User`s guide

42 DC 900-1516D
ICP2432 User’s Guide for OpenVMS Alpha (DLITE Interface)
• dlWrite
Using non-blocking I/O, a successful operation returns OK, and dlerrno has the value of
EWOULDBLOCK. The application is notified of I/O completion through the I/O com-
pletion handler (IOCH). The completed I/O operation is retrieved using a
dlPoll request
for read/write complete. See Section 3.3.2.5 on page 48 for more information on call-
backs and I/O completion.
3.3.2.3 Changes in DLI/TSI
The lack of a network connection has eliminated the need for some of the client/server
communications between the current DLI and TSI. While the user buffer is not affected,
some data previously in the DLI header (i.e. the Freeway header) and the TSI header is
no longer built by the API. These changes are transparent to the user but may be noted
when examining DLITE trace files.
3.3.2.4 Changes in DLI Functions
No changes are required in the user interface to DLI. Some DLI functions have changed
in their implementation, which might affect the user’s expected behavior of the func-
tion. Changes in the affected functions are described below.
dlBufAlloc
Implementation of buffer allocation has changed. Rather than allocating buffers from a
pre-allocated buffer pool managed by TSI, buffer allocation requests presented to
DLITE (using
dlBufAlloc) invoke VMS system memory services to allocate buffers
(using
malloc calls). Do not assume any type of buffer initialization. Also, the size
requested in
dlBufAlloc can be thought of as the size requested from the system (the
actual size is somewhat larger, which includes some DLITE overhead requirements). If
the application requests one byte for the data buffer size, it should assume only one byte
is returned.