/*------------------------------------------------------------------------
* lflRead -- read from a previously opened local file
*------------------------------------------------------------------------
*/
devcall lflRead (
struct dentry *devptr, /* entry in device switch table */
char *buff, /* buffer to hold bytes */
int32 count /* max bytes to read */
)
{
uint32 numread; /* number of bytes read */
// int32 nxtbyte; /* character or SYSERR/EOF */
kprintf("In lflRead\r\n");
if (count < 0) {
kprintf("Exiting lflRead: count < 0\r\n");
return SYSERR;
}
/*for (numread=0 ; numread < count ; numread++) {
nxtbyte = lflGetc(devptr);
if (nxtbyte == SYSERR) {
return SYSERR;
} else if (nxtbyte == EOF) {
if (numread == 0) {
return EOF;
} else {
return numread;
}
} else {
*buff++ = (char) (0xff & nxtbyte);
}
}*/
struct lflcblk *lfptr = &lfltab[devptr->dvminor];
if(lfptr->lfstate != LF_USED)
{
signal(lfptr->lfmutex);
kprintf("Exiting lflRead: lfstate != LF_USED\r\n");
return SYSERR;
}
if(lfptr->lfpos >= lfptr->size)
{
signal(lfptr->lfmutex);
kprintf("Exiting lflRead\r\n");
return EOF;
}
numread = 0;
do
{
if(lfptr->lfbyte >= &lfptr->lfdblock[LF_BLKSIZ])
{
lfsetup(lfptr);
}
*buff++ = (char)(0XFF & *lfptr->lfbyte++);
lfptr->lfpos++;
}while(++numread < count && lfptr->lfpos < lfptr->size);
kprintf("Exiting lflRead\r\n");
return numread;
}
/*------------------------------------------------------------------------
* lflPutc - write a single byte to an open local file
*------------------------------------------------------------------------
*/
devcall lflPutc (
struct dentry *devptr, /* entry in device switch table */
char ch /* character (byte) to write */
)
{
struct lflcblk *lfptr; /* ptr to open file table entry */
//struct ldentry *ldptr; /* ptr to file's entry in the */
/* in-memory directory */
/* Obtain exclusive use of the file */
lfptr = &lfltab[devptr->dvminor];
wait(lfptr->lfmutex);
/* If file is not open, return an error */
if (lfptr->lfstate != LF_USED) {
signal(lfptr->lfmutex);
return SYSERR;
}
/* Return SYSERR for an attempt to skip bytes beyond the */
/* current end of the file */
//ldptr = lfptr->lfdirptr;
if (lfptr->lfpos > lfptr->fileSize) {
signal(lfptr->lfmutex);
return SYSERR;
}
/* If pointer is outside current block, set up new block */
if (lfptr->lfbyte >= &lfptr->lfdblock[LF_BLKSIZ]) {
/* Set up block for current file position */
lfsetup(lfptr);
}
/* If appending a byte to the file, increment the file size. */
/* Note: comparison might be equal, but should not be greater. */
if (lfptr->lfpos >= lfptr->fileSize ) {
lfptr->fileSize++;
}
/* Place byte in buffer and mark buffer "dirty" */
*lfptr->lfbyte++ = ch;
lfptr->lfpos++;
lfptr->lfdbdirty = TRUE;
if(DEBUG_1)
{
// kprintf("lflPutc Writing Character %c\r\n",ch);
// kprintf("lflPutc Writing Character %d\r\n",ch);
}
signal(lfptr->lfmutex);
return OK;
}
/*------------------------------------------------------------------------
* lflRead -- read from a previously opened local file
*------------------------------------------------------------------------
*/
devcall lflRead (
struct dentry *devptr, /* entry in device switch table */
char *buff, /* buffer to hold bytes */
int32 count /* max bytes to read */
)
{
uint32 numread; /* number of bytes read */
int32 nxtbyte; /* character or SYSERR/EOF */
struct lflcblk *lfptr; /* ptr to open file table entry */
struct ldentry *ldptr; /* ptr to file's entry in the */
/* in-memory directory */
//kprintf("Read begins!\r\n");
if (count < 0) {
signal(lfptr->lfmutex);
return SYSERR;
}
for (numread=0 ; numread < count ; numread++) {
lfptr = &lfltab[devptr->dvminor];
wait(lfptr->lfmutex);
if (lfptr->lfstate != LF_USED) {
signal(lfptr->lfmutex);
nxtbyte = SYSERR;
}
ldptr = lfptr->lfdirptr;
if (lfptr->lfpos >= ldptr->ld_size) {
signal(lfptr->lfmutex);
nxtbyte = EOF;
}
if (lfptr->lfbyte >= &lfptr->lfdblock[LF_BLKSIZ]) {
lfsetup(lfptr);
}
nxtbyte = 0xff & *lfptr->lfbyte++;
lfptr->lfpos++;
signal(lfptr->lfmutex);
if (nxtbyte == SYSERR) {
//kprintf("nxtbyte == SYSERR\r\n");
return SYSERR;
} else if (nxtbyte == EOF) { /* EOF before finished */
if (numread == 0) {
//kprintf("nxtbyte = EOF and numread = 0\r\n");
return EOF;
} else {
//kprintf("nxtbyte = EOF and numread = %d\r\n", numread);
return numread;
}
} else {
*buff++ = (char) (0xff & nxtbyte);
}
}
//kprintf("Read returns %d\r\n", numread);
return numread;
}
/*------------------------------------------------------------------------
* lflGetc -- Read the next byte from an open local file
*------------------------------------------------------------------------
*/
devcall lflGetc (
struct dentry *devptr /* entry in device switch table */
)
{
struct lflcblk *lfptr; /* ptr to open file table entry */
struct ldentry *ldptr; /* ptr to file's entry in the */
/* in-memory directory */
int32 onebyte; /* next data byte in the file */
/* Obtain exclusive use of the file */
lfptr = &lfltab[devptr->dvminor];
wait(lfptr->lfmutex);
/* If file is not open, return an error */
if (lfptr->lfstate != LF_USED) {
signal(lfptr->lfmutex);
return SYSERR;
}
/* Return EOF for any attempt to read beyond the end-of-file */
ldptr = lfptr->lfdirptr;
if (lfptr->lfpos >= ldptr->ld_size) {
signal(lfptr->lfmutex);
return EOF;
}
/* If byte pointer is beyond the current data block, */
/* set up a new data block */
if (lfptr->lfbyte >= &lfptr->lfdblock[LF_BLKSIZ]) {
lfsetup(lfptr);
}
/* Extract the next byte from block, update file position, and */
/* return the byte to the caller */
onebyte = 0xff & *lfptr->lfbyte++;
lfptr->lfpos++;
signal(lfptr->lfmutex);
return onebyte;
}
//------------------------------------------------------------------------
// lfseek -- seek to a specified position of a file
//------------------------------------------------------------------------
int
lfseek(struct devsw *devptr, long offset)
{
struct flblk *flptr;
int ps;
ps = disable();
flptr = (struct flblk *)devptr->iobuf;
if (flptr->fl_mode & FLWRITE) {
if (flptr->fl_dch)
lfsflush(flptr);
} else if (offset > (flptr->fl_dent)->fdlen) {
restore(ps);
return SYSERR;
}
flptr->fl_pos = offset;
lfsetup(flptr->fl_dev, flptr);
restore(ps);
return OK;
}
