struct buf;
struct context;
struct file;
struct inode;
struct pipe;
struct proc;
struct spinlock;
struct stat;
struct superblock;

void OkLoop(void);
void NotOkLoop(void);

void uart_putc(u32);
void cprintf(char*, ...);
void SetGpio(u32, u32);
void SetGpioFunction(u32, u32);
void Wait(u32);
void consoleinit(void);
void uart_init(void);
void mmuinit1(void);
void barriers(void);
void dsb_barrier(void);
void flush_tlb(void);
void flush_dcache(u32 va1, u32 va2);
void flush_idcache(void);
void set_pgtbase(u32 base);

// bio.c
void            binit(void);
struct buf*     bread(uint, uint);
void            brelse(struct buf*);
void            bwrite(struct buf*);

// fs.c
void            readsb(int dev, struct superblock *sb);
int             dirlink(struct inode*, char*, uint);
struct inode*   dirlookup(struct inode*, char*, uint*);
struct inode*   ialloc(uint, short);
struct inode*   idup(struct inode*);
void            iinit(void);
void            ilock(struct inode*);
void            iput(struct inode*);
void            iunlock(struct inode*);
void            iunlockput(struct inode*);
void            iupdate(struct inode*);
int             namecmp(const char*, const char*);
struct inode*   namei(char*);
struct inode*   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            ideinit(void);
void            ideintr(void);
void            iderw(struct buf*);

// exec.c
int             exec(char*, char**);

// file.c
struct file*    filealloc(void);
void            fileclose(struct file*);
struct file*    filedup(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
void            readsb(int dev, struct superblock *sb);
int             dirlink(struct inode*, char*, uint);
struct inode*   dirlookup(struct inode*, char*, uint*);
struct inode*   ialloc(uint, short);
struct inode*   idup(struct inode*);
void            iinit(void);
void            ilock(struct inode*);
void            iput(struct inode*);
void            iunlock(struct inode*);
void            iunlockput(struct inode*);
void            iupdate(struct inode*);
int             namecmp(const char*, const char*);
struct inode*   namei(char*);
struct inode*   nameiparent(char*, char*);
int             readi(struct inode*, char*, uint, uint);
void            stati(struct inode*, struct stat*);
int             writei(struct inode*, char*, uint, uint);

// kalloc.c
char*           kalloc(void);
void            kfree(char*);
void            kinit1(void*, void*);
void            kinit2(void*, void*);


// log.c
void            initlog(void);
void            log_write(struct buf*);
void            begin_trans();
void            commit_trans();

// pipe.c
int             pipealloc(struct file**, struct file**);
void            pipeclose(struct pipe*, int);
int             piperead(struct pipe*, char*, int);
int             pipewrite(struct pipe*, char*, int);

//PAGEBREAK: 16
// proc.c
struct proc*    copyproc(struct proc*);
void            exit(void);
int             fork(void);
int             growproc(int);
int             kill(int);
void            pinit(void);
void            procdump(void);
void            scheduler(void) __attribute__((noreturn));
void            sched(void);
void            sleep(void*, struct spinlock*);
void            userinit(void);
int             wait(void);
void            wakeup(void*);
void            yield(void);


// swtch.S
void            swtch(struct context**, struct context*);

// syscall.c
int             argint(int, int*);
int             argptr(int, char**, int);
int             argstr(int, char**);
int             fetchint(uint, int*);
int             fetchstr(uint, char**);
void            syscall(void);

void kvmalloc(void);


void drawCharacter(u8, u32, u32);
int UsbInitialise(void);
void KeyboardUpdate(void);
char KeyboardGetChar(void);
void gpuputc(u32);
u32 KeyboardCount(void);
u32 KeyboardGetAddress(u32);
struct KeyboardLeds KeyboardGetLedSupport(u32);

void panic(char *s);

// spinlock.c
void            acquire(struct spinlock*);
void            getcallerpcs(void*, uint*);
int             holding(struct spinlock*);
void            initlock(struct spinlock*, char*);
void            release(struct spinlock*);
void            pushcli(void);
void            popcli(void);

// 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);
char*           strncpy(char*, const char*, int);
u32 		div(u32 n, u32 d);

// syscall.c
int             argint(int, int*);
int             argptr(int, char**, int);
int             argstr(int, char**);
int             fetchint(uint, int*);
int             fetchstr(uint, char**);
void            syscall(void);

// trap.c
void            trap_init(void);
extern uint     ticks;
extern struct spinlock tickslock;


// vm.c
void            seginit(void);
void            kvmalloc(void);
void            vmenable(void);
pde_t*          setupkvm(void);
char*           uva2ka(pde_t*, char*);
int             allocuvm(pde_t*, uint, uint);
int             deallocuvm(pde_t*, uint, uint);
void            freevm(pde_t*);
void            inituvm(pde_t*, char*, uint);
int             loaduvm(pde_t*, char*, struct inode*, uint, uint);
pde_t*          copyuvm(pde_t*, uint);
void            switchuvm(struct proc*);
void            switchkvm(void);
int             copyout(pde_t*, uint, void*, uint);
void            clearpteu(pde_t *pgdir, char *uva);



// number of elements in fixed-size array
#define NELEM(x) (sizeof(x)/sizeof((x)[0]))