-
-/* ===========================================================================
- * Send the block data compressed using the given Huffman trees
- */
-local void compress_block(s, ltree, dtree)
- deflate_state *s;
- const ct_data *ltree; /* literal tree */
- const ct_data *dtree; /* distance tree */
-{
- unsigned dist; /* distance of matched string */
- int lc; /* match length or unmatched char (if dist == 0) */
- unsigned sx = 0; /* running index in sym_buf */
- unsigned code; /* the code to send */
- int extra; /* number of extra bits to send */
-
- if (s->sym_next != 0) do {
- dist = s->sym_buf[sx++] & 0xff;
- dist += (unsigned)(s->sym_buf[sx++] & 0xff) << 8;
- lc = s->sym_buf[sx++];
- if (dist == 0) {
- send_code(s, lc, ltree); /* send a literal byte */
- Tracecv(isgraph(lc), (stderr," '%c' ", lc));
- } else {
- /* Here, lc is the match length - MIN_MATCH */
- code = _length_code[lc];
- send_code(s, code + LITERALS + 1, ltree); /* send length code */
- extra = extra_lbits[code];
- if (extra != 0) {
- lc -= base_length[code];
- send_bits(s, lc, extra); /* send the extra length bits */
- }
- dist--; /* dist is now the match distance - 1 */
- code = d_code(dist);
- Assert (code < D_CODES, "bad d_code");
-
- send_code(s, code, dtree); /* send the distance code */
- extra = extra_dbits[code];
- if (extra != 0) {
- dist -= (unsigned)base_dist[code];
- send_bits(s, dist, extra); /* send the extra distance bits */
- }
- } /* literal or match pair ? */
-
- /* Check that the overlay between pending_buf and sym_buf is ok: */
- Assert(s->pending < s->lit_bufsize + sx, "pendingBuf overflow");
-
- } while (sx < s->sym_next);
-
- send_code(s, END_BLOCK, ltree);
-}
-
-/* ===========================================================================
- * Check if the data type is TEXT or BINARY, using the following algorithm:
- * - TEXT if the two conditions below are satisfied:
- * a) There are no non-portable control characters belonging to the
- * "block list" (0..6, 14..25, 28..31).
- * b) There is at least one printable character belonging to the
- * "allow list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
- * - BINARY otherwise.
- * - The following partially-portable control characters form a
- * "gray list" that is ignored in this detection algorithm:
- * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
- * IN assertion: the fields Freq of dyn_ltree are set.
- */
-local int detect_data_type(s)
- deflate_state *s;
-{
- /* block_mask is the bit mask of block-listed bytes
- * set bits 0..6, 14..25, and 28..31
- * 0xf3ffc07f = binary 11110011111111111100000001111111
- */
- unsigned long block_mask = 0xf3ffc07fUL;
- int n;
-
- /* Check for non-textual ("block-listed") bytes. */
- for (n = 0; n <= 31; n++, block_mask >>= 1)
- if ((block_mask & 1) && (s->dyn_ltree[n].Freq != 0))
- return Z_BINARY;
-
- /* Check for textual ("allow-listed") bytes. */
- if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
- || s->dyn_ltree[13].Freq != 0)
- return Z_TEXT;
- for (n = 32; n < LITERALS; n++)
- if (s->dyn_ltree[n].Freq != 0)
- return Z_TEXT;
-
- /* There are no "block-listed" or "allow-listed" bytes:
- * this stream either is empty or has tolerated ("gray-listed") bytes only.
- */
- return Z_BINARY;
-}
-
-/* ===========================================================================
- * Reverse the first len bits of a code, using straightforward code (a faster
- * method would use a table)
- * IN assertion: 1 <= len <= 15
- */
-local unsigned bi_reverse(code, len)
- unsigned code; /* the value to invert */
- int len; /* its bit length */
-{
- register unsigned res = 0;
- do {
- res |= code & 1;
- code >>= 1, res <<= 1;
- } while (--len > 0);
- return res >> 1;
-}
-
-/* ===========================================================================
- * Flush the bit buffer, keeping at most 7 bits in it.
- */
-local void bi_flush(s)
- deflate_state *s;
-{
- if (s->bi_valid == 16) {
- put_short(s, s->bi_buf);
- s->bi_buf = 0;
- s->bi_valid = 0;
- } else if (s->bi_valid >= 8) {
- put_byte(s, (Byte)s->bi_buf);
- s->bi_buf >>= 8;
- s->bi_valid -= 8;
- }
-}
-
-/* ===========================================================================
- * Flush the bit buffer and align the output on a byte boundary
- */
-local void bi_windup(s)
- deflate_state *s;
-{
- if (s->bi_valid > 8) {
- put_short(s, s->bi_buf);
- } else if (s->bi_valid > 0) {
- put_byte(s, (Byte)s->bi_buf);
- }
- s->bi_buf = 0;
- s->bi_valid = 0;
-#ifdef ZLIB_DEBUG
- s->bits_sent = (s->bits_sent + 7) & ~7;
-#endif
-}