Fixed parsing of bin/config output (by TomHol in rel-3-6-1).

[libucw.git] / lib / lizard.c

diff --git a/lib/lizard.c b/lib/lizard.c
index ee2e245cd199992450ba7684de0cc08981a591a7..6167fee043ba90c07befef746cd6bd917c5c21d7 100644 (file)
--- a/lib/lizard.c
+++ b/lib/lizard.c
@@ -181,7 +181,7 @@ lizard_compress(byte *in, uns in_len, byte *out)
     uns len = find_match(hash_tab[hash], hash_rec, in, in_end, &best, head);
     if (len < 3)
 #if 0                  // TODO: now, our routine does not detect matches of length 2
     uns len = find_match(hash_tab[hash], hash_rec, in, in_end, &best, head);
     if (len < 3)
 #if 0                  // TODO: now, our routine does not detect matches of length 2

-      if (len == 2 && (in - best->string) < ((1<<10) + 1))
+      if (len == 2 && (in - best->string - 1) < (1<<10))

       { /* pass-thru */ }
       else
 #endif
       { /* pass-thru */ }
       else
 #endif


@@ -212,26 +212,27 @@ literal:
        goto dump_2sequence;
     } else
 #endif
        goto dump_2sequence;
     } else
 #endif

-    if (len == 3 && is_in_copy_mode && shift >= (1<<11) && shift < (1<<11) + (1<<10))
+    /* now, len >= 3 */
+    if (shift < (1<<11) && len <= 8)

     {
     {

-      /* optimisation for length-3 matches after a copy command */
-      shift -= 1<<11;
+      shift |= (len-3 + 2)<<11;

 dump_2sequence:
       if (copy_len)
        out = flush_copy_command(bof, out, copy_start, copy_len);
       *out++ = (shift>>6) & ~3;                        /* shift fits into 10 bits */
       *out++ = shift & 0xff;
     }
 dump_2sequence:
       if (copy_len)
        out = flush_copy_command(bof, out, copy_start, copy_len);
       *out++ = (shift>>6) & ~3;                        /* shift fits into 10 bits */
       *out++ = shift & 0xff;
     }

-    /* now, len >= 3 */
-    else if (shift < (1<<11) && len <= 8)
+    else if (len == 3 && is_in_copy_mode)

     {
     {

-      shift |= (len-3 + 2)<<11;
-      goto dump_2sequence;                     /* shift has 11 bits and contains also len */
+      if (shift < (1<<11) + (1<<10))           /* optimisation for length-3 matches after a copy command */
+      {
+       shift -= 1<<11;
+       goto dump_2sequence;                    /* shift has 11 bits and contains also len */
+      }
+      else                                     /* avoid 3-sequence compressed to 3 sequence if it can simply be appended */
+       goto literal;

     }
     /* We have to use a 3-byte sequence.  */
     }
     /* We have to use a 3-byte sequence.  */

-    else if (len == 3 && is_in_copy_mode)
-      /* avoid 3-sequence compressed to 3 sequence if it can simply be appended */
-      goto literal;

     else
     {
       if (copy_len)
     else
     {
       if (copy_len)


@@ -414,18 +415,22 @@ perform_copy_command:
 Description of the LZO1X format :
 =================================
 
 Description of the LZO1X format :
 =================================
 

+The meaning of the commands depends on the current mode. It can be either
+the compressed mode or the copy mode. In some cases, the compressed mode
+also distinguishes whether we just left the copy mode or not.
+

 Beginning of file:
 ------------------
 
 Beginning of file:
 ------------------
 

-If the first byte is 00010001, it means probably EOF (empty file), so switch
-to the compressed mode.  If it is bigger, subtract 17 and copy this number of
-the following characters to the ouput and switch to the compressed mode.  If
-it is smaller, go to the copy mode.
+Start in copy mode. If the first byte is 00010001, it means probably EOF (empty file),
+so switch to the compressed mode.  If it is bigger, subtract 17 and copy this number of
+the following characters to the output and switch to the compressed mode.
+If it is smaller, interpret it as a regular copy mode command.

 
 

-Compressed mode :
------------------
+Compressed mode:
+----------------

 
 

-Read the first byte of the sequence and determine the type of bit-encoding by
+Read the first byte of the sequence and determine the type of bit encoding by

 looking at the most significant bits.  The sequence is always at least 2 bytes
 long.  Decode sequences of these types until the EOF or END marker is read.
 
 looking at the most significant bits.  The sequence is always at least 2 bytes
 long.  Decode sequences of these types until the EOF or END marker is read.
 


@@ -449,20 +454,18 @@ long.  Decode sequences of these types until the EOF or END marker is read.
 
 pattern                                        length          position
 
 
 pattern                                        length          position
 

-0000ppCC                pppppppp       2               10 bits (*)
-0001pLLL L*    ppppppCC pppppppp       3..9 + extend   15 bits + EOF
+0000ppCC                pppppppp       2               10 bits         [default interpretation]
+0000ppCC                pppppppp       3               10 bits + 2048  [just after return from copy mode]
+0001pLLL L*    ppppppCC pppppppp       3..9 + extend   15 bits         [pos 0 interpreted as EOF]

 001LLLLL L*    ppppppCC pppppppp       3..33 + extend  14 bits
 001LLLLL L*    ppppppCC pppppppp       3..33 + extend  14 bits

-01\
-10 \
-11  \
-LLLpppCC                pppppppp       3..8            11 bits
+LLLpppCC                pppppppp       3..8            11 bits         [LLL >= 010]

 
 

-Copy mode :
------------
+Copy mode:
+----------

 
 Read the first byte and, if the most significant bits are 0000, perform the
 following command, otherwise switch to the compressed mode (and evaluate the
 
 Read the first byte and, if the most significant bits are 0000, perform the
 following command, otherwise switch to the compressed mode (and evaluate the

-command).
+command there).

 
 pattern                                        length          position
 
 
 pattern                                        length          position
 


@@ -471,9 +474,4 @@ pattern                                     length          position
   Copy L characters from the compressed text to the output.  The overhead for
   incompressible strings is only roughly 1/256 + epsilon.
 
   Copy L characters from the compressed text to the output.  The overhead for
   incompressible strings is only roughly 1/256 + epsilon.
 

-(*) After reading one copy command, switch to the compressed mode with the
-following "optimisation": the pattern 0000ppCC expands to length 3 instead of 2
-and 2048 is added to the position (now it is slightly more than 11 bits),
-because a sequence of length 2 would never be used.
-

 */
 */