const { return OverflowSafeInt(-this->m_value); } + + /** + * Safe implementation of addition. + * @param other the amount to add + * @note when the addition would yield more than T_MAX (or less than T_MIN), + * it will be T_MAX (respectively T_MIN). + */ + FORCEINLINE OverflowSafeInt& operator += (const OverflowSafeInt& other) + { + if ((T_MAX - abs(other.m_value)) < abs(this->m_value) && + (this->m_value < 0) == (other.m_value < 0)) { + this->m_value = (this->m_value < 0) ? T_MIN : T_MAX ; + } else { + this->m_value += other.m_value; + } + return *this; + } + + /* Operators for addition and substraction */ + FORCEINLINE OverflowSafeInt operator + (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result += other; return result; } + FORCEINLINE OverflowSafeInt operator + (const int other) const { OverflowSafeInt result = *this; result += (int64)other; return result; } + FORCEINLINE OverflowSafeInt operator + (const uint other) const { OverflowSafeInt result = *this; result += (int64)other; return result; } + FORCEINLINE OverflowSafeInt& operator -= (const OverflowSafeInt& other) { return *this += (-other); } + FORCEINLINE OverflowSafeInt operator - (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result -= other; return result; } + FORCEINLINE OverflowSafeInt operator - (const int other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; } + FORCEINLINE OverflowSafeInt operator - (const uint other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; } + + FORCEINLINE OverflowSafeInt& operator ++ () { return *this += 1; } + FORCEINLINE OverflowSafeInt& operator -- () { return *this += -1; } + FORCEINLINE OverflowSafeInt operator ++ (int) { OverflowSafeInt org = *this; *this += 1; return org; } + FORCEINLINE 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). + */ + FORCEINLINE OverflowSafeInt& operator *= (const int factor) + { + if (factor != 0 && (T_MAX / abs(factor)) < abs(this->m_value)) { + this->m_value = ((this->m_value < 0) == (factor < 0)) ? T_MAX : T_MIN ; + } else { + this->m_value *= factor ; + } + return *this; + } + + /* Operators for multiplication */ + FORCEINLINE OverflowSafeInt operator * (const int64 factor) const { OverflowSafeInt result = *this; result *= factor; return result; } + FORCEINLINE OverflowSafeInt operator * (const int factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; } + FORCEINLINE OverflowSafeInt operator * (const uint factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; } + FORCEINLINE OverflowSafeInt operator * (const uint16 factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; } + FORCEINLINE OverflowSafeInt operator * (const byte factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; } + + /* Operators for division */ + FORCEINLINE OverflowSafeInt& operator /= (const int divisor) { this->m_value /= divisor; return *this; } + FORCEINLINE OverflowSafeInt operator / (const OverflowSafeInt& divisor) const { OverflowSafeInt result = *this; result /= divisor.m_value; return result; } + FORCEINLINE OverflowSafeInt operator / (const int divisor) const { OverflowSafeInt result = *this; result /= divisor; return result; } + FORCEINLINE OverflowSafeInt operator / (const uint divisor) const { OverflowSafeInt result = *this; result /= (int)divisor; return result; } + + /* Operators for modulo */ + FORCEINLINE OverflowSafeInt& operator %= (const int divisor) { this->m_value %= divisor; return *this; } + FORCEINLINE OverflowSafeInt operator % (const int divisor) const { OverflowSafeInt result = *this; result %= divisor; return result; } + + /* Operators for shifting */ + FORCEINLINE OverflowSafeInt& operator <<= (const int shift) { this->m_value <<= shift; return *this; } + FORCEINLINE OverflowSafeInt operator << (const int shift) const { OverflowSafeInt result = *this; result <<= shift; return result; } + FORCEINLINE OverflowSafeInt& operator >>= (const int shift) { this->m_value >>= shift; return *this; } + FORCEINLINE OverflowSafeInt operator >> (const int shift) const { OverflowSafeInt result = *this; result >>= shift; return result; } + + /* Operators for (in)equality when comparing overflow safe ints */ + FORCEINLINE bool operator == (const OverflowSafeInt& other) const { return this->m_value == other.m_value; } + FORCEINLINE bool operator != (const OverflowSafeInt& other) const { return !(*this == other); } + FORCEINLINE bool operator > (const OverflowSafeInt& other) const { return this->m_value > other.m_value; } + FORCEINLINE bool operator >= (const OverflowSafeInt& other) const { return this->m_value >= other.m_value; } + FORCEINLINE bool operator < (const OverflowSafeInt& other) const { return !(*this >= other); } + FORCEINLINE bool operator <= (const OverflowSafeInt& other) const { return !(*this > other); } + + /* Operators for (in)equality when comparing non-overflow safe ints */ + FORCEINLINE bool operator == (const int other) const { return this->m_value == other; } + FORCEINLINE bool operator != (const int other) const { return !(*this == other); } + FORCEINLINE bool operator > (const int other) const { return this->m_value > other; } + FORCEINLINE bool operator >= (const int other) const { return this->m_value >= other; } + FORCEINLINE bool operator < (const int other) const { return !(*this >= other); } + FORCEINLINE bool operator <= (const int other) const { return !(*this > other); } + + FORCEINLINE operator int64 () const { return this->m_value; } +}; + +/* Sometimes we got int64 operator OverflowSafeInt instead of vice versa. Handle that properly */ +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; } +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; } +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; } +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; } + +/* Sometimes we got int operator OverflowSafeInt instead of vice versa. Handle that properly */ +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; } +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; } +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; } +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; } + +/* Sometimes we got uint operator OverflowSafeInt instead of vice versa. Handle that properly */ +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; } +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; } +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; } +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; } + +/* Sometimes we got byte operator OverflowSafeInt instead of vice versa. Handle that properly */ +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; } +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; } +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; } +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; } + +typedef OverflowSafeInt<int64, INT64_MAX, INT64_MIN> OverflowSafeInt64; + +#endif /* OVERFLOWSAFE_TYPE_HPP */ |