-#define SYS_halt 0 /* Halts the operating system. */
-#define SYS_exit 1 /* Terminates this process. */
-#define SYS_exec 2 /* Start another process. */
-#define SYS_join 3 /* Waits for a child process to die. */
-#define SYS_create 4 /* Creates a file. */
-#define SYS_remove 5 /* Deletes a file. */
-#define SYS_open 6 /* Opens a file. */
-#define SYS_read 7 /* Reads from a file. */
-#define SYS_write 8 /* Writes to a file. */
-#define SYS_close 9 /* Closes a file. */
-#define SYS_length 10 /* Obtains a file's size. */
-#define SYS_mmap 11 /* Maps a file into memory. */
-#define SYS_munmap 12 /* Removes a memory mapping. */
+enum
+ {
+ /* Projects 2 and later. */
+ SYS_HALT, /* Halt the operating system. */
+ SYS_EXIT, /* Terminate this process. */
+ SYS_EXEC, /* Start another process. */
+ SYS_WAIT, /* Wait for a child process to die. */
+ SYS_CREATE, /* Create a file. */
+ SYS_REMOVE, /* Delete a file. */
+ SYS_OPEN, /* Open a file. */
+ SYS_FILESIZE, /* Obtain a file's size. */
+ SYS_READ, /* Read from a file. */
+ SYS_WRITE, /* Write to a file. */
+ SYS_SEEK, /* Change position in a file. */
+ SYS_TELL, /* Report current position in a file. */
+ SYS_CLOSE, /* Close a file. */