Merging upstream version 0.4.

Signed-off-by: Daniel Baumann <mail@daniel-baumann.ch>

14 files changed, 750 insertions, 727 deletions

diff --git a/ChangeLog b/ChangeLog
index b0ef7eb..194ad70 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2010-01-31  Antonio Diaz Diaz  <ant_diaz@teleline.es>
+
+	* Version 0.4 released.
+	* main.cc (show_version): Show the version of lzlib being used.
+	* Code reorganization. Class Packet_courier now coordinates data
+	  movement and synchronization among threads.
+
 2010-01-24  Antonio Diaz Diaz  <ant_diaz@teleline.es>
 
 	* Version 0.3 released.
diff --git a/Makefile.in b/Makefile.in
index 6eea4bf..ca6b899 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -7,7 +7,7 @@ INSTALL_DIR = $(INSTALL) -d -m 755
 LIBS = -llz -lpthread
 SHELL = /bin/sh
 
-objs = arg_parser.o plzip.o main.o
+objs = arg_parser.o compress.o decompress.o main.o
 
 
 .PHONY : all install install-info install-man install-strip \
@@ -30,8 +30,9 @@ main.o : main.cc
 
 $(objs)       : Makefile
 arg_parser.o  : arg_parser.h
+compress.o    : plzip.h
+decompress.o  : plzip.h
 main.o        : arg_parser.h plzip.h
-plzip.o       : plzip.h
 
 doc : info man
 
@@ -53,30 +54,30 @@ check : all
 	@$(VPATH)/testsuite/check.sh $(VPATH)/testsuite
 
 install : all install-info install-man
-	if [ ! -d $(DESTDIR)$(bindir) ] ; then $(INSTALL_DIR) $(DESTDIR)$(bindir) ; fi
-	$(INSTALL_PROGRAM) ./$(progname) $(DESTDIR)$(bindir)/$(progname)
+	if [ ! -d "$(DESTDIR)$(bindir)" ] ; then $(INSTALL_DIR) "$(DESTDIR)$(bindir)" ; fi
+	$(INSTALL_PROGRAM) ./$(progname) "$(DESTDIR)$(bindir)/$(progname)"
 
 install-info :
-	if [ ! -d $(DESTDIR)$(infodir) ] ; then $(INSTALL_DIR) $(DESTDIR)$(infodir) ; fi
-	$(INSTALL_DATA) $(VPATH)/doc/$(pkgname).info $(DESTDIR)$(infodir)/$(pkgname).info
-	-install-info --info-dir=$(DESTDIR)$(infodir) $(DESTDIR)$(infodir)/$(pkgname).info
+	if [ ! -d "$(DESTDIR)$(infodir)" ] ; then $(INSTALL_DIR) "$(DESTDIR)$(infodir)" ; fi
+	$(INSTALL_DATA) $(VPATH)/doc/$(pkgname).info "$(DESTDIR)$(infodir)/$(pkgname).info"
+	-install-info --info-dir="$(DESTDIR)$(infodir)" "$(DESTDIR)$(infodir)/$(pkgname).info"
 
 install-man :
-	if [ ! -d $(DESTDIR)$(mandir)/man1 ] ; then $(INSTALL_DIR) $(DESTDIR)$(mandir)/man1 ; fi
-	$(INSTALL_DATA) $(VPATH)/doc/$(progname).1 $(DESTDIR)$(mandir)/man1/$(progname).1
+	if [ ! -d "$(DESTDIR)$(mandir)/man1" ] ; then $(INSTALL_DIR) "$(DESTDIR)$(mandir)/man1" ; fi
+	$(INSTALL_DATA) $(VPATH)/doc/$(progname).1 "$(DESTDIR)$(mandir)/man1/$(progname).1"
 
 install-strip : all
 	$(MAKE) INSTALL_PROGRAM='$(INSTALL_PROGRAM) -s' install
 
 uninstall : uninstall-info uninstall-man
-	-rm -f $(DESTDIR)$(bindir)/$(progname)
+	-rm -f "$(DESTDIR)$(bindir)/$(progname)"
 
 uninstall-info :
-	-install-info --info-dir=$(DESTDIR)$(infodir) --remove $(DESTDIR)$(infodir)/$(pkgname).info
-	-rm -f $(DESTDIR)$(infodir)/$(pkgname).info
+	-install-info --info-dir="$(DESTDIR)$(infodir)" --remove "$(DESTDIR)$(infodir)/$(pkgname).info"
+	-rm -f "$(DESTDIR)$(infodir)/$(pkgname).info"
 
 uninstall-man :
-	-rm -f $(DESTDIR)$(mandir)/man1/$(progname).1
+	-rm -f "$(DESTDIR)$(mandir)/man1/$(progname).1"
 
 dist : doc
 	ln -sf $(VPATH) $(DISTNAME)
diff --git a/NEWS b/NEWS
index 08b0074..4e4b50c 100644
--- a/NEWS
+++ b/NEWS
@@ -1,11 +1,6 @@
-Changes in version 0.3:
+Changes in version 0.4:
 
-New option "--data-size" has been added.
+The option "--version" now shows the version of lzlib being used.
 
-Output file is now removed if plzip is interrupted.
-
-This version automatically chooses the smallest possible dictionary size
-for each member during compression, saving memory during decompression.
-
-Regular files are now open in binary mode in non-POSIX platforms
-defining the O_BINARY macro.
+A code reorganization has been made. The new class "Packet_courier" now
+coordinates data movement and synchronization among threads.
diff --git a/README b/README
index c9b0c03..1f5b745 100644
--- a/README
+++ b/README
@@ -1,6 +1,10 @@
 Description
 
-Plzip is a parallel version of the lzip data compressor. Currently only
+Plzip is a massively parallel (multithreaded) data compressor compatible
+with the lzip file format. The files produced by plzip are fully
+compatible with lzip-1.4 or newer. Plzip is intended for faster
+compression/decompression of big files on multiprocessor machines. On
+files big enough, plzip can use hundreds of processors. Currently only
 compression is performed in parallel. Parallel decompression is planned
 to be implemented later.
 
