:: commit 9ccc841d44bd2f815fb86bd0b7b53a2a200a2325

diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..1020f85
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1 @@
+build-aux/* linguist-vendored
diff --git a/.github/workflows/MacOS.yml b/.github/workflows/MacOS.yml
deleted file mode 100644
index ac88ab7..0000000
--- a/.github/workflows/MacOS.yml
+++ /dev/null
@@ -1,17 +0,0 @@
-name: MacOS
-
-on:
-  push:
-    branches: [ master ]
-  pull_request:
-    branches: [ master ]
-
-jobs:
-  build:
-    runs-on: macos-latest
-    steps:
-    - uses: actions/checkout@v3
-    - name: make
-      run: make
-    - name: make check
-      run: make check
diff --git a/.github/workflows/Ubuntu-x64.yml b/.github/workflows/Ubuntu-x64.yml
deleted file mode 100644
index 3dba67f..0000000
--- a/.github/workflows/Ubuntu-x64.yml
+++ /dev/null
@@ -1,19 +0,0 @@
-name: Ubuntu-x64
-
-on:
-  push:
-    branches: [ master ]
-  pull_request:
-    branches: [ master ]
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v3
-    - name: make
-      run: make
-    - name: make check
-      run: make check
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
new file mode 100644
index 0000000..729ef00
--- /dev/null
+++ b/.github/workflows/build.yml
@@ -0,0 +1,68 @@
+name: Build
+
+on: [ push, pull_request ]
+
+jobs:
+
+  dist:
+    name: Package
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Configure
+      run: |
+        ./bootstrap.sh
+        ./configure
+    - name: Make source package
+      run: make VERSION=${{ github.sha }} dist
+    - name: Upload source package artifact
+      uses: actions/upload-artifact@v3
+      with:
+        name: bzip3-${{ github.sha }}
+        path: bzip3-${{ github.sha }}.tar.gz
+    - name: Run distcheck
+      run: make distcheck
+
+  build:
+    name: Build Matrix
+    needs: [ dist ]
+    strategy:
+      fail-fast: false
+      matrix:
+        platform: [ ubuntu-latest, macos-latest ]
+        compiler: [ clang, gcc ]
+        feature: [ enable-pthread, disable-pthread ]
+    runs-on: ${{ matrix.platform }}
+    steps:
+    - name: Download source package artifact
+      uses: actions/download-artifact@v3
+      with:
+        name: bzip3-${{ github.sha }}
+    - name: Extract source package
+      run: tar --strip-components=1 -xf bzip3-${{ github.sha}}.tar.gz
+    - name: Configure
+      run: ./configure CC=${{ matrix.compiler }} --${{ matrix.feature }}
+    - name: Make
+      run: make
+    - name: Check
+      run: make check
+
+  build-bsd:
+    name: Build on FreeBSD
+    needs: [ dist ]
+    runs-on: macos-10.15
+    steps:
+    - name: Download source package artifact
+      uses: actions/download-artifact@v3
+      with:
+        name: bzip3-${{ github.sha }}
+    - name: Extract source package
+      run: tar --strip-components=1 -xf bzip3-${{ github.sha}}.tar.gz
+    - name: Build in FreeBSD VM
+      uses: vmactions/freebsd-vm@v0.1.5
+      with:
+        usesh: true
+        run: |
+          ./configure
+          make
+          make check
diff --git a/.github/workflows/freebsd.yml b/.github/workflows/freebsd.yml
deleted file mode 100644
index e92dfd9..0000000
--- a/.github/workflows/freebsd.yml
+++ /dev/null
@@ -1,23 +0,0 @@
-name: FreeBSD
-
-on:
-  push:
-    branches: [ master ]
-  pull_request:
-    branches: [ master ]
-
-jobs:
-  build:
-    runs-on: macos-10.15
-    name: FreeBSD
-    steps:
-    - uses: actions/checkout@v2
-    - name: FreeBSD
-      id: freebsd
-      uses: vmactions/freebsd-vm@v0.1.5
-      with:
-        usesh: true
-        prepare: pkg install -y llvm gmake
-        run: |
-          gmake
-          gmake check
diff --git a/.gitignore b/.gitignore
index 69ed57f..c265f26 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,36 +1,33 @@
-
+# Developer stuff
 corpus/
+*.bz3
+etc/bitflip
 
