Burger::IntMath Class Reference

Helper routines for integer math. More...

#include <fxfixed.h>

List of all members.

Static Public Member Functions
static Word BURGER_INLINE	GetLoWord (Word32 uInput)
	Return the low 16 bits of a 32 bit value..
static Word BURGER_INLINE	GetHiWord (Word32 uInput)
	Return the upper 16 bits of a 32 bit value..
static Word32 BURGER_API	HexIt (Word uInput)
	Convert a 16 bit value into a 4 char string in an integer.
static void BURGER_API	HexIt (char *pOutput, Word uInput)
	Convert a 16 bit value into a 4 char string.
static Word32 BURGER_INLINE	UMultiply (Word uInputA, Word uInputB)
	Multiply two unsigned Word32 values.
static Int32 BURGER_INLINE	Multiply (Int32 iInputA, Int32 iInputB)
	Multiply two signed Int32 values.
static int BURGER_INLINE	FromFixedFloor (Fixed32 fInput)
	Convert a fixed point value to an integer using round down.
static int BURGER_INLINE	FromFixed (Fixed32 fInput)
	Convert a fixed point value to an integer using round to zero.
static int BURGER_INLINE	FromFixedCeil (Fixed32 fInput)
	Convert a fixed point value to an integer using round up.
static int BURGER_INLINE	FromFixedNearest (Fixed32 fInput)
	Convert a fixed point value to an integer using round to nearest.
static Int32 BURGER_INLINE	Abs (Int32 iInput)
	Get the absolute value of an integer..
static Word BURGER_API	SqrtFromInt (Word32 uInput)
	Get the square root of an integer.
static Word BURGER_API	SqrtFromFixed (Fixed32 fInput)
	Get the square root of a Fixed32.
static Int32 BURGER_API	Mul32GetUpper32 (Int32 iInputA, Int32 iInputB)
	Get the upper 32 bits from a 32x32 bit multiplication.
static Int32 BURGER_API	Mul32x32To64Div32 (Int32 iInputMulA, Int32 iInputMulB, Int32 iInputDiv)
	Perform a (32x32)/32 operation with 64 bit accuracy.
static Int32 BURGER_API	FromFloatFloor (float fInput)
	Convert a single float to an integer using floor().
static Int32 BURGER_API	FromFloat (float fInput)
	Convert a single float to an integer using round to zero.
static Int32 BURGER_API	FromFloatCeil (float fInput)
	Convert a single float to an integer using ceil().
static Int32 BURGER_API	FromFloatNearest (float fInput)
	Convert a single float to an integer using round to nearest.
static void BURGER_INLINE	FromFloatFloor (Int32 *pOutput, float fInput)
	Convert a single float to an integer using floor().
static void BURGER_INLINE	FromFloat (Int32 *pOutput, float fInput)
	Convert a single float to an integer using round to zero.
static void BURGER_INLINE	FromFloatCeil (Int32 *pOutput, float fInput)
	Convert a single float to an integer using ceil().
static void BURGER_INLINE	FromFloatNearest (Int32 *pOutput, float fInput)
	Convert a single float to an integer using round to nearest.

---

Detailed Description

Helper routines for integer math.

Some compilers don't have common math functions, also some function require intermediate values of a higher precision that can be provided by the compiler.

Many of these functions are inline or written in assembly language for speed.

---

Member Function Documentation

Burger::IntMath::Abs

(

Int32

iInput

)

[inline, static]

Get the absolute value of an integer..

Without branching, calculate the absolute value of an integer.

Parameters:

iInput

Value to get the absolute value of.

Returns:

The absolute value of iInput.

See also:

Burger::FixedMath::Abs(Fixed32)

Burger::IntMath::FromFixed

(

Fixed32

fInput

)

[inline, static]

Convert a fixed point value to an integer using round to zero.

Convert a Fixed32 into a int using round to zero.

Parameters:

fInput

Value to convert to an integer.

