lzx-compress.c: Faster extension of repeat offset matches

[wimlib] / src / xpress-decompress.c

diff --git a/src/xpress-decompress.c b/src/xpress-decompress.c
index 855f2cb311ccb156db1ecd9e00600c86255e458a..8d7741090dbae4519f9c97ccfb43c77836110b10 100644 (file)
--- a/src/xpress-decompress.c
+++ b/src/xpress-decompress.c
@@ -69,9 +69,9 @@
 #  include "config.h"
 #endif
 
-#include "wimlib.h"
 #include "wimlib/decompressor_ops.h"
 #include "wimlib/decompress_common.h"
+#include "wimlib/error.h"
 #include "wimlib/xpress.h"
 
 /*
@@ -85,16 +85,12 @@
  * Returns the match length, or -1 if the data is invalid.
  */
 static int
-xpress_decode_match(unsigned sym, input_idx_t window_pos,
-                   input_idx_t window_len, u8 window[restrict],
+xpress_decode_match(unsigned sym, u32 window_pos,
+                   u32 window_len, u8 window[restrict],
                    struct input_bitstream * restrict istream)
 {
-
        unsigned len_hdr;
        unsigned offset_bsr;
-       u8 *match_dest;
-       u8 *match_src;
-       unsigned i;
        unsigned match_len;
        unsigned match_offset;
 
@@ -119,21 +115,14 @@ xpress_decode_match(unsigned sym, input_idx_t window_pos,
        }
        match_len += XPRESS_MIN_MATCH_LEN;
 
-
-       /* Verify the match is in bounds, then copy its data to the current
-        * position.  */
-
-       if (window_pos + match_len > window_len)
+       if (unlikely(match_len > window_len - window_pos))
                return -1;
 
-       if (match_offset > window_pos)
+       if (unlikely(match_offset > window_pos))
                return -1;
 
-       match_dest = window + window_pos;
-       match_src = match_dest - match_offset;
-
-       for (i = 0; i < match_len; i++)
-               match_dest[i] = match_src[i];
+       lz_copy(&window[window_pos], match_len, match_offset,
+               &window[window_len]);
 
        return match_len;
 }
@@ -146,15 +135,13 @@ xpress_lz_decode(struct input_bitstream * restrict istream,
                 unsigned uncompressed_len,
                 const u16 decode_table[restrict])
 {
-       input_idx_t curpos;
+       u32 curpos;
        unsigned match_len;
 
        for (curpos = 0; curpos < uncompressed_len; curpos += match_len) {
                unsigned sym;
                int ret;
 
-               bitstream_ensure_bits(istream, 16);
-
                sym = read_huffsym(istream, decode_table,
                                   XPRESS_TABLEBITS, XPRESS_MAX_CODEWORD_LEN);
                if (sym < XPRESS_NUM_CHARS) {
@@ -212,6 +199,16 @@ xpress_decompress(const void *compressed_data, size_t compressed_size,
                                uncompressed_size, decode_table);
 }
 
+static int
+xpress_create_decompressor(size_t max_block_size, void **dec_ret)
+{
+       if (max_block_size > XPRESS_MAX_OFFSET + 1)
+               return WIMLIB_ERR_INVALID_PARAM;
+
+       return 0;
+}
+
 const struct decompressor_ops xpress_decompressor_ops = {
-       .decompress = xpress_decompress,
+       .create_decompressor = xpress_create_decompressor,
+       .decompress          = xpress_decompress,
 };