diff --git a/compress.cc b/compress.cc
new file mode 100644
index 0000000..e66b537
--- /dev/null
+++ b/compress.cc
@@ -0,0 +1,460 @@
+/*  Plzip - A parallel compressor compatible with lzip
+    Copyright (C) 2009 Laszlo Ersek.
+    Copyright (C) 2009, 2010 Antonio Diaz Diaz.
+
+    This program is free software: you can redistribute it and/or modify
+    it under the 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.
+
+    This program 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 General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#define _FILE_OFFSET_BITS 64
+
+#include <algorithm>
+#include <cassert>
+#include <cerrno>
+#include <climits>
+#include <csignal>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <queue>
+#include <string>
+#include <vector>
+#include <pthread.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <lzlib.h>
+
+#include "plzip.h"
+
+#ifndef LLONG_MAX
+#define LLONG_MAX  0x7FFFFFFFFFFFFFFFLL
+#endif
+#ifndef LLONG_MIN
+#define LLONG_MIN  (-LLONG_MAX - 1LL)
+#endif
+#ifndef ULLONG_MAX
+#define ULLONG_MAX 0xFFFFFFFFFFFFFFFFULL
+#endif
+
+
+void xinit( pthread_cond_t * cond, pthread_mutex_t * mutex )
+  {
+  int ret = pthread_mutex_init( mutex, 0 );
+  if( ret != 0 ) { show_error( "pthread_mutex_init", ret ); fatal(); }
+
+  ret = pthread_cond_init( cond, 0 );
+  if( ret != 0 ) { show_error( "pthread_cond_init", ret ); fatal(); }
+  }
+
+
+void xdestroy( pthread_cond_t * cond, pthread_mutex_t * mutex )
+  {
+  int ret = pthread_cond_destroy( cond );
+  if( ret != 0 ) { show_error( "pthread_cond_destroy", ret ); fatal(); }
+
+  ret = pthread_mutex_destroy( mutex );
+  if( ret != 0 ) { show_error( "pthread_mutex_destroy", ret ); fatal(); }
+  }
+
+
+void xlock( pthread_mutex_t * mutex )
+  {
+  int ret = pthread_mutex_lock( mutex );
+  if( ret != 0 ) { show_error( "pthread_mutex_lock", ret ); fatal(); }
+  }
+
+
+void xunlock( pthread_mutex_t * mutex )
+  {
+  int ret = pthread_mutex_unlock( mutex );
+  if( ret != 0 ) { show_error( "pthread_mutex_unlock", ret ); fatal(); }
+  }
+
+
+void xwait( pthread_cond_t * cond, pthread_mutex_t * mutex )
+  {
+  int ret = pthread_cond_wait( cond, mutex );
+  if( ret != 0 ) { show_error( "pthread_cond_wait", ret ); fatal(); }
+  }
+
+
+void xsignal( pthread_cond_t * cond )
+  {
+  int ret = pthread_cond_signal( cond );
+  if( ret != 0 ) { show_error( "pthread_cond_signal", ret ); fatal(); }
+  }
+
+
+void xbroadcast( pthread_cond_t * cond )
+  {
+  int ret = pthread_cond_broadcast( cond );
+  if( ret != 0 ) { show_error( "pthread_cond_broadcast", ret ); fatal(); }
+  }
+
+
+void xcreate( pthread_t *thread, void *(*routine)(void *), void *arg )
+  {
+  int ret = pthread_create( thread, 0, routine, arg );
+  if( ret != 0 ) { show_error( "pthread_create", ret ); fatal(); }
+  }
+
+
+void xjoin( pthread_t thread )
+  {
+  int ret = pthread_join( thread, 0 );
+  if( ret != 0 ) { show_error( "pthread_join", ret ); fatal(); }
+  }
+
+
+namespace {
+
+long long in_size = 0;
+long long out_size = 0;
+
+
+struct Packet			// data block with a serial number
+  {
+  unsigned long long id;	// serial number assigned as received
+  int size;			// # of bytes in data
+  uint8_t * data;
+  };
+
+
+class Packet_courier			// moves packets around
+  {
+public:
+  unsigned long icheck_counter;
+  unsigned long iwait_counter;
+  unsigned long ocheck_counter;
+  unsigned long owait_counter;
+private:
+  unsigned long long receive_id;	// id assigned to next packet received
+  unsigned long long deliver_id;	// id of next packet to be delivered
+  Slot_tally slot_tally;
+  std::queue< Packet * > packet_queue;
+  std::vector< Packet * > circular_buffer;
+  int num_working;			// Number of workers still running
+  const int num_slots;			// max packets in circulation
+  pthread_mutex_t imutex;
+  pthread_cond_t iav_or_eof;	// input packet available or splitter done
+  pthread_mutex_t omutex;
+  pthread_cond_t oav_or_exit;	// output packet available or all workers exited
+  bool eof;			// splitter done
+
+public:
+  Packet_courier( const int num_workers, const int slots )
+    : icheck_counter( 0 ), iwait_counter( 0 ),
+      ocheck_counter( 0 ), owait_counter( 0 ),
+      receive_id( 0 ), deliver_id( 0 ),
+      slot_tally( slots ), circular_buffer( slots, (Packet *) 0 ),
+      num_working( num_workers ), num_slots( slots ), eof( false )
+    { xinit( &iav_or_eof, &imutex ); xinit( &oav_or_exit, &omutex ); }
+
+  ~Packet_courier()
+    { xdestroy( &iav_or_eof, &imutex ); xdestroy( &oav_or_exit, &omutex ); }
+
+  // make a packet with data received from splitter
+  void receive_packet( uint8_t * const data, const int size )
+    {
+    Packet * ipacket = new Packet;
+    ipacket->id = receive_id++;
+    ipacket->size = size;
+    ipacket->data = data;
+    slot_tally.get_slot();		// wait for a free slot
+    xlock( &imutex );
+    packet_queue.push( ipacket );
+    xsignal( &iav_or_eof );
+    xunlock( &imutex );
+    }
+
+  // distribute a packet to a worker
+  Packet * distribute_packet()
+    {
+    Packet * ipacket = 0;
+    xlock( &imutex );
+    ++icheck_counter;
+    while( packet_queue.empty() && !eof )
+      {
+      ++iwait_counter;
+      xwait( &iav_or_eof, &imutex );
+      }
+    if( !packet_queue.empty() )
+      {
+      ipacket = packet_queue.front();
+      packet_queue.pop();
+      }
+    xunlock( &imutex );
+    if( ipacket == 0 )
+      {
+      // Notify muxer when last worker exits
+      xlock( &omutex );
+      if( --num_working == 0 )
+        xsignal( &oav_or_exit );
+      xunlock( &omutex );
+      }
+    return ipacket;
+    }
+
+  // collect a packet from a worker
+  void collect_packet( Packet * const opacket )
+    {
+    xlock( &omutex );
+    // id collision shouldn't happen
+    assert( circular_buffer[opacket->id%num_slots] == 0 );
+    // Merge packet into circular buffer
+    circular_buffer[opacket->id%num_slots] = opacket;
+    if( opacket->id == deliver_id ) xsignal( &oav_or_exit );
+    xunlock( &omutex );
+    }
+
+  // deliver a packet to muxer
+  Packet * deliver_packet()
+    {
+    xlock( &omutex );
+    ++ocheck_counter;
+    while( circular_buffer[deliver_id%num_slots] == 0 && num_working > 0 )
+      {
+      ++owait_counter;
+      xwait( &oav_or_exit, &omutex );
+      }
+    Packet * opacket = circular_buffer[deliver_id%num_slots];
+    circular_buffer[deliver_id%num_slots] = 0;
+    ++deliver_id;
+    xunlock( &omutex );
+    if( opacket != 0 )
+      slot_tally.leave_slot();		// return a slot to the tally
+    return opacket;
+    }
+
+  void finish()			// splitter has no more packets to send
+    {
+    xlock( &imutex );
+    eof = true;
+    xbroadcast( &iav_or_eof );
+    xunlock( &imutex );
+    }
+
+  bool finished()		// all packets delivered to muxer
+    {
+    if( !slot_tally.all_free() || !eof || !packet_queue.empty() ||
+        num_working != 0 ) return false;
+    for( int i = 0; i < num_slots; ++i )
+      if( circular_buffer[i] != 0 ) return false;
+    return true;
+    }
+