Returns:

The input converted to an integer using the truth table below.

    floorint = Burger::IntMath::FromFixed(FLOATTOFIXED(1.1f));      //1
    floorint = Burger::IntMath::FromFixed(FLOATTOFIXED(1.95f));     //1
    floorint = Burger::IntMath::FromFixed(FLOATTOFIXED(-1.1f));     //-1
    floorint = Burger::IntMath::FromFixed(FLOATTOFIXED(-1.95f));    //-1
    floorint = Burger::IntMath::FromFixed(FLOATTOFIXED(0.1f));      //0
    floorint = Burger::IntMath::FromFixed(FLOATTOFIXED(0.95f));     //0
    floorint = Burger::IntMath::FromFixed(FLOATTOFIXED(-0.1f));     //0
    floorint = Burger::IntMath::FromFixed(FLOATTOFIXED(-0.95f));    //0

Burger::IntMath::FromFixedCeil

(

Fixed32

fInput

)

[inline, static]

Convert a fixed point value to an integer using round up.

Convert a Fixed32 into a int using the same formula as ceil().

Parameters:

fInput

Value to convert to an integer.

Returns:

The input converted to an integer using the truth table below.

    floorint = Burger::IntMath::FromFixedCeil(FLOATTOFIXED(1.1f));      //2
    floorint = Burger::IntMath::FromFixedCeil(FLOATTOFIXED(1.95f));     //2
    floorint = Burger::IntMath::FromFixedCeil(FLOATTOFIXED(-1.1f));     //-1
    floorint = Burger::IntMath::FromFixedCeil(FLOATTOFIXED(-1.95f));    //-1
    floorint = Burger::IntMath::FromFixedCeil(FLOATTOFIXED(0.1f));      //1
    floorint = Burger::IntMath::FromFixedCeil(FLOATTOFIXED(0.95f));     //1
    floorint = Burger::IntMath::FromFixedCeil(FLOATTOFIXED(-0.1f));     //0
    floorint = Burger::IntMath::FromFixedCeil(FLOATTOFIXED(-0.95f));    //0

Burger::IntMath::FromFixedFloor

(

Fixed32

fInput

)

[inline, static]

Convert a fixed point value to an integer using round down.

Convert a Fixed32 into a int using the same formula as floor().

Parameters:

fInput

Value to convert to an integer.

Returns:

The input converted to an integer using the truth table below.

    floorint = Burger::IntMath::FromFixedFloor(FLOATTOFIXED(1.1f));     //1
    floorint = Burger::IntMath::FromFixedFloor(FLOATTOFIXED(1.95f));    //1
    floorint = Burger::IntMath::FromFixedFloor(FLOATTOFIXED(-1.1f));    //-2
    floorint = Burger::IntMath::FromFixedFloor(FLOATTOFIXED(-1.95f));   //-2
    floorint = Burger::IntMath::FromFixedFloor(FLOATTOFIXED(0.1f));     //0
    floorint = Burger::IntMath::FromFixedFloor(FLOATTOFIXED(0.95f));    //0
    floorint = Burger::IntMath::FromFixedFloor(FLOATTOFIXED(-0.1f));    //-1
    floorint = Burger::IntMath::FromFixedFloor(FLOATTOFIXED(-0.95f));   //-1

Burger::IntMath::FromFixedNearest

(

Fixed32

fInput

)

[inline, static]

Convert a fixed point value to an integer using round to nearest.

Convert a Fixed32 into a int using round to nearest.

Parameters:

fInput

Value to convert to an integer.

Returns:

The input converted to an integer using the truth table below.

    floorint = Burger::IntMath::FromFixedNearest(FLOATTOFIXED(1.1f));   //1
    floorint = Burger::IntMath::FromFixedNearest(FLOATTOFIXED(1.95f));  //2
    floorint = Burger::IntMath::FromFixedNearest(FLOATTOFIXED(-1.1f));  //-1
    floorint = Burger::IntMath::FromFixedNearest(FLOATTOFIXED(-1.95f)); //-2
    floorint = Burger::IntMath::FromFixedNearest(FLOATTOFIXED(0.1f));   //0
    floorint = Burger::IntMath::FromFixedNearest(FLOATTOFIXED(0.95f));  //1
    floorint = Burger::IntMath::FromFixedNearest(FLOATTOFIXED(-0.1f));  //0
    floorint = Burger::IntMath::FromFixedNearest(FLOATTOFIXED(-0.95f)); //-1

Note:

This can be used to replace FixRound() from MacOS.

