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

ZSPI Data Definitions

SPI Programming Manual—427506-006

4-45

Token Length

The second part of the token code is the token length. For fixed-length token values up

to 254 bytes long, this field gives the length of the token value in bytes. When the

value of this field is 255, the token value is either variable length or a fixed length

greater than 254 bytes. When the fixed length is greater than 254, the actual length is

supplied in a succeeding word. The special operator ZSPI-TKN-LEN returns the token

length. For a variable-length token, the actual length is in the first 16 bits of the token

value. To protect against overwriting data, check the length of a variable-length token

before calling SSGET to retrieve it.

ZSPI-TLN-VARIABLE

ZSPI-TLN-VARIABLE is the token-length value 255 that indicates a variable-length

token or a token longer than 254 bytes.

Command Numbers

Basic SPI defines a single command number, ZSPI-CMD-GETVERSION, for the

GETVERSION command. Any additional commands must be defined by a subsystem

or drawn from some other common source, such as the SPI common extensions

ZCOM definitions described in the

SPI Common Extensions Manual

ZSPI-CMD-GETVERSION

ZSPI-CMD-GETVERSION is the command number for the GETVERSION command.

Its value is zero. Subsystems use this value to define the command number for their

GETVERSION commands.

Object-Type Numbers

Basic SPI does not define any object-type numbers. However, SPI does require that

subsystems use the number 0 to represent the null object type, which is used in

commands when it is either unnecessary or inappropriate to specify a particular object

type. (SPI defines ZSPI-VAL-NULL-OBJECT-TYPE for this purpose. See

Miscellaneous Values

on page 4-47.) All other object types must be defined by a

subsystem or drawn from some other common source, like the SPI common

extensions ZCOM definitions described in the

SPI Common Extensions Manual.

constant ZSPI-TLN-VARIABLE value is 255.

constant ZSPI-CMD-GETVERSION value is 0.