Getoid - Motorola LA-51XX Driver Programmer's Manual

2-6 LA-51XX Compact Flash Adapter Driver Programmer's Guide
PIMFOR Header Description
Version: The current PIMFOR version.
Operation: The operation is one of the following:
Get and Set are only sent by a PIMFOR sender such as application/ driver; Response, Error, and Trap are only
sent by a PIMFOR receiver i.e. firmware on device. When the operation is Get, the sender asks the receiver
to retrieve the value for the variable specified in the OID field and to send this back in a Response. When the
operation is Set, the sender instructs the receiver to set the variable specified in the OID field to the value
(encoded in an opaque octet string) in the Value field. The Value Length field indicates the length of the octet
string contained in the Value field. There is no type information involved: sender and receiver must be aware
of syntactical and semantic constraints of the OID on which they are operating.
Both Get and Set normally yield a response (Operation is set to Response). For Get, the response contains
the value of the requested OID. For Set, the response is merely an acknowledgment that the set was
successful. There is no new information in the response to a Set; it is identical to the Set, except for the
Operation field. An error is returned in response to a Get or a Set if the receiver cannot process the request
correctly (for example in the case of an unknown OID). A trap is an asynchronous notification from the
firmware on device to alert driver on host to a specific situation or change. The OID and value contained in
the Trap indicate to which variable the notification refers. Reserved is not being used and reserved for future
use.
OID: The OID is a 32-bit value uniquely representing a variable or managed object in a system. There is only
one OID involved in a PIMFOR packet.
Value Length: Value Length indicates the length of the value that follows in the Value field. For a Get, the
Value Length must be greater than or equal to the length of the value (expressed as an octet string) of the
variable that is retrieved. For example, for a variable representing a 32-bit integer, Value Length typically is
four. Value Length can be set to zero for a Get, whereupon the PIMFOR receiver shall return a PIMFOR Error.
In this case however, the PIMFOR receiver sets Value Length to indicate the number of bytes that are
necessary to retrieve the value of that variable. Another request can then be sent using a large enough buffer
to contain the number of bytes required. This can be used for arrays of unknown length or for variable-length
strings. Value: An (opaque) octet string of length Value Length that must be present in each PIMFOR packet.
For a Get, this field must also be present, but it is ignored by a PIMFOR receiver. For Set and Response, this
field contains the value of the variable represented as an octet string. Again, it is implementation-specific
as to how a value of a specific type is converted to an octet string.

2.2.2 Getoid

This section depicts the flow of management (control) information when a getoid is called from the
application running on host to fetch the information from firmware running on host.