+# Editor stuff
 .vscode/
+*.~
+tags
 
-bzip3
-
-libsais.o
-
-main.o
-
+# Generated
 *.o
-
+*.lo
+*.la
+*.so
+bzip3
+bzip3-*
+
+# Autotools
+.deps/
+.libs/
+.dirstamp
+/aclocal.m4
+/config.log
+/config.status
+/configure
+/libtool
+Makefile
+Makefile.in
 autom4te.cache/
-
-config.log
-
-config.status
-
-config.h.in~
-
-config.h
-
-configure~
-
-bzip3.so
-
-libbz3.so
-
-etc/bitflip
-
-etc/shakespeare.bz3
-
-libbzip3.so
-
-etc/shakespeare.txt.bz3
+build-aux/
+!build-aux/ax_pthread.m4
+!build-aux/ax_check_compile_flag.m4
diff --git a/Makefile b/Makefile
deleted file mode 100644
index b11143a..0000000
--- a/Makefile
+++ /dev/null
@@ -1,39 +0,0 @@
-
-CC?=clang
-CFLAGS?=-O2 -march=native -mtune=native -flto -g3 -fPIC
-CFLAGS+=-Iinclude
-PREFIX?=/usr/local
-
-.PHONY: all clean format install cloc check
-
-LIBBZ3_OBJECTS=obj/libsais.o obj/crc32.o obj/rle.o obj/cm.o \
-               obj/libbz3.o obj/lzp.o
-
-all: bzip3 libbzip3.so
-
-obj/%.o: src/%.c
-	$(CC) $(CFLAGS) -c $< -o $@
-
-libbzip3.so: $(LIBBZ3_OBJECTS)
-	$(CC) -shared $(CFLAGS) -o $@ $^ -lpthread
-
-bzip3: obj/main.o $(LIBBZ3_OBJECTS)
-	$(CC) $(CFLAGS) -o $@ $^ -lpthread
-
-clean:
-	rm -f bzip3 libbzip3.so obj/*.o
-
-format:
-	clang-format -i src/*.c include/*.h
-
-install:
-	install -c -v -m 755 bzip3 $(PREFIX)/bin
-	install -c -v -m 755 libbzip3.so $(PREFIX)/lib
-	install -c -v -m 755 include/libbz3.h $(PREFIX)/include
-
-cloc:
-	cloc src/*.c include/*.h
-
-check: bzip3
-	time ./bzip3 -e -b 6 etc/shakespeare.txt
-	time ./bzip3 -d etc/shakespeare.txt.bz3
diff --git a/Makefile.am b/Makefile.am
new file mode 100644
index 0000000..596b6bd
--- /dev/null
+++ b/Makefile.am
@@ -0,0 +1,42 @@
+ACLOCAL_AMFLAGS = -I build-aux
+
+AM_CFLAGS = -I$(top_srcdir)/include
+AM_LDFLAGS = -avoid-version
+
+EXTRA_DIST = LICENSE PORTING.md README.md
+
+include_HEADERS = include/libbz3.h
+noinst_HEADERS = include/cm.h \
+						 include/common.h \
+						 include/crc32.h \
+						 include/libsais.h \
+						 include/lzp.h \
+						 include/rle.h
+
+lib_LTLIBRARIES = libbzip3.la
+libbzip3_la_SOURCES = src/cm.c \
+					  src/crc32.c \
+					  src/libbz3.c \
+					  src/libsais.c \
+					  src/lzp.c \
+					  src/rle.c
+
+bin_PROGRAMS = bzip3
+bzip3_CFLAGS = $(AM_CFLAGS)
+bzip3_LDDADD = libbzip3.la
+bzip3_SOURCES = src/main.c $(libbzip3_la_SOURCES)
+
+# End standard autotools stuff, begin developer convenience targets
+
+.PHONY: format
+format: $(bzip3_SOURCES) $(include_HEADERS) $(noinst_HEADERS)
+	clang-format -i $^
+
+.PHONY: cloc
+cloc: $(bzip3_SOURCES) $(include_HEADERS) $(noinst_HEADERS)
+	cloc $^
+
+.PHONY: roundtrip
+roundtrip: $(bin_PROGRAMS)
+	time ./$< -e -b 6 etc/shakespeare.txt
+	time ./$< -d etc/shakespeare.txt.bz3
diff --git a/PORTING.md b/PORTING.md
index 2757d24..6931c19 100644
--- a/PORTING.md
+++ b/PORTING.md
@@ -1,12 +1,15 @@
-
 ## Windows
 
-Crosscompiling to Windows is supported:
+Cross-compiling Windows binaries is supported:
+
+```console
+# For x86_64 (64bit)
+$ ./configure CC=x86_64-w64-mingw32-gcc --host x86_64-w64-mingw32
+$ make
 
-```bash
-CC=i686-w64-mingw32-gcc make
-# or
-CC=x86_64-w64-mingw32-gcc make
+# For i686 (32bit)
+$ ./configure CC=i866-w64-mingw32-gcc --host i686-w64-mingw32
+$ make
 ```
 
 ## M1 MacOS
diff --git a/README.md b/README.md
index a814ac4..f3d572c 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,3 @@
-
 # BZip3
 
 A better, faster and stronger spiritual successor to BZip2. Features higher compression ratios and better performance thanks to a order-0 context mixing entropy coder, a fast Burrows-Wheeler transform code making use of suffix arrays and a RLE with Lempel Ziv+Prediction pass based on LZ77-style string matching and PPM-style context modeling.
@@ -7,8 +6,14 @@ Like its ancestor, **BZip3 excels at compressing text or code**.
 
 ## Installation
 
-```
-make all && sudo make install
+```console
+# If using a git clone (not needed for source packages), first...
+$ ./bootstrap.sh
+
+# All...
+$ ./configure
+$ make
+$ sudo make install
 ```
 
