Intel EP80579 Benutzerhandbuch

Intel

®

 EP80579 Software for Security Applications on Intel

®

 QuickAssist Technology

PG

August 2009

46

Order Number: 320183-004US

• There is a 1:1 relationship between an asynchronous request call and a completion 

callback (response). 

 allows for 1:N relationships here. The complexity 

associated with managing multiple responses per callback was judged to outweigh 

the potential performance benfit of coalescing responses. As a result of this:

— There is only one asynchronous response per callback.
— There is no need for an overall status.
— There is no need for the callback data to contain a number/array of 

asynchronous responses.

For a summary of what is contained within this callback data structure, see 

.

Note that the context in which callbacks are invoked is described in 

.

, Section 6.4, briefly discusses memory ownership. To make the issue clearer, 

the following conventions have been adopted.

For all output parameters on asynchronous API functions, the following memory 

allocation model applies:

• Memory should be allocated by the client
• The memory is passed into the Acceleration API function as a pointer.
• The pointer is returned in the callback data structure, which is a parameter to the 

completion callback function. 

• Memory should be freed by the client.

This means that ownership is temporarily granted to the asynchronous API 

implementation, and reverts to the client only after the function completion callback 

function is invoked. See 

 for details.

In some of the EP80579 security software APIs, there are numerous input and output 

parameters, and/or multiple parameters within a single data structure, some of which 

are inputs and some of which are outputs. To make the memory ownership clear in 

these cases, all memory for which ownership is temporarily granted to the API 

implementation should be grouped into a single data structure. By convention, this 

data structure has the suffix “_op_data_t” (for operation data). 

Where there is a single output parameter, this struct is typically not created.

Any exceptions to this model are documented by the corresponding APIs. For example, 

in some cases, the ownership of a data structure is retained by the API implementation 

even after the function completion callback has been invoked.  

The function completion callback function takes the following parameters:

• Correlator (discussed in 

)

• Callback data structure, which contains the following information:

— Status of the requested operation