ddi_dma_movwin(9F)

NAME

     ddi_dma_movwin - shift current DMA window

SYNOPSIS

     #include <sys/ddi.h>
     #include <sys/sunddi.h>

     int  ddi_dma_movwin(ddi_dma_handle_t  handle,  off_t  *offp,
     uint_t *lenp, ddi_dma_cookie_t *cookiep);

INTERFACE LEVEL

     This interface is  obsolete.  ddi_dma_getwin(9F)  should  be
     used instead.

PARAMETERS

     handle
           The   DMA   handle   filled   in   by   a   call    to
           ddi_dma_setup(9F).

     offp  A pointer to an offset to set the DMA window to.  Upon
           a successful return, it will be filled in with the new
           offset from the beginning of the object resources  are
           allocated for.

     lenp  A pointer to a value which must either be the  current
           size  of  the  DMA  window  (as  known  from a call to
           ddi_dma_curwin(9F)  or  from  a   previous   call   to
           ddi_dma_movwin()).  Upon  a successful return, it will
           be filled in with the size, in bytes, of  the  current
           window.

     cookiep
           A pointer to a DMA  cookie  (see  ddi_dma_cookie(9S)).
           Upon a successful return, cookiep is filled in just as
           if an implicit ddi_dma_htoc(9F) had been made.

DESCRIPTION

     ddi_dma_movwin() shifts the current DMA  window.  If  a  DMA
     request  allows  the  system  to allocate resources for less
     than the entire object by setting the  DDI_DMA_PARTIAL  flag
     in the ddi_dma_req(9S) structure, the current DMA window can
     be shifted by a call to ddi_dma_movwin().

     The caller must first determine the current DMA window  size
     by  a  call  to ddi_dma_curwin(9F). Using the current offset
     and size  of  the  window  thus  retrieved,  the  caller  of
     ddi_dma_movwin()  may  change  the window onto the object by
     changing the offset by a value which is some multiple of the
     size of the DMA window.

     ddi_dma_movwin() takes care of underlying resource synchron-
     izations  required to shift the window. However, if you want
     to access the data prior to  or  after  moving  the  window,
     further    synchronizations   using   ddi_dma_sync(9F)   are
     required.

     This function is normally called from an interrupt  routine.
     The  first  invocation  of  the  DMA engine is done from the
     driver. All subsequent invocations of  the  DMA  engine  are
     done  from  the  interrupt  routine.  The  interrupt routine
     checks to see if the request has been completed. If it  has,
     it  returns without invoking another DMA transfer. Otherwise
     it calls ddi_dma_movwin() to shift the  current  window  and
     starts another DMA transfer.

RETURN VALUES

     ddi_dma_movwin() returns:

     DDI_SUCCESS
           The current length and offset are legal and have  been
           set.

     DDI_FAILURE
           Otherwise.

CONTEXT

     ddi_dma_movwin() can be called from user or  interrupt  con-
     text.

ATTRIBUTES

     See attributes(5) for a description of the following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Stability Level             | Obsolete                    |
    |_____________________________|_____________________________|

SEE ALSO

     attributes(5),    ddi_dma_curwin(9F),    ddi_dma_getwin(9F),
     ddi_dma_htoc(9F),    ddi_dma_setup(9F),    ddi_dma_sync(9F),
     ddi_dma_cookie(9S), ddi_dma_req(9S)

     Writing Device Drivers

WARNINGS

     The caller must guarantee that the  resources  used  by  the
     object are inactive prior to calling this function.