 ## Disclaimers
diff --git a/bootstrap.sh b/bootstrap.sh
new file mode 100755
index 0000000..95d80c4
--- /dev/null
+++ b/bootstrap.sh
@@ -0,0 +1,4 @@
+#!/usr/bin/env sh
+set -e
+
+autoreconf --install
diff --git a/build-aux/ax_check_compile_flag.m4 b/build-aux/ax_check_compile_flag.m4
new file mode 100644
index 0000000..bd753b3
--- /dev/null
+++ b/build-aux/ax_check_compile_flag.m4
@@ -0,0 +1,53 @@
+# ===========================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
+#
+# DESCRIPTION
+#
+#   Check whether the given FLAG works with the current language's compiler
+#   or gives an error.  (Warnings, however, are ignored)
+#
+#   ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
+#   success/failure.
+#
+#   If EXTRA-FLAGS is defined, it is added to the current language's default
+#   flags (e.g. CFLAGS) when the check is done.  The check is thus made with
+#   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
+#   force the compiler to issue an error when a bad flag is given.
+#
+#   INPUT gives an alternative input source to AC_COMPILE_IFELSE.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
+#   macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
+
+#serial 6
+
+AC_DEFUN([AX_CHECK_COMPILE_FLAG],
+[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
+AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
+AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
+  ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
+  _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
+  AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
+    [AS_VAR_SET(CACHEVAR,[yes])],
+    [AS_VAR_SET(CACHEVAR,[no])])
+  _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
+AS_VAR_IF(CACHEVAR,yes,
+  [m4_default([$2], :)],
+  [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_COMPILE_FLAGS
diff --git a/build-aux/ax_pthread.m4 b/build-aux/ax_pthread.m4
new file mode 100644
index 0000000..9f35d13
--- /dev/null
+++ b/build-aux/ax_pthread.m4
@@ -0,0 +1,522 @@
+# ===========================================================================
+#        https://www.gnu.org/software/autoconf-archive/ax_pthread.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
+#
+# DESCRIPTION
+#
+#   This macro figures out how to build C programs using POSIX threads. It
+#   sets the PTHREAD_LIBS output variable to the threads library and linker
+#   flags, and the PTHREAD_CFLAGS output variable to any special C compiler
+#   flags that are needed. (The user can also force certain compiler
+#   flags/libs to be tested by setting these environment variables.)
+#
+#   Also sets PTHREAD_CC and PTHREAD_CXX to any special C compiler that is
+#   needed for multi-threaded programs (defaults to the value of CC
+#   respectively CXX otherwise). (This is necessary on e.g. AIX to use the
+#   special cc_r/CC_r compiler alias.)
+#
+#   NOTE: You are assumed to not only compile your program with these flags,
+#   but also to link with them as well. For example, you might link with
+#   $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
+#   $PTHREAD_CXX $CXXFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
+#
+#   If you are only building threaded programs, you may wish to use these
+#   variables in your default LIBS, CFLAGS, and CC:
+#
+#     LIBS="$PTHREAD_LIBS $LIBS"
+#     CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+#     CXXFLAGS="$CXXFLAGS $PTHREAD_CFLAGS"
+#     CC="$PTHREAD_CC"
+#     CXX="$PTHREAD_CXX"
+#
+#   In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute constant
+#   has a nonstandard name, this macro defines PTHREAD_CREATE_JOINABLE to
+#   that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
+#
+#   Also HAVE_PTHREAD_PRIO_INHERIT is defined if pthread is found and the
+#   PTHREAD_PRIO_INHERIT symbol is defined when compiling with
+#   PTHREAD_CFLAGS.
+#
+#   ACTION-IF-FOUND is a list of shell commands to run if a threads library
+#   is found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it
+#   is not found. If ACTION-IF-FOUND is not specified, the default action
+#   will define HAVE_PTHREAD.
+#
+#   Please let the authors know if this macro fails on any platform, or if
+#   you have any other suggestions or comments. This macro was based on work
+#   by SGJ on autoconf scripts for FFTW (http://www.fftw.org/) (with help
+#   from M. Frigo), as well as ac_pthread and hb_pthread macros posted by
+#   Alejandro Forero Cuervo to the autoconf macro repository. We are also
+#   grateful for the helpful feedback of numerous users.
+#
+#   Updated for Autoconf 2.68 by Daniel Richard G.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
+#   Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>
+#   Copyright (c) 2019 Marc Stevens <marc.stevens@cwi.nl>
+#
+#   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 <https://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 31
+
+AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
+AC_DEFUN([AX_PTHREAD], [
+AC_REQUIRE([AC_CANONICAL_HOST])
+AC_REQUIRE([AC_PROG_CC])
+AC_REQUIRE([AC_PROG_SED])
+AC_LANG_PUSH([C])
+ax_pthread_ok=no
+
+# We used to check for pthread.h first, but this fails if pthread.h
+# requires special compiler flags (e.g. on Tru64 or Sequent).
+# It gets checked for in the link test anyway.
