Package mars.mips.instructions.syscalls

Class AbstractSyscall

java.lang.Object
mars.mips.instructions.syscalls.AbstractSyscall
All Implemented Interfaces:
Syscall
Direct Known Subclasses:
SyscallClose, SyscallConfirmDialog, SyscallExit, SyscallExit2, SyscallInputDialogDouble, SyscallInputDialogFloat, SyscallInputDialogInt, SyscallInputDialogString, SyscallMessageDialog, SyscallMessageDialogDouble, SyscallMessageDialogFloat, SyscallMessageDialogInt, SyscallMessageDialogString, SyscallMidiOut, SyscallMidiOutSync, SyscallOpen, SyscallPrintChar, SyscallPrintDouble, SyscallPrintFloat, SyscallPrintInt, SyscallPrintIntBinary, SyscallPrintIntHex, SyscallPrintIntUnsigned, SyscallPrintString, SyscallRandDouble, SyscallRandFloat, SyscallRandInt, SyscallRandIntRange, SyscallRandSeed, SyscallRead, SyscallReadChar, SyscallReadDouble, SyscallReadFloat, SyscallReadInt, SyscallReadString, SyscallSbrk, SyscallSleep, SyscallTime, SyscallWrite
public abstract class AbstractSyscall extends Object implements Syscall
Abstract class that a MIPS syscall system service may extend. A qualifying service must be a class in the mars.mips.instructions.syscalls package that implements the Syscall interface, must be compiled into a .class file, and its .class file must be in the same folder as Syscall.class. Mars will detect a qualifying syscall upon startup, create an instance using its no-argument constructor and add it to its syscall list. When its service is invoked at runtime ("syscall" instruction with its service number stored in register $v0), its simulate() method will be invoked.

  • Constructor Details

    • AbstractSyscall

      public AbstractSyscall​(int number, String name)
      Constructor is provided so subclass may initialize instance variables.
      Parameters:
      number - default assigned service number
      name - service name which may be used for reference independent of number

  • Method Details

    • getName

      public String getName()
      Return the name you have chosen for this syscall. This can be used by a MARS user to refer to the service when choosing to override its default service number in the configuration file.
      Specified by:
      getName in interface Syscall
      Returns:
      service name as a string

    • setNumber

      public void setNumber​(int num)
      Set the service number. This is provided to allow MARS implementer or user to override the default service number.
      Specified by:
      setNumber in interface Syscall
      Parameters:
      num - specified service number to override the default.

    • getNumber

      public int getNumber()
      Return the assigned service number. This is the number the MIPS programmer must store into $v0 before issuing the SYSCALL instruction.
      Specified by:
      getNumber in interface Syscall
      Returns:
      assigned service number

    • simulate

      public abstract void simulate​(ProgramStatement statement) throws ProcessingException
      Performs syscall function. It will be invoked when the service is invoked at simulation time. Service is identified by value stored in $v0.
      Specified by:
      simulate in interface Syscall
      Parameters:
      statement - ProgramStatement object for this syscall instruction.
      Throws:
      ProcessingException