/* Get bytes with decoding - this decodes repetition,
* calls getuhuff to decode file stream into byte
* level code with only repetition encoding.
*
* The code is simple passing through of bytes except
* that DLE is encoded as DLE-zero and other values
* repeated more than twice are encoded as value-DLE-count.
*/
int
getcr(ib)
FILE *ib;
{
int c;
if(repct > 0) {
/* Expanding a repeated char */
--repct;
return value;
} else {
/* Nothing unusual */
if((c = getuhuff(ib)) != DLE) {
/* It's not the special delimiter */
value = c;
if(value == EOF)
repct = LARGE;
return value;
} else {
/* Special token */
if((repct = getuhuff(ib)) == 0)
/* DLE, zero represents DLE */
return DLE;
else {
/* Begin expanding repetition */
repct -= 2; /* 2nd time */
return value;
}
}
}
}
/* eject eject */
/* Decode file stream into a byte level code with only
* repetition encoding remaining.
*/
int
getuhuff(ib)
FILE *ib;
{
int i;
int bitval;
/* Follow bit stream in tree to a leaf*/
i = 0; /* Start at root of tree */
do {
if(++bpos > 7) {
if((curin = getc(ib)) == ERROR)
return ERROR;
bpos = 0;
/* move a level deeper in tree */
i = dnode[i].children[1 & curin];
} else
i = dnode[i].children[1 & (curin >>= 1)];
} while(i >= 0);
/* Decode fake node index to original data value */
i = -(i + 1);
/* Decode special endfile token to normal EOF */
i = (i == SPEOF) ? EOF : i;
return i;
}
