'\" te
.\"  Copyright (c) 2006 Sun Microsystems, Inc.  All Rights Reserved.
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
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.TH DDI_FFS 9F "Jan 16, 2006"
.SH NAME
ddi_ffs, ddi_fls \- find first (last) bit set in a long integer
.SH SYNOPSIS
.LP
.nf
#include <sys/conf.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>



\fBint\fR\fBddi_ffs\fR(\fBlong\fR \fImask\fR);
.fi

.LP
.nf
\fBint\fR \fBddi_fls\fR(\fBlong\fR \fImask\fR);
.fi

.SH INTERFACE LEVEL
.sp
.LP
Solaris DDI specific (Solaris DDI).
.SH PARAMETERS
.sp
.ne 2
.na
\fB\fImask\fR\fR
.ad
.RS 8n
A 32-bit argument value to search through.
.RE

.SH DESCRIPTION
.sp
.LP
The function \fBddi_ffs()\fR takes its argument and returns the shift count
that the first (least significant) bit set in the argument corresponds to. The
function \fBddi_fls()\fR does the same, only it returns the shift count for the
last (most significant) bit set in the argument.
.SH RETURN VALUES
.sp
.ne 2
.na
\fB\fB0\fR\fR
.ad
.RS 5n
No bits are set in mask.
.RE

.sp
.ne 2
.na
\fB\fIN\fR\fR
.ad
.RS 5n
Bit  \fIN\fR is the least significant (\fBddi_ffs\fR) or most significant
(\fBddi_fls\fR) bit set in mask. Bits are numbered from  \fB1\fR to  \fB32\fR,
with bit \fB1\fR being the least significant bit position and bit \fB32\fR the
most significant position.
.RE

.SH CONTEXT
.sp
.LP
This function can be called from user, interrupt, or kernel context.
.SH SEE ALSO
.sp
.LP
\fIWriting Device Drivers\fR