+AM_CONDITIONAL([WIN32], [test -z "${host_os##mingw*}" || test -z "${host_os##cygwin*}"])
+
+# Initialize pkg-config.
+# We require at least 0.22, as "Requires.private" behaviour changed there.
+PKG_PROG_PKG_CONFIG
+
+############################
+## Package dependencies ##
+############################
+
+# Initialize pkg-config.
+# We require at least 0.22, as "Requires.private" behaviour changed there.
+PKG_PROG_PKG_CONFIG([0.22])
+
+# Collect the pkg-config module names of all dependencies in SRD_PKGLIBS.
+# These are used to derive the compiler flags and for the "Requires.private"
+# field in the generated libsigrokdecode.pc file.
+SRD_PKGLIBS=
+SRD_PKGLIBS_TESTS=
+
+# Keep track of all checked modules so we can list them at the end.
+SR_PKG_CHECK_SUMMARY([srd_pkglibs_summary])
+
+# Python 3 is always needed.
+SR_PKG_CHECK([python3], [SRD_PKGLIBS],
+ [python3 >= 3.2], [python-3.6 >= 3.6], [python-3.5 >= 3.5], [python-3.4 >= 3.4], [python-3.3 >= 3.3], [python-3.2 >= 3.2])
+AS_IF([test "x$sr_have_python3" = xno],
+ [AC_MSG_ERROR([Cannot find Python 3 development headers.])])
+
+# We also need to find the name of the python3 executable (for 'make install').
+# Some OSes call this python3, some call it python3.2, etc. etc.
+AC_ARG_VAR([PYTHON3], [Python 3 interpreter])
+AC_CHECK_PROGS([PYTHON3], [python3.6 python3.5 python3.4 python3.3 python3.2 python3])
+AS_IF([test "x$PYTHON3" = x],
+ [AC_MSG_ERROR([Cannot find Python 3 interpreter.])])
+
+######################
+## Feature checks ##
+######################
+
+# Keep track of all checked modules so we can list them at the end.
+SR_PKG_CHECK_SUMMARY([srd_pkglibs_opt_summary])