NAME    [Toc]    [Back]

       trunc_page - General: Truncates the specified address

SYNOPSIS    [Toc]    [Back]

       #include <mach/vm_param.h>

       vm_offset_t trunc_page(
               vm_offset_t address );

ARGUMENTS    [Toc]    [Back]

       Specifies  the  address  that is being truncated to a page
       boundary.

DESCRIPTION    [Toc]    [Back]

       The trunc_page routine truncates the specified address  to
       be  aligned  on  a page boundary. 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 trunc_page in preparation
       for doing a DMA operation on 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 trunc_page routine returns an address truncated  to  a
       page boundary.

SEE ALSO    [Toc]    [Back]

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



                                                   trunc_page(9r)