+
+# First of all, check if the user has set any of the PTHREAD_LIBS,
+# etcetera environment variables, and if threads linking works using
+# them:
+if test "x$PTHREAD_CFLAGS$PTHREAD_LIBS" != "x"; then
+        ax_pthread_save_CC="$CC"
+        ax_pthread_save_CFLAGS="$CFLAGS"
+        ax_pthread_save_LIBS="$LIBS"
+        AS_IF([test "x$PTHREAD_CC" != "x"], [CC="$PTHREAD_CC"])
+        AS_IF([test "x$PTHREAD_CXX" != "x"], [CXX="$PTHREAD_CXX"])
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+        AC_MSG_CHECKING([for pthread_join using $CC $PTHREAD_CFLAGS $PTHREAD_LIBS])
+        AC_LINK_IFELSE([AC_LANG_CALL([], [pthread_join])], [ax_pthread_ok=yes])
+        AC_MSG_RESULT([$ax_pthread_ok])
+        if test "x$ax_pthread_ok" = "xno"; then
+                PTHREAD_LIBS=""
+                PTHREAD_CFLAGS=""
+        fi
+        CC="$ax_pthread_save_CC"
+        CFLAGS="$ax_pthread_save_CFLAGS"
+        LIBS="$ax_pthread_save_LIBS"
+fi
+
+# We must check for the threads library under a number of different
+# names; the ordering is very important because some systems
+# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
+# libraries is broken (non-POSIX).
+
+# Create a list of thread flags to try. Items with a "," contain both
+# C compiler flags (before ",") and linker flags (after ","). Other items
+# starting with a "-" are C compiler flags, and remaining items are
+# library names, except for "none" which indicates that we try without
+# any flags at all, and "pthread-config" which is a program returning
+# the flags for the Pth emulation library.
+
+ax_pthread_flags="pthreads none -Kthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
+
+# The ordering *is* (sometimes) important.  Some notes on the
+# individual items follow:
+
+# pthreads: AIX (must check this before -lpthread)
+# none: in case threads are in libc; should be tried before -Kthread and
+#       other compiler flags to prevent continual compiler warnings
+# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
+# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads), Tru64
+#           (Note: HP C rejects this with "bad form for `-t' option")
+# -pthreads: Solaris/gcc (Note: HP C also rejects)
+# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
+#      doesn't hurt to check since this sometimes defines pthreads and
+#      -D_REENTRANT too), HP C (must be checked before -lpthread, which
+#      is present but should not be used directly; and before -mthreads,
+#      because the compiler interprets this as "-mt" + "-hreads")
+# -mthreads: Mingw32/gcc, Lynx/gcc
+# pthread: Linux, etcetera
+# --thread-safe: KAI C++
+# pthread-config: use pthread-config program (for GNU Pth library)
+
+case $host_os in
+
+        freebsd*)
+
+        # -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
+        # lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
+
+        ax_pthread_flags="-kthread lthread $ax_pthread_flags"
+        ;;
+
+        hpux*)
+
+        # From the cc(1) man page: "[-mt] Sets various -D flags to enable
+        # multi-threading and also sets -lpthread."
+
+        ax_pthread_flags="-mt -pthread pthread $ax_pthread_flags"
+        ;;
+
+        openedition*)
+
+        # IBM z/OS requires a feature-test macro to be defined in order to
+        # enable POSIX threads at all, so give the user a hint if this is
+        # not set. (We don't define these ourselves, as they can affect
+        # other portions of the system API in unpredictable ways.)
+
+        AC_EGREP_CPP([AX_PTHREAD_ZOS_MISSING],
+            [
+#            if !defined(_OPEN_THREADS) && !defined(_UNIX03_THREADS)
+             AX_PTHREAD_ZOS_MISSING
+#            endif
+            ],
+            [AC_MSG_WARN([IBM z/OS requires -D_OPEN_THREADS or -D_UNIX03_THREADS to enable pthreads support.])])
+        ;;
+
+        solaris*)
+
+        # On Solaris (at least, for some versions), libc contains stubbed
+        # (non-functional) versions of the pthreads routines, so link-based
+        # tests will erroneously succeed. (N.B.: The stubs are missing
+        # pthread_cleanup_push, or rather a function called by this macro,
+        # so we could check for that, but who knows whether they'll stub
+        # that too in a future libc.)  So we'll check first for the
+        # standard Solaris way of linking pthreads (-mt -lpthread).
+
+        ax_pthread_flags="-mt,-lpthread pthread $ax_pthread_flags"
+        ;;
+esac
+
+# Are we compiling with Clang?
+
+AC_CACHE_CHECK([whether $CC is Clang],
+    [ax_cv_PTHREAD_CLANG],
+    [ax_cv_PTHREAD_CLANG=no
+     # Note that Autoconf sets GCC=yes for Clang as well as GCC
+     if test "x$GCC" = "xyes"; then
+        AC_EGREP_CPP([AX_PTHREAD_CC_IS_CLANG],
+            [/* Note: Clang 2.7 lacks __clang_[a-z]+__ */
+#            if defined(__clang__) && defined(__llvm__)
+             AX_PTHREAD_CC_IS_CLANG
+#            endif
+            ],
+            [ax_cv_PTHREAD_CLANG=yes])
+     fi
+    ])
+ax_pthread_clang="$ax_cv_PTHREAD_CLANG"
+
+
+# GCC generally uses -pthread, or -pthreads on some platforms (e.g. SPARC)
+
+# Note that for GCC and Clang -pthread generally implies -lpthread,
+# except when -nostdlib is passed.
