1

/* $Id$ */

     2

     3

/** @file overflowsafe_type.hpp An overflow safe integer-like type. */

     4

     5

#ifndef OVERFLOWSAFE_TYPE_HPP

     6

#define OVERFLOWSAFE_TYPE_HPP

     7

     8

#include "math_func.hpp"

     9

    10

/**

    11

 * Overflow safe template for integers, i.e. integers that will never overflow

    12

 * you multiply the maximum value with 2, or add 2, or substract somethng from

    13

 * the minimum value, etc.

    14

 * @param T     the type these integers are stored with.

    15

 * @param T_MAX the maximum value for the integers.

    16

 * @param T_MIN the minimum value for the integers.

    17

 */

    18

template <class T, T T_MAX, T T_MIN>

    19

class OverflowSafeInt

    20

{

    21

private:

    22

	/** The non-overflow safe backend to store the value in. */

    23

	T m_value;

    24

public:

    25

	OverflowSafeInt() : m_value(0) { }

    26

    27

	OverflowSafeInt(const OverflowSafeInt& other) { this->m_value = other.m_value; }

    28

	OverflowSafeInt(const int64 int_)             { this->m_value = int_; }

    29

    30

	FORCEINLINE OverflowSafeInt& operator = (const OverflowSafeInt& other) { this->m_value = other.m_value; return *this; }

    31

    32

	FORCEINLINE OverflowSafeInt operator - () const { return OverflowSafeInt(-this->m_value); }

    33

    34

	/**

    35

	 * Safe implementation of addition.

    36

	 * @param other the amount to add

    37

	 * @note when the addition would yield more than T_MAX (or less than T_MIN),

    38

	 *       it will be T_MAX (respectively T_MIN).

    39

	 */

    40

	FORCEINLINE OverflowSafeInt& operator += (const OverflowSafeInt& other)

    41

	{

    42

		if ((T_MAX - abs(other.m_value)) < abs(this->m_value) &&

    43

				(this->m_value < 0) == (other.m_value < 0)) {

    44

			this->m_value = (this->m_value < 0) ? T_MIN : T_MAX ;

    45

		} else {

    46

			this->m_value += other.m_value;

    47

		}

    48

		return *this;

    49

	}

    50

    51

	/* Operators for addition and substraction */

    52

	FORCEINLINE OverflowSafeInt  operator +  (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result += other; return result; }

    53

	FORCEINLINE OverflowSafeInt  operator +  (const int              other) const { OverflowSafeInt result = *this; result += (int64)other; return result; }

    54

	FORCEINLINE OverflowSafeInt  operator +  (const uint             other) const { OverflowSafeInt result = *this; result += (int64)other; return result; }

    55

	FORCEINLINE OverflowSafeInt& operator -= (const OverflowSafeInt& other)       { return *this += (-other); }

    56

	FORCEINLINE OverflowSafeInt  operator -  (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result -= other; return result; }

    57

	FORCEINLINE OverflowSafeInt  operator -  (const int              other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; }

    58

	FORCEINLINE OverflowSafeInt  operator -  (const uint             other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; }

    59

    60

	FORCEINLINE OverflowSafeInt& operator ++ () { return *this += 1; }

    61

	FORCEINLINE OverflowSafeInt& operator -- () { return *this += -1; }

    62

	FORCEINLINE OverflowSafeInt operator ++ (int) { OverflowSafeInt org = *this; *this += 1; return org; }

    63

	FORCEINLINE OverflowSafeInt operator -- (int) { OverflowSafeInt org = *this; *this += -1; return org; }

    64

    65

	/**

    66

	 * Safe implementation of multiplication.

    67

	 * @param factor the factor to multiply this with.

    68

	 * @note when the multiplication would yield more than T_MAX (or less than T_MIN),

    69

	 *       it will be T_MAX (respectively T_MIN).

