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/* ****************************************************************************
*
* Copyright (c) Microsoft Corporation.
*
* This source code is subject to terms and conditions of the Microsoft Public License. A
* copy of the license can be found in the License.html file at the root of this distribution. If
* you cannot locate the Microsoft Public License, please send an email to
* dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound
* by the terms of the Microsoft Public License.
*
* You must not remove this notice, or any other, from this software.
*
*
* ***************************************************************************/
using System;
namespace Microsoft.Scripting.Utils {
using Math = System.Math;
public static class MathUtils {
/// <summary>
/// Calculates the quotient of two 32-bit signed integers rounded towards negative infinity.
/// </summary>
/// <param name="x">Dividend.</param>
/// <param name="y">Divisor.</param>
/// <returns>The quotient of the specified numbers rounded towards negative infinity, or <code>(int)Floor((double)x/(double)y)</code>.</returns>
/// <exception cref="DivideByZeroException"><paramref name="y"/> is 0.</exception>
/// <remarks>The caller must check for overflow (x = Int32.MinValue, y = -1)</remarks>
public static int FloorDivideUnchecked(int x, int y) {
int q = x / y;
if (x >= 0) {
if (y > 0) {
return q;
} else if (x % y == 0) {
return q;
} else {
return q - 1;
}
} else {
if (y > 0) {
if (x % y == 0) {
return q;
} else {
return q - 1;
}
} else {
return q;
}
}
}
/// <summary>
/// Calculates the quotient of two 32-bit signed integers rounded towards negative infinity.
/// </summary>
/// <param name="x">Dividend.</param>
/// <param name="y">Divisor.</param>
/// <returns>The quotient of the specified numbers rounded towards negative infinity, or <code>(int)Floor((double)x/(double)y)</code>.</returns>
/// <exception cref="DivideByZeroException"><paramref name="y"/> is 0.</exception>
/// <remarks>The caller must check for overflow (x = Int64.MinValue, y = -1)</remarks>
public static long FloorDivideUnchecked(long x, long y) {
long q = x / y;
if (x >= 0) {
if (y > 0) {
return q;
} else if (x % y == 0) {
return q;
} else {
return q - 1;
}
} else {
if (y > 0) {
if (x % y == 0) {
return q;
} else {
return q - 1;
}
} else {
return q;
}
}
}
/// <summary>
/// Calculates the remainder of floor division of two 32-bit signed integers.
/// </summary>
/// <param name="x">Dividend.</param>
/// <param name="y">Divisor.</param>
/// <returns>The remainder of of floor division of the specified numbers, or <code>x - (int)Floor((double)x/(double)y) * y</code>.</returns>
/// <exception cref="DivideByZeroException"><paramref name="y"/> is 0.</exception>
public static int FloorRemainder(int x, int y) {
if (y == -1) return 0;
int r = x % y;
if (x >= 0) {
if (y > 0) {
return r;
} else if (r == 0) {
return 0;
} else {
return r + y;
}
} else {
if (y > 0) {
if (r == 0) {
return 0;
} else {
return r + y;
}
} else {
return r;
}
}
}
/// <summary>
/// Calculates the remainder of floor division of two 32-bit signed integers.
/// </summary>
/// <param name="x">Dividend.</param>
/// <param name="y">Divisor.</param>
/// <returns>The remainder of of floor division of the specified numbers, or <code>x - (int)Floor((double)x/(double)y) * y</code>.</returns>
/// <exception cref="DivideByZeroException"><paramref name="y"/> is 0.</exception>
public static long FloorRemainder(long x, long y) {
if (y == -1) return 0;
long r = x % y;
if (x >= 0) {
if (y > 0) {
return r;
} else if (r == 0) {
return 0;
} else {
return r + y;
}
} else {
if (y > 0) {
if (r == 0) {
return 0;
} else {
return r + y;
}
} else {
return r;
}
}
}
/// <summary>
/// Behaves like Math.Round(value, MidpointRounding.AwayFromZero)
/// Needed because CoreCLR doesn't support this particular overload of Math.Round
/// </summary>
public static double RoundAwayFromZero(double value) {
#if !SILVERLIGHT
return Math.Round(value, MidpointRounding.AwayFromZero);
#else
if (value < 0) {
return -RoundAwayFromZero(-value);
}
// we can assume positive value
double result = Math.Floor(value);
if (value - result >= 0.5) {
result += 1.0;
}
return result;
#endif
}
private static readonly double[] _RoundPowersOfTens = new double[] { 1E0, 1E1, 1E2, 1E3, 1E4, 1E5, 1E6, 1E7, 1E8, 1E9, 1E10, 1E11, 1E12, 1E13, 1E14, 1E15 };
private static double GetPowerOf10(int precision) {
return (precision < 16) ? _RoundPowersOfTens[precision] : Math.Pow(10, precision);
}
/// <summary>
/// Behaves like Math.Round(value, precision, MidpointRounding.AwayFromZero)
/// However, it works correctly on negative precisions and cases where precision is
/// outside of the [-15, 15] range.
///
/// (This function is also needed because CoreCLR lacks this overload.)
/// </summary>
public static double RoundAwayFromZero(double value, int precision) {
if (precision >= 0) {
double num = GetPowerOf10(precision);
return RoundAwayFromZero(value * num) / num;
} else {
// Note: this code path could be merged with the precision >= 0 path,
// (by extending the cache to negative powers of 10)
// but the results seem to be more precise if we do it this way
double num = GetPowerOf10(-precision);
return RoundAwayFromZero(value / num) * num;
}
}
public static bool IsNegativeZero(double self) {
#if SILVERLIGHT // BitConverter.DoubleToInt64Bits
if ( self != 0.0 ) {
return false;
}
byte[] bits = BitConverter.GetBytes(self);
return (bits[7] == 0x80 && bits[6] == 0x00 && bits[5] == 0x00 && bits[4] == 0x00
&& bits[3] == 0x00 && bits[2] == 0x00 && bits[1] == 0x00 && bits[0] == 0x00);
#else
return (self == 0.0 && 1.0 / self < 0);
#endif
}
}
}
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