+# This is problematic using libtool to build C++ shared libraries with pthread:
+# [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25460
+# [2] https://bugzilla.redhat.com/show_bug.cgi?id=661333
+# [3] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=468555
+# To solve this, first try -pthread together with -lpthread for GCC
+
+AS_IF([test "x$GCC" = "xyes"],
+      [ax_pthread_flags="-pthread,-lpthread -pthread -pthreads $ax_pthread_flags"])
+
+# Clang takes -pthread (never supported any other flag), but we'll try with -lpthread first
+
+AS_IF([test "x$ax_pthread_clang" = "xyes"],
+      [ax_pthread_flags="-pthread,-lpthread -pthread"])
+
+
+# The presence of a feature test macro requesting re-entrant function
+# definitions is, on some systems, a strong hint that pthreads support is
+# correctly enabled
+
+case $host_os in
+        darwin* | hpux* | linux* | osf* | solaris*)
+        ax_pthread_check_macro="_REENTRANT"
+        ;;
+
+        aix*)
+        ax_pthread_check_macro="_THREAD_SAFE"
+        ;;
+
+        *)
+        ax_pthread_check_macro="--"
+        ;;
+esac
+AS_IF([test "x$ax_pthread_check_macro" = "x--"],
+      [ax_pthread_check_cond=0],
+      [ax_pthread_check_cond="!defined($ax_pthread_check_macro)"])
+
+
+if test "x$ax_pthread_ok" = "xno"; then
+for ax_pthread_try_flag in $ax_pthread_flags; do
+
+        case $ax_pthread_try_flag in
+                none)
+                AC_MSG_CHECKING([whether pthreads work without any flags])
+                ;;
+
+                *,*)
+                PTHREAD_CFLAGS=`echo $ax_pthread_try_flag | sed "s/^\(.*\),\(.*\)$/\1/"`
+                PTHREAD_LIBS=`echo $ax_pthread_try_flag | sed "s/^\(.*\),\(.*\)$/\2/"`
+                AC_MSG_CHECKING([whether pthreads work with "$PTHREAD_CFLAGS" and "$PTHREAD_LIBS"])
+                ;;
+
+                -*)
+                AC_MSG_CHECKING([whether pthreads work with $ax_pthread_try_flag])
+                PTHREAD_CFLAGS="$ax_pthread_try_flag"
+                ;;
+
+                pthread-config)
+                AC_CHECK_PROG([ax_pthread_config], [pthread-config], [yes], [no])
+                AS_IF([test "x$ax_pthread_config" = "xno"], [continue])
+                PTHREAD_CFLAGS="`pthread-config --cflags`"
+                PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
+                ;;
+
+                *)
+                AC_MSG_CHECKING([for the pthreads library -l$ax_pthread_try_flag])
+                PTHREAD_LIBS="-l$ax_pthread_try_flag"
+                ;;
+        esac
+
+        ax_pthread_save_CFLAGS="$CFLAGS"
+        ax_pthread_save_LIBS="$LIBS"
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+
+        # Check for various functions.  We must include pthread.h,
+        # since some functions may be macros.  (On the Sequent, we
+        # need a special flag -Kthread to make this header compile.)
+        # We check for pthread_join because it is in -lpthread on IRIX
+        # while pthread_create is in libc.  We check for pthread_attr_init
+        # due to DEC craziness with -lpthreads.  We check for
+        # pthread_cleanup_push because it is one of the few pthread
+        # functions on Solaris that doesn't have a non-functional libc stub.
+        # We try pthread_create on general principles.
+
+        AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>
+#                       if $ax_pthread_check_cond
+#                        error "$ax_pthread_check_macro must be defined"
+#                       endif
+                        static void *some_global = NULL;
+                        static void routine(void *a)
+                          {
+                             /* To avoid any unused-parameter or
+                                unused-but-set-parameter warning.  */
+                             some_global = a;
+                          }
+                        static void *start_routine(void *a) { return a; }],
+                       [pthread_t th; pthread_attr_t attr;
+                        pthread_create(&th, 0, start_routine, 0);
+                        pthread_join(th, 0);
+                        pthread_attr_init(&attr);
+                        pthread_cleanup_push(routine, 0);
+                        pthread_cleanup_pop(0) /* ; */])],
+            [ax_pthread_ok=yes],
+            [])
+
+        CFLAGS="$ax_pthread_save_CFLAGS"
+        LIBS="$ax_pthread_save_LIBS"
+
+        AC_MSG_RESULT([$ax_pthread_ok])
+        AS_IF([test "x$ax_pthread_ok" = "xyes"], [break])
+
+        PTHREAD_LIBS=""
+        PTHREAD_CFLAGS=""
+done
+fi
+
+
+# Clang needs special handling, because older versions handle the -pthread
+# option in a rather... idiosyncratic way
+
+if test "x$ax_pthread_clang" = "xyes"; then
+
+        # Clang takes -pthread; it has never supported any other flag
+
+        # (Note 1: This will need to be revisited if a system that Clang
+        # supports has POSIX threads in a separate library.  This tends not
+        # to be the way of modern systems, but it's conceivable.)
+
+        # (Note 2: On some systems, notably Darwin, -pthread is not needed
+        # to get POSIX threads support; the API is always present and
+        # active.  We could reasonably leave PTHREAD_CFLAGS empty.  But