+  const Slot_tally & tally() const { return slot_tally; }
+  };
+
+
+struct Splitter_arg
+  {
+  Packet_courier * courier;
+  int infd;
+  int data_size;
+  };
+
+
+       // split data from input file into chunks and pass them to
+       // courier for packaging and distribution to workers.
+void * splitter( void * arg )
+  {
+  const Splitter_arg & tmp = *(Splitter_arg *)arg;
+  Packet_courier & courier = *tmp.courier;
+  const int infd = tmp.infd;
+  const int data_size = tmp.data_size;
+
+  for( bool first_post = true; ; first_post = false )
+    {
+    uint8_t * data = new( std::nothrow ) uint8_t[data_size];
+    if( data == 0 ) { show_error( "not enough memory" ); fatal(); }
+    const int size = readblock( infd, data, data_size );
+    if( size != data_size && errno ) { show_error( "read", errno ); fatal(); }
+
+    if( size > 0 || first_post )	// first packet can be empty
+      {
+      in_size += size;
+      courier.receive_packet( data, size );
+      }
+    else
+      {
+      delete[] data;
+      courier.finish();			// no more packets to send
+      break;
+      }
+    }
+  return 0;
+  }
+
+
+struct Worker_arg
+  {
+  int dictionary_size;
+  int match_len_limit;
+  Packet_courier * courier;
+  };
+
+
+       // get packets from courier, replace their contents, and return
+       // them to courier.
+void * worker( void * arg )
+  {
+  const Worker_arg & tmp = *(Worker_arg *)arg;
+  const int dictionary_size = tmp.dictionary_size;
+  const int match_len_limit = tmp.match_len_limit;
+  Packet_courier & courier = *tmp.courier;
+
+  while( true )
+    {
+    Packet * packet = courier.distribute_packet();
+    if( packet == 0 ) break;		// no more packets to process
+
+    const int compr_size = 42 + packet->size + ( ( packet->size + 7 ) / 8 );
+    uint8_t * const new_data = new( std::nothrow ) uint8_t[compr_size];
+    if( new_data == 0 ) { show_error( "not enough memory" ); fatal(); }
+    const int dict_size = std::max( LZ_min_dictionary_size(),
+                                    std::min( dictionary_size, packet->size ) );
+    LZ_Encoder * const encoder =
+      LZ_compress_open( dict_size, match_len_limit, LLONG_MAX );
+    if( !encoder || LZ_compress_errno( encoder ) != LZ_ok )
+      { show_error( "LZ_compress_open failed." ); fatal(); }
+
+    int written = 0;
+    int new_size = 0;
+    while( true )
+      {
+      if( LZ_compress_write_size( encoder ) > 0 )
+        {
+        if( written < packet->size )
+          {
+          const int wr = LZ_compress_write( encoder, packet->data + written,
+                                            packet->size - written );
+          if( wr < 0 ) { show_error( "LZ_compress_write failed." ); fatal(); }
+          written += wr;
+          }
+        if( written >= packet->size ) LZ_compress_finish( encoder );
+        }
+      const int rd = LZ_compress_read( encoder, new_data + new_size,
+                                       compr_size - new_size );
+      if( rd < 0 ) { show_error( "LZ_compress_read failed." ); fatal(); }
+      new_size += rd;
+      assert( new_size <= compr_size );
+      if( LZ_compress_finished( encoder ) == 1 ) break;
+      }
+
+    if( LZ_compress_close( encoder ) < 0 )
+      { show_error( "LZ_compress_close failed." ); fatal(); }
+
+    delete[] packet->data;
+    packet->size = new_size;
+    packet->data = new_data;
+    courier.collect_packet( packet );
+    }
+  return 0;
+  }
+
+
+     // get from courier the processed and sorted packets, and write
+     // their contents to the output file.
+void muxer( Packet_courier & courier, const int outfd )
+  {
+  while( true )
+    {
+    Packet * opacket = courier.deliver_packet();
+    if( opacket == 0 ) break;	// queue is empty. all workers exited
+
+    out_size += opacket->size;
+
+    if( outfd >= 0 )
+      {
+      const int wr = writeblock( outfd, opacket->data, opacket->size );
+      if( wr != opacket->size )
+        { show_error( "write", errno ); fatal(); }
+      }
+    delete[] opacket->data;
+    delete opacket;
+    }
+  }
+
+} // end namespace
+
+
+    // init the courier, then start the splitter and the workers and
+    // call the muxer.
+int compress( const int data_size, const int dictionary_size,
+              const int match_len_limit, const int num_workers,
+              const int num_slots, const int infd, const int outfd,
+              const int debug_level )
+  {
+  in_size = 0;
+  out_size = 0;
+  Packet_courier courier( num_workers, num_slots );
+
+  Splitter_arg splitter_arg;
+  splitter_arg.courier = &courier;
+  splitter_arg.infd = infd;
+  splitter_arg.data_size = data_size;
+
+  pthread_t splitter_thread;
+  xcreate( &splitter_thread, splitter, &splitter_arg );
+
+  Worker_arg worker_arg;
+  worker_arg.dictionary_size = dictionary_size;
+  worker_arg.match_len_limit = match_len_limit;
+  worker_arg.courier = &courier;
+
+  pthread_t * worker_threads = new( std::nothrow ) pthread_t[num_workers];
+  if( worker_threads == 0 )
+    { show_error( "not enough memory" ); fatal(); }
+  for( int i = 0; i < num_workers; ++i )
+    xcreate( &worker_threads[i], worker, &worker_arg );
+
+  muxer( courier, outfd );
+
+  for( int i = num_workers - 1; i >= 0; --i )
+    xjoin(worker_threads[i]);
+  delete[] worker_threads; worker_threads = 0;
+
+  xjoin( splitter_thread );
+
+  if( verbosity >= 1 )
+    {
+    if( in_size <= 0 || out_size <= 0 )
+      std::fprintf( stderr, "no data compressed.\n" );
+    else
+      std::fprintf( stderr, "%6.3f:1, %6.3f bits/byte, "
+                            "%5.2f%% saved, %lld in, %lld out.\n",
+                    (double)in_size / out_size,
+                    ( 8.0 * out_size ) / in_size,
+                    100.0 * ( 1.0 - ( (double)out_size / in_size ) ),
+                    in_size, out_size );
+    }
+
+  if( debug_level & 1 )
+    std::fprintf( stderr,
+      "splitter tried to send a packet           %8lu times\n"
+      "splitter had to wait                      %8lu times\n"
+      "any worker tried to consume from splitter %8lu times\n"
+      "any worker had to wait                    %8lu times\n"
+      "muxer tried to consume from workers       %8lu times\n"
+      "muxer had to wait                         %8lu times\n",
+      courier.tally().check_counter,
+      courier.tally().wait_counter,
+      courier.icheck_counter,
+      courier.iwait_counter,
+      courier.ocheck_counter,
+      courier.owait_counter );
+
+  assert( courier.finished() );
+  return 0;
+  }
diff --git a/configure b/configure
index 3cd1dc8..e9ccd08 100755
--- a/configure
+++ b/configure
@@ -1,16 +1,16 @@
 #! /bin/sh
-# configure script for Plzip - A parallel version of the lzip data compressor
+# configure script for Plzip - A parallel compressor compatible with lzip
 # Copyright (C) 2009, 2010 Antonio Diaz Diaz.
 #
 # This configure script is free software: you have unlimited permission
 # to copy, distribute and modify it.
 #
-# Date of this version: 2010-01-24
+# Date of this version: 2010-01-31
 
