Functions
unsigned	powerOfTwo (unsigned a)
	Returns the smallest number that is both >=a and a power of two. More...

bool	isPowerOfTwo (unsigned a)
	Is the given number an integer power of 2? Not correct for zero (according to this test 0 is a power of 2). More...

template<int LO, int HI>
int	clip (int x)
	Clips x to the range [LO,HI]. More...

short	clipIntToShort (int x)
	Clip x to range [-32768,32767]. More...

byte	clipIntToByte (int x)
	Clip x to range [0,255]. More...

template<int LO, int HI>
int	clip (float r, float factor)
	Clips r * factor to the range [LO,HI]. More...

unsigned	gcd (unsigned a, unsigned b)
	Calculate greatest common divider of two strictly positive integers. More...

unsigned	reverseNBits (unsigned x, unsigned bits)
	Reverse the lower N bits of a given value. More...

byte	reverseByte (byte a)
	Reverse the bits in a byte. More...

template<typename T >
T	floodRight (T x)
	Returns the smallest number of the form 2^n-1 that is greater or equal to the given number. More...

unsigned	countLeadingZeros (unsigned x)
	Count the number of leading zero-bits in the given word. More...

Function Documentation

template<int LO, int HI>

int openmsx::Math::clip ( int x )

inline

Clips x to the range [LO,HI].

Slightly faster than std::min(HI, std::max(LO, x)) especially when no clipping is required.

Definition at line 29 of file Math.hh.

template<int LO, int HI>

int openmsx::Math::clip	(	float	r,
		float	factor
	)

inline

Clips r * factor to the range [LO,HI].

Definition at line 55 of file Math.hh.

byte openmsx::Math::clipIntToByte ( int x )

inline

Clip x to range [0,255].

Optimized for the case when no clipping is needed.

Definition at line 46 of file Math.hh.

References likely.

short openmsx::Math::clipIntToShort ( int x )

inline

Clip x to range [-32768,32767].

Special case of the version above. Optimized for the case when no clipping is needed.

Definition at line 37 of file Math.hh.

References likely.

Referenced by openmsx::WavImage::getSampleAt(), and openmsx::Y8950::Impl::writeReg().

unsigned openmsx::Math::countLeadingZeros ( unsigned x )

inline

Count the number of leading zero-bits in the given word.

The result is undefined when the input is zero (all bits are zero).

Definition at line 188 of file Math.hh.

template<typename T >

T openmsx::Math::floodRight ( T x )

inline

Returns the smallest number of the form 2^n-1 that is greater or equal to the given number.

The resulting number has the same number of leading zeros as the input, but starting from the first 1-bit in the input all bits more to the right are also 1.

Definition at line 174 of file Math.hh.

Referenced by openmsx::VRAMWindow::getReadArea(), openmsx::VRAMWindow::getReadAreaPlanar(), and powerOfTwo().

unsigned openmsx::Math::gcd	(	unsigned	a,
		unsigned	b
	)

inline

Calculate greatest common divider of two strictly positive integers.

Classical implementation is like this: while (unsigned t = b % a) { b = a; a = t; } return a; The following implementation avoids the costly modulo operation. It is about 40% faster on my machine.

require: a != 0 && b != 0

Definition at line 70 of file Math.hh.

Referenced by openmsx::FBPostProcessor< Pixel >::paint().

bool openmsx::Math::isPowerOfTwo ( unsigned a )

inline

Is the given number an integer power of 2? Not correct for zero (according to this test 0 is a power of 2).

Definition at line 15 of file Math.hh.

Referenced by openmsx::MemoryOps::mallocAligned().

unsigned openmsx::Math::powerOfTwo ( unsigned a )

Returns the smallest number that is both >=a and a power of two.

Definition at line 8 of file Math.cc.

References floodRight().

Referenced by openmsx::SDLGLOutputSurface::init(), and openmsx::SDLSoundDriver::SDLSoundDriver().

byte openmsx::Math::reverseByte ( byte a )

inline

Reverse the bits in a byte.

This is equivalent to (but faster than) reverseNBits(x, 8);

Definition at line 148 of file Math.hh.

Referenced by openmsx::ImagePrinter::printGraphicByte(), and openmsx::LaserdiscPlayer::serialize().

unsigned openmsx::Math::reverseNBits	(	unsigned	x,
		unsigned	bits
	)

inline

Reverse the lower N bits of a given value.

The upper 32-N bits from the input are ignored and will be returned as 0. For example reverseNBits('xxxabcde', 5) returns '000edcba' (binary notation).

Definition at line 98 of file Math.hh.

Referenced by openmsx::LaserdiscPlayer::serialize().

Functions

Function Documentation