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Add some information about return values. 

git-svn-id: svn://svn.linux1394.org/libraw1394/trunk@45 53a565d1-3bb7-0310-b661-cf11e63c67ab
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aeb 2000-11-25 01:58:34 +00:00
parent f1b4b5e18f
commit 02154eb2c2
1 changed files with 29 additions and 3 deletions
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32
README
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@ -28,8 +28,34 @@ files.
3. API documentation
There is currently no external document describing the library functions,
but you can find documentation for all functions in the header file raw1394.h.
There is currently no external document describing the library
functions, but you can find documentation for all functions in the header file
raw1394.h. Some real documentation will come Real Soon Now.
To clear up some confusion (it wasn't documented before, what was I
thinking), here is a description of the return values of the
raw1394_(read|write|lock) functions and also the errcode parameter of
tag_handler_t or reeqhandler_t:
If it is negative it signals an error in handling the request locally
(1394 target node not reached) and errno contains a Unix error code just like
with other library functions. If it is positive it still does not signal
success of the request itself, just that it was properly communicated to the
1394 target node. To know whether it succeeded the lower 32 bits have to be
further decoded.
The upper 16 bits contain the acknowledge code from the other node, the
lower 16 bits the response code. Both of these codes are the standard codes
from the 1394 standard with the exception of 0x10 for the ack which is set on an
access to the local node (there is no 1394 bus involved and therefore no ack
exists). Most of the acks completely determine the success of the request
(ack_complete or one of the error codes). The response code has to be
interpreted if the ack is ack_pending or the dummy ack 0x10. Only in this case
is the response code valid.
This way of reporting errors will be replaced by a more sensible
approach with (one of the, but hopefully) the next version of libraw.
Documented here only for those who can't wait.
4. Multithreading
@ -51,4 +77,4 @@ http://sourceforge.net/project/?group_id=2514 for more information. You can
also submit bugs through this page.
2000-03-18 Andreas Bombe
2000-11-25 Andreas Bombe