'\" te
.\"  Copyright 1989 AT&T
.\" Copyright (c) 2006, Sun Microsystems, Inc.  All Rights Reserved
.TH btop 9F "16 Jan 2006" "SunOS 5.11" "Kernel Functions for Drivers"
.SH NAME
btop \- convert size in bytes to size in pages (round down)
.SH SYNOPSIS
.LP
.nf
#include <sys/ddi.h>

\fBunsigned long\fR \fBbtop\fR(\fBunsigned long\fR \fInumbytes\fR);
.fi

.SH INTERFACE LEVEL
.sp
.LP
Architecture independent level 1 (DDI/DKI).
.SH PARAMETERS
.sp
.ne 2
.mk
.na
\fB\fInumbytes\fR\fR
.ad
.RS 12n
.rt  
Number of bytes.
.RE

.SH DESCRIPTION
.sp
.LP
The \fBbtop()\fR function returns the number of memory pages that are contained in the specified number of bytes, with downward rounding in the case that the byte count is not a page multiple. For example, if the page size is \fB2048\fR, then \fBbtop(4096)\fR returns \fB2\fR, and \fBbtop(4097)\fR returns \fB2\fR as well. \fBbtop(0)\fR returns \fB0\fR.
.SH RETURN VALUES
.sp
.LP
The return value is always the number of pages. There are no invalid input values, and therefore no error return values.
.SH CONTEXT
.sp
.LP
The \fBbtop()\fR function can be called from user, interrupt, or kernel context.
.SH SEE ALSO
.sp
.LP
\fBbtopr\fR(9F), \fBddi_btop\fR(9F), \fBptob\fR(9F) 
.sp
.LP
\fIWriting Device Drivers for Oracle Solaris 11.2\fR