Int32 BURGER_API Burger::IntMath::FromFloat

(

float

fInput

)

[static]

Convert a single float to an integer using round to zero.

Convert a single precision floating point number to an integer using the round to zero fractional truncation

Parameters:

fInput

A valid single precision floating point number.

Returns:

Signed integer equivalent value after applying round to zero on the floating point number.

void Burger::IntMath::FromFloat	(	Int32 *	pOutput,
		float	fInput
	)			[inline, static]

Convert a single float to an integer using round to zero.

Convert a single precision floating point number to an integer using the round to zero fractional truncation and store it to memory

Parameters:

	pOutput	A valid pointer to a 32-bit integer to receive the result.
	fInput	A valid single precision floating point number.

Int32 BURGER_API Burger::IntMath::FromFloatCeil

(

float

fInput

)

[static]

Convert a single float to an integer using ceil().

Convert a single precision floating point number to an integer using the ceil() form of fractional truncation

Parameters:

fInput

A valid single precision floating point number.

Returns:

Signed integer equivalent value after applying ceil() on the floating point number.

void Burger::IntMath::FromFloatCeil	(	Int32 *	pOutput,
		float	fInput
	)			[inline, static]

Convert a single float to an integer using ceil().

Convert a single precision floating point number to an integer using the ceil() form of fractional truncation and store it to memory

Parameters:

	pOutput	A valid pointer to a 32-bit integer to receive the result.
	fInput	A valid single precision floating point number.

Int32 BURGER_API Burger::IntMath::FromFloatFloor

(

float

fInput

)

[static]

Convert a single float to an integer using floor().

Convert a single precision floating point number to an integer using the floor() form of fractional truncation

Parameters:

fInput

A valid single precision floating point number.

Returns:

Signed integer equivalent value after applying floor() on the floating point number.

void Burger::IntMath::FromFloatFloor	(	Int32 *	pOutput,
		float	fInput
	)			[inline, static]

Convert a single float to an integer using floor().

Convert a single precision floating point number to an integer using the floor() form of fractional truncation and store it to memory

Parameters:

	pOutput	A valid pointer to a 32-bit integer to receive the result.
	fInput	A valid single precision floating point number.

void Burger::IntMath::FromFloatNearest	(	Int32 *	pOutput,
		float	fInput
	)			[inline, static]

Convert a single float to an integer using round to nearest.

Convert a single precision floating point number to an integer using the round to nearest fractional truncation and store it to memory

Parameters:

	pOutput	A valid pointer to a 32-bit integer to receive the result.
	fInput	A valid single precision floating point number.

Int32 BURGER_API Burger::IntMath::FromFloatNearest

(

float

fInput

)

[static]

Convert a single float to an integer using round to nearest.

Convert a single precision floating point number to an integer using the round to nearest fractional truncation

Parameters:

fInput

A valid single precision floating point number.

Returns:

Signed integer equivalent value after applying round to nearest on the floating point number.

Burger::IntMath::GetHiWord

(

Word32

uInput

)

[inline, static]

Return the upper 16 bits of a 32 bit value..

This is a direct replacement of the MacOS macro HiWord(). Take the 32 bit input and shift it to the right 16 bits, effectively uInput>>16.

Parameters:

uInput

32-bit integer value.

Returns:

Value shifted to the right 16 bits

Burger::IntMath::GetLoWord

(

Word32

uInput

)

[inline, static]

Return the low 16 bits of a 32 bit value..

This is a direct replacement of the MacOS macro LoWord(). Take the 32 bit input and mask it with 0xFFFF, then return the result.

Parameters:

uInput

32-bit integer value.

Returns:

Value masked with 0xFFFF.

void BURGER_API Burger::IntMath::HexIt	(	char *	pOutput,
		Word	uInput
	)			[static]

Convert a 16 bit value into a 4 char string.

