SPI Programming Manual (G06.24+, H06.03+, J06.03+)

SPI Concepts and Protocol
SPI Programming Manual—427506-006
2-19
Lists
When so directed, each SPI procedure updates the checksum after any modification of
the buffer. Each time an SPI procedure is called, it first recomputes the checksum and
compares it against the checksum stored in the buffer. If they do not match, the
procedure reports a checksum error, indicating that the buffer has been corrupted
since the last SPI procedure call.
By default, SPI does not calculate buffer checksums. To enable checksum protection,
use SSINIT or SSPUT to set the header token ZSPI-TKN-CHECKSUM to a nonzero
value.
Lists
Lists are used in SPI response messages to organize tokens into logical groups. Lists
appear only in response messages, not in command messages. Lists can be nested—
lists can contain other lists. The four types of lists are:
Normally, to access tokens in a list, a program must select the list token that marks the
beginning of the list. To exit from a list, the program must select the corresponding
ENDLIST token. (The exception is the SSGET NEXTTOKEN special operation.) For
more information about lists, see Working With Lists
on page 5-5.
Data Lists
Data lists are used in response messages to delimit response records. When a
command is applied to more than one object, the tokens describing the results are
returned in data lists, one list for each object. By default, response tokens for a
command that is applied to a single object are not returned in a data list. However,
even in this case a requester can have the response record returned in a data list by
using SSINIT or SSPUT to assign a value of 1 to the header token ZSPI-TKN-
MAXRESP. A data list consists of all tokens between ZSPI-TKN-DATALIST and the
corresponding ZSPI-TKN-ENDLIST.
Error Lists
Error lists contain tokens describing an error that occurred during command
processing. SPI requires that certain information be included in error lists. For a full
description of error list structure and contents, see Errors and Warnings
on page 2-47.
An error list consists of all tokens between ZSPI-TKN-ERRLIST and the corresponding
ZSPI-TKN-ENDLIST.
Data Lists (ZSPI-TKN-DATALIST…ZSPI-TKN-ENDLIST)
Error lists (ZSPI-TKN-ERRLIST…ZSPI-TKN-ENDLIST)
Segment lists (ZSPI-TKN-SEGLIST…ZSPI-TKN-ENDLIST)
Generic Lists (ZSPI-TKN-LIST…ZSPI-TKN-ENDLIST)