+        # -pthread does define _REENTRANT, and while the Darwin headers
+        # ignore this macro, third-party headers might not.)
+
+        # However, older versions of Clang make a point of warning the user
+        # that, in an invocation where only linking and no compilation is
+        # taking place, the -pthread option has no effect ("argument unused
+        # during compilation").  They expect -pthread to be passed in only
+        # when source code is being compiled.
+        #
+        # Problem is, this is at odds with the way Automake and most other
+        # C build frameworks function, which is that the same flags used in
+        # compilation (CFLAGS) are also used in linking.  Many systems
+        # supported by AX_PTHREAD require exactly this for POSIX threads
+        # support, and in fact it is often not straightforward to specify a
+        # flag that is used only in the compilation phase and not in
+        # linking.  Such a scenario is extremely rare in practice.
+        #
+        # Even though use of the -pthread flag in linking would only print
+        # a warning, this can be a nuisance for well-run software projects
+        # that build with -Werror.  So if the active version of Clang has
+        # this misfeature, we search for an option to squash it.
+
+        AC_CACHE_CHECK([whether Clang needs flag to prevent "argument unused" warning when linking with -pthread],
+            [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG],
+            [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG=unknown
+             # Create an alternate version of $ac_link that compiles and
+             # links in two steps (.c -> .o, .o -> exe) instead of one
+             # (.c -> exe), because the warning occurs only in the second
+             # step
+             ax_pthread_save_ac_link="$ac_link"
+             ax_pthread_sed='s/conftest\.\$ac_ext/conftest.$ac_objext/g'
+             ax_pthread_link_step=`AS_ECHO(["$ac_link"]) | sed "$ax_pthread_sed"`
+             ax_pthread_2step_ac_link="($ac_compile) && (echo ==== >&5) && ($ax_pthread_link_step)"
+             ax_pthread_save_CFLAGS="$CFLAGS"
+             for ax_pthread_try in '' -Qunused-arguments -Wno-unused-command-line-argument unknown; do
+                AS_IF([test "x$ax_pthread_try" = "xunknown"], [break])
+                CFLAGS="-Werror -Wunknown-warning-option $ax_pthread_try -pthread $ax_pthread_save_CFLAGS"
+                ac_link="$ax_pthread_save_ac_link"
+                AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
+                    [ac_link="$ax_pthread_2step_ac_link"
+                     AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
+                         [break])
+                    ])
+             done
+             ac_link="$ax_pthread_save_ac_link"
+             CFLAGS="$ax_pthread_save_CFLAGS"
+             AS_IF([test "x$ax_pthread_try" = "x"], [ax_pthread_try=no])
+             ax_cv_PTHREAD_CLANG_NO_WARN_FLAG="$ax_pthread_try"
+            ])
+
+        case "$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG" in
+                no | unknown) ;;
+                *) PTHREAD_CFLAGS="$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG $PTHREAD_CFLAGS" ;;
+        esac
+
+fi # $ax_pthread_clang = yes
+
+
+
+# Various other checks:
+if test "x$ax_pthread_ok" = "xyes"; then
+        ax_pthread_save_CFLAGS="$CFLAGS"
+        ax_pthread_save_LIBS="$LIBS"
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+
+        # Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
+        AC_CACHE_CHECK([for joinable pthread attribute],
+            [ax_cv_PTHREAD_JOINABLE_ATTR],
+            [ax_cv_PTHREAD_JOINABLE_ATTR=unknown
+             for ax_pthread_attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
+                 AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>],
+                                                 [int attr = $ax_pthread_attr; return attr /* ; */])],
+                                [ax_cv_PTHREAD_JOINABLE_ATTR=$ax_pthread_attr; break],
+                                [])
+             done
+            ])
+        AS_IF([test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xunknown" && \
+               test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xPTHREAD_CREATE_JOINABLE" && \
+               test "x$ax_pthread_joinable_attr_defined" != "xyes"],
+              [AC_DEFINE_UNQUOTED([PTHREAD_CREATE_JOINABLE],
+                                  [$ax_cv_PTHREAD_JOINABLE_ATTR],
+                                  [Define to necessary symbol if this constant
+                                   uses a non-standard name on your system.])
+               ax_pthread_joinable_attr_defined=yes
+              ])
+
+        AC_CACHE_CHECK([whether more special flags are required for pthreads],
+            [ax_cv_PTHREAD_SPECIAL_FLAGS],
+            [ax_cv_PTHREAD_SPECIAL_FLAGS=no
+             case $host_os in
+             solaris*)
+             ax_cv_PTHREAD_SPECIAL_FLAGS="-D_POSIX_PTHREAD_SEMANTICS"
+             ;;
+             esac
+            ])
+        AS_IF([test "x$ax_cv_PTHREAD_SPECIAL_FLAGS" != "xno" && \
+               test "x$ax_pthread_special_flags_added" != "xyes"],
