Predefined Constants in SPL

SPL constants defining the call addresses for Interrupts/Exceptions/Modules

Name	Default Value	Comments
EX_HANDLER / EXCEPTION	1024	Starting address of Exception Handler
TIMER	2048	Starting address of Timer Interrupt Routine
DISK	3072	Starting address of Disk Controller Interrupt Routine
CONSOLE	4096	Starting address of Console Interrupt Routine
INT_4	5120	(Create, 1)*, (Delete, 4)
INT_5	6144	(Seek, 6), (Open, 2), (Close,3)
INT_6	7168	(Read, 7)
INT_7	8192	(Write, 5)
INT_8	9216	(Fork, 8)
INT_9	10240	(Exec, 9)
INT_10	11264	(Exit, 10)
INT_11	12288	(Getpid, 11), (Getppid, 12), (Wait, 13), (Signal, 14)
INT_12	13312	(Logout, 28)
INT_13	14336	(Semget, 17), (Semrelease, 18)
INT_14	15360	(SemLock, 19), (SemUnLock, 20)
INT_15	16384	(Shutdown, 21)
INT_16	17408	(Newusr, 22), (Remusr, 23), (Setpwd, 24), (Getuname, 25), (Getuid, 26)
INT_17	18432	(Login, 27)
INT_18	19456	(Test0, 96), (Test1, 97), (Test2, 98), (Test3, 99)
MOD_0 / RESOURCE_MANAGER	20480	Resource Manager
MOD_1 / PROCESS_MANAGER	21504	Process Manager
MOD_2 / MEMORY_MANAGER	22528	Memory Manager
MOD_3 / FILE_MANAGER	23552	File Manager
MOD_4 / DEVICE_MANAGER	24576	Device Manager
MOD_5 / CONTEXT_SWITCH / SCHEDULER	25600	Context Switch Module (Scheduler Module)
MOD_6 / PAGER_MODULE	26624	Pager Module
MOD_7 / BOOT_MODULE	27648	Boot Module

*(System Call Name, System Call Number)

SPL constants for the System Call Numbers

Name	System Call Number	Comments
INT_CREATE	1	Create System Call
INT_OPEN	2	Open System Call
INT_CLOSE	3	Close System Call
INT_DELETE	4	Delete System Call
INT_WRITE	5	Write System Call
INT_SEEK	6	Seek System Call
INT_READ	7	Read System Call
INT_FORK	8	Fork System Call
INT_EXEC	9	Exec System Call
INT_EXIT	10	Exit System Call
INT_GETPID	11	Getpid System Call
INT_GETPPID	12	Getppid System Call
INT_WAIT	13	Wait System Call
INT_SIGNAL	14	Signal System Call
INT_SEMGET	17	Semget System Call
INT_SEMRELEASE	18	Semrelease System Call
INT_SEMLOCK	19	SemLock System Call
INT_SEMUNLOCK	20	SemUnLock System Call
INT_SHUTDOWN	21	Shutdown System Call
INT_NEWUSR	22	Newusr System Call
INT_REMUSR	23	Remusr System Call
INT_SETPWD	24	Setpwd System Call
INT_GETUNAME	25	Getuname System Call
INT_GETUID	26	Getuid System Call
INT_LOGIN	27	Login System Call
INT_LOGOUT	28	Logout System Call
INT_TEST0	96	Test System Call 0
INT_TEST1	97	Test System Call 1
INT_TEST2	98	Test System Call 2
INT_TEST3	99	Test System Call 3

