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Reworked some paragraphs. 

Added chapters on generation numbers and error codes.
Added some function reference entries.


git-svn-id: svn://svn.linux1394.org/libraw1394/trunk@72 53a565d1-3bb7-0310-b661-cf11e63c67ab
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aeb 2001-07-09 00:27:09 +00:00
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@ -73,8 +73,9 @@
</para>
<para>
If you are familiar with CSR architectures (as defined in --FIXME--), then
you already know most of 1394, which is a CSR implementation.
If you are familiar with CSR architectures (as defined in IEEE 1212
(FIXME?)), then you already know most of 1394, which is a CSR
implementation.
</para>
<sect1>
@ -85,9 +86,9 @@
document are the quadlet (32 bit quantity) and the octlet (64 bit
quantity) and blocks (any quantity of bytes). The bus byte ordering is
big endian. A transmission can be sent at one of multiple possible
speeds, from the slowest 100 Mbit/s over 200 and 400 Mbit/s up to 3.2
Gbit/s in the future (these speeds are also referred to as S100, S200,
...).
speeds, which are 100, 200 and 400 Mbit/s for the currently mostly used
IEEE 1394a spec and up to 3.2 Gbit/s in the recently finalized 1394.b
standard (these speeds are also referred to as S100, S200, ...).
</para>
<para>
@ -188,16 +189,8 @@
later time from the targetted node to the source node (this is called a
split transaction). Only writes can succeed and complete in the ack
code, reads and locks require a response. Error and packet pending can
happen for every transaction.
</para>
<para>
The response packets contain a response code (rcode) which signifies
success or type of error. libraw1394 contains a function to convert
ack/rcode pairs into errno codes which convey roughly the same meaning.
This is done automatically for the synchronous read/write/lock wrapper
functions, i.e. they return a negative value for failure and a standard
error code can be found in the global variable <symbol>errno</symbol>.
happen for every transaction. The response packets contain a response
code (rcode) which signifies success or type of error.
</para>
<para>
@ -411,15 +404,15 @@
</para>
<para>
A list of available ports together with some information about it
(name of the hardware, number of connected nodes) is available via
A list of available ports together with some information about it (name
of the hardware, number of connected nodes) is available via
<function>raw1394_get_port_info()</function>, which is to be called
right getting a fresh handle. The user should be presented with a
right after getting a fresh handle. The user should be presented with a
choice of available ports if there is more than one. It may be good
practice to do that even if there is only one port, since that may
result from a normally configured port just not being available,
making it confusing to be dropped right into the application attached
to a port without a choice and notion of anything going wrong.
result from a normally configured port just not being available, making
it confusing to be dropped right into the application attached to a port
without a choice and notion of anything going wrong.
</para>
<para>
@ -551,6 +544,64 @@
</para>
</sect1>
<sect1>
<title>Generation Numbers</title>
<para>
libraw1394 and the kernel code use generation numbers to identify the
current bus configuration and increment those on every configuration
change. The most important generation number is stored per connected
1394 bus and incremented on every bus reset. There is another number
managed by raw1394 which identifies global changes (like a complete port
being added or removed), which is used for the
<function>raw1394_set_port()</function> function to make sure you don't
use stale port numbers. This is done transparently to you.
</para>
<para>
The bus generation number is more relevant for your work. Since nodes
can change IDs with every bus reset, it is very likely that you don't
want to send a packet you constructed with the old ID before you noticed
the bus reset. This does not apply to isochronous transmissions, since
they are broadcast and do not depend on bus configuration. Therefore
every packet is automatically tagged with the expected generation
number, and it will fail to send if that does not match the number
managed in the kernel for the port in question.
</para>
<para>
You get the current generation number through the bus reset handler. If
you don't set a custom bus reset handler, the default handler will
update the generation number automatically. If you set your own
handler, you can update the generation number to be used through
<function>raw1394_update_generation()</function> directly in the handler
or later.
</para>
</sect1>
<sect1>
<title>Error and Success Codes</title>
<para>
libraw1394 returns the ack/rcode pair in most transaction cases. The
rcode is undefined in cases where the ack code is not equal to
<symbol>ack_pending</symbol>. This is stored in a type
<type>raw1394_errcode_t</type>, from which the ack and rcode parts can
be extracted using two macros.
</para>
<para>
With the function <function>raw1394_errcode_to_errno()</function> it is
possible to convert this to an errno number that conveys roughly the
same meaning. Many developers will find that easier to handle. This is
done automatically for the synchronous read/write/lock wrapper
functions, i.e. they return 0 for success and a negative value for
failure, in which case they also set the <symbol>errno</symbol> variable
to the appropriate code. The raw ack/rcode pair can then still be
retrieved using <function>raw1394_get_errcode()</function>.
</para>
</sect1>
</chapter>
<chapter id="functions">
@ -563,7 +614,7 @@
</refmeta>
<refnamediv>
<refname>raw1394_net_handle</refname>
<refname>raw1394_new_handle</refname>
<refpurpose>create new handle</refpurpose>
</refnamediv>
@ -644,6 +695,87 @@
</refsect1>
</refentry>
<refentry>
<refmeta>
<refentrytitle>raw1394_get_port_info</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>raw1394_get_port_info</refname>
<refpurpose>get information about connected ports</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>int <function>raw1394_get_port_info</function></funcdef>
<paramdef>raw1394handle_t <parameter>handle</parameter></paramdef>
<paramdef>struct raw1394_port_info *<parameter>pinf</parameter></paramdef>
<paramdef>int <parameter>maxports</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>pinf</parameter></term>
<listitem>
<para>Pointer to an array of structure of type
<structname>raw1394_port_info</structname> which will be filled in
by the function.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>maxports</parameter></term>
<listitem>
<para>Maximum number of <parameter>pinf</parameter> structures to
fill in. Zero is valid.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>
The number of ports currently existing.
</para>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Before you can set which port to use, you use this function to find
out which ports exist. The <structname>raw1394_port_info</structname>
structure looks like this:
<programlisting>
struct <structname>raw1394_portinfo</structname> {
int <structfield>nodes</structfield>;
char <structfield>name</structfield>[32];
};
</programlisting>
</para>
<para>
The field <structfield>nodes</structfield> contains the number of
nodes that are currently connected to that port, the field
<structfield>name</structfield> contains the name of the hardware
type. If your program is interactive, you should present the user
with this list to let them decide which port to use. A
non-interactive program (and probably interactive ones, too) should
provide a command line option to choose the port.
</para>
</refsect1>
</refentry>
<refentry>
<refmeta>
<refentrytitle>raw1394_get_fd</refentrytitle>