NAME    [Toc]    [Back]

       round_page - General: Rounds the specified address

SYNOPSIS    [Toc]    [Back]

       #include <mach/vm_param.h>

       vm_offset_t round_page(
               vm_offset_t address );

ARGUMENTS    [Toc]    [Back]

       Specifies  the  address  (or  byte  count)  that  is being
       rounded.

DESCRIPTION    [Toc]    [Back]

       The round_page routine rounds the  specified  address  (or
       byte  count)  to a multiple of the page size. For example,
       round_page would round a 1-byte count to be equal  to  the
       size  of one page.  This routine shields the driver writer
       from having to know the page size  of  the  system,  which
       could vary in different CPU architectures and on different
       CPU types  within  the  same  architecture.  Typically,  a
       device  driver calls round_page in preparation for doing a
       DMA operation to a user's buffer. The  value  returned  by
       this  routine  is  used in the call to the vm_map_pageable
       routine. To use  this  routine,  the  driver  writer  must
       include the <mach/vm_param.h> header file in the driver.

RETURN VALUES    [Toc]    [Back]

       The round_page routine returns the rounded address or byte
       count.

SEE ALSO    [Toc]    [Back]

       Routines: current_task(9r),  trunc_page(9r),  vm_map_pageable(9r)



                                                   round_page(9r)