diff --git a/defs.h b/defs.h
index 49c0296..3b8127d 100644
--- a/defs.h
+++ b/defs.h
@@ -1,147 +1,144 @@
-// kalloc.c
-char* kalloc(int);
-void kfree(char*, int);
-void kinit(void);
-
-// console.c
-void console_init(void);
-void cprintf(char*, ...);
-void panic(char*) __attribute__((noreturn));
-void kbd_intr(void);
-
-// proc.c
-void pinit(void);
-struct proc;
-void setupsegs(struct proc*);
-struct proc* copyproc(struct proc*);
-struct spinlock;
-int growproc(int);
-void sleep(void*, struct spinlock*);
-void wakeup(void*);
-void scheduler(void);
-void proc_exit(void);
-int proc_kill(int);
-int proc_wait(void);
-void yield(void);
-void procdump(void);
-void userinit(void);
-
-// setjmp.S
+struct buf;
+struct file;
+struct inode;
 struct jmpbuf;
-int setjmp(struct jmpbuf*);
-void longjmp(struct jmpbuf*);
-
-// trap.c
-void tvinit(void);
-void idtinit(void);
-
-// string.c
-void* memset(void*, int, uint);
-int memcmp(const void*, const void*, uint);
-void* memmove(void*, const void*, uint);
-int strncmp(const char*, const char*, uint);
-char* safestrcpy(char*, const char*, int);
-int strlen(const char*);
-
-// syscall.c
-void syscall(void);
-int fetchint(struct proc*, uint, int*);
-int fetchstr(struct proc*, uint, char**);
-int argint(int, int*);
-int argptr(int, char**, int);
-int argstr(int, char**);
-
-// picirq.c
-void pic_init(void);
-void irq_enable(int);
+struct pipe;
+struct proc;
+struct spinlock;
+struct stat;
+struct uinode;
 
 // 8253pit.c
-void pit8253_timerinit(void);
-
-// mp.c
-extern int ismp;
-void mp_init(void);
-void mp_startthem(void);
-int mp_bcpu(void);
-
-// lapic.c
-extern uint *lapicaddr;
-void lapic_init(int);
-void lapic_startap(uchar, int);
-void lapic_timerinit(void);
-void lapic_timerintr(void);
-void lapic_enableintr(void);
-void lapic_disableintr(void);
-void lapic_eoi(void);
-int cpu(void);
-
-// ioapic.c
-extern uchar ioapic_id;
-void ioapic_init(void);
-void ioapic_enable(int irq, int cpu);
-
-// spinlock.c
-struct spinlock;
-void initlock(struct spinlock*, char*);
-void acquire(struct spinlock*);
-void release(struct spinlock*);
-int holding(struct spinlock*);
-void getcallerpcs(void*, uint*);
-
-// main.c
-void load_icode(struct proc*, uchar*, uint);
-
-// pipe.c
-struct pipe;
-struct file;
-int pipe_alloc(struct file**, struct file**);
-void pipe_close(struct pipe*, int);
-int pipe_write(struct pipe*, char*, int);
-int pipe_read(struct pipe*, char*, int);
-
-// file.c
-struct stat;
-void fileinit(void);
-struct file* filealloc(void);
-void fileclose(struct file*);
-int fileread(struct file*, char*, int n);
-int filewrite(struct file*, char*, int n);
-int filestat(struct file*, struct stat*);
-void fileincref(struct file*);
-
-// ide.c
-void ide_init(void);
-void ide_intr(void);
-void ide_rw(int, uint, void*, uint, int);
+void            pit8253_timerinit(void);
 
 // bio.c
-void binit(void);
-struct buf;
-struct buf* bread(uint, uint);
-void bwrite(struct buf*);
-void brelse(struct buf*);
+void            binit(void);
+struct buf*     bread(uint, uint);
+void            brelse(struct buf*);
+void            bwrite(struct buf*);
 
