void ZipDeflate::compress_block(zip_ct_data* ltree, zip_ct_data* dtree)
{
UINT dist, lx(0), code;
int lc, extra;
if(last_lit) do
{
dist = d_buf[lx];
lc = l_buf[lx++];
if(dist == 0)
{
send_code(lc, ltree);
}
else
{
code = _length_code[lc];
send_code(code + LITERALS + 1, ltree);
extra = extra_lbits[code];
if(extra) {lc -= base_length[code]; send_bits(lc, extra);}
dist--;
code = d_code(dist);
send_code(code, dtree);
extra = extra_dbits[code];
if(extra) {dist -= base_dist[code]; send_bits(dist, extra);}
}
} while(lx < last_lit);
send_code(END_BLOCK, ltree);
}
/* Save the match info and tally the frequency counts.
Return true if the current block must be flushed. */
int CodeTree::ct_tally (int dist, int lc)
{
l_buf[last_lit++] = (byte)lc;
if (dist == 0) {
/* lc is the unmatched char */
dyn_ltree[lc].Freq++;
} else {
/* Here, lc is the match length - MIN_MATCH */
dist--; /* dist = match distance - 1 */
assert((word16)dist < (word16)MAX_DIST &&
(word16)lc <= (word16)(MAX_MATCH-MIN_MATCH) &&
(word16)d_code(dist) < (word16)D_CODES);
dyn_ltree[length_code[lc]+LITERALS+1].Freq++;
dyn_dtree[d_code(dist)].Freq++;
d_buf[last_dist++] = dist;
flags |= flag_bit;
}
flag_bit <<= 1;
/* Output the flags if they fill a byte: */
if ((last_lit & 7) == 0) {
flag_buf[last_flags++] = flags;
flags = 0, flag_bit = 1;
}
/* Try to guess if it is profitable to stop the current block here */
if (deflate_level > 2 && (last_lit & 0xfff) == 0) {
/* Compute an upper bound for the compressed length */
word32 out_length = (word32)last_lit*8L;
word32 in_length = (word32)strstart-block_start;
int dcode;
for (dcode = 0; dcode < D_CODES; dcode++) {
out_length += (word32)dyn_dtree[dcode].Freq*(5L+extra_dbits[dcode]);
}
out_length >>= 3;
// Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
// last_lit, last_dist, in_length, out_length,
// 100L - out_length*100L/in_length));
if (last_dist < last_lit/2 && out_length < in_length/2) return 1;
}
