1
2
3
4
5
6
7
8
9
|
1
2
3
4
5
6
7
8
9
|
-
+
|
/* trees.c -- output deflated data using Huffman coding
* Copyright (C) 1995-2021 Jean-loup Gailly
* Copyright (C) 1995-2024 Jean-loup Gailly
* detect_data_type() function provided freely by Cosmin Truta, 2006
* For conditions of distribution and use, see copyright notice in zlib.h
*/
/*
* ALGORITHM
*
|
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
|
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
|
-
+
+
+
+
+
+
|
/* ===========================================================================
* Send the block data compressed using the given Huffman trees
*/
local void compress_block(deflate_state *s, const ct_data *ltree,
const ct_data *dtree) {
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 sx = 0; /* running index in symbol buffers */
unsigned code; /* the code to send */
int extra; /* number of extra bits to send */
if (s->sym_next != 0) do {
#ifdef LIT_MEM
dist = s->d_buf[sx];
lc = s->l_buf[sx++];
#else
dist = s->sym_buf[sx++] & 0xff;
dist += (unsigned)(s->sym_buf[sx++] & 0xff) << 8;
lc = s->sym_buf[sx++];
#endif
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 */
|
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
|
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
|
-
+
+
+
+
+
|
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: */
/* Check for no overlay of pending_buf on needed symbols */
#ifdef LIT_MEM
Assert(s->pending < 2 * (s->lit_bufsize + sx), "pendingBuf overflow");
#else
Assert(s->pending < s->lit_bufsize + sx, "pendingBuf overflow");
#endif
} while (sx < s->sym_next);
send_code(s, END_BLOCK, ltree);
}
/* ===========================================================================
|
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
|
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
|
+
+
+
+
+
|
}
/* ===========================================================================
* Save the match info and tally the frequency counts. Return true if
* the current block must be flushed.
*/
int ZLIB_INTERNAL _tr_tally(deflate_state *s, unsigned dist, unsigned lc) {
#ifdef LIT_MEM
s->d_buf[s->sym_next] = (ush)dist;
s->l_buf[s->sym_next++] = (uch)lc;
#else
s->sym_buf[s->sym_next++] = (uch)dist;
s->sym_buf[s->sym_next++] = (uch)(dist >> 8);
s->sym_buf[s->sym_next++] = (uch)lc;
#endif
if (dist == 0) {
/* lc is the unmatched char */
s->dyn_ltree[lc].Freq++;
} else {
s->matches++;
/* Here, lc is the match length - MIN_MATCH */
dist--; /* dist = match distance - 1 */
|