From 445a785e10d3beb025dfe565e58603930ea09edc Mon Sep 17 00:00:00 2001
From: Alexandre Duret-Lutz <adl@lrde.epita.fr>
Date: Wed, 13 Apr 2011 11:31:36 +0200
Subject: [PATCH] Fix compression of large repetitions

* src/misc/intvcomp.cc (stream_compression_base::run): Limit
repeatitions to 40, not 42.
(stream_decompression_base::refill): Refill the end of the stream
with 0.
(stream_decompression_base::look_n_bits): Add assertion.
* src/tgbatest/intvcomp.cc: Add a new test case.
---
 ChangeLog                | 11 +++++++++++
 src/misc/intvcomp.cc     | 10 +++++-----
 src/tgbatest/intvcomp.cc | 13 +++++++++++++
 3 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 6c8a5aca2..6d51e28b2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2011-04-13  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
+
+	Fix compression of large repetitions
+
+	* src/misc/intvcomp.cc (stream_compression_base::run): Limit
+	repeatitions to 40, not 42.
+	(stream_decompression_base::refill): Refill the end of the stream
+	with 0.
+	(stream_decompression_base::look_n_bits): Add assertion.
+	* src/tgbatest/intvcomp.cc: Add a new test case.
+
 2011-04-12  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
 
 	More interfaces to the int array compression routines.
diff --git a/src/misc/intvcomp.cc b/src/misc/intvcomp.cc
index 35aec14ec..98022e82c 100644
--- a/src/misc/intvcomp.cc
+++ b/src/misc/intvcomp.cc
@@ -97,7 +97,7 @@ namespace spot
 	    if (val == last_val)
 	      {
 		unsigned int count = 1;
-		while (count <= 41 && self().skip_if(val))
+		while (count < 40 && self().skip_if(val))
 		  ++count;
 
 		if ((val == 0 && count < 3) || (val == 1 && count == 1))
@@ -376,9 +376,10 @@ namespace spot
 	buffer_ &= buffer_mask_;
 	look_bits_ += fill_size;
 
-	if (buffer_bits_ == 0 && self().have_comp_data())
+	if (buffer_bits_ == 0)
 	  {
-	    buffer_ = self().next_comp_data();
+	    if (self().have_comp_data())
+	      buffer_ = self().next_comp_data();
 	    buffer_bits_ = max_bits;
 	    buffer_mask_ = -1U;
 	    if (look_bits_ != max_bits)
@@ -399,12 +400,11 @@ namespace spot
 	  }
       }
 
-      // 010 00 00 010 00 101:011 010 00 101:010 010
-      // 010 00010000001000010010000100000
       unsigned int look_n_bits(unsigned int n)
       {
 	if (look_bits_ < n)
 	  refill();
+	assert(n <= look_bits_);
 	return look_ >> (look_bits_ - n);
       }
 
diff --git a/src/tgbatest/intvcomp.cc b/src/tgbatest/intvcomp.cc
index 2aa507c4b..99564c50e 100644
--- a/src/tgbatest/intvcomp.cc
+++ b/src/tgbatest/intvcomp.cc
@@ -205,5 +205,18 @@ int main()
   int comp9[] = { 0, 0, 0, 0, 0, 0, 0, 0, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
   errors += check(comp9, sizeof(comp9) / sizeof(*comp9));
 
+  int comp10[] = { 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0,
+		   0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		   0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
+		   0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		   1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0,
+		   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0,
+		   9, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 10,
+		   0, 0, 0, 0, 0, 0, 0, 0, 9 };
+  errors += check(comp10, sizeof(comp10) / sizeof(*comp10));
+
   return errors;
 }