opensolaris man page for btop

btop(9F)						   Kernel Functions for Drivers 						  btop(9F)

NAME
       btop - convert size in bytes to size in pages (round down)

SYNOPSIS
       #include <sys/ddi.h>

       unsigned long btop(unsigned long numbytes);

INTERFACE LEVEL
       Architecture independent level 1 (DDI/DKI).

PARAMETERS
       numbytes    Number of bytes.

DESCRIPTION
       The  btop()  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 2048, then btop(4096) returns 2, and btop(4097) returns 2
       as well. btop(0) returns 0.

RETURN VALUES
       The return value is always the number of pages. There are no invalid input values, and therefore no error return values.

CONTEXT
       The btop() function can be called from user, interrupt, or kernel context.

SEE ALSO
       btopr(9F), ddi_btop(9F), ptob(9F)

       Writing Device Drivers

SunOS 5.11							    16 Jan 2006 							  btop(9F)