make the endian detection into a function so we don't have to

place namespace games...

add the pure python version of the interleaver in case the user
hasn't compiled the C version..  only make it a warning as it
is only a performance improvement..

[git-p4: depot-paths = "//depot/": change = 1431]

flac.py

@@ -8,24 +8,36 @@ from ctypes import *
 __all__ = [ 'FLACDec' ]
 
 # Find out if we need to endian swap the buffer
-t = array.array('H', '\x00\x01')
-if t[0] == 1:
-	is_little_endian = False
-else:
-	is_little_endian = True
-del t
-
-interleavelib = CDLL(os.path.join(os.path.dirname(__file__), '_interleave.so'))
+def _islittleendian():
+	'''Run a check to see if the box is little endian or not.'''
+
+	t = array.array('H', '\x00\x01')
+	if t[0] == 1:
+		return False
+	else:
+		return True
+
+is_little_endian = _islittleendian()
+
 inter = {}
 
-for i in (16, ):
-	f = getattr(interleavelib, 'interleave%d' % i)
-	f.restype = None
-	# bigendian, nchan, chanmap, chansamps, data, out
-	outtype = locals()['c_int%d' % i]
-	f.argtypes = [ c_int, POINTER(c_int), c_int,
-	    POINTER(POINTER(c_int32)), POINTER(outtype), ]
-	inter[i] = outtype, f
+try:
+	interleavelib = CDLL(os.path.join(os.path.dirname(__file__), '_interleave.so'))
+	for i in (16, ):
+		f = getattr(interleavelib, 'interleave%d' % i)
+		f.restype = None
+		# bigendian, nchan, chanmap, chansamps, data, out
+		outtype = locals()['c_int%d' % i]
+		f.argtypes = [ c_int, POINTER(c_int), c_int,
+		    POINTER(POINTER(c_int32)), POINTER(outtype), ]
+		inter[i] = outtype, f
+except OSError:
+	import warnings
+	warnings.warn('Using slow interleaver, compile the _interleave.so module to improve performance.')
+
+	inter[16] = None, lambda nchan, chanmap, blksize, inbuf, ignore: \
+	    array.array('h', [ inbuf[chanmap[x % nchan]][x / nchan] for x in
+	    xrange(blksize * nchan)])
 
 flaclib = CDLL('libFLAC.so')
 
@@ -541,24 +553,22 @@ class FLACDec(object):
 		#print 'sample number:', frame.header.number.sample_number
 		self.cursamp = frame.header.number.sample_number
 		self.curcnt = frame.header.blocksize
-		if True:
-			outtype, fun = inter[frame.header.bits_per_sample]
+		outtype, fun = inter[frame.header.bits_per_sample]
+		if outtype is None:
+			outbuf = None
+		else:
 			outbuf = (outtype * (nchan * frame.header.blocksize))()
-			# nchan, chanmap, chansamps, data, out
-			assert nchan == 2
-			fun(nchan, (c_int * 2)(0, 1),
-			    frame.header.blocksize, buffer_pp, outbuf)
-			self.curdata = array.array('h', outbuf)
-			if is_little_endian:
-				self.curdata.byteswap()
-		elif frame.header.bits_per_sample == 16:
-			self.curdata = array.array('h',
-			    [ buffer_pp[x % nchan][x / nchan] for x in
-			    xrange(frame.header.blocksize * nchan)])
-			if is_little_endian:
-				self.curdata.byteswap()
+		# nchan, chanmap, chansamps, data, out
+		assert nchan == 2
+		r = fun(nchan, (c_int * 2)(0, 1), frame.header.blocksize,
+		    buffer_pp, outbuf)
+		if outtype is None:
+			self.curdata = r
 		else:
-			print 'ERROR!'
+			self.curdata = array.array('h', outbuf)
+
+		if is_little_endian:
+			self.curdata.byteswap()
 
 		return 0