FFS.ih.xx-x86-gcc File Reference

Implements the X86 on GCC compiler version of the FFS routines. More...

Functions
FFS__LCL_FNC int	FFSL (unsigned int w)
	Find first leading set bit in a 32-bit word, MSb = 0.
FFS__LCL_FNC int	FFSl (unsigned int w)
	Find first leading set bit in a 32-bit word, LSb = 0.
FFS__LCL_FNC int	FFST (unsigned int w)
	Find first trailing set bit in a 32-bit word, MSb = 0.
FFS__LCL_FNC int	FFSt (unsigned int w)
	Find first trailing set bit in a 32-bit word, LSb = 0.
FFS__LCL_FNC int	CNTLZ (unsigned int w)
	Counts the number of leading 0's in a 32 bit word.
FFS__LCL_FNC int	CNTTZ (unsigned int w)
	Counts the number of trailing 0's in a 32 bit word.

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Detailed Description

Implements the X86 on GCC compiler version of the FFS routines.

Author:

JJRussell - russell@slac.stanford.edu

    CVS $Id: FFS.ih.xx-x86-gcc,v 1.1.1.1 2006/02/10 21:45:37 saxton Exp $

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Function Documentation

FFS__LCL_FNC int CNTLZ

(

unsigned int

w

)

Counts the number of leading 0's in a 32 bit word.

Parameters:

w

The 32 bit word to be examined.

Returns:

The number of leading 0's in a 32 bit word.

This routine examines a 32 bit longword, returning the count of leading 0s (left (MSb) to right (LSb)) If it finds a bit it returns a value in the range 0-31. This routine is almost a synomyn for FFSL, but it is protected against 0, returning 32 if the word is 0.

References FFSL().

FFS__LCL_FNC int CNTTZ

(

unsigned int

w

)

Counts the number of trailing 0's in a 32 bit word.

Parameters:

w

The 32 bit word to be examined.

Returns:

The number of trailing 0's in a 32 bit word.

This routine examines a 32 bit longword, returning the count of trailing 0s (left (MSb) to right (LSb)) If it finds a bit it returns a value in the range 0-31. This routine is almost a synomyn for FFSt, but it is protected against 0, returning 32 if the word is 0.

References FFSt().

FFS__LCL_FNC int FFSl

(

unsigned int

w

)

Find first leading set bit in a 32-bit word, LSb = 0.

Parameters:

w

The 32 bit word to examined from the MSb to LSb for the first set bit.

Returns:

The number of the first set bit in w, where LSb = 0

This routine examines a 32 bit longword from left (MSb) to right (LSb) looking for the first bit set. If it finds a bit it returns a value in the range 0-31. The routine is not protected against 0 as an input and the result is undefined.

FFS__LCL_FNC int FFSL

(

unsigned int

w

)

Find first leading set bit in a 32-bit word, MSb = 0.

Parameters:

w

The 32 bit word to examined from the MSb to LSb for the first set bit.

Returns:

The number of the first set bit in w, where MSb = 0

This routine examines a 32 bit longword from left (MSb) to right (LSb) looking for the first bit set. If it finds a bit it returns a value in the range 0-31. The routine is not protected against 0 as an input and the result is undefined.

Referenced by CNTLZ(), lsu__scale(), and lsu_calc().

FFS__LCL_FNC int FFSt

(

unsigned int

w

)

Find first trailing set bit in a 32-bit word, LSb = 0.

Parameters:

w

The 32 bit word to examined from the LSb to MSb for the first set bit.

Returns:

The number of the first set bit in w, where LSb = 0

This routine examines a 32 bit longword from right (MSb) to left (LSb) looking for the first bit set. If it finds a bit it returns a value in the range 0-31. The routine is not protected against 0 as an input and the result is undefined.

Referenced by CNTTZ().

FFS__LCL_FNC int FFST

(

unsigned int

w

)

Find first trailing set bit in a 32-bit word, MSb = 0.

Parameters:

w

The 32 bit word to examined from the LSb to MSb for the first set bit.

Returns:

The number of the first set bit in w, where MSb = 0

This routine examines a 32 bit longword from right (MSb) to left (LSb) looking for the first bit set. If it finds a bit it returns a value in the range 0-31. The routine is not protected against 0 as an input and the result is undefined.