+              [PTHREAD_CFLAGS="$ax_cv_PTHREAD_SPECIAL_FLAGS $PTHREAD_CFLAGS"
+               ax_pthread_special_flags_added=yes])
+
+        AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],
+            [ax_cv_PTHREAD_PRIO_INHERIT],
+            [AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <pthread.h>]],
+                                             [[int i = PTHREAD_PRIO_INHERIT;
+                                               return i;]])],
+                            [ax_cv_PTHREAD_PRIO_INHERIT=yes],
+                            [ax_cv_PTHREAD_PRIO_INHERIT=no])
+            ])
+        AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes" && \
+               test "x$ax_pthread_prio_inherit_defined" != "xyes"],
+              [AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], [1], [Have PTHREAD_PRIO_INHERIT.])
+               ax_pthread_prio_inherit_defined=yes
+              ])
+
+        CFLAGS="$ax_pthread_save_CFLAGS"
+        LIBS="$ax_pthread_save_LIBS"
+
+        # More AIX lossage: compile with *_r variant
+        if test "x$GCC" != "xyes"; then
+            case $host_os in
+                aix*)
+                AS_CASE(["x/$CC"],
+                    [x*/c89|x*/c89_128|x*/c99|x*/c99_128|x*/cc|x*/cc128|x*/xlc|x*/xlc_v6|x*/xlc128|x*/xlc128_v6],
+                    [#handle absolute path differently from PATH based program lookup
+                     AS_CASE(["x$CC"],
+                         [x/*],
+                         [
+			   AS_IF([AS_EXECUTABLE_P([${CC}_r])],[PTHREAD_CC="${CC}_r"])
+			   AS_IF([test "x${CXX}" != "x"], [AS_IF([AS_EXECUTABLE_P([${CXX}_r])],[PTHREAD_CXX="${CXX}_r"])])
+			 ],
+                         [
+			   AC_CHECK_PROGS([PTHREAD_CC],[${CC}_r],[$CC])
+			   AS_IF([test "x${CXX}" != "x"], [AC_CHECK_PROGS([PTHREAD_CXX],[${CXX}_r],[$CXX])])
+			 ]
+                     )
+                    ])
+                ;;
+            esac
+        fi
+fi
+
+test -n "$PTHREAD_CC" || PTHREAD_CC="$CC"
+test -n "$PTHREAD_CXX" || PTHREAD_CXX="$CXX"
+
+AC_SUBST([PTHREAD_LIBS])
+AC_SUBST([PTHREAD_CFLAGS])
+AC_SUBST([PTHREAD_CC])
+AC_SUBST([PTHREAD_CXX])
+
+# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
+if test "x$ax_pthread_ok" = "xyes"; then
+        ifelse([$1],,[AC_DEFINE([HAVE_PTHREAD],[1],[Define if you have POSIX threads libraries and header files.])],[$1])
+        :
+else
+        ax_pthread_ok=no
+        $2
+fi
+AC_LANG_POP
+])dnl AX_PTHREAD
diff --git a/configure.ac b/configure.ac
new file mode 100644
index 0000000..ded435e
--- /dev/null
+++ b/configure.ac
@@ -0,0 +1,55 @@
+AC_PREREQ([2.68])
+AC_INIT([bzip3], [1.0.1], [https://github.com/kspalaiologos/bzip3])
+AC_CONFIG_AUX_DIR([build-aux])
+AM_INIT_AUTOMAKE([foreign subdir-objects tar-pax color-tests])
+AM_SILENT_RULES([yes])
+AC_CONFIG_MACRO_DIR([build-aux])
+
+AC_PROG_CC([clang gcc icc])
+LT_INIT
+
+AC_MSG_CHECKING([whether system or user specificed compiler flags are set])
+AM_CONDITIONAL([PASSED_CFLAGS], [test -z "$CFLAGS"])
+AM_COND_IF([PASSED_CFLAGS], [AC_MSG_RESULT([yes])], [AC_MSG_RESULT([no])])
+
+AC_ARG_WITH([pthread],
+			  AS_HELP_STRING([--without-pthread], [Disable use of pthread library]))
+AM_CONDITIONAL([WITH_PTHREAD], [test x"$with_pthread" != xno])
+AM_COND_IF([WITH_PTHREAD], [
+	AC_CHECK_HEADER(pthread.h,
+					[AX_PTHREAD([CFLAGS="$CFLAGS $PTHREAD_CFLAGS -DPTHREAD" LIBS="$LIBS $PTHREAD_LIBS"])],
+					[AC_MSG_ERROR([pthread.h not found, use --without-pthread to skip])])
+])
+
+AC_ARG_ENABLE([arch-native],
+			AS_HELP_STRING([--disable-arch-native], [Disable CPU-specific optimizations]))
+AM_CONDITIONAL([ENABLE_ARCH_NATIVE], [test x"$enable_arch_native" != xno])
+
+AC_ARG_ENABLE([link-time-optimization],
+			AS_HELP_STRING([--disable-link-time-optimization], [Disable link time optimization]))
+AM_CONDITIONAL([ENABLE_LINK_TIME_OPTIMIZATION], [test x"$enable_link_time_optimization" != xno])
+
+AM_COND_IF([PASSED_CFLAGS], [
+	AC_MSG_NOTICE([skipping compiler feature detection, using '$CFLAGS'])
+], [
+	AX_CHECK_COMPILE_FLAG([-O2], [CFLAGS="$CFLAGS -O2"], [])
+	AX_CHECK_COMPILE_FLAG([-g3], [CFLAGS="$CFLAGS -g3"], [])
+	AX_CHECK_COMPILE_FLAG([-fPIC], [CFLAGS="$CFLAGS -fPIC"], [])
+	AC_MSG_NOTICE([using '$CFLAGS' plus compiler feature detection])
+
+	AM_COND_IF([ENABLE_ARCH_NATIVE], [
+				AX_CHECK_COMPILE_FLAG([-march=native], [CFLAGS="$CFLAGS -march=native"],
+									[AC_MSG_ERROR([Compiler does not support native optimizations, use --disable-arch-native])])
+				AX_CHECK_COMPILE_FLAG([-mtune=native], [CFLAGS="$CFLAGS -mtune=native"],
+									[AC_MSG_ERROR([Compiler does not support native optimizations, use --disable-arch-native])])
+	])
+
+	AM_COND_IF([ENABLE_LINK_TIME_OPTIMIZATION], [
+				AX_CHECK_COMPILE_FLAG([-flto], [CFLAGS="$CFLAGS -flto"],
+									[AC_MSG_ERROR([Compiler does not support link time optimization, use --disable-link-time-optimization])])
+	])
+])
+
+AC_CONFIG_FILES([Makefile])
+AC_ARG_PROGRAM
+AC_OUTPUT
diff --git a/obj/.gitkeep b/obj/.gitkeep
deleted file mode 100644
index e69de29..0000000
diff --git a/src/libbz3.c b/src/libbz3.c
index 580f115..a712ac9 100644
--- a/src/libbz3.c
+++ b/src/libbz3.c
@@ -288,6 +288,8 @@ PUBLIC_API s32 bz3_decode_block(struct bz3_state * state, u8 * buffer, s32 data_
 
