xahaud/beast/Arithmetic.h

//------------------------------------------------------------------------------
/*
    This file is part of Beast: https://github.com/vinniefalco/Beast
    Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>

    Portions of this file are from JUCE.
    Copyright (c) 2013 - Raw Material Software Ltd.
    Please visit http://www.juce.com

    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================

#ifndef BEAST_ARITHMETIC_H_INCLUDED
#define BEAST_ARITHMETIC_H_INCLUDED

#include "Config.h"
#include "CStdInt.h"

#include <cmath>
#include <algorithm>

namespace beast {

// Some indispensible min/max functions

/** Returns the larger of two values. */
template <typename Type>
inline Type bmax (const Type a, const Type b)
    { return (a < b) ? b : a; }

/** Returns the larger of three values. */
template <typename Type>
inline Type bmax (const Type a, const Type b, const Type c)
    { return (a < b) ? ((b < c) ? c : b) : ((a < c) ? c : a); }

/** Returns the larger of four values. */
template <typename Type>
inline Type bmax (const Type a, const Type b, const Type c, const Type d)
    { return bmax (a, bmax (b, c, d)); }

/** Returns the smaller of two values. */
template <typename Type>
inline Type bmin (const Type a, const Type b)
    { return (b < a) ? b : a; }

/** Returns the smaller of three values. */
template <typename Type>
inline Type bmin (const Type a, const Type b, const Type c)
    { return (b < a) ? ((c < b) ? c : b) : ((c < a) ? c : a); }

/** Returns the smaller of four values. */
template <typename Type>
inline Type bmin (const Type a, const Type b, const Type c, const Type d)
    { return bmin (a, bmin (b, c, d)); }

/** Scans an array of values, returning the minimum value that it contains. */
template <typename Type>
const Type findMinimum (const Type* data, int numValues)
{
    if (numValues <= 0)
        return Type();

    Type result (*data++);

    while (--numValues > 0) // (> 0 rather than >= 0 because we've already taken the first sample)
    {
        const Type& v = *data++;
        if (v < result)  result = v;
    }

    return result;
}

/** Scans an array of values, returning the maximum value that it contains. */
template <typename Type>
const Type findMaximum (const Type* values, int numValues)
{
    if (numValues <= 0)
        return Type();

    Type result (*values++);

    while (--numValues > 0) // (> 0 rather than >= 0 because we've already taken the first sample)
    {
        const Type& v = *values++;
        if (result < v)  result = v;
    }

    return result;
}

/** Scans an array of values, returning the minimum and maximum values that it contains. */
template <typename Type>
void findMinAndMax (const Type* values, int numValues, Type& lowest, Type& highest)
{
    if (numValues <= 0)
    {
        lowest = Type();
        highest = Type();
    }
    else
    {
        Type mn (*values++);
        Type mx (mn);

        while (--numValues > 0) // (> 0 rather than >= 0 because we've already taken the first sample)
        {
            const Type& v = *values++;

            if (mx < v)  mx = v;
            if (v < mn)  mn = v;
        }

        lowest = mn;
        highest = mx;
    }
}

//==============================================================================
/** Constrains a value to keep it within a given range.

    This will check that the specified value lies between the lower and upper bounds
    specified, and if not, will return the nearest value that would be in-range. Effectively,
    it's like calling bmax (lowerLimit, bmin (upperLimit, value)).

    Note that it expects that lowerLimit <= upperLimit. If this isn't true,
    the results will be unpredictable.

    @param lowerLimit           the minimum value to return
    @param upperLimit           the maximum value to return
    @param valueToConstrain     the value to try to return
    @returns    the closest value to valueToConstrain which lies between lowerLimit
                and upperLimit (inclusive)
    @see blimit0To, bmin, bmax
*/
template <typename Type>
inline Type blimit (const Type lowerLimit,
                    const Type upperLimit,
                    const Type valueToConstrain) noexcept
{
    bassert (lowerLimit <= upperLimit); // if these are in the wrong order, results are unpredictable..

    return (valueToConstrain < lowerLimit) ? lowerLimit
                                           : ((upperLimit < valueToConstrain) ? upperLimit
                                                                              : valueToConstrain);
}

/** Returns true if a value is at least zero, and also below a specified upper limit.
    This is basically a quicker way to write:
    @code valueToTest >= 0 && valueToTest < upperLimit
    @endcode
*/
template <typename Type>
inline bool isPositiveAndBelow (Type valueToTest, Type upperLimit) noexcept
{
    bassert (Type() <= upperLimit); // makes no sense to call this if the upper limit is itself below zero..
    return Type() <= valueToTest && valueToTest < upperLimit;
}

template <>
inline bool isPositiveAndBelow (const int valueToTest, const int upperLimit) noexcept
{
    bassert (upperLimit >= 0); // makes no sense to call this if the upper limit is itself below zero..
    return static_cast <unsigned int> (valueToTest) < static_cast <unsigned int> (upperLimit);
}

