static int read_offset(LHALH1Decoder *decoder, unsigned int *result)
{
unsigned int offset;
int future, offset2;
// The offset can be up to 8 bits long, but is likely not
// that long. Use the lookup table to find the offset
// and its length.
future = peek_bits(&decoder->bit_stream_reader, 8);
if (future < 0) {
return 0;
}
offset = decoder->offset_lookup[future];
// Skip past the offset bits and also read the following
// lower-order bits.
read_bits(&decoder->bit_stream_reader,
decoder->offset_lengths[offset]);
offset2 = read_bits(&decoder->bit_stream_reader, 6);
if (offset2 < 0) {
return 0;
}
*result = (offset << 6) | (unsigned int) offset2;
return 1;
}
static inline int get_run(stream_CFD_state *ss, stream_cursor_read *pr, const cfd_node decode[],
int initial_bits, int min_bits, int *runlen, const char *str)
{
cfd_declare_state;
const cfd_node *np;
int clen;
cfd_load_state();
HCD_ENSURE_BITS_ELSE(initial_bits) {
/* We might still have enough bits for the specific code. */
if (bits_left < min_bits)
goto outl;
np = &decode[hcd_peek_bits_left() << (initial_bits - bits_left)];
if ((clen = np->code_length) > bits_left)
goto outl;
goto locl;
}
np = &decode[peek_bits(initial_bits)];
if ((clen = np->code_length) > initial_bits) {
IF_DEBUG(uint init_bits = peek_bits(initial_bits));
if (!avail_bits(clen)) goto outl;
clen -= initial_bits;
skip_bits(initial_bits);
ensure_bits(clen, outl); /* can't goto outl */
np = &decode[np->run_length + peek_var_bits(clen)];
if_debug4('W', "%s xcode=0x%x,%d rlen=%d\n", str,
(init_bits << np->code_length) +
peek_var_bits(np->code_length),
initial_bits + np->code_length,
np->run_length);
skip_bits(np->code_length);
} else {
locl:
if_debug4('W', "%s code=0x%x,%d rlen=%d\n", str,
peek_var_bits(clen), clen, np->run_length);
skip_bits(clen);
}
*runlen = np->run_length;
cfd_store_state();
return(0);
outl:
cfd_store_state();
return(-1);
}
static int read_bits(BitStreamReader *reader,
unsigned int n)
{
int result;
result = peek_bits(reader, n);
if (result >= 0) {
reader->bit_buffer <<= n;
reader->bits -= n;
}
return result;
}
