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machine.h File Reference

#include "copyright.h"
#include "utility.h"
#include "translate.h"

Go to the source code of this file.

Compounds
class	Machine
	The following class defines the simulated host workstation hardware, as seen by user programs -- the CPU registers, main memory, etc. User programs shouldn't be able to tell that they are running on our simulator or on the real hardware, except we don't support floating point instructions the system call interface to Nachos is not the same as UNIX (10 system calls in Nachos vs. 200 in UNIX!) If we were to implement more of the UNIX system calls, we ought to be able to run Nachos on top of Nachos! The procedures in this class are defined in machine.cc, mipssim.cc, and translate.cc. More...
Defines
#define	StackReg   29
	User's stack pointer. More...
#define	RetAddrReg   31
	Holds return address for procedure calls. More...
#define	NumGPRegs   32
	32 general purpose registers on MIPS. More...
#define	HiReg   32
	Double register to hold multiply result. More...
#define	LoReg   33
#define	PCReg   34
	Current program counter. More...
#define	NextPCReg   35
	Next program counter (for branch delay). More...
#define	PrevPCReg   36
	Previous program counter (for debugging). More...
#define	LoadReg   37
	The register target of a delayed load. More...
#define	LoadValueReg   38
	The value to be loaded by a delayed load. More...
#define	BadVAddrReg   39
	The failing virtual address on an exception. More...
#define	NumTotalRegs   40
Enumerations
enum	ExceptionType {   NoException, SyscallException, PageFaultException, ReadOnlyException,   BusErrorException, AddressErrorException, OverflowException, IllegalInstrException,   NumExceptionTypes }
Functions
void	ExceptionHandler (ExceptionType which)
	Entry point into Nachos for handling user system calls and exceptions Defined in exception.cc. More...
unsigned int	WordToHost (unsigned int word)
unsigned short	ShortToHost (unsigned short shortword)
unsigned int	WordToMachine (unsigned int word)
unsigned short	ShortToMachine (unsigned short shortword)
Variables
const int	PageSize = 128
	set the page size equal to the disk sector size, for simplicity. More...
const int	NumPhysPages = 32
const int	MemorySize = (NumPhysPages * PageSize)
const int	TLBSize = 4
	if there is a TLB, make it small. More...

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Define Documentation

#define BadVAddrReg   39

The failing virtual address on an exception. Definition at line 68 of file machine.h.

#define HiReg   32

Double register to hold multiply result. Definition at line 61 of file machine.h.

#define LoReg   33

Definition at line 62 of file machine.h.

#define LoadReg   37

The register target of a delayed load. Definition at line 66 of file machine.h.

#define LoadValueReg   38

The value to be loaded by a delayed load. Definition at line 67 of file machine.h.

#define NextPCReg   35

Next program counter (for branch delay). Definition at line 64 of file machine.h.

#define NumGPRegs   32

32 general purpose registers on MIPS. Definition at line 60 of file machine.h.

#define NumTotalRegs   40

Definition at line 70 of file machine.h.

#define PCReg   34

Current program counter. Definition at line 63 of file machine.h.

#define PrevPCReg   36

Previous program counter (for debugging). Definition at line 65 of file machine.h.

#define RetAddrReg   31

Holds return address for procedure calls. Definition at line 59 of file machine.h.

#define StackReg   29

User's stack pointer. Definition at line 58 of file machine.h.

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Enumeration Type Documentation

enum ExceptionType

Enumeration values: NoException   Everything ok! SyscallException   A program executed a system call. PageFaultException   No valid translation found. ReadOnlyException   Write attempted to page marked "read-only". BusErrorException   Translation resulted in an invalid physical address. AddressErrorException   Unaligned reference or one that was beyond the end of the address space. OverflowException   Integer overflow in add or sub. IllegalInstrException   Unimplemented or reserved instr. NumExceptionTypes   Definition at line 37 of file machine.h.

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Function Documentation

void ExceptionHandler ( ExceptionType which )

Entry point into Nachos for handling user system calls and exceptions Defined in exception.cc. ExceptionHandler Entry point into the Nachos kernel. Called when a user program is executing, and either does a syscall, or generates an addressing or arithmetic exception. For system calls, the following is the calling convention: system call code -- r2 arg1 -- r4 arg2 -- r5 arg3 -- r6 arg4 -- r7 The result of the system call, if any, must be put back into r2. And don't forget to increment the pc before returning. (Or else you'll loop making the same system call forever! "which" is the kind of exception. The list of possible exceptions are in machine.h. Definition at line 57 of file exception.cc.

unsigned short ShortToHost ( unsigned short shortword )

Definition at line 54 of file translate.cc.

unsigned short ShortToMachine ( unsigned short shortword )

Definition at line 69 of file translate.cc.

unsigned int WordToHost ( unsigned int word )

Definition at line 40 of file translate.cc.

unsigned int WordToMachine ( unsigned int word )

Definition at line 66 of file translate.cc.

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Variable Documentation

const int MemorySize = (NumPhysPages * PageSize)

Definition at line 34 of file machine.h.

const int NumPhysPages = 32

Definition at line 33 of file machine.h.

const int PageSize = 128

set the page size equal to the disk sector size, for simplicity. Definition at line 30 of file machine.h.

const int TLBSize = 4

if there is a TLB, make it small. Definition at line 35 of file machine.h.

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