SPL constants for indicating the Function Numbers in Modules

Name	Default Value	Comments
ACQUIRE_BUFFER	1	Resource Manager Function #1
RELEASE_BUFFER	2	Resource Manager Function #2
ACQUIRE_DISK	3	Resource Manager Function #3
ACQUIRE_INODE	4	Resource Manager Function #4
RELEASE_INODE	5	Resource Manager Function #5
ACQUIRE_SEMAPHORE	6	Resource Manager Function #6
RELEASE_SEMAPHORE	7	Resource Manager Function #7
ACQUIRE_TERMINAL	8	Resource Manager Function #8
RELEASE TERMINAL	9	Resource Manager Function #9
GET_PCB_ENTRY	1	Process Manager Function #1
FREE_USER_AREA_PAGE	2	Process Manager Function #2
EXIT_PROCESS	3	Process Manager Function #3
FREE_PAGE_TABLE	4	Process Manager Function #4
KILL_ALL	5	Process Manager Function #5
GET_FREE_PAGE	1	Memory Manager Function #1
RELEASE_PAGE	2	Memory Manager Function #2
GET_FREE_BLOCK	3	Memory Manager Function #3
RELEASE_BLOCK	4	Memory Manager Function #4
GET_CODE_PAGE	5	Memory Manager Function #5
GET_SWAP_BLOCK	6	Memory Manager Function #6
BUFFERED_WRITE	1	File Manager Function #1
BUFFERED_READ	2	File Manager Function #2
OPEN	3	File Manager Function #3
CLOSE	4	File Manager Function #4
DISK_STORE	1	Device Manager Function #1
DISK_LOAD	2	Device Manager Function #2
TERMINAL_WRITE	3	Device Manager Function #3
TERMINAL_READ	4	Device Manager Function #4
SWAP_OUT	1	Pager Module Function #1
SWAP_IN	2	Pager Module Function #2

SPL constants for indicating the starting addresses of Kernel Data Structures in Memory (See Memory Organisation)

Name	Default Value	Comments
PROCESS_TABLE	28672	Starting address of Process Table
OPEN_FILE_TABLE	28928	Starting address of Open File Table
SEMAPHORE_TABLE	29056	Starting address of Semaphore Table
MEMORY_FREE_LIST	29184	Starting address of Memory Free List
FILE_STATUS_TABLE	29312	Starting address of File Status Table
DISK_STATUS_TABLE	29552	Starting address of Disk Status Table
SYSTEM_STATUS_TABLE	29560	Starting address of System Status Table
TERMINAL_STATUS_TABLE	29568	Starting address of Terminal Status Table
PAGE_TABLE_BASE	29696	Starting address of Page tables
BUFFER_TABLE	30016	Starting address of Buffer Table
DISK_MAP_TABLE	30032	Starting address of Disk Map Table
INODE_TABLE	30208	Starting address of Inode Table
USER_TABLE	31168	Starting address of User Table
DISK_FREE_LIST	31232	Starting address of Disk Free List
ROOT_FILE	31744	Starting address of Root File
BUFFER	36352	Starting address of Buffer Cache
BUFFER_BASE	71	Starting page number of Buffer Cache

SPL constants for related to User Programs loaded by the Kernel to Memory (See Memory Organisation)

Name	Default Value	Comments
LIBRARY	32256	Starting address of eXpOS Library
INIT / LOGIN	33280	Starting address of INIT/Login Program
SHELL	34304	Starting address of Shell Program
IDLE / SWAPPER	35328	Starting address of Idle/Swapper Program
IDLE_PROCESS	0	PID of the Idle Process
INIT_PROCESS / LOGIN_PROCESS	1	PID of the Init/Login Proces
SHELL_PROCESS	2	PID of the Shell
SWAPPER_DAEMON	15	PID of the Swapper Daemon

SPL constants for indicating the Process States

Name	Default Value	Comments
READY	1	Process State READY
RUNNING	2	Process State RUNNING
CREATED	3	Process State CREATED
TERMINATED	4	Process State TERMINATED
WAIT_DISK	5	Process is waiting to acquire disk
WAIT_FILE	6	Process is waiting for release on an Inode
WAIT_BUFFER	7	Process is waiting for release of buffer cache
WAIT_TERMINAL	8	Process is waiting to acquire terminal
WAIT_PROCESS	9	Process is waiting for a signal from another process
WAIT_SEMAPHORE	10	Process is waiting to acquire a semaphore
WAIT_MEM	11	Process is waiting as memory is not available
ALLOCATED	12	Process Table entry has been allocated for the process, but process creation is not complete