/** Returns true if a value is at least zero, and also less than or equal to a specified upper limit.
    This is basically a quicker way to write:
    @code valueToTest >= 0 && valueToTest <= upperLimit
    @endcode
*/
template <typename Type>
inline bool isPositiveAndNotGreaterThan (Type valueToTest, Type upperLimit) noexcept
{
    bassert (Type() <= upperLimit); // makes no sense to call this if the upper limit is itself below zero..
    return Type() <= valueToTest && valueToTest <= upperLimit;
}

template <>
inline bool isPositiveAndNotGreaterThan (const int valueToTest, const int upperLimit) noexcept
{
    bassert (upperLimit >= 0); // makes no sense to call this if the upper limit is itself below zero..
    return static_cast <unsigned int> (valueToTest) <= static_cast <unsigned int> (upperLimit);
}

//==============================================================================
/** Handy function to swap two values. */
template <typename Type>
inline void swapVariables (Type& variable1, Type& variable2)
{
    std::swap (variable1, variable2);
}

/** Handy function for getting the number of elements in a simple const C array.
    E.g.
    @code
    static int myArray[] = { 1, 2, 3 };

    int numElements = numElementsInArray (myArray) // returns 3
    @endcode
*/
template <typename Type, int N>
int numElementsInArray (Type (&array)[N])
{
    (void) array; // (required to avoid a spurious warning in MS compilers)
    (void) sizeof (0[array]); // This line should cause an error if you pass an object with a user-defined subscript operator
    return N;
}

//==============================================================================
// Some useful maths functions that aren't always present with all compilers and build settings.

/** Using beast_hypot is easier than dealing with the different types of hypot function
    that are provided by the various platforms and compilers. */
template <typename Type>
inline Type beast_hypot (Type a, Type b) noexcept
{
   #if BEAST_MSVC
    return static_cast <Type> (_hypot (a, b));
   #else
    return static_cast <Type> (hypot (a, b));
   #endif
}

/** 64-bit abs function. */
inline int64 abs64 (const int64 n) noexcept
{
    return (n >= 0) ? n : -n;
}

//==============================================================================
/** A predefined value for Pi, at double-precision.
    @see float_Pi
*/
const double  double_Pi  = 3.1415926535897932384626433832795;

/** A predefined value for Pi, at single-precision.
    @see double_Pi
*/
const float   float_Pi   = 3.14159265358979323846f;


//==============================================================================
/** The isfinite() method seems to vary between platforms, so this is a
    platform-independent function for it.
*/
template <typename FloatingPointType>
inline bool beast_isfinite (FloatingPointType value)
{
   #if BEAST_WINDOWS
    return _finite (value);
   #elif BEAST_ANDROID
    return isfinite (value);
   #else
    return std::isfinite (value);
   #endif
}

//==============================================================================
#if BEAST_MSVC
 #pragma optimize ("t", off)
 #ifndef __INTEL_COMPILER
  #pragma float_control (precise, on, push)
 #endif
#endif

/** Fast floating-point-to-integer conversion.

    This is faster than using the normal c++ cast to convert a float to an int, and
    it will round the value to the nearest integer, rather than rounding it down
    like the normal cast does.

    Note that this routine gets its speed at the expense of some accuracy, and when
    rounding values whose floating point component is exactly 0.5, odd numbers and
    even numbers will be rounded up or down differently.
*/
template <typename FloatType>
inline int roundToInt (const FloatType value) noexcept
{
  #ifdef __INTEL_COMPILER
   #pragma float_control (precise, on, push)
  #endif

    union { int asInt[2]; double asDouble; } n;
    n.asDouble = ((double) value) + 6755399441055744.0;

   #if BEAST_BIG_ENDIAN
    return n.asInt [1];
   #else
    return n.asInt [0];
   #endif
}

#if BEAST_MSVC
 #ifndef __INTEL_COMPILER
  #pragma float_control (pop)
 #endif
 #pragma optimize ("", on)  // resets optimisations to the project defaults
#endif

/** Fast floating-point-to-integer conversion.

    This is a slightly slower and slightly more accurate version of roundDoubleToInt(). It works
    fine for values above zero, but negative numbers are rounded the wrong way.
*/
inline int roundToIntAccurate (const double value) noexcept
{
   #ifdef __INTEL_COMPILER
    #pragma float_control (pop)
   #endif

    return roundToInt (value + 1.5e-8);
}

/** Fast floating-point-to-integer conversion.

    This is faster than using the normal c++ cast to convert a double to an int, and
    it will round the value to the nearest integer, rather than rounding it down
    like the normal cast does.