-// fs.c
-struct inode;
-struct uinode;
-void iinit(void);
-struct inode* ilock(struct uinode*);
-struct uinode* iunlock(struct inode*);
-void iput(struct uinode*);
-struct uinode* idup(struct uinode*);
-struct uinode* namei(char*);
-void stati(struct inode*, struct stat*);
-int readi(struct inode*, char*, uint, uint);
-int writei(struct inode*, char*, uint, uint);
-int dirlink(struct inode *dp, char *name, uint ino);
-struct uinode* dirlookup(struct inode *dp, char *name, uint *poff);
-void iupdate(struct inode *ip);
-int namecmp(const char *s, const char *t);
-struct uinode* ialloc(uint, short);
-struct uinode* nameiparent(char *path, char *name);
+// console.c
+void            console_init(void);
+void            cprintf(char*, ...);
+void            kbd_intr(void);
+void            panic(char*) __attribute__((noreturn));
 
 // exec.c
-int exec(char*, char**);
+int            exec(char*, char**);
+
+// file.c
+struct file*    filealloc(void);
+void            fileclose(struct file*);
+void            fileincref(struct file*);
+void            fileinit(void);
+int             fileread(struct file*, char*, int n);
+int             filestat(struct file*, struct stat*);
+int             filewrite(struct file*, char*, int n);
+
+// fs.c
+int             dirlink(struct inode*, char*, uint);
+struct uinode*  dirlookup(struct inode*, char*, uint*);
+struct uinode*  ialloc(uint, short);
+struct uinode*  idup(struct uinode*);
+void            iinit(void);
+struct inode*   ilock(struct uinode*);
+struct uinode*  iunlock(struct inode*);
+void            iput(struct uinode*);
+void            iupdate(struct inode*);
+int             namecmp(const char*, const char*);
+struct uinode*  namei(char*);
+struct uinode*  nameiparent(char*, char*);
+int             readi(struct inode*, char*, uint, uint);
+void            stati(struct inode*, struct stat*);
+int             writei(struct inode*, char*, uint, uint);
+
+// ide.c
+void            ide_init(void);
+void            ide_intr(void);
+void            ide_rw(int, uint, void*, uint, int);
+
+// ioapic.c
+void            ioapic_enable(int irq, int cpu);
+extern uchar    ioapic_id;
+void            ioapic_init(void);
+
+// kalloc.c
+char*           kalloc(int);
+void            kfree(char*, int);
+void            kinit(void);
+
+// lapic.c
+int             cpu(void);
+extern uint*    lapicaddr;
+void            lapic_disableintr(void);
+void            lapic_enableintr(void);
+void            lapic_eoi(void);
+void            lapic_init(int);
+void            lapic_startap(uchar, int);
+void            lapic_timerinit(void);
+void            lapic_timerintr(void);
+
+// mp.c
+extern int      ismp;
+int             mp_bcpu(void);
+void            mp_init(void);
+void            mp_startthem(void);
+
+// picirq.c
+void            irq_enable(int);
+void            pic_init(void);
+
+// pipe.c
+int             pipe_alloc(struct file**, struct file**);
+void            pipe_close(struct pipe*, int);
+int             pipe_read(struct pipe*, char*, int);
+int             pipe_write(struct pipe*, char*, int);
+
+// proc.c
+struct proc*    copyproc(struct proc*);
+int             growproc(int);
+void            pinit(void);
+void            proc_exit(void);
+int             proc_kill(int);
+int             proc_wait(void);
+void            procdump(void);
+void            scheduler(void);
+void            setupsegs(struct proc*);
+void            sleep(void*, struct spinlock*);
+void            userinit(void);
+void            wakeup(void*);
+void            yield(void);
+
+// setjmp.S
+void            longjmp(struct jmpbuf*);
+int             setjmp(struct jmpbuf*);
+
+// spinlock.c
+void            acquire(struct spinlock*);
+void            getcallerpcs(void*, uint*);
+int             holding(struct spinlock*);
+void            initlock(struct spinlock*, char*);
+void            release(struct spinlock*);
+
+// string.c
+int             memcmp(const void*, const void*, uint);
+void*           memmove(void*, const void*, uint);
+void*           memset(void*, int, uint);
+char*           safestrcpy(char*, const char*, int);
+int             strlen(const char*);
+int             strncmp(const char*, const char*, uint);
+
+// syscall.c
+int             argint(int, int*);
+int             argptr(int, char**, int);
+int             argstr(int, char**);
+int             fetchint(struct proc*, uint, int*);
+int             fetchstr(struct proc*, uint, char**);
+void            syscall(void);
+
+// trap.c
+void            idtinit(void);
+void            tvinit(void);
 
 // number of elements in fixed-size array
 #define NELEM(x) (sizeof(x)/sizeof((x)[0]))