sbc: ARMv6 optimized version of analysis filter for SBC encoder

The optimized filter gets enabled when the code is compiled
with -mcpu=/-march options set to target the processors which
support ARMv6 instructions. This code is also disabled when
NEON is used (which is a lot better alternative). For additional
safety ARM EABI is required and thumb mode should not be used.

Benchmarks from ARM11:

== 8 subbands ==

$ time ./sbcenc -b53 -s8 -j test.au > /dev/null

real    0m 35.65s
user    0m 34.17s
sys     0m 1.28s

$ time ./sbcenc.armv6 -b53 -s8 -j test.au > /dev/null

real    0m 17.29s
user    0m 15.47s
sys     0m 0.67s

== 4 subbands ==

$ time ./sbcenc -b53 -s4 -j test.au > /dev/null

real    0m 25.28s
user    0m 23.76s
sys     0m 1.32s

$ time ./sbcenc.armv6 -b53 -s4 -j test.au > /dev/null

real    0m 18.64s
user    0m 15.78s
sys     0m 2.22s

1 files changed, 52 insertions, 0 deletions

diff --git a/src/modules/bluetooth/sbc/sbc_primitives_armv6.h b/src/modules/bluetooth/sbc/sbc_primitives_armv6.h
new file mode 100644
index 00000000..1862aede
--- /dev/null
+++ b/src/modules/bluetooth/sbc/sbc_primitives_armv6.h
@@ -0,0 +1,52 @@
+/*
+ *
+ *  Bluetooth low-complexity, subband codec (SBC) library
+ *
+ *  Copyright (C) 2008-2010  Nokia Corporation
+ *  Copyright (C) 2004-2010  Marcel Holtmann <marcel@holtmann.org>
+ *  Copyright (C) 2004-2005  Henryk Ploetz <henryk@ploetzli.ch>
+ *  Copyright (C) 2005-2006  Brad Midgley <bmidgley@xmission.com>
+ *
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library 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
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifndef __SBC_PRIMITIVES_ARMV6_H
+#define __SBC_PRIMITIVES_ARMV6_H
+
+#include "sbc_primitives.h"
+
+#if defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || \
+	defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6Z__) || \
+	defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_6T2__) || \
+	defined(__ARM_ARCH_6M__) || defined(__ARM_ARCH_7__) || \
+	defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || \
+	defined(__ARM_ARCH_7M__)
+#define SBC_HAVE_ARMV6 1
+#endif
+
+#if !defined(SBC_HIGH_PRECISION) && (SCALE_OUT_BITS == 15) && \
+	defined(__GNUC__) && defined(SBC_HAVE_ARMV6) && \
+	defined(__ARM_EABI__) && !defined(__thumb__) && \
+	!defined(__ARM_NEON__)
+
+#define SBC_BUILD_WITH_ARMV6_SUPPORT
+
+void sbc_init_primitives_armv6(struct sbc_encoder_state *encoder_state);
+
+#endif
+
+#endif