 #undef swap
 
+#ifdef PTHREAD
+
 #include <pthread.h>
 
 typedef struct {
@@ -343,3 +345,5 @@ PUBLIC_API void bz3_decode_blocks(struct bz3_state * states[], uint8_t * buffers
     }
     for (int32_t i = 0; i < n; i++) pthread_join(threads[i], NULL);
 }
+
+#endif
diff --git a/src/main.c b/src/main.c
index afa24ac..99be0c4 100644
--- a/src/main.c
+++ b/src/main.c
@@ -82,6 +82,7 @@ int main(int argc, char * argv[]) {
                 i++;
             } else if (argv[i][1] == 'c') {
                 force_stdstreams = 1;
+#ifdef PTHREAD
             } else if (argv[i][1] == 'j') {
                 if (i + 1 >= argc) {
                     fprintf(stderr, "Error: -j requires an argument.\n");
@@ -95,6 +96,7 @@ int main(int argc, char * argv[]) {
 
                 workers = atoi(argv[i + 1]);
                 i++;
+#endif
             } else if (argv[i][1] == '-') {
                 double_dash = 1;
             } else {
@@ -129,7 +131,9 @@ int main(int argc, char * argv[]) {
         fprintf(stderr, "Extra flags:\n");
         fprintf(stderr, "  -c: force reading/writing from standard streams\n");
         fprintf(stderr, "  -b N: set block size in MiB\n");
+#ifdef PTHREAD
         fprintf(stderr, "  -j N: set the amount of parallel threads\n");
+#endif
         return 1;
     }
 
@@ -237,12 +241,14 @@ int main(int argc, char * argv[]) {
         }
     }
 
+#ifdef PTHREAD
     if (workers > 16 || workers < 0) {
         fprintf(stderr, "Number of workers must be between 0 and 16.\n");
         return 1;
     }
 
     if (workers <= 1) {
+#endif
         struct bz3_state * state = bz3_new(block_size);
 
         if (state == NULL) {
@@ -326,6 +332,7 @@ int main(int argc, char * argv[]) {
 
         fclose(input_des);
         fclose(output_des);
+#ifdef PTHREAD
     } else {
         struct bz3_state * states[workers];
         u8 * buffers[workers];
@@ -422,4 +429,5 @@ int main(int argc, char * argv[]) {
             bz3_free(states[i]);
         }
     }
+#endif
 }