'\" te
.\" Copyright (c) 1994, Sun Microsystems, Inc.
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
.\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE.  If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
.TH ddi_dma_nextcookie 9F "26 Sep 1994" "SunOS 5.11" "Kernel Functions for Drivers"
.SH NAME
ddi_dma_nextcookie \- retrieve subsequent DMA cookie
.SH SYNOPSIS
.LP
.nf
#include <sys/ddi.h> 
#include <sys/sunddi.h>



\fBvoid\fR \fBddi_dma_nextcookie\fR(\fBddi_dma_handle_t\fR \fIhandle\fR, 
     \fBddi_dma_cookie_t *\fR\fIcookiep\fR);
.fi

.SH PARAMETERS
.sp
.ne 2
.mk
.na
\fB\fIhandle\fR\fR
.ad
.RS 11n
.rt  
The handle previously allocated by a call to  \fBddi_dma_alloc_handle\fR(9F).
.RE

.sp
.ne 2
.mk
.na
\fB\fIcookiep\fR\fR
.ad
.RS 11n
.rt  
A pointer to a  \fBddi_dma_cookie\fR(9S) structure.
.RE

.SH INTERFACE LEVEL
.sp
.LP
Solaris DDI specific (Solaris DDI).
.SH DESCRIPTION
.sp
.LP
\fBddi_dma_nextcookie()\fR retrieves subsequent  \fBDMA\fR cookies for a
\fBDMA\fR object.   \fBddi_dma_nextcookie()\fR fills in the
\fBddi_dma_cookie\fR(9S) structure pointed to by  \fIcookiep\fR. The
\fBddi_dma_cookie\fR(9S) structure must be allocated prior to calling
\fBddi_dma_nextcookie()\fR.
.sp
.LP
The \fBDMA\fR cookie count returned by \fBddi_dma_buf_bind_handle\fR(9F),
\fBddi_dma_addr_bind_handle\fR(9F), or \fBddi_dma_getwin\fR(9F) indicates the
number of \fBDMA\fR cookies a \fBDMA\fR object consists of. If the resulting
cookie count,  \fIN\fR, is larger than 1,  \fBddi_dma_nextcookie()\fR must be
called \fIN\fR-1 times to retrieve all  \fBDMA\fR cookies.
.SH CONTEXT
.sp
.LP
\fBddi_dma_nextcookie()\fR can be called from user, kernel, or interrupt
context.
.SH EXAMPLES
.LP
\fBExample 1 \fRProcess a scatter-gather list of I/O requests.
.sp
.LP
This example demonstrates the use of  \fBddi_dma_nextcookie()\fR to process a
scatter-gather list of I/O requests.

.sp
.in +2
.nf
/* setup scatter-gather list with multiple DMA cookies */
ddi_dma_cookie_t  dmacookie;
uint_t            ccount;
\&...

status = ddi_dma_buf_bind_handle(handle, bp, DDI_DMA_READ,
	NULL, NULL, &dmacookie, &ccount);
 
if (status == DDI_DMA_MAPPED) {

	/* program DMA engine with first cookie */
 
	while (--ccount > 0) {
		ddi_dma_nextcookie(handle, &dmacookie);
		/* program DMA engine with next cookie */
	}
}
\&...  
.fi
.in -2

.SH SEE ALSO
.sp
.LP
\fBddi_dma_addr_bind_handle\fR(9F), \fBddi_dma_alloc_handle\fR(9F),
\fBddi_dma_buf_bind_handle\fR(9F), \fBddi_dma_unbind_handle\fR(9F),
\fBddi_dma_cookie\fR(9S)
.sp
.LP
\fIWriting Device Drivers\fR