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Fix compression of large repetitions

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* 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.
This commit is contained in:
Alexandre Duret-Lutz 2011-04-13 11:31:36 +02:00
parent 1b447c3676
commit 445a785e10
3 changed files with 29 additions and 5 deletions
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11
ChangeLog
View file

@ -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> 2011-04-12 Alexandre Duret-Lutz <adl@lrde.epita.fr>
More interfaces to the int array compression routines. More interfaces to the int array compression routines.

10
src/misc/intvcomp.cc
View file

@ -97,7 +97,7 @@ namespace spot
if (val == last_val) if (val == last_val)
{ {
unsigned int count = 1; unsigned int count = 1;
while (count <= 41 && self().skip_if(val)) while (count < 40 && self().skip_if(val))
++count; ++count;
if ((val == 0 && count < 3) || (val == 1 && count == 1)) if ((val == 0 && count < 3) || (val == 1 && count == 1))
@ -376,9 +376,10 @@ namespace spot
buffer_ &= buffer_mask_; buffer_ &= buffer_mask_;
look_bits_ += fill_size; 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_bits_ = max_bits;
buffer_mask_ = -1U; buffer_mask_ = -1U;
if (look_bits_ != max_bits) 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) unsigned int look_n_bits(unsigned int n)
{ {
if (look_bits_ < n) if (look_bits_ < n)
refill(); refill();
assert(n <= look_bits_);
return look_ >> (look_bits_ - n); return look_ >> (look_bits_ - n);
} }

13
src/tgbatest/intvcomp.cc
View file

@ -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 }; 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)); 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; return errors;
} }