SPL constants identifying the File Type/Permission in Inode Table

Name	Default Value	Comments
EXCLUSIVE	0	EXCLUSIVE file permission
OPEN_ACCESS	1	OPEN ACCESS file permission
ROOT	1	Indicates that the file is the root file
DATA	2	Indicates that the file is a data file
EXEC	3	Indicates that the file is an executable file

SPL constants related to Per-process Resource Table

Name	Default Value	Comments
FILE	0	Indicates that the resource is a file in the resource table
SEMAPHORE	1	Indicates that the resource is a semaphore in the resource table
RESOURCE_TABLE_OFFSET	496	Offset of the Resource Table from the start of user area page

SPL constants related to Swapping

Name	Default Value	Comments
MEM_LOW	4	Memory is critically low so that swap out has to be initiated
MEM_HIGH	12	Memory is high enough such that a process can be swapped in
MAX_TICK	1000	Indicates the threshold after which a swapped out process must be swapped back in

SPL constants related to eXpFS Disk (See Disk Origanisation)

Name	Default Value	Comments
XFS_BSIZE	512	Number of words in a disk block
MAX_FILE_BLOCKS	4	Maximum number of blocks allocatable to each file.
DISK_SWAP_AREA	256	Starting block number of Swap Area in the disk
DISK_FREE_AREA	69	Starting block number of User Block area in the disk
DISK_SIZE	512	Number of blocks in the disk

SPL constants defining the maximum limits

Name	Default Value	Comments
PAGE_SIZE	512	Size of a memory page in eXpOS
NUM_MEM_PAGES	128	Number of memory pages in eXpOS
MAX_PROC_NUM	16	Max. number of process allowed by eXpOS
PT_ENTRY_SIZE	16	Size of one page table entry
MAX_OPENFILE_NUM	32	Max. number of open files allowed by eXpOS
MAX_MEM_PAGE	128	Max. number of memory pages availble to eXpOS
MAX_SEM_COUNT	32	Max. number of semaphores allowed by eXpOS
MAX_PROC_PAGES	10	Max. number of pages allowed for each process
MAX_BUFFER	4	Max. number of file read/write buffers in eXpOS
MAX_FILE_NUM	60	Max. number of files possible
MAX_FILE_SIZE	2048	Max. words in a file
MAX_USER_NUM	16	Max. number of users allowed

Miscellaneous Constants

Name	Default Value	Comments
INODE_ROOT	0	Inode Index field of the Open File Table is set to INODE_ROOT if the file is the Root file.
KERNEL	0	Indicates the Kernel user in the CURRENT_USER_ID field of the System Status Table
ZERO	0	Zero
ONE	1	One

Constants for NEXSM

Name	Default Value	Comments
OS_SECONDARY	65536	Starting address of OS Startup code for secondary core.
INT_19	66560	(Test4, 100), (Test5, 101), (Test6, 102), (Test7, 103)
MOD_8 / ACCESS_CONTROL	67584	Access Control Module
MOD_9 / TESTA	68608	TestA (Reserved for Future use)
MOD_10 / TESTB	69632	TestB (Reserved for Future use)
MOD_11 / TESTC	70656	TestC (Reserved for Future use)
IDLE2_PROCESS	14	PID of the Idle Process for secondary core
INT_TEST4	100	Test System Call 4
INT_TEST5	101	Test System Call 5
INT_TEST6	102	Test System Call 6
INT_TEST7	103	Test System Call 7
ACQUIRE_KERN_LOCK	1	Access Control Module Function #1
ACQUIRE_SCHED_LOCK	2	Access Control Module Function #2
ACQUIRE_GLOCK	3	Access Control Module Function #3
RELEASE_LOCK	4	Access Control Module Function #4
PRIMARY_CORE	0	Indicates that the current core is primary core
SECONDARY_CORE	1	Indicates that the current core is secondary core
ACCESS_LOCK_TABLE	29576	Starting address of Access Lock Table
KERN_LOCK	29576	Kernel Lock
SCHED_LOCK	29577	Scheduler Lock
GLOCK	29578	General Purpose Lock
NUM_MEM_PAGES *	144	Number of memory pages in eXpOS
DISK_SIZE *	528	Number of blocks in the disk

*These constants are redefined.