
UDI Services
3-12
Universal Debugger Interface Specification
As a special case, bit 31 of the DFEIPCId and TIPIPCId parameters are
used to indicate the endianness of the DFE or TIP. Bit 31 set indicates a
little-endian DFE or TIP, Bit 31 clear indicates a big-endian DFE or TIP.
At the procedural interface, a DFE or TIP usually need only be concerned
with the endianness of the other side for vendor-specific extensions where
non-byte quantities are being sent.
The
DFE
parameter indicates to the TIP what version of UDI the DFE prefers,
i.e., the latest version number the DFE understands. The TIP examines the
DFE’s UDI version and determines whether it can support that version. If the
TIP is capable of supporting the DFE at the DFE’s preferred UDI level, the
TIP returns that level in the TIP parameter. If the TIP’s UDI version is lower
than the DFE’s, the TIP returns the TIP’s version in the TIP parameter. If the
TIP’s UDI version is higher than the DFE’s, but the TIP cannot support
obsolete features of the DFE’s version, the TIP returns 0 in the
TIP
parameter.
Upon returning, the DFE should examine the TIP’s UDI version. If the TIP’s
UDI version is the same as the DFE’s, communication can take place without
problems. If the TIP’s UDI version is 0, the DFE should immediately
disconnect because further communication is unlikely. If the TIP’s UDI
version is other than 0 or the DFE’s version, the DFE can communicate with
the TIP at the TIP’s level.
The
TIPString
parameter is a buffer of
BufSize
characters that the TIP fills
with information that may further modify the TIP identification information,
setting
CountDone
to the number of bytes (including the null terminator)
returned. A typical example of the kind of information returned in TIPString
would be a human-readable listing of the TIP and/or target’s configuration. If
CountDone
is equal to
BufSize
, the DFE should continue calling
UDICapabilities
to get the rest of the
TIPString
. It is recommended that DFEs
provide a
TIPString
buffer of at least 1Kbyte to avoid multiple calls to the TIP.
The TIP is allowed to have embedded end–of–line characters in the returned
TIPString
. It is recommended that DFEs display this information on a line by
itself immediately following a line where the various
Id
fields have been
displayed.