 args=
 no_create=
 pkgname=plzip
-pkgversion=0.3
+pkgversion=0.4
 progname=plzip
 srctrigger=plzip.h
 
@@ -135,7 +135,7 @@ if [ -z "${CXX}" ] ; then		# Let the user override the test.
 fi
 
 echo
-if [ -z ${no_create} ] ; then
+if [ -z "${no_create}" ] ; then
 	echo "creating config.status"
 	rm -f config.status
 	cat > config.status << EOF
@@ -166,7 +166,7 @@ echo "CXXFLAGS = ${CXXFLAGS}"
 echo "LDFLAGS = ${LDFLAGS}"
 rm -f Makefile
 cat > Makefile << EOF
-# Makefile for Plzip - A parallel version of the lzip data compressor
+# Makefile for Plzip - A parallel compressor compatible with lzip
 # Copyright (C) 2009, 2010 Antonio Diaz Diaz.
 # This file was generated automatically by configure. Do not edit.
 #
diff --git a/decompress.cc b/decompress.cc
new file mode 100644
index 0000000..0a125d0
--- /dev/null
+++ b/decompress.cc
@@ -0,0 +1,123 @@
+/*  Plzip - A parallel compressor compatible with lzip
+    Copyright (C) 2009 Laszlo Ersek.
+    Copyright (C) 2009, 2010 Antonio Diaz Diaz.
+
+    This program is free software: you can redistribute it and/or modify
+    it under the 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.
+
+    This program 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 General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#define _FILE_OFFSET_BITS 64
+
+#include <algorithm>
+#include <cerrno>
+#include <climits>
+#include <csignal>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <queue>
+#include <string>
+#include <vector>
+#include <pthread.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <lzlib.h>
+
+#include "plzip.h"
+
+
+namespace {
+
+int do_decompress( LZ_Decoder * const decoder, const int infd, const int outfd,
+                   const Pretty_print & pp, const bool testing )
+  {
+  const int in_buffer_size = 65536, out_buffer_size = 8 * in_buffer_size;
+  uint8_t in_buffer[in_buffer_size], out_buffer[out_buffer_size];
+
+  while( true )
+    {
+    int in_size = std::min( LZ_decompress_write_size( decoder ), in_buffer_size );
+    if( in_size > 0 )
+      {
+      const int max_in_size = in_size;
+      in_size = readblock( infd, in_buffer, max_in_size );
+      if( in_size != max_in_size && errno )
+        { pp(); show_error( "read error", errno ); return 1; }
+      if( in_size == 0 ) LZ_decompress_finish( decoder );
+      else if( in_size != LZ_decompress_write( decoder, in_buffer, in_size ) )
+        internal_error( "library error (LZ_decompress_write)" );
+      }
+    int out_size = LZ_decompress_read( decoder, out_buffer, out_buffer_size );
+//    std::fprintf( stderr, "%5d in_size, %6d out_size.\n", in_size, out_size );
+    if( out_size < 0 )
+      {
+      const LZ_Errno lz_errno = LZ_decompress_errno( decoder );
+      if( lz_errno == LZ_header_error )
+        {
+        if( LZ_decompress_total_out_size( decoder ) > 0 )
+          break;				// trailing garbage
+        pp( "error reading member header" );
+        return 1;
+        }
+      if( lz_errno == LZ_mem_error )
+        {
+        pp( "not enough memory. Find a machine with more memory" );
+        return 1;
+        }
+      pp();
+      if( lz_errno == LZ_unexpected_eof )
+        {
+        if( verbosity >= 0 )
+          std::fprintf( stderr, "file ends unexpectedly at pos %lld\n",
+                        LZ_decompress_total_in_size( decoder ) );
+        return 2;
+        }
+      if( verbosity >= 0 )
+        std::fprintf( stderr, "LZ_decompress_read error: %s.\n",
+                      LZ_strerror( LZ_decompress_errno( decoder ) ) );
+      return 1;
+      }
+    else if( out_size > 0 && outfd >= 0 )
+      {
+      const int wr = writeblock( outfd, out_buffer, out_size );
+      if( wr != out_size )
+        { pp(); show_error( "write error", errno ); return 1; }
+      }
+    if( LZ_decompress_finished( decoder ) == 1 ) break;
+    if( in_size == 0 && out_size == 0 )
+      internal_error( "library error (LZ_decompress_read)" );
+    }
+  if( verbosity >= 1 )
+    { if( testing ) std::fprintf( stderr, "ok\n" );
+      else std::fprintf( stderr, "done\n" ); }
+  return 0;
+  }
+
+} // end namespace
+
+
+int decompress( const int infd, const int outfd, const Pretty_print & pp,
+                const bool testing )
+  {
+  LZ_Decoder * const decoder = LZ_decompress_open();
+  int retval;
+
+  if( !decoder || LZ_decompress_errno( decoder ) != LZ_ok )
+    {
+    pp( "not enough memory" );
+    retval = 1;
+    }
+  else retval = do_decompress( decoder, infd, outfd, pp, testing );
+  LZ_decompress_close( decoder );
+  return retval;
+  }
diff --git a/doc/plzip.1 b/doc/plzip.1
index feb0aa1..148c95b 100644
--- a/doc/plzip.1
+++ b/doc/plzip.1
@@ -1,12 +1,12 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.36.
-.TH PLZIP "1" "January 2010" "Plzip 0.3" "User Commands"
+.TH PLZIP "1" "January 2010" "Plzip 0.4" "User Commands"
 .SH NAME
 Plzip \- data compressor based on the LZMA algorithm
 .SH SYNOPSIS
 .B plzip
 [\fIoptions\fR] [\fIfiles\fR]
 .SH DESCRIPTION
-Plzip \- A parallel version of the lzip data compressor.
+Plzip \- A parallel compressor compatible with lzip.
 .SH OPTIONS
 .TP
 \fB\-h\fR, \fB\-\-help\fR
@@ -71,6 +71,7 @@ Plzip home page: http://www.nongnu.org/lzip/plzip.html
 Copyright \(co 2009 Laszlo Ersek.
 .br
 Copyright \(co 2010 Antonio Diaz Diaz.
+Using Lzlib 0.9-rc1
 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
 .br
 This is free software: you are free to change and redistribute it.
diff --git a/doc/plzip.info b/doc/plzip.info
index 9a48fcb..c4dc967 100644
--- a/doc/plzip.info
+++ b/doc/plzip.info
@@ -3,7 +3,7 @@ plzip.texinfo.
 
 INFO-DIR-SECTION Data Compression
 START-INFO-DIR-ENTRY
-* Plzip: (plzip).               Parallel version of the lzip data compressor
+* Plzip: (plzip).               Parallel compressor compatible with lzip
 END-INFO-DIR-ENTRY
 
 
@@ -12,7 +12,7 @@ File: plzip.info,  Node: Top,  Next: Introduction,  Up: (dir)
 Plzip Manual
 ************
 
-This manual is for Plzip (version 0.3, 24 January 2010).
+This manual is for Plzip (version 0.4, 31 January 2010).
 
 * Menu:
 
@@ -34,11 +34,13 @@ File: plzip.info,  Node: Introduction,  Next: Invoking Plzip,  Prev: Top,  Up: T
 1 Introduction
 **************
 
-Plzip is a parallel version of the lzip data compressor. The files
-produced by plzip are fully compatible with lzip-1.4 or newer. Plzip is
-intended for faster compression/decompression of big files on
-multiprocessor machines. Currently only compression is performed in
-parallel. Parallel decompression is planned to be implemented later.
+Plzip is a massively parallel (multithreaded) data compressor compatible
+with the lzip file format. The files produced by plzip are fully
+compatible with lzip-1.4 or newer. Plzip is intended for faster
+compression/decompression of big files on multiprocessor machines. On
+files big enough, plzip can use hundreds of processors. Currently only
+compression is performed in parallel. Parallel decompression is planned
+to be implemented later.
 
    Lzip is a lossless data compressor based on the LZMA algorithm, with
 very safe integrity checking and a user interface similar to the one of
@@ -303,11 +305,11 @@ Concept Index
 
 
 Tag Table:
-Node: Top227
-Node: Introduction750
-Node: Invoking Plzip3571
-Node: File Format7260
-Node: Problems9216
-Node: Concept Index9745
+Node: Top223
+Node: Introduction746
+Node: Invoking Plzip3669
+Node: File Format7358
+Node: Problems9314
+Node: Concept Index9843
 
 End Tag Table
diff --git a/doc/plzip.texinfo b/doc/plzip.texinfo
index 04bf822..12ac4c8 100644
--- a/doc/plzip.texinfo
+++ b/doc/plzip.texinfo
@@ -5,12 +5,12 @@
 @finalout
 @c %**end of header
 
-@set UPDATED 24 January 2010
-@set VERSION 0.3
+@set UPDATED 31 January 2010
+@set VERSION 0.4
 
 @dircategory Data Compression
 @direntry
-* Plzip: (plzip).               Parallel version of the lzip data compressor
+* Plzip: (plzip).               Parallel compressor compatible with lzip
 @end direntry
 
 
@@ -50,11 +50,13 @@ to copy, distribute and modify it.
 @chapter Introduction
 @cindex introduction
 
-Plzip is a parallel version of the lzip data compressor. The files
-produced by plzip are fully compatible with lzip-1.4 or newer. Plzip is
-intended for faster compression/decompression of big files on
-multiprocessor machines. Currently only compression is performed in
-parallel. Parallel decompression is planned to be implemented later.
+Plzip is a massively parallel (multithreaded) data compressor compatible
+with the lzip file format. The files produced by plzip are fully
+compatible with lzip-1.4 or newer. Plzip is intended for faster
+compression/decompression of big files on multiprocessor machines. On
+files big enough, plzip can use hundreds of processors. Currently only
+compression is performed in parallel. Parallel decompression is planned
+to be implemented later.
 
 Lzip is a lossless data compressor based on the LZMA algorithm, with
 very safe integrity checking and a user interface similar to the one of
diff --git a/main.cc b/main.cc
index f3f12e0..db70e00 100644
--- a/main.cc
+++ b/main.cc
@@ -1,4 +1,4 @@
-/*  Plzip - A parallel version of the lzip data compressor
+/*  Plzip - A parallel compressor compatible with lzip
     Copyright (C) 2009 Laszlo Ersek.
     Copyright (C) 2009, 2010 Antonio Diaz Diaz.
 
