ddi_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>
int ddi_ffs(long mask);
int ddi_fls(long mask);

INTERFACE LEVEL

Solaris DDI specific (Solaris DDI).

ARGUMENTS

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.

Museum