header Kernel uses System, List, BitMap const SYSTEM_STACK_SIZE = 1000 -- in words STACK_SENTINEL = 0x24242424 -- in ASCII, this is "$$$$" -- The kernel code will load into the first megabyte of physical memory. This -- should be more than enough. We will use the second megabyte for page frames. -- Thus, the frame region is 128 page frames of 8K each. PAGE_SIZE = 8192 -- in hex: 0x0000 2000 PHYSICAL_ADDRESS_OF_FIRST_PAGE_FRAME = 1048576 -- in hex: 0x0010 0000 --NUMBER_OF_PHYSICAL_PAGE_FRAMES = 512 -- in hex: 0x0000 0200 NUMBER_OF_PHYSICAL_PAGE_FRAMES = 27 -- for testing only MAX_NUMBER_OF_PROCESSES = 10 MAX_STRING_SIZE = 20 MAX_PAGES_PER_VIRT_SPACE = 20 MAX_FILES_PER_PROCESS = 10 MAX_NUMBER_OF_FILE_CONTROL_BLOCKS = 10 MAX_NUMBER_OF_OPEN_FILES = 10 USER_STACK_SIZE_IN_PAGES = 1 NUMBER_OF_ENVIRONMENT_PAGES = 0 SERIAL_IN_BUFFER_SIZE = 10 SERIAL_OUT_BUFFER_SIZE = 10 enum JUST_CREATED, READY, RUNNING, BLOCKED, UNUSED -- Thread status enum ENABLED, DISABLED -- Interrupt status enum FILE, TERMINAL, PIPE -- Kinds of OpenFile -- Syscall code numbers for kernel interface routines -- NOTE: These codes must exactly match an identical enum in UserSystem.h enum SYSCALL_EXIT = 1, SYSCALL_SHUTDOWN, SYSCALL_YIELD, SYSCALL_FORK, SYSCALL_JOIN, SYSCALL_EXEC, SYSCALL_CREATE, SYSCALL_OPEN, SYSCALL_READ, SYSCALL_WRITE, SYSCALL_SEEK, SYSCALL_CLOSE enum ACTIVE, ZOMBIE, FREE -- Status of a ProcessControlBlock var readyList: List [Thread] currentThread: ptr to Thread mainThread: Thread = new Thread idleThread: Thread = new Thread threadsToBeDestroyed: List [Thread] currentInterruptStatus: int processManager: ProcessManager threadManager: ThreadManager frameManager: FrameManager --diskDriver: DiskDriver --serialDriver: SerialDriver --fileManager: FileManager functions -- These routines are called from the Runtime.s assembly code when -- the corresponding interrupt/syscall occurs: TimerInterruptHandler () DiskInterruptHandler () SerialInterruptHandler () IllegalInstructionHandler () ArithmeticExceptionHandler () AddressExceptionHandler () PageInvalidExceptionHandler () PageReadonlyExceptionHandler () PrivilegedInstructionHandler () AlignmentExceptionHandler () SyscallTrapHandler (syscallCodeNum, arg1, arg2, arg3, arg4: int) returns int -- These routines are invoked when a kernel call is made: Handle_Sys_Fork () returns int Handle_Sys_Yield () Handle_Sys_Exec (filename: ptr to array of char) returns int Handle_Sys_Join (processID: int) returns int Handle_Sys_Exit (returnStatus: int) Handle_Sys_Create (filename: String) returns int Handle_Sys_Open (filename: String) returns int Handle_Sys_Read (fileDesc: int, buffer: ptr to char, sizeInBytes: int) returns int Handle_Sys_Write (fileDesc: int, buffer: ptr to char, sizeInBytes: int) returns int Handle_Sys_Seek (fileDesc: int, newCurrentPos: int) returns int Handle_Sys_Close (fileDesc: int) Handle_Sys_Shutdown () InitializeScheduler () Run (nextThread: ptr to Thread) PrintReadyList () ThreadStart () ThreadFinish () FatalError_ThreadVersion (errorMessage: ptr to array of char) SetInterruptsTo (newStatus: int) returns int ProcessFinish (exitStatus: int) -- Routines from Switch.s: external Switch (prevThread, nextThread: ptr to Thread) external ThreadStartUp () external GetOldUserPCFromSystemStack () returns int external LoadPageTableRegs (ptbr, ptlr: int) -- Execute "LDPTBR" and "LDPTLR" external SaveUserRegs (p: ptr to int) -- Execute "readu" instructions external RestoreUserRegs (p: ptr to int) -- Execute "writeu" instructions -- The following routine sets the "InterruptsEnabled" bit, sets the -- "PagingEnabled" bit, clears the "SystemMode" bit, and jumps to the -- address given by "initPC". external BecomeUserThread (initStack, initPC, initSystemStack: int) --------------- Semaphore --------------- class Semaphore superclass Object fields count: int waitingThreads: List [Thread] methods Init (initialCount: int) Wait () Signal () endClass --------------- Mutex --------------- class Mutex superclass Object fields heldBy: ptr to Thread -- Null means this mutex is unlocked. waitingThreads: List [Thread] methods Init () Lock () Unlock () IsHeldByCurrentThread () returns bool endClass --------------- Condition --------------- class Condition superclass Object fields waitingThreads: List [Thread] methods Init () Wait (mutex: ptr to Mutex) Signal (mutex: ptr to Mutex) Broadcast (mutex: ptr to Mutex) endClass --------------- Thread --------------- class Thread superclass Listable fields -- The first two fields are at fixed offsets, hardwired into Switch! regs: array [13] of int -- Space for r2..r14 stackTop: ptr to void -- Space for r15 (system stack top ptr) name: ptr to array of char status: int -- JUST_CREATED, READY, RUNNING, BLOCKED, UNUSED systemStack: array [SYSTEM_STACK_SIZE] of int isUserThread: bool userRegs: array [15] of int -- Space for r1..r15 myProcess: ptr to ProcessControlBlock methods Init (n: ptr to array of char) Fork (fun: ptr to function (int), arg: int) Yield () Sleep () CheckOverflow () Print () endClass ----------------------------- ThreadManager --------------------------------- -- -- There is only one instance of this class, created at startup time. -- class ThreadManager superclass Object fields threadTable: array [MAX_NUMBER_OF_PROCESSES] of Thread freeList: List [Thread] methods Init () Print () GetANewThread () returns ptr to Thread FreeThread (th: ptr to Thread) endClass ----------------------------- ProcessControlBlock --------------------------------- -- -- There are a fixed, preset number of these objects, which are created at -- startup and are kept in the array "ProcessManager.processTable". When -- a process is started, a ProcessControlBlock is allocated from this -- array and the state of the process is kept in this object. -- class ProcessControlBlock superclass Listable fields pid: int -- The process ID parentsPid: int -- The pid of the parent of this process status: int -- ACTIVE, ZOMBIE, or FREE myThread: ptr to Thread -- Each process has one thread exitStatus: int -- The value passed to Sys_Exit addrSpace: AddrSpace -- The logical address space -- fileDescriptor: array [MAX_FILES_PER_PROCESS] of ptr to OpenFile methods Init () Print () PrintShort () endClass ----------------------------- ProcessManager --------------------------------- -- -- There is only one instance of this class, created at startup time. -- class ProcessManager superclass Object fields processTable: array [MAX_NUMBER_OF_PROCESSES] of ProcessControlBlock processManagerLock: Mutex -- These synchronization objects aProcessBecameFree: Condition -- apply to the "freeList" freeList: List [ProcessControlBlock] aProcessDied: Condition -- Signalled for new ZOMBIEs nextPid: int methods Init () Print () PrintShort () GetANewProcess () returns ptr to ProcessControlBlock FreeProcess (p: ptr to ProcessControlBlock) --TurnIntoZombie (p: ptr to ProcessControlBlock) --WaitForZombie (proc: ptr to ProcessControlBlock) returns int endClass ----------------------------- FrameManager --------------------------------- -- -- There is only one instance of this class. -- class FrameManager superclass Object fields framesInUse: BitMap numberFreeFrames: int frameManagerLock: Mutex newFramesAvailable: Condition methods Init () Print () GetAFrame () returns int -- returns addr of frame GetNewFrames (aPageTable: ptr to AddrSpace, numFramesNeeded: int) ReturnAllFrames (aPageTable: ptr to AddrSpace) endClass ----------------------------- AddrSpace --------------------------------- -- -- There is one instance for every virtual address space. -- class AddrSpace superclass Object fields numberOfPages: int pageTable: array [MAX_PAGES_PER_VIRT_SPACE] of int methods Init (numPages: int) Print () ExtractFrameAddr (entry: int) returns int ExtractUndefinedBits (entry: int) returns int SetFrameAddr (entry: int, frameAddr: int) IsDirty (entry: int) returns bool SetDirty (entry: int) IsReferenced (entry: int) returns bool IsWritable (entry: int) returns bool IsValid (entry: int) returns bool SetWritable (entry: int) ClearWritable (entry: int) SetValid (entry: int) ClearValid (entry: int) SetToThisPageTable () CopyBytesFromVirtual (kernelAddr, virtAddr, numBytes: int) returns int CopyBytesToVirtual (virtAddr, kernelAddr, numBytes: int) returns int GetStringFromVirtual (kernelAddr: String, virtAddr, maxSize: int) returns int endClass endHeader