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/* $Id$ */
/** @file math_func.hpp Integer math functions */
#ifndef MATH_FUNC_HPP
#define MATH_FUNC_HPP
#ifdef min
#undef min
#endif
#ifdef max
#undef max
#endif
#ifdef abs
#undef abs
#endif
/**
* Returns the maximum of two values.
*
* This function returns the greater value of two given values.
* If they are equal the value of a is returned.
*
* @param a The first value
* @param b The second value
* @return The greater value or a if equals
*/
template<typename T> static inline T max(const T a, const T b)
{
return (a >= b) ? a : b;
}
/**
* Returns the minimum of two values.
*
* This function returns the smaller value of two given values.
* If they are equal the value of b is returned.
*
* @param a The first value
* @param b The second value
* @return The smaller value or b if equals
*/
template<typename T> static inline T min(const T a, const T b)
{
return (a < b) ? a : b;
}
/**
* Returns the minimum of two integer.
*
* This function returns the smaller value of two given integers.
*
* @param a The first integer
* @param b The second integer
* @return The smaller value
*/
static inline int min(const int a, const int b)
{
return (a < b) ? a : b;
}
/**
* Returns the minimum of two unsigned integers.
*
* This function returns the smaller value of two given unsigned integers.
*
* @param a The first unsigned integer
* @param b The second unsigned integer
* @return The smaller value
*/
static inline uint minu(const uint a, const uint b)
{
return (a < b) ? a : b;
}
/**
* Returns the absolute value of (scalar) variable.
*
* @note assumes variable to be signed
* @param a The value we want to unsign
* @return The unsigned value
*/
template <typename T> static inline T abs(const T a)
{
return (a < (T)0) ? -a : a;
}
/**
* Return the smallest multiple of n equal or greater than x
*
* @note n must be a power of 2
* @param x The min value
* @param n The base of the number we are searching
* @return The smallest multiple of n equal or greater than x
*/
template<typename T> static inline T Align(const T x, uint n)
{
n--;
return (T)((x + n) & ~(n));
}
/**
* Clamp an integer between an interval.
*
* This function returns a value which is between the given interval of
* min and max. If the given value is in this interval the value itself
* is returned otherwise the border of the interval is returned, according
* which side of the interval was 'left'.
*
* @note The min value must be less or equal of max or you get some
* unexpected results.
* @param a The value to clamp/truncate.
* @param min The minimum of the interval.
* @param max the maximum of the interval.
* @returns A value between min and max which is closest to a.
* @see ClampU(uint, uint, uint)
*/
static inline int Clamp(const int a, const int min, const int max)
{
if (a <= min) return min;
if (a >= max) return max;
return a;
}
/**
* Clamp an unsigned integer between an interval.
*
* This function returns a value which is between the given interval of
* min and max. If the given value is in this interval the value itself
* is returned otherwise the border of the interval is returned, according
* which side of the interval was 'left'.
*
* @note The min value must be less or equal of max or you get some
* unexpected results.
* @param a The value to clamp/truncate.
* @param min The minimum of the interval.
* @param max the maximum of the interval.
* @returns A value between min and max which is closest to a.
* @see Clamp(int, int, int)
*/
static inline uint ClampU(const uint a, const uint min, const uint max)
{
if (a <= min) return min;
if (a >= max) return max;
return a;
}
/**
* Reduce a signed 64-bit int to a signed 32-bit one
*
* This function clamps a 64-bit integer to a 32-bit integer.
* If the 64-bit value is smaller than the smallest 32-bit integer
* value 0x80000000 this value is returned (the left one bit is the sign bit).
* If the 64-bit value is greater than the greatest 32-bit integer value 0x7FFFFFFF
* this value is returned. In all other cases the 64-bit value 'fits' in a
* 32-bits integer field and so the value is casted to int32 and returned.
*
* @param a The 64-bit value to clamps
* @return The 64-bit value reduced to a 32-bit value
* @see Clamp(int, int, int)
*/
static inline int32 ClampToI32(const int64 a)
{
if (a <= (int32)0x80000000) return 0x80000000;
if (a >= (int32)0x7FFFFFFF) return 0x7FFFFFFF;
return (int32)a;
}
/**
* Returns the (absolute) difference between two (scalar) variables
*
* @param a The first scalar
* @param b The second scalar
* @return The absolute difference between the given scalars
*/
template <typename T> static inline T Delta(const T a, const T b) {
return (a < b) ? b - a : a - b;
}
/**
* Checks if a value is between a window started at some base point.
*
* This function checks if the value x is between the value of base
* and base+size. If x equals base this returns true. If x equals
* base+size this returns false.
*
* @param x The value to check
* @param base The base value of the interval
* @param size The size of the interval
* @return True if the value is in the interval, false else.
*/
template<typename T> static inline bool IsInsideBS(const T x, const uint base, const uint size)
{
return (uint)(x - base) < size;
}
/**
* Checks if a value is in an interval.
*
* Returns true if a value is in the interval of [min, max).
*
* @param a The value to check
* @param min The minimum of the interval
* @param max The maximum of the interval
* @see IsInsideBS()
*/
template<typename T> static inline bool IsInsideMM(const T x, const uint min, const uint max)
{
return (uint)(x - min) < (max - min);
}
/**
* Type safe swap operation
* @param a variable to swap with b
* @param b variable to swap with a
*/
template<typename T> void Swap(T& a, T& b)
{
T t = a;
a = b;
b = t;
}
#endif /* MATH_FUNC_HPP */
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