/** * Initialize the processor's registers in preparation for running the program loaded into this * process. Set the PC register to point at the start function, set the stack pointer register to * point at the top of the stack, set the A0 and A1 registers to argc and argv, respectively, and * initialize all other registers to 0. */ public void initRegisters() { Processor processor = Machine.processor(); // by default, everything's 0 for (int i = 0; i < processor.numUserRegisters; i++) processor.writeRegister(i, 0); // initialize PC and SP according processor.writeRegister(Processor.regPC, initialPC); processor.writeRegister(Processor.regSP, initialSP); // initialize the first two argument registers to argc and argv processor.writeRegister(Processor.regA0, argc); processor.writeRegister(Processor.regA1, argv); }
/** * Handle a user exception. Called by <tt>UserKernel.exceptionHandler()</tt>. The <i>cause</i> * argument identifies which exception occurred; see the <tt>Processor.exceptionZZZ</tt> * constants. * * @param cause the user exception that occurred. */ public void handleException(int cause) { Processor processor = Machine.processor(); switch (cause) { case Processor.exceptionSyscall: int result = handleSyscall( processor.readRegister(Processor.regV0), processor.readRegister(Processor.regA0), processor.readRegister(Processor.regA1), processor.readRegister(Processor.regA2), processor.readRegister(Processor.regA3)); processor.writeRegister(Processor.regV0, result); processor.advancePC(); break; default: Lib.debug(dbgProcess, "Unexpected exception: " + Processor.exceptionNames[cause]); handleExit(-1); Lib.assertNotReached("Unexpected exception"); } }
public void handleTLBMiss() { int vaddr = Machine.processor().readRegister(Processor.regBadVAddr); int vpn = Processor.pageFromAddress(vaddr); allocatePage(vpn); }