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

NAME

       ddi_dma_nextseg - get next DMA segment

SYNOPSIS

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

       int ddi_dma_nextseg(ddi_dma_win_t win, ddi_dma_seg_t seg, ddi_dma_seg_t *nseg);

INTERFACE LEVEL

       This interface is obsolete.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

PARAMETERS

       win	       A DMA window.

       seg	       The current  DMA segment or NULL.

       nseg	       A pointer to the next DMA segment to be filled in. If seg is NULL, a pointer to the first segment within the specified win-
		       dow is returned.

DESCRIPTION

       ddi_dma_nextseg() gets the next DMA segment within the specified window win. If the current segment is NULL, the first DMA  segment  within
       the window is returned.

       A  DMA segment is always required for a DMA window.  A DMA segment is a contiguous portion of a DMA window (see	ddi_dma_nextwin(9F)) which
       is entirely addressable by the device for a data transfer operation.

       An example where multiple DMA segments are allocated is where the system does not contain DVMA capabilities and the object may be  non-con-
       tiguous.  In this example the object will be broken into smaller contiguous DMA segments. Another example is where the device has  an upper
       limit on its  transfer  size  (for  example  an	8-bit  address	register)  and	has  expressed	this  in  the  DMA  limit  structure  (see
       ddi_dma_lim_sparc(9S) or ddi_dma_lim_x86(9S)). In this example the object will be broken into smaller addressable DMA segments.

RETURN VALUES

       ddi_dma_nextseg() returns:

       DDI_SUCCESS	       Successfully filled in the next segment pointer.

       DDI_DMA_DONE	       There is no next segment. The current segment is the final segment within the specified window.

       DDI_DMA_STALE	       win does not refer to the currently active window.

CONTEXT

       ddi_dma_nextseg() can be called from user or interrupt context.

EXAMPLES

       For an example, see ddi_dma_segtocookie(9F).

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Stability Level 	     |Obsolete			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       attributes(5),	ddi_dma_addr_setup(9F),   ddi_dma_buf_setup(9F),   ddi_dma_nextcookie(9F),  ddi_dma_nextwin(9F),  ddi_dma_segtocookie(9F),
       ddi_dma_sync(9F), ddi_dma_lim_sparc(9S), ddi_dma_lim_x86(9S), ddi_dma_req(9S)

       Writing Device Drivers

SunOS 5.10							    27 Sep 2002 					       ddi_dma_nextseg(9F)