@@ -58,8 +58,6 @@
 #define ULLONG_MAX 0xFFFFFFFFFFFFFFFFULL
 #endif
 
-void internal_error( const char * msg );
-
 
 namespace {
 
@@ -93,44 +91,10 @@ bool delete_output_on_interrupt = false;
 pthread_t main_thread;
 pid_t main_thread_pid;
 
-class Pretty_print
-  {
-  const char * const stdin_name;
-  const unsigned int stdin_name_len;
-  unsigned int longest_name;
-  std::string name_;
-  mutable bool first_post;
-
-public:
-  Pretty_print( const std::vector< std::string > & filenames )
-    : stdin_name( "(stdin)" ), stdin_name_len( std::strlen( stdin_name ) ),
-      longest_name( 0 ), first_post( false )
-    {
-    for( unsigned int i = 0; i < filenames.size(); ++i )
-      {
-      const std::string & s = filenames[i];
-      const unsigned int len = ( ( s == "-" ) ? stdin_name_len : s.size() );
-      if( len > longest_name ) longest_name = len;
-      }
-    if( longest_name == 0 ) longest_name = stdin_name_len;
-    }
-
-  void set_name( const std::string & filename )
-    {
-    if( filename.size() && filename != "-" ) name_ = filename;
-    else name_ = stdin_name;
-    first_post = true;
-    }
-
-  void reset() const throw() { if( name_.size() ) first_post = true; }
-  const char * name() const throw() { return name_.c_str(); }
-  void operator()( const char * const msg = 0 ) const throw();
-  };
-
 
 void show_help() throw()
   {
-  std::printf( "%s - A parallel version of the lzip data compressor.\n", Program_name );
+  std::printf( "%s - A parallel compressor compatible with lzip.\n", Program_name );
   std::printf( "\nUsage: %s [options] [files]\n", invocation_name );
   std::printf( "\nOptions:\n" );
   std::printf( "  -h, --help                 display this help and exit\n" );
@@ -154,7 +118,7 @@ void show_help() throw()
   std::printf( "      --best                 alias for -9\n" );
   if( verbosity > 0 )
     {
-    std::printf( "  -D, --debug=<level>        (0-3) print debug statistics to stderr\n" );
+    std::printf( "  -D, --debug=<level>        (0-1) print debug statistics to stderr\n" );
     }
   std::printf( "If no file names are given, %s compresses or decompresses\n", program_name );
   std::printf( "from standard input to standard output.\n" );
@@ -170,6 +134,7 @@ void show_version() throw()
   std::printf( "%s %s\n", Program_name, PROGVERSION );
   std::printf( "Copyright (C) 2009 Laszlo Ersek.\n" );
   std::printf( "Copyright (C) %s Antonio Diaz Diaz.\n", program_year );
+  std::printf( "Using Lzlib %s\n", LZ_version() );
   std::printf( "License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>\n" );
   std::printf( "This is free software: you are free to change and redistribute it.\n" );
   std::printf( "There is NO WARRANTY, to the extent permitted by law.\n" );
@@ -413,89 +378,6 @@ void close_and_set_permissions( const struct stat * const in_statsp )
   }
 
 
-int do_decompress( LZ_Decoder * const decoder, const int inhandle,
-                   const Pretty_print & pp, const bool testing )
-  {
-  const int in_buffer_size = 65536, out_buffer_size = 8 * in_buffer_size;
-  uint8_t in_buffer[in_buffer_size], out_buffer[out_buffer_size];
-
-  while( true )
-    {
-    int in_size = std::min( LZ_decompress_write_size( decoder ), in_buffer_size );
-    if( in_size > 0 )
-      {
-      const int max_in_size = in_size;
-      in_size = readblock( inhandle, in_buffer, max_in_size );
-      if( in_size != max_in_size && errno )
-        { pp(); show_error( "read error", errno ); return 1; }
-      if( in_size == 0 ) LZ_decompress_finish( decoder );
-      else if( in_size != LZ_decompress_write( decoder, in_buffer, in_size ) )
-        internal_error( "library error (LZ_decompress_write)" );
-      }
-    int out_size = LZ_decompress_read( decoder, out_buffer, out_buffer_size );
-//    std::fprintf( stderr, "%5d in_size, %6d out_size.\n", in_size, out_size );
-    if( out_size < 0 )
-      {
-      const LZ_Errno lz_errno = LZ_decompress_errno( decoder );
-      if( lz_errno == LZ_header_error )
-        {
-        if( LZ_decompress_total_out_size( decoder ) > 0 )
-          break;				// trailing garbage
-        pp( "error reading member header" );
-        return 1;
-        }
-      if( lz_errno == LZ_mem_error )
-        {
-        pp( "not enough memory. Find a machine with more memory" );
-        return 1;
-        }
-      pp();
-      if( lz_errno == LZ_unexpected_eof )
-        {
-        if( verbosity >= 0 )
-          std::fprintf( stderr, "file ends unexpectedly at pos %lld\n",
-                        LZ_decompress_total_in_size( decoder ) );
-        return 2;
-        }
-      if( verbosity >= 0 )
-        std::fprintf( stderr, "LZ_decompress_read error: %s.\n",
-                      LZ_strerror( LZ_decompress_errno( decoder ) ) );
-      return 1;
-      }
-    else if( out_size > 0 && outhandle >= 0 )
-      {
-      const int wr = writeblock( outhandle, out_buffer, out_size );
-      if( wr != out_size )
-        { pp(); show_error( "write error", errno ); return 1; }
-      }
-    if( LZ_decompress_finished( decoder ) == 1 ) break;
-    if( in_size == 0 && out_size == 0 )
-      internal_error( "library error (LZ_decompress_read)" );
-    }
-  if( verbosity >= 1 )
-    { if( testing ) std::fprintf( stderr, "ok\n" );
-      else std::fprintf( stderr, "done\n" ); }
-  return 0;
-  }
-
-
-int decompress( const int inhandle, const Pretty_print & pp,
-                const bool testing )
-  {
-  LZ_Decoder * const decoder = LZ_decompress_open();
-  int retval;
-
-  if( !decoder || LZ_decompress_errno( decoder ) != LZ_ok )
-    {
-    pp( "not enough memory" );
-    retval = 1;
-    }
-  else retval = do_decompress( decoder, inhandle, pp, testing );
-  LZ_decompress_close( decoder );
-  return retval;
-  }
-
-
 extern "C" void signal_handler( int sig ) throw()
   {
   if( !pthread_equal( pthread_self(), main_thread ) )
@@ -810,7 +692,7 @@ int main( const int argc, const char * argv[] )
                       encoder_options.match_len_limit, num_workers,
                       num_slots, inhandle, outhandle, debug_level );
     else
-      tmp = decompress( inhandle, pp, program_mode == m_test );
+      tmp = decompress( inhandle, outhandle, pp, program_mode == m_test );
     if( tmp > retval ) retval = tmp;
     if( tmp && program_mode != m_test ) cleanup_and_fail( retval );
 
