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Kernel Functions for Driversddi_ffs(9F)

NAME

 ddi_ffs, ddi_fls - find first (last) bit set in a long integer

SYNOPSIS

  
#include <sys/conf.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
intddi_ffs(long mask);
 int ddi_fls(long mask);

INTERFACE LEVEL

 

Solaris DDI specific (Solaris DDI).

PARAMETERS

 
mask
A 32-bit argument value to search through.

DESCRIPTION

 

The function ddi_ffs() takes its argument and returns the shift count that the first (least significant) bit set in the argument corresponds to. The function ddi_fls() does the same, only it returns the shift count for the last (most significant) bit set in the argument.

RETURN VALUES

 
0
No bits are set in mask.
N
Bit N is the least significant (ddi_ffs) or most significant (ddi_fls) bit set in mask. Bits are numbered from 1 to 32, with bit 1 being the least significant bit position and bit 32 the most significant position.

CONTEXT

 

This function can be called from user or interrupt context.

SEE ALSO

 

Writing Device Drivers

SunOS 5.9Go To TopLast Changed 20 Dec 1995
 
      
      
Copyright 2002 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.