2016-07-09 19:54:35 +08:00
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.. _media_ioc_enum_links:
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2016-06-30 21:18:56 +08:00
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**************************
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ioctl MEDIA_IOC_ENUM_LINKS
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**************************
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2016-07-06 02:14:35 +08:00
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Name
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2016-07-05 18:58:48 +08:00
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====
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2016-06-30 21:18:56 +08:00
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2016-07-05 18:58:48 +08:00
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MEDIA_IOC_ENUM_LINKS - Enumerate all pads and links for a given entity
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2016-06-30 21:18:56 +08:00
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2016-07-06 02:14:35 +08:00
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Synopsis
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2016-06-30 21:18:56 +08:00
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========
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2016-08-20 03:59:55 +08:00
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.. c:function:: int ioctl( int fd, MEDIA_IOC_ENUM_LINKS, struct media_links_enum *argp )
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:name: MEDIA_IOC_ENUM_LINKS
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2016-06-30 21:18:56 +08:00
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2016-07-05 18:58:48 +08:00
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2016-07-06 02:14:35 +08:00
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Arguments
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2016-06-30 21:18:56 +08:00
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=========
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``fd``
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File descriptor returned by :ref:`open() <media-func-open>`.
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``argp``
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2018-08-04 17:48:36 +08:00
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Pointer to struct :c:type:`media_links_enum`.
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2016-07-06 02:14:35 +08:00
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Description
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2016-06-30 21:18:56 +08:00
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===========
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To enumerate pads and/or links for a given entity, applications set the
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2016-08-30 04:37:59 +08:00
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entity field of a struct :c:type:`media_links_enum`
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structure and initialize the struct
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:c:type:`media_pad_desc` and struct
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:c:type:`media_link_desc` structure arrays pointed by
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the ``pads`` and ``links`` fields. They then call the
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MEDIA_IOC_ENUM_LINKS ioctl with a pointer to this structure.
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If the ``pads`` field is not NULL, the driver fills the ``pads`` array
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with information about the entity's pads. The array must have enough
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room to store all the entity's pads. The number of pads can be retrieved
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2016-07-09 19:54:35 +08:00
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with :ref:`MEDIA_IOC_ENUM_ENTITIES`.
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2016-06-30 21:18:56 +08:00
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If the ``links`` field is not NULL, the driver fills the ``links`` array
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with information about the entity's outbound links. The array must have
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enough room to store all the entity's outbound links. The number of
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2016-07-09 19:54:35 +08:00
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outbound links can be retrieved with :ref:`MEDIA_IOC_ENUM_ENTITIES`.
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2016-06-30 21:18:56 +08:00
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Only forward links that originate at one of the entity's source pads are
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returned during the enumeration process.
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2016-08-30 04:37:59 +08:00
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.. c:type:: media_links_enum
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2016-06-30 21:18:56 +08:00
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[media] docs-rst: add tabularcolumns to all tables
LaTeX doesn't handle too well auto-width on tables, and ReST
markup requires an special tag to give it the needed hints.
As we're using A4 paper, we have 17cm of useful spaces. As
most media tables have widths, let's use it to generate the
needed via the following perl script:
my ($line_size, $table_header, $has_cols) = (17.5, 0, 0);
my $out;
my $header = "";
my @widths = ();
sub round { $_[0] > 0 ? int($_[0] + .5) : -int(-$_[0] + .5) }
while (<>) {
if (!$table_header) {
$has_cols = 1 if (m/..\s+tabularcolumns::/);
if (m/..\s+flat-table::/) {
$table_header = 1;
$header = $_;
next;
}
$out .= $_;
next;
}
$header .= $_;
@widths = split(/ /, $1) if (m/:widths:\s+(.*)/);
if (m/^\n$/) {
if (!$has_cols && @widths) {
my ($tot, $t, $i) = (0, 0, 0);
foreach my $v(@widths) { $tot += $v; };
$out .= ".. tabularcolumns:: |";
for ($i = 0; $i < scalar @widths - 1; $i++) {
my $v = $widths[$i];
my $w = round(10 * ($v * $line_size) / $tot) / 10;
$out .= sprintf "p{%.1fcm}|", $w;
$t += $w;
}
my $w = $line_size - $t;
$out .= sprintf "p{%.1fcm}|\n\n", $w;
}
$out .= $header;
$table_header = 0;
$has_cols = 0;
$header = "";
@widths = ();
}
}
print $out;
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2016-08-17 19:14:19 +08:00
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.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
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2016-06-30 21:18:56 +08:00
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.. flat-table:: struct media_links_enum
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 2
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2018-06-15 21:19:44 +08:00
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* - __u32
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2016-06-30 21:18:56 +08:00
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- ``entity``
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- Entity id, set by the application.
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2018-06-15 21:19:44 +08:00
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* - struct :c:type:`media_pad_desc`
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2016-07-04 23:46:04 +08:00
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- \*\ ``pads``
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- Pointer to a pads array allocated by the application. Ignored if
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NULL.
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2016-06-30 21:18:56 +08:00
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2018-06-15 21:19:44 +08:00
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* - struct :c:type:`media_link_desc`
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2016-07-04 23:46:04 +08:00
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- \*\ ``links``
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- Pointer to a links array allocated by the application. Ignored if
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NULL.
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2016-06-30 21:18:56 +08:00
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2016-08-30 04:37:59 +08:00
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.. c:type:: media_pad_desc
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2016-06-30 21:18:56 +08:00
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[media] docs-rst: add tabularcolumns to all tables
LaTeX doesn't handle too well auto-width on tables, and ReST
markup requires an special tag to give it the needed hints.
