Fix up LZ77 compression code and prepare v1.0.3

[wimlib] / src / lzx-comp.c

diff --git a/src/lzx-comp.c b/src/lzx-comp.c
index 601513dd4435a77b948b4ca2cd3391912160edfa..8267a2eaece40d28187adee2c114a953f2ebe825 100644 (file)
--- a/src/lzx-comp.c
+++ b/src/lzx-comp.c
@@ -14,16 +14,16 @@
  * This file is part of wimlib, a library for working with WIM files.
  *
  * wimlib is free software; you can redistribute it and/or modify it under the
- * terms of the GNU Lesser General Public License as published by the Free
- * Software Foundation; either version 2.1 of the License, or (at your option)
+ * terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 3 of the License, or (at your option)
  * any later version.
  *
  * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
- * A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
+ * A PARTICULAR PURPOSE. See the GNU General Public License for more
  * details.
  *
- * You should have received a copy of the GNU Lesser General Public License
+ * You should have received a copy of the GNU General Public License
  * along with wimlib; if not, see http://www.gnu.org/licenses/.
  */
 
@@ -599,7 +599,11 @@ static void do_call_insn_preprocessing(u8 uncompressed_data[],
 
 
 static const struct lz_params lzx_lz_params = {
+
+        /* LZX_MIN_MATCH == 2, but 2-character matches are rarely useful; the
+         * minimum match for compression is set to 3 instead. */
        .min_match      = 3,
+
        .max_match      = LZX_MAX_MATCH,
        .good_match     = LZX_MAX_MATCH,
        .nice_match     = LZX_MAX_MATCH,
@@ -638,6 +642,7 @@ int lzx_compress(const void *__uncompressed_data, uint uncompressed_len,
        uint compressed_len;
        uint i;
        int ret;
+       int block_type = LZX_BLOCKTYPE_ALIGNED;
 
        LZX_DEBUG("uncompressed_len = %u", uncompressed_len);
 
@@ -676,7 +681,7 @@ int lzx_compress(const void *__uncompressed_data, uint uncompressed_len,
 
        /* The first three bits tell us what kind of block it is, and are one
         * of the LZX_BLOCKTYPE_* values.  */
-       bitstream_put_bits(&ostream, LZX_BLOCKTYPE_ALIGNED, 3);
+       bitstream_put_bits(&ostream, block_type, 3);
 
        /* The next bit indicates whether the block size is the default (32768),
         * indicated by a 1 bit, or whether the block size is given by the next
@@ -691,9 +696,10 @@ int lzx_compress(const void *__uncompressed_data, uint uncompressed_len,
        /* Write out the aligned offset tree. Note that M$ lies and says that
         * the aligned offset tree comes after the length tree, but that is
         * wrong; it actually is before the main tree.  */
-       for (i = 0; i < LZX_ALIGNEDTREE_NUM_SYMBOLS; i++)
-               bitstream_put_bits(&ostream, codes.aligned_lens[i], 
-                                  LZX_ALIGNEDTREE_ELEMENT_SIZE);
+       if (block_type == LZX_BLOCKTYPE_ALIGNED)
+               for (i = 0; i < LZX_ALIGNEDTREE_NUM_SYMBOLS; i++)
+                       bitstream_put_bits(&ostream, codes.aligned_lens[i],
+                                          LZX_ALIGNEDTREE_ELEMENT_SIZE);
 
        /* Write the pre-tree and lengths for the first LZX_NUM_CHARS symbols in the
         * main tree. */
@@ -717,7 +723,7 @@ int lzx_compress(const void *__uncompressed_data, uint uncompressed_len,
                return ret;
 
        /* Write the compressed literals. */
-       ret = lzx_write_compressed_literals(&ostream, LZX_BLOCKTYPE_ALIGNED,
+       ret = lzx_write_compressed_literals(&ostream, block_type,
                                            match_tab, num_matches, &codes);
        if (ret != 0)
                return ret;