diff --git a/plzip.cc b/plzip.cc
deleted file mode 100644
index dcae860..0000000
--- a/plzip.cc
+++ /dev/null
@@ -1,548 +0,0 @@
-/*  Plzip - A parallel version of the lzip data compressor
-    Copyright (C) 2009 Laszlo Ersek.
-    Copyright (C) 2009, 2010 Antonio Diaz Diaz.
-
-    This program is free software: you can redistribute it and/or modify
-    it under the 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.
-
-    This program 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 General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
-*/
-
-#define _FILE_OFFSET_BITS 64
-
-#include <algorithm>
-#include <cassert>
-#include <cerrno>
-#include <climits>
-#include <csignal>
-#include <cstdio>
-#include <cstdlib>
-#include <vector>
-#include <pthread.h>
-#include <stdint.h>
-#include <unistd.h>
-#include <lzlib.h>
-
-#include "plzip.h"
-
-#ifndef LLONG_MAX
-#define LLONG_MAX  0x7FFFFFFFFFFFFFFFLL
-#endif
-#ifndef LLONG_MIN
-#define LLONG_MIN  (-LLONG_MAX - 1LL)
-#endif
-#ifndef ULLONG_MAX
-#define ULLONG_MAX 0xFFFFFFFFFFFFFFFFULL
-#endif
-
-
-namespace {
-
-long long in_size = 0;
-long long out_size = 0;
-
-void *(*mallocf)( size_t size );
-void (*freef)( void *ptr );
-
-
-void * trace_malloc( size_t size )
-  {
-  int save_errno = 0;
-
-  void * ret = malloc( size );
-  if( ret == 0 ) save_errno = errno;
-  std::fprintf( stderr, "malloc(%lu) == %p\n", (unsigned long)size, ret );
-  if( ret == 0 ) errno = save_errno;
-  return ret;
-  }
-
-
-void trace_free( void *ptr )
-  {
-  std::fprintf( stderr, "free(%p)\n", ptr );
-  free( ptr );
-  }
-
-
-void * xalloc( size_t size )
-  {
-  void *ret = (*mallocf)( size );
-  if( ret == 0 ) { show_error( "not enough memory", errno ); fatal(); }
-  return ret;
-  }
-
-
-void xinit( pthread_cond_t * cond, pthread_mutex_t * mutex )
-  {
-  int ret = pthread_mutex_init( mutex, 0 );
-  if( ret != 0 ) { show_error( "pthread_mutex_init", ret ); fatal(); }
-
-  ret = pthread_cond_init( cond, 0 );
-  if( ret != 0 ) { show_error( "pthread_cond_init", ret ); fatal(); }
-  }
-
-
-void xdestroy( pthread_cond_t * cond, pthread_mutex_t * mutex )
-  {
-  int ret = pthread_cond_destroy( cond );
-  if( ret != 0 ) { show_error( "pthread_cond_destroy", ret ); fatal(); }
-
-  ret = pthread_mutex_destroy( mutex );
-  if( ret != 0 ) { show_error( "pthread_mutex_destroy", ret ); fatal(); }
-  }
-
-
-void xlock( pthread_mutex_t * mutex )
-  {
-  int ret = pthread_mutex_lock( mutex );
-  if( ret != 0 ) { show_error( "pthread_mutex_lock", ret ); fatal(); }
-  }
-
-
-void xunlock( pthread_mutex_t * mutex )
-  {
-  int ret = pthread_mutex_unlock( mutex );
-  if( ret != 0 ) { show_error( "pthread_mutex_unlock", ret ); fatal(); }
-  }
-
-
-void xwait( pthread_cond_t * cond, pthread_mutex_t * mutex )
-  {
-  int ret = pthread_cond_wait( cond, mutex );
-  if( ret != 0 ) { show_error( "pthread_cond_wait", ret ); fatal(); }
-  }
-
-
-void xsignal( pthread_cond_t * cond )
-  {
-  int ret = pthread_cond_signal( cond );
-  if( ret != 0 ) { show_error( "pthread_cond_signal", ret ); fatal(); }
-  }
-
-
-void xbroadcast( pthread_cond_t * cond )
-  {
-  int ret = pthread_cond_broadcast( cond );
-  if( ret != 0 ) { show_error( "pthread_cond_broadcast", ret ); fatal(); }
-  }
-
-
-void xcreate( pthread_t *thread, void *(*routine)(void *), void *arg )
-  {
-  int ret = pthread_create( thread, 0, routine, arg );
-  if( ret != 0 ) { show_error( "pthread_create", ret ); fatal(); }
-  }
-
-
-void xjoin( pthread_t thread )
-  {
-  int ret = pthread_join( thread, 0 );
-  if( ret != 0 ) { show_error( "pthread_join", ret ); fatal(); }
-  }
-
-
-struct Slot_tally			// Synchronizes splitter to muxer
-  {
-  unsigned long check_counter;
-  unsigned long wait_counter;
-  int num_free;				// Number of free slots
-  pthread_mutex_t mutex;
-  pthread_cond_t slot_av;		// Free slot available
-
-  Slot_tally( const int slots )
-    : check_counter( 0 ), wait_counter( 0 ), num_free( slots )
-    { xinit( &slot_av, &mutex ); }
-
-  ~Slot_tally() { xdestroy( &slot_av, &mutex ); }
-  };
-
-
-struct S2w_blk			// Splitter to worker data block
-  {
-  unsigned long long id;	// Block serial number as read from infd
-  S2w_blk *next;		// Next in queue
-  int loaded;			// # of bytes in plain, may be 0 for 1st
-  uint8_t plain[1];		// Data read from infd, allocated: data_size
-  };
-
-
-struct S2w_queue
-  {
-  S2w_blk * head;		// Next ready worker shall compress this
-  S2w_blk * tail;		// Splitter will append here
-  unsigned long check_counter;
-  unsigned long wait_counter;
-  pthread_mutex_t mutex;
-  pthread_cond_t av_or_eof;	// New block available or splitter done
-  bool eof;			// Splitter done
-
-  S2w_queue()
-    : head( 0 ), tail( 0 ), check_counter( 0 ), wait_counter( 0 ), eof( false )
-    { xinit( &av_or_eof, &mutex ); }
-
-  ~S2w_queue() { xdestroy( &av_or_eof, &mutex ); }
-  };
-
-
-struct W2m_blk			// Worker to muxer data block
-  {
-  unsigned long long id;	// Block index as read from infd
-  W2m_blk *next;		// Next block in list (unordered)
-  int produced;			// Number of bytes in compr
-  uint8_t compr[1];		// Data to write to outfd, alloc.: compr_size
-  };
-
-
-struct W2m_queue
-  {
-  unsigned long long needed_id;	// Block needed for resuming writing
-  W2m_blk *head;		// Block list (unordered)
-  unsigned long check_counter;
-  unsigned long wait_counter;
-  int num_working;		// Number of workers still running
-  pthread_mutex_t mutex;
-  pthread_cond_t av_or_exit;	// New block available or all workers exited
-
-  W2m_queue( const int num_workers )
-    : needed_id( 0 ), head( 0 ), check_counter( 0 ), wait_counter( 0 ),
-      num_working( num_workers )
-    { xinit( &av_or_exit, &mutex ); }
-
-  ~W2m_queue() { xdestroy( &av_or_exit, &mutex ); }
-  };
-
-
-struct Splitter_arg
-  {
-  Slot_tally * slot_tally;
-  S2w_queue * s2w_queue;
-  int infd;
-  int data_size;
-  int s2w_blk_size;
-  };
-
-
-void * splitter( void * arg )
-  {
-  const Splitter_arg & tmp = *(Splitter_arg *)arg;
-  Slot_tally & slot_tally = *tmp.slot_tally;
-  S2w_queue & s2w_queue = *tmp.s2w_queue;
-  const int infd = tmp.infd;
-  const int data_size = tmp.data_size;
-  const int s2w_blk_size = tmp.s2w_blk_size;
-
-  for( unsigned long long id = 0; ; ++id )
-    {
-    S2w_blk * s2w_blk = (S2w_blk *)xalloc( s2w_blk_size );
-
-    // Fill block
-    const int rd = readblock( infd, s2w_blk->plain, data_size );
-    if( rd != data_size && errno ) { show_error( "read", errno ); fatal(); }
-
-    if( rd > 0 || id == 0 )		// first block can be empty
-      {
-      s2w_blk->id = id;
-      s2w_blk->next = 0;
-      s2w_blk->loaded = rd;
-      in_size += rd;
-      xlock( &slot_tally.mutex );		// Grab a free slot
-      ++slot_tally.check_counter;
-      while( slot_tally.num_free == 0 )
-        {
-        ++slot_tally.wait_counter;
-        xwait( &slot_tally.slot_av, &slot_tally.mutex );
-        }
-      --slot_tally.num_free;
-      xunlock( &slot_tally.mutex );
-      }
-    else
-      { (*freef)( s2w_blk ); s2w_blk = 0; }
-
-    xlock( &s2w_queue.mutex );
-    if( s2w_blk != 0 )
-      {
-      if( s2w_queue.tail == 0 ) s2w_queue.head = s2w_blk;
-      else s2w_queue.tail->next = s2w_blk;
-      s2w_queue.tail = s2w_blk;
-      xsignal( &s2w_queue.av_or_eof );
-      }
-    else
-      {
-      s2w_queue.eof = true;
-      xbroadcast( &s2w_queue.av_or_eof );
-      }
-    xunlock( &s2w_queue.mutex );
-
-    if( s2w_blk == 0 ) break;
-    }
-  return 0;
-  }
-
-
-void work_compr( const int dictionary_size, const int match_len_limit,
-                 const S2w_blk & s2w_blk, W2m_queue & w2m_queue,
-                 const int compr_size, const int w2m_blk_size )
-  {
-  assert( s2w_blk.loaded > 0 || s2w_blk.id == 0 );
-
-  W2m_blk * w2m_blk = (W2m_blk *)xalloc( w2m_blk_size );
-
-  const int dict_size = std::max( LZ_min_dictionary_size(),
-                                  std::min( dictionary_size, s2w_blk.loaded ) );
-  LZ_Encoder * const encoder =
-    LZ_compress_open( dict_size, match_len_limit, LLONG_MAX );
-  if( !encoder || LZ_compress_errno( encoder ) != LZ_ok )
-    { show_error( "LZ_compress_open failed." ); fatal(); }
-