    70

	 */

    71

	FORCEINLINE OverflowSafeInt& operator *= (const int factor)

    72

	{

    73

		if (factor != 0 && (T_MAX / abs(factor)) < abs(this->m_value)) {

    74

			 this->m_value = ((this->m_value < 0) == (factor < 0)) ? T_MAX : T_MIN ;

    75

		} else {

    76

			this->m_value *= factor ;

    77

		}

    78

		return *this;

    79

	}

    80

    81

	/* Operators for multiplication */

    82

	FORCEINLINE OverflowSafeInt operator * (const int64  factor) const { OverflowSafeInt result = *this; result *= factor; return result; }

    83

	FORCEINLINE OverflowSafeInt operator * (const int    factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }

    84

	FORCEINLINE OverflowSafeInt operator * (const uint   factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }

    85

	FORCEINLINE OverflowSafeInt operator * (const uint16 factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }

    86

	FORCEINLINE OverflowSafeInt operator * (const byte   factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }

    87

    88

	/* Operators for division */

    89

	FORCEINLINE OverflowSafeInt& operator /= (const int              divisor)       { this->m_value /= divisor; return *this; }

    90

	FORCEINLINE OverflowSafeInt  operator /  (const OverflowSafeInt& divisor) const { OverflowSafeInt result = *this; result /= divisor.m_value; return result; }

    91

	FORCEINLINE OverflowSafeInt  operator /  (const int              divisor) const { OverflowSafeInt result = *this; result /= divisor; return result; }

    92

	FORCEINLINE OverflowSafeInt  operator /  (const uint             divisor) const { OverflowSafeInt result = *this; result /= (int)divisor; return result; }

    93

    94

	/* Operators for modulo */

    95

	FORCEINLINE OverflowSafeInt& operator %= (const int  divisor)       { this->m_value %= divisor; return *this; }

    96

	FORCEINLINE OverflowSafeInt  operator %  (const int  divisor) const { OverflowSafeInt result = *this; result %= divisor; return result; }

    97

    98

	/* Operators for shifting */

    99

	FORCEINLINE OverflowSafeInt& operator <<= (const int shift)       { this->m_value <<= shift; return *this; }

   100

	FORCEINLINE OverflowSafeInt  operator <<  (const int shift) const { OverflowSafeInt result = *this; result <<= shift; return result; }

   101

	FORCEINLINE OverflowSafeInt& operator >>= (const int shift)       { this->m_value >>= shift; return *this; }

   102

	FORCEINLINE OverflowSafeInt  operator >>  (const int shift) const { OverflowSafeInt result = *this; result >>= shift; return result; }

   103

   104

	/* Operators for (in)equality when comparing overflow safe ints */

   105

	FORCEINLINE bool operator == (const OverflowSafeInt& other) const { return this->m_value == other.m_value; }

   106

	FORCEINLINE bool operator != (const OverflowSafeInt& other) const { return !(*this == other); }

   107

	FORCEINLINE bool operator >  (const OverflowSafeInt& other) const { return this->m_value > other.m_value; }

   108

	FORCEINLINE bool operator >= (const OverflowSafeInt& other) const { return this->m_value >= other.m_value; }

   109

	FORCEINLINE bool operator <  (const OverflowSafeInt& other) const { return !(*this >= other); }

   110

	FORCEINLINE bool operator <= (const OverflowSafeInt& other) const { return !(*this > other); }

   111

   112

	/* Operators for (in)equality when comparing non-overflow safe ints */

   113

	FORCEINLINE bool operator == (const int other) const { return this->m_value == other; }

   114

	FORCEINLINE bool operator != (const int other) const { return !(*this == other); }

   115

	FORCEINLINE bool operator >  (const int other) const { return this->m_value > other; }

   116

	FORCEINLINE bool operator >= (const int other) const { return this->m_value >= other; }

   117

	FORCEINLINE bool operator <  (const int other) const { return !(*this >= other); }

   118

	FORCEINLINE bool operator <= (const int other) const { return !(*this > other); }

   119

   120

	FORCEINLINE operator int64 () const { return this->m_value; }

   121

};

   122

   123

/* Sometimes we got int64 operator OverflowSafeInt instead of vice versa. Handle that properly */

   124

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; }

   125

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; }

   126

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; }

   127

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; }

   128

   129

/* Sometimes we got int operator OverflowSafeInt instead of vice versa. Handle that properly */

   130

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; }

   131

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; }

   132

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; }

   133

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; }

   134

   135

/* Sometimes we got uint operator OverflowSafeInt instead of vice versa. Handle that properly */

   136

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; }

   137

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; }

   138

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; }

   139

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; }

   140

   141

/* Sometimes we got byte operator OverflowSafeInt instead of vice versa. Handle that properly */

   142

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; }

   143

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; }

   144

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; }

   145

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; }

   146

   147

typedef OverflowSafeInt<int64, INT64_MAX, INT64_MIN> OverflowSafeInt64;

   148

   149

#endif /* OVERFLOWSAFE_TYPE_HPP */