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'\" te
.\" Copyright (c) 2006, 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_NEXTSEG 9F "Apr 04, 2006"
.SH NAME
ddi_dma_nextseg \- get next DMA segment
.SH SYNOPSIS
.LP
.nf
#include <sys/ddi.h>
#include <sys/sunddi.h>
\fBint\fR \fBddi_dma_nextseg\fR(\fBddi_dma_win_t\fR \fIwin\fR, \fBddi_dma_seg_t\fR \fIseg\fR,
\fBddi_dma_seg_t *\fR\fInseg\fR);
.fi
.SH INTERFACE LEVEL
.sp
.LP
This interface is obsolete. \fBddi_dma_nextcookie\fR(9F) should be used
instead.
.SH PARAMETERS
.sp
.ne 2
.na
\fB\fIwin\fR\fR
.ad
.RS 8n
A \fBDMA\fR window.
.RE
.sp
.ne 2
.na
\fB\fIseg\fR\fR
.ad
.RS 8n
The current \fBDMA\fR segment or \fINULL\fR.
.RE
.sp
.ne 2
.na
\fB\fInseg\fR\fR
.ad
.RS 8n
A pointer to the next \fBDMA\fR segment to be filled in. If \fIseg\fR is
\fINULL\fR, a pointer to the first segment within the specified window is
returned.
.RE
.SH DESCRIPTION
.sp
.LP
The \fBddi_dma_nextseg()\fR function gets the next \fBDMA\fR segment within the
specified window \fIwin\fR. If the current segment is \fINULL\fR, the first
\fBDMA\fR segment within the window is returned.
.sp
.LP
A \fBDMA\fR segment is always required for a \fBDMA\fR window. A \fBDMA\fR
segment is a contiguous portion of a \fBDMA\fR window (see
\fBddi_dma_nextwin\fR(9F)) which is entirely addressable by the device for a
data transfer operation.
.sp
.LP
An example where multiple \fBDMA\fR segments are allocated is where the system
does not contain \fBDVMA\fR capabilities and the object may be non-contiguous.
In this example the object will be broken into smaller contiguous \fBDMA\fR
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 \fBDMA\fR limit structure (see \fBddi_dma_lim_sparc\fR(9S) or
\fBddi_dma_lim_x86\fR(9S)). In this example the object will be broken into
smaller addressable \fBDMA\fR segments.
.SH RETURN VALUES
.sp
.LP
The \fBddi_dma_nextseg()\fR function returns:
.sp
.ne 2
.na
\fB\fBDDI_SUCCESS\fR\fR
.ad
.RS 17n
Successfully filled in the next segment pointer.
.RE
.sp
.ne 2
.na
\fB\fBDDI_DMA_DONE\fR\fR
.ad
.RS 17n
There is no next segment. The current segment is the final segment within the
specified window.
.RE
.sp
.ne 2
.na
\fB\fBDDI_DMA_STALE\fR\fR
.ad
.RS 17n
\fIwin\fR does not refer to the currently active window.
.RE
.SH CONTEXT
.sp
.LP
The \fBddi_dma_nextseg()\fR function can be called from user, interrupt, or
kernel context.
.SH EXAMPLES
.sp
.LP
For an example, see \fBddi_dma_segtocookie\fR(9F).
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for a description of the following attributes:
.sp
.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE ATTRIBUTE VALUE
_
Stability Level Obsolete
.TE
.SH SEE ALSO
.sp
.LP
\fBattributes\fR(5), \fBddi_dma_addr_setup\fR(9F), \fBddi_dma_buf_setup\fR(9F),
\fBddi_dma_nextcookie\fR(9F), \fBddi_dma_nextwin\fR(9F),
\fBddi_dma_segtocookie\fR(9F), \fBddi_dma_sync\fR(9F),
\fBddi_dma_lim_sparc\fR(9S), \fBddi_dma_lim_x86\fR(9S), \fBddi_dma_req\fR(9S)
.sp
.LP
\fIWriting Device Drivers\fR
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