Convert a 16-bit value into a 4 character ASCII string. This function will NOT zero terminate the string and it's expecting a buffer of at least 4 bytes in length.

Input : 0x1234 Output : "1234"

Parameters:

	uInput	Value to convert
	pOutput	Pointer to a four character buffer.

Note:

The upper 16 bits of the input are ignored.

Word32 BURGER_API Burger::IntMath::HexIt

(

Word

uInput

)

[static]

Convert a 16 bit value into a 4 char string in an integer.

This is a compatibility function of HexIt() from MacOS.

Convert a 16-bit value into a Word32 that contains the ASCII value of the short... The result is BIG Endian so that it can be directly stored into an ASCII buffer without an Endian swap

Input : 0x1234 Output : '1','2','3','4' -> 0x31323334 (Big Endian)

Parameters:

uInput

Value to convert

Returns:

Big Endian "String" in a Word32.

Note:

The upper 16 bits of the input are ignored.

Int32 Burger::IntMath::Mul32GetUpper32	(	Int32	iInputA,
		Int32	iInputB
	)			[static]

Get the upper 32 bits from a 32x32 bit multiplication.

Multiply two 32-bit values and create a 64 bit result. Discard the lower 32 bits and return only the upper 32 bits. This is a signed multiplication.

Parameters:

	iInputA	First value to multiply.
	iInputB	Second value to multiply.

Returns:

The upper 32 bits of the 64 bit result.

Note:

On PowerPC, this becomes the mulhw instruction and Intel it's the imul edx instruction.

Int32 Burger::IntMath::Mul32x32To64Div32	(	Int32	iInputMulA,
		Int32	iInputMulB,
		Int32	iInputDiv
	)			[static]

Perform a (32x32)/32 operation with 64 bit accuracy.

Multiply two 32-bit values and create a 64 bit result. Then divide this value by a 32 bit number. This will allow several ratio functions to operate with high accuracy. Result = ((int64)32*(int64)32)/32).

Parameters:

	iInputMulA	First value to multiply.
	iInputMulB	Second value to multiply.
	iInputDiv	Value to divide the 64 bit value by

Returns:

Output from the formula (A*B)/C

Note:

On Intel, this becomes imul edx followed by idiv ebx

Burger::IntMath::Multiply	(	Int32	iInputA,
		Int32	iInputB
	)			[inline, static]

Multiply two signed Int32 values.

This function is considered obsolete and remains only for backwards compatibilty.

Parameters:

	iInputA	32-bit signed integer value.
	iInputB	32-bit signed integer value.

Returns:

The result of the multiplication of the two inputs.

Note:

No overflow checking is performed.

Word BURGER_API Burger::IntMath::SqrtFromFixed

(

Fixed32

fInput

)

[static]

Get the square root of a Fixed32.

Return the square root of a Fixed32 and return the integer result. The maximum value is 255.998 (256) for the square root of 0x7FFFFFFF. This routine is 100% accurate.

Negative numbers will return zero for the result.

Parameters:

fInput

Value to return the square root of.

Returns:

Return the square root as an integer.

Note:

This will perform a round to nearest for the fraction so if the calculated square root is 1.6, it will return 2.

Word BURGER_API Burger::IntMath::SqrtFromInt

(

Word32

uInput

)

[static]

Get the square root of an integer.

Return the square root of an integer. The maximum value is 46341 for the square root of 0x7FFFFFFF. This routine is 100% accurate.

Parameters:

uInput

Value to return the square root of.

Returns:

Return the square root as an integer.

Note:

This will perform a round to nearest for the fraction so if the calculated square root is 1.6, it will return 2.

Burger::IntMath::UMultiply	(	Word	uInputA,
		Word	uInputB
	)			[inline, static]

Multiply two unsigned Word32 values.

This is a direct replacement of the MacOS function Multiply(). This function is considered obsolete and remains only for backwards compatibilty.

Parameters:

	uInputA	32-bit unsigned integer value.
	uInputB	32-bit unsigned integer value.

Returns:

The result of the multiplication of the two inputs.

Note:

No overflow checking is performed.