-  int written = 0;
-  w2m_blk->produced = 0;
-  while( true )
-    {
-    if( LZ_compress_write_size( encoder ) > 0 )
-      {
-      if( written < s2w_blk.loaded )
-        {
-        const int wr = LZ_compress_write( encoder, s2w_blk.plain + written,
-                                          s2w_blk.loaded - written );
-        if( wr < 0 ) { show_error( "LZ_compress_write failed." ); fatal(); }
-        written += wr;
-        }
-      if( written >= s2w_blk.loaded ) LZ_compress_finish( encoder );
-      }
-    assert( w2m_blk->produced < compr_size );
-    const int rd = LZ_compress_read( encoder, w2m_blk->compr + w2m_blk->produced,
-                                     compr_size - w2m_blk->produced );
-    if( rd < 0 ) { show_error( "LZ_compress_read failed." ); fatal(); }
-    w2m_blk->produced += rd;
-    if( LZ_compress_finished( encoder ) == 1 ) break;
-    }
-
-  if( LZ_compress_close( encoder ) < 0 )
-    { show_error( "LZ_compress_close failed." ); fatal(); }
-
-  w2m_blk->id = s2w_blk.id;
-
-  // Push block to muxer queue
-  xlock( &w2m_queue.mutex );
-  w2m_blk->next = w2m_queue.head;
-  w2m_queue.head = w2m_blk;
-  if( w2m_blk->id == w2m_queue.needed_id ) xsignal( &w2m_queue.av_or_exit );
-  xunlock( &w2m_queue.mutex );
-  }
-
-
-struct Worker_arg
-  {
-  int dictionary_size;
-  int match_len_limit;
-  S2w_queue * s2w_queue;
-  W2m_queue * w2m_queue;
-  int compr_size;
-  int w2m_blk_size;
-  };
-
-
-void * worker( void * arg )
-  {
-  const Worker_arg & tmp = *(Worker_arg *)arg;
-  const int dictionary_size = tmp.dictionary_size;
-  const int match_len_limit = tmp.match_len_limit;
-  S2w_queue & s2w_queue = *tmp.s2w_queue;
-  W2m_queue & w2m_queue = *tmp.w2m_queue;
-  const int compr_size = tmp.compr_size;
-  const int w2m_blk_size = tmp.w2m_blk_size;
-
-  while( true )
-    {
-    S2w_blk *s2w_blk;
-
-    // Grab a block to work on
-    xlock( &s2w_queue.mutex );
-    ++s2w_queue.check_counter;
-    while( s2w_queue.head == 0 && !s2w_queue.eof )
-      {
-      ++s2w_queue.wait_counter;
-      xwait( &s2w_queue.av_or_eof, &s2w_queue.mutex );
-      }
-    if( s2w_queue.head == 0 )	// No blocks available and splitter exited
-      {
-      xunlock( &s2w_queue.mutex );
-      break;
-      }
-    s2w_blk = s2w_queue.head;
-    s2w_queue.head = s2w_blk->next;
-    if( s2w_queue.head == 0 ) s2w_queue.tail = 0;
-    xunlock( &s2w_queue.mutex );
-
-    work_compr( dictionary_size, match_len_limit, *s2w_blk, w2m_queue,
-                compr_size, w2m_blk_size );
-    (*freef)( s2w_blk );
-    }
-
-  // Notify muxer when last worker exits
-  xlock( &w2m_queue.mutex );
-  if( --w2m_queue.num_working == 0 && w2m_queue.head == 0 )
-    xsignal( &w2m_queue.av_or_exit );
-  xunlock( &w2m_queue.mutex );
-  return 0;
-  }
-
-
-void muxer( Slot_tally & slot_tally, W2m_queue & w2m_queue,
-            const int num_slots, const int outfd )
-  {
-  unsigned long long needed_id = 0;
-  std::vector< W2m_blk * > circular_buffer( num_slots, (W2m_blk *)0 );
-
-  xlock( &w2m_queue.mutex );
-  while( true )
-    {
-    // Grab all available compressed blocks in one step
-    ++w2m_queue.check_counter;
-    while( w2m_queue.head == 0 && w2m_queue.num_working > 0 )
-      {
-      ++w2m_queue.wait_counter;
-      xwait( &w2m_queue.av_or_exit, &w2m_queue.mutex );
-      }
-    if( w2m_queue.head == 0 ) break;	// queue is empty. all workers exited
-
-    W2m_blk * w2m_blk = w2m_queue.head;
-    w2m_queue.head = 0;
-    xunlock( &w2m_queue.mutex );
-
-    // Merge blocks fetched this time into circular buffer
-    do {
-      // id collision shouldn't happen
-      assert( circular_buffer[w2m_blk->id%num_slots] == 0 );
-      circular_buffer[w2m_blk->id%num_slots] = w2m_blk;
-      W2m_blk * next = w2m_blk->next;
-      w2m_blk->next = 0;
-      w2m_blk = next;
-      } while( w2m_blk != 0 );
-
-    // Write out initial continuous sequence of reordered blocks
-    while( true )
-      {
-      w2m_blk = circular_buffer[needed_id%num_slots];
-      if( w2m_blk == 0 ) break;
-
-      out_size += w2m_blk->produced;
-
-      if( outfd >= 0 )
-        {
-        const int wr = writeblock( outfd, w2m_blk->compr, w2m_blk->produced );
-        if( wr != w2m_blk->produced )
-          { show_error( "write", errno ); fatal(); }
-        }
-      circular_buffer[needed_id%num_slots] = 0;
-      ++needed_id;
-
-      xlock( &slot_tally.mutex );
-      if( slot_tally.num_free++ == 0 ) xsignal( &slot_tally.slot_av );
-      xunlock( &slot_tally.mutex );
-
-      (*freef)( w2m_blk );
-      }
-
-    xlock( &w2m_queue.mutex );
-    w2m_queue.needed_id = needed_id;
-    }
-  xunlock( &w2m_queue.mutex );
-
-  for( int i = 0; i < num_slots; ++i )
-    if( circular_buffer[i] != 0 )
-      { show_error( "circular buffer not empty" ); fatal(); }
-  }
-
-} // end namespace
-
-
-int compress( const int data_size, const int dictionary_size,
-              const int match_len_limit, const int num_workers,
-              const int num_slots, const int infd, const int outfd,
-              const int debug_level )
-  {
-  if( debug_level & 2 ) { mallocf = trace_malloc; freef = trace_free; }
-  else { mallocf = malloc; freef = free; }
-
-  Slot_tally slot_tally( num_slots );
-  S2w_queue s2w_queue;
-  W2m_queue w2m_queue( num_workers );
-
-  Splitter_arg splitter_arg;
-  splitter_arg.slot_tally = &slot_tally;
-  splitter_arg.s2w_queue = &s2w_queue;
-  splitter_arg.infd = infd;
-  splitter_arg.data_size = data_size;
-  splitter_arg.s2w_blk_size = sizeof (S2w_blk) + data_size - 1;
-
-  pthread_t splitter_thread;
-  xcreate( &splitter_thread, splitter, &splitter_arg );
-
-  Worker_arg worker_arg;
-  worker_arg.dictionary_size = dictionary_size;
-  worker_arg.match_len_limit = match_len_limit;
-  worker_arg.s2w_queue = &s2w_queue;
-  worker_arg.w2m_queue = &w2m_queue;
-  worker_arg.compr_size = 6 + 20 + ( ( data_size / 8 ) * 9 );
-  worker_arg.w2m_blk_size = sizeof (W2m_blk) + worker_arg.compr_size - 1;
-
-  pthread_t * worker_threads = new( std::nothrow ) pthread_t[num_workers];
-  if( worker_threads == 0 )
-    { show_error( "not enough memory.", errno ); fatal(); }
-  for( int i = 0; i < num_workers; ++i )
-    xcreate( &worker_threads[i], worker, &worker_arg );
-
-  muxer( slot_tally, w2m_queue, num_slots, outfd );
-
-  for( int i = num_workers - 1; i >= 0; --i )
-    xjoin(worker_threads[i]);
-  delete[] worker_threads; worker_threads = 0;
-
-  xjoin( splitter_thread );
-
-  if( verbosity >= 1 )
-    {
-    if( in_size <= 0 || out_size <= 0 )
-      std::fprintf( stderr, "no data compressed.\n" );
-    else
-      std::fprintf( stderr, "%6.3f:1, %6.3f bits/byte, "
-                            "%5.2f%% saved, %lld in, %lld out.\n",
-                    (double)in_size / out_size,
-                    ( 8.0 * out_size ) / in_size,
-                    100.0 * ( 1.0 - ( (double)out_size / in_size ) ),
-                    in_size, out_size );
-    }
-
-  const int FW = ( sizeof (unsigned long) * 8 ) / 3 + 1;
-  if( debug_level & 1 )
-    std::fprintf( stderr,
-      "any worker tried to consume from splitter: %*lu\n"
-      "any worker stalled                       : %*lu\n"
-      "muxer tried to consume from workers      : %*lu\n"
-      "muxer stalled                            : %*lu\n"
-      "splitter tried to fill a block           : %*lu\n"
-      "splitter stalled                         : %*lu\n",
-      FW, s2w_queue.check_counter,
-      FW, s2w_queue.wait_counter,
-      FW, w2m_queue.check_counter,
-      FW, w2m_queue.wait_counter,
-      FW, slot_tally.check_counter,
-      FW, slot_tally.wait_counter );
-
-  assert( slot_tally.num_free == num_slots );
-  assert( s2w_queue.eof );
-  assert( s2w_queue.head == 0 );
-  assert( s2w_queue.tail == 0 );
-  assert( w2m_queue.num_working == 0 );
-  assert( w2m_queue.head == 0 );
-  return 0;
-  }
diff --git a/plzip.h b/plzip.h
index d7bb760..6615fc1 100644
--- a/plzip.h
+++ b/plzip.h
@@ -1,4 +1,4 @@
-/*  Plzip - A parallel version of the lzip data compressor
+/*  Plzip - A parallel compressor compatible with lzip
     Copyright (C) 2009 Laszlo Ersek.
     Copyright (C) 2009, 2010 Antonio Diaz Diaz.
 
