T-Kernel Specification (1.B0.02)

5.7. SYSTEM CONFIGURATION INFORMATION MANAGEMENT FUNCTIONS 253
5.7 System Configuration Information Management Functions
System configuration information management functions are provided for storing, managing and making
available information about the system configuration (maximum number of tasks, etc.) and any other
information. These are not functions for adding or modifying information when the system is running.
How the system configuration information is to be stored is not specified here, but it is generally put
in memory (ROM/RAM). This functionality is therefore not intended for storing large amounts of
information.
Standard definitions are specified for some system configuration information, but additional information
may be defined and used for applications, subsystems, or device drivers.
The format of system configuration information consists of a name and defined data as a set.
• Name
The name is a string of up to 16 characters.
Characters that can be used (UB) are a to z, A to Z, 0 to 9 and
(underbar).
• Defined data
Data consists of numbers (integers) or character strings.
Characters that can be used (UB) are any characters other than 0x00 to 0x1F, 0x7F, or 0 xFF
(character codes).
Sample:
Name Defined Data
SysVer 1 0
SysName T-Kernel Version 1.00
5.7.1 System Configuration Information Acquisition
System configuration information is acquired by using extended SVC. This function is used inside T-
Kernel, and can also be used by applications, subsystems, device drivers and so on. Use inside T-Kernel
does not have to go through extended SVC; this choice is implementation-dependent.
• INT tk_get_cfn( UB *name, INT *val, INT max )
name
val
max
return code
Name
Array storing numeric strings
Number of elements in val array
Defined numeric information count or error
Gets numeric string information from system configuration information. This function gets up to
max items of numerical string information defined by the name designated in the name parameter
and stores the acquired information in val. The number of items of defined numeric string
information is passed in the return code. If return code > max, this indicates that not all the
information could be stored. By designating max = 0, the number of numeric strings can be found
out without actually storing them in val.
E NOEXS is returned if no information is defined with the name designated in the name parameter.
The behavior if the information defined as name is a character string is indeterminate.
This function can be invoked from any protection level, without being limited by the protection
level from which T-Kernel/OS system call can be invoked.
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T-Kernel 1.B0.02