    Note that this routine gets its speed at the expense of some accuracy, and when
    rounding values whose floating point component is exactly 0.5, odd numbers and
    even numbers will be rounded up or down differently. For a more accurate conversion,
    see roundDoubleToIntAccurate().
*/
inline int roundDoubleToInt (const double value) noexcept
{
    return roundToInt (value);
}

/** Fast floating-point-to-integer conversion.

    This is faster than using the normal c++ cast to convert a float to an int, and
    it will round the value to the nearest integer, rather than rounding it down
    like the normal cast does.

    Note that this routine gets its speed at the expense of some accuracy, and when
    rounding values whose floating point component is exactly 0.5, odd numbers and
    even numbers will be rounded up or down differently.
*/
inline int roundFloatToInt (const float value) noexcept
{
    return roundToInt (value);
}

//==============================================================================
/** Returns true if the specified integer is a power-of-two.
*/
template <typename IntegerType>
bool isPowerOfTwo (IntegerType value)
{
   return (value & (value - 1)) == 0;
}

/** Returns the smallest power-of-two which is equal to or greater than the given integer.
*/
inline int nextPowerOfTwo (int n) noexcept
{
    --n;
    n |= (n >> 1);
    n |= (n >> 2);
    n |= (n >> 4);
    n |= (n >> 8);
    n |= (n >> 16);
    return n + 1;
}

/** Performs a modulo operation, but can cope with the dividend being negative.
    The divisor must be greater than zero.
*/
template <typename IntegerType>
IntegerType negativeAwareModulo (IntegerType dividend, const IntegerType divisor) noexcept
{
    bassert (divisor > 0);
    dividend %= divisor;
    return (dividend < 0) ? (dividend + divisor) : dividend;
}

//==============================================================================
#if (BEAST_INTEL && BEAST_32BIT) || defined (DOXYGEN)
 /** This macro can be applied to a float variable to check whether it contains a denormalised
     value, and to normalise it if necessary.
     On CPUs that aren't vulnerable to denormalisation problems, this will have no effect.
 */
 #define BEAST_UNDENORMALISE(x)   x += 1.0f; x -= 1.0f;
#else
 #define BEAST_UNDENORMALISE(x)
#endif

//==============================================================================
/** This namespace contains a few template classes for helping work out class type variations.
*/
namespace TypeHelpers
{
   #if BEAST_VC8_OR_EARLIER
    #define PARAMETER_TYPE(type) const type&
   #else
    /** The ParameterType struct is used to find the best type to use when passing some kind
        of object as a parameter.

        Of course, this is only likely to be useful in certain esoteric template situations.

        Because "typename TypeHelpers::ParameterType<SomeClass>::type" is a bit of a mouthful, there's
        a PARAMETER_TYPE(SomeClass) macro that you can use to get the same effect.

        E.g. "myFunction (PARAMETER_TYPE (int), PARAMETER_TYPE (MyObject))"
        would evaluate to "myfunction (int, const MyObject&)", keeping any primitive types as
        pass-by-value, but passing objects as a const reference, to avoid copying.
    */
    template <typename Type> struct ParameterType                   { typedef const Type& type; };

   #if ! DOXYGEN
    template <typename Type> struct ParameterType <Type&>           { typedef Type& type; };
    template <typename Type> struct ParameterType <Type*>           { typedef Type* type; };
    template <>              struct ParameterType <char>            { typedef char type; };
    template <>              struct ParameterType <unsigned char>   { typedef unsigned char type; };
    template <>              struct ParameterType <short>           { typedef short type; };
    template <>              struct ParameterType <unsigned short>  { typedef unsigned short type; };
    template <>              struct ParameterType <int>             { typedef int type; };
    template <>              struct ParameterType <unsigned int>    { typedef unsigned int type; };
    template <>              struct ParameterType <long>            { typedef long type; };
    template <>              struct ParameterType <unsigned long>   { typedef unsigned long type; };
    template <>              struct ParameterType <int64>           { typedef int64 type; };
    template <>              struct ParameterType <uint64>          { typedef uint64 type; };
    template <>              struct ParameterType <bool>            { typedef bool type; };
    template <>              struct ParameterType <float>           { typedef float type; };
    template <>              struct ParameterType <double>          { typedef double type; };
   #endif

    /** A helpful macro to simplify the use of the ParameterType template.
        @see ParameterType
    */
    #define PARAMETER_TYPE(a)    typename TypeHelpers::ParameterType<a>::type
   #endif


    /** These templates are designed to take a type, and if it's a double, they return a double
        type; for anything else, they return a float type.
    */
    template <typename Type> struct SmallestFloatType             { typedef float  type; };
    template <>              struct SmallestFloatType <double>    { typedef double type; };
}

}

#endif