code/userprog/syscall.h
/* syscalls.h
* Nachos system call interface. These are Nachos kernel operations
* that can be invoked from user programs, by trapping to the kernel
* via the "syscall" instruction.
*
* This file is included by user programs and by the Nachos kernel.
*
* Copyright (c) 1992-1993 The Regents of the University of California.
* All rights reserved. See copyright.h for copyright notice and limitation
* of liability and disclaimer of warranty provisions.
*/
#ifndef SYSCALLS_H
#define SYSCALLS_H
#include "copyright.h"
/* system call codes -- used by the stubs to tell the kernel which system call
* is being asked for
*/
#define SC_Halt 0
#define SC_Exit 1
#define SC_Exec 2
#define SC_Join 3
#define SC_Create 4
#define SC_Open 5
#define SC_Read 6
#define SC_Write 7
#define SC_Close 8
#define SC_Fork 9
#define SC_Yield 10
#ifndef IN_ASM
/* The system call interface. These are the operations the Nachos
* kernel needs to support, to be able to run user programs.
*
* Each of these is invoked by a user program by simply calling the
* procedure; an assembly language stub stuffs the system call code
* into a register, and traps to the kernel. The kernel procedures
* are then invoked in the Nachos kernel, after appropriate error checking,
* from the system call entry point in exception.cc.
*/
/* Stop Nachos, and print out performance stats */
void Halt();
/* Address space control operations: Exit, Exec, and Join */
/* This user program is done (status = 0 means exited normally). */
void Exit(int status);
/* A unique identifier for an executing user program (address space) */
typedef int SpaceId;
/* Run the executable, stored in the Nachos file "name", and return the
* address space identifier
*/
SpaceId Exec(char *name);
/* Only return once the the user program "id" has finished.
* Return the exit status.
*/
int Join(SpaceId id);
/* File system operations: Create, Open, Read, Write, Close
* These functions are patterned after UNIX -- files represent
* both files *and* hardware I/O devices.
*
* If this assignment is done before doing the file system assignment,
* note that the Nachos file system has a stub implementation, which
* will work for the purposes of testing out these routines.
*/
/* A unique identifier for an open Nachos file. */
typedef int OpenFileId;
/* when an address space starts up, it has two open files, representing
* keyboard input and display output (in UNIX terms, stdin and stdout).
* Read and Write can be used directly on these, without first opening
* the console device.
*/
#define ConsoleInput 0
#define ConsoleOutput 1
/* Create a Nachos file, with "name" */
void Create(char *name);
/* Open the Nachos file "name", and return an "OpenFileId" that can
* be used to read and write to the file.
*/
OpenFileId Open(char *name);
/* Write "size" bytes from "buffer" to the open file. */
void Write(char *buffer, int size, OpenFileId id);
/* Read "size" bytes from the open file into "buffer".
* Return the number of bytes actually read -- if the open file isn't
* long enough, or if it is an I/O device, and there aren't enough
* characters to read, return whatever is available (for I/O devices,
* you should always wait until you can return at least one character).
*/
int Read(char *buffer, int size, OpenFileId id);
/* Close the file, we're done reading and writing to it. */
void Close(OpenFileId id);
/* User-level thread operations: Fork and Yield. To allow multiple
* threads to run within a user program.
*/
/* Fork a thread to run a procedure ("func") in the *same* address space
* as the current thread.
*/
void Fork(void (*func)());
/* Yield the CPU to another runnable thread, whether in this address space
* or not.
*/
void Yield();
#endif /* IN_ASM */
#endif /* SYSCALL_H */