@@ -16,19 +16,113 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+class Pretty_print
+  {
+  const char * const stdin_name;
+  const unsigned int stdin_name_len;
+  unsigned int longest_name;
+  std::string name_;
+  mutable bool first_post;
+
+public:
+  Pretty_print( const std::vector< std::string > & filenames )
+    : stdin_name( "(stdin)" ), stdin_name_len( std::strlen( stdin_name ) ),
+      longest_name( 0 ), first_post( false )
+    {
+    for( unsigned int i = 0; i < filenames.size(); ++i )
+      {
+      const std::string & s = filenames[i];
+      const unsigned int len = ( ( s == "-" ) ? stdin_name_len : s.size() );
+      if( len > longest_name ) longest_name = len;
+      }
+    if( longest_name == 0 ) longest_name = stdin_name_len;
+    }
+
+  void set_name( const std::string & filename )
+    {
+    if( filename.size() && filename != "-" ) name_ = filename;
+    else name_ = stdin_name;
+    first_post = true;
+    }
+
+  void reset() const throw() { if( name_.size() ) first_post = true; }
+  const char * name() const throw() { return name_.c_str(); }
+  void operator()( const char * const msg = 0 ) const throw();
+  };
+
+
+/*--------------------- Defined in compress.cc ---------------------*/
+
+void xinit( pthread_cond_t * cond, pthread_mutex_t * mutex );
+void xdestroy( pthread_cond_t * cond, pthread_mutex_t * mutex );
+void xlock( pthread_mutex_t * mutex );
+void xunlock( pthread_mutex_t * mutex );
+void xwait( pthread_cond_t * cond, pthread_mutex_t * mutex );
+void xsignal( pthread_cond_t * cond );
+void xbroadcast( pthread_cond_t * cond );
+void xcreate( pthread_t *thread, void *(*routine)(void *), void *arg );
+void xjoin( pthread_t thread );
+
+
+class Slot_tally
+  {
+public:
+  unsigned long check_counter;
+  unsigned long wait_counter;
+private:
+  const int num_slots;			// total slots
+  int num_free;				// remaining free slots
+  pthread_mutex_t mutex;
+  pthread_cond_t slot_av;		// free slot available
+
+public:
+  Slot_tally( const int slots )
+    : check_counter( 0 ), wait_counter( 0 ),
+      num_slots( slots ), num_free( slots )
+    { xinit( &slot_av, &mutex ); }
+
+  ~Slot_tally() { xdestroy( &slot_av, &mutex ); }
+
+  bool all_free() { return ( num_free == num_slots ); }
+
+  void get_slot()			// wait for a free slot
+    {
+    xlock( &mutex );
+    ++check_counter;
+    while( num_free == 0 )
+      { ++wait_counter; xwait( &slot_av, &mutex ); }
+    --num_free;
+    xunlock( &mutex );
+    }
+
+  void leave_slot()			// return a slot to the tally
+    {
+    xlock( &mutex );
+    if( num_free++ == 0 ) xsignal( &slot_av );
+    xunlock( &mutex );
+    }
+  };
+
+
 int compress( const int data_size, const int dictionary_size,
               const int match_len_limit, const int num_workers,
               const int num_slots, const int infd, const int outfd,
               const int debug_level );
 
 
+/*-------------------- Defined in decompress.cc --------------------*/
+
+int decompress( const int infd, const int outfd, const Pretty_print & pp,
+                const bool testing );
+
+
 /*----------------------- Defined in main.cc -----------------------*/
 
+extern int verbosity;
+
 void show_error( const char * msg, const int errcode = 0, const bool help = false ) throw();
+void internal_error( const char * msg );
 int readblock( const int fd, uint8_t * buf, const int size ) throw();
 int writeblock( const int fd, const uint8_t * buf, const int size ) throw();
 
-
 void fatal();		// Terminate the process
-
-extern int verbosity;
diff --git a/testsuite/check.sh b/testsuite/check.sh
index 409e563..f71faca 100755
--- a/testsuite/check.sh
+++ b/testsuite/check.sh
@@ -1,5 +1,5 @@
 #! /bin/sh
-# check script for Plzip - A parallel version of the lzip data compressor
+# check script for Plzip - A parallel compressor compatible with lzip
 # Copyright (C) 2009, 2010 Antonio Diaz Diaz.
 #
 # This script is free software: you have unlimited permission