As we're using A4 paper, we have 17cm of useful spaces. As
most media tables have widths, let's use it to generate the
needed via the following perl script:
my ($line_size, $table_header, $has_cols) = (17.5, 0, 0);
my $out;
my $header = "";
my @widths = ();
sub round { $_[0] > 0 ? int($_[0] + .5) : -int(-$_[0] + .5) }
while (<>) {
if (!$table_header) {
$has_cols = 1 if (m/..\s+tabularcolumns::/);
if (m/..\s+flat-table::/) {
$table_header = 1;
$header = $_;
next;
}
$out .= $_;
next;
}
$header .= $_;
@widths = split(/ /, $1) if (m/:widths:\s+(.*)/);
if (m/^\n$/) {
if (!$has_cols && @widths) {
my ($tot, $t, $i) = (0, 0, 0);
foreach my $v(@widths) { $tot += $v; };
$out .= ".. tabularcolumns:: |";
for ($i = 0; $i < scalar @widths - 1; $i++) {
my $v = $widths[$i];
my $w = round(10 * ($v * $line_size) / $tot) / 10;
$out .= sprintf "p{%.1fcm}|", $w;
$t += $w;
}
my $w = $line_size - $t;
$out .= sprintf "p{%.1fcm}|\n\n", $w;
}
$out .= $header;
$table_header = 0;
$has_cols = 0;
$header = "";
@widths = ();
}
}
print $out;
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2016-08-17 19:14:19 +08:00
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.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
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2016-06-30 21:18:56 +08:00
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.. flat-table:: struct media_pad_desc
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 2
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2018-06-15 21:19:44 +08:00
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* - __u32
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2016-06-30 21:18:56 +08:00
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- ``entity``
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- ID of the entity this pad belongs to.
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2018-06-15 21:19:44 +08:00
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* - __u16
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- ``index``
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2018-06-29 19:29:52 +08:00
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- Pad index, starts at 0.
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2018-06-15 21:19:44 +08:00
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* - __u32
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2016-06-30 21:18:56 +08:00
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- ``flags``
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- Pad flags, see :ref:`media-pad-flag` for more details.
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2018-06-15 21:19:44 +08:00
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* - __u32
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2018-02-04 02:26:07 +08:00
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- ``reserved[2]``
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- Reserved for future extensions. Drivers and applications must set
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the array to zero.
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2016-06-30 21:18:56 +08:00
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2016-08-30 04:37:59 +08:00
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.. c:type:: media_link_desc
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2016-06-30 21:18:56 +08:00
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[media] docs-rst: add tabularcolumns to all tables
LaTeX doesn't handle too well auto-width on tables, and ReST
markup requires an special tag to give it the needed hints.
As we're using A4 paper, we have 17cm of useful spaces. As
most media tables have widths, let's use it to generate the
needed via the following perl script:
my ($line_size, $table_header, $has_cols) = (17.5, 0, 0);
my $out;
my $header = "";
my @widths = ();
sub round { $_[0] > 0 ? int($_[0] + .5) : -int(-$_[0] + .5) }
while (<>) {
if (!$table_header) {
$has_cols = 1 if (m/..\s+tabularcolumns::/);
if (m/..\s+flat-table::/) {
$table_header = 1;
$header = $_;
next;
}
$out .= $_;
next;
}
$header .= $_;
@widths = split(/ /, $1) if (m/:widths:\s+(.*)/);
if (m/^\n$/) {
if (!$has_cols && @widths) {
my ($tot, $t, $i) = (0, 0, 0);
foreach my $v(@widths) { $tot += $v; };
$out .= ".. tabularcolumns:: |";
for ($i = 0; $i < scalar @widths - 1; $i++) {
my $v = $widths[$i];
my $w = round(10 * ($v * $line_size) / $tot) / 10;
$out .= sprintf "p{%.1fcm}|", $w;
$t += $w;
}
my $w = $line_size - $t;
$out .= sprintf "p{%.1fcm}|\n\n", $w;
}
$out .= $header;
$table_header = 0;
$has_cols = 0;
$header = "";
@widths = ();
}
}
print $out;
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2016-08-17 19:14:19 +08:00
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.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
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2016-06-30 21:18:56 +08:00
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.. flat-table:: struct media_link_desc
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 2
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2018-06-15 21:19:44 +08:00
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* - struct :c:type:`media_pad_desc`
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2016-06-30 21:18:56 +08:00
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- ``source``
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- Pad at the origin of this link.
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2018-06-15 21:19:44 +08:00
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* - struct :c:type:`media_pad_desc`
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2016-06-30 21:18:56 +08:00
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- ``sink``
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- Pad at the target of this link.
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2018-06-15 21:19:44 +08:00
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* - __u32
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2016-06-30 21:18:56 +08:00
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- ``flags``
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- Link flags, see :ref:`media-link-flag` for more details.
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2018-06-15 21:19:44 +08:00
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* - __u32
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2018-02-04 02:26:07 +08:00
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- ``reserved[4]``
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- Reserved for future extensions. Drivers and applications must set
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the array to zero.
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2016-06-30 21:18:56 +08:00
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2016-07-06 02:14:35 +08:00
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Return Value
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============
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On success 0 is returned, on error -1 and the ``errno`` variable is set
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appropriately. The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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EINVAL
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2016-08-30 04:37:59 +08:00
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The struct :c:type:`media_links_enum` ``id``
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2016-06-30 21:18:56 +08:00
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references a non-existing entity.
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