Transceiver52M: Add ARM NEON support

Similar to the existing Intel SSE cases, add support for NEON vector
floating point SIMD processing. In this case, use ARM assembly
directly as the NEON intrinsics do not generate preferential code
output.

Currently support NEON vectorized convolution and floating point
integer conversions.

Signed-off-by: Thomas Tsou <tom@tsou.cc>

12 files changed, 743 insertions, 5 deletions

diff --git a/Transceiver52M/Makefile.am b/Transceiver52M/Makefile.am
index c1cfb1b..981447f 100644
--- a/Transceiver52M/Makefile.am
+++ b/Transceiver52M/Makefile.am
@@ -24,9 +24,13 @@ include $(top_srcdir)/Makefile.common
 AM_CPPFLAGS = $(STD_DEFINES_AND_INCLUDES) -I./common
 AM_CXXFLAGS = -ldl -lpthread
 
-SUBDIRS = x86
+SUBDIRS = arm x86
 
+if ARCH_ARM
+ARCH_LA = arm/libarch.la
+else
 ARCH_LA = x86/libarch.la
+endif
 
 if USRP1 
 AM_CPPFLAGS += $(USRP_CFLAGS)
@@ -72,7 +76,8 @@ noinst_HEADERS = \
 	USRPDevice.h \
 	Resampler.h \
 	common/convolve.h \
-	common/convert.h
+	common/convert.h \
+	common/scale.h
 
 transceiver_SOURCES = runTransceiver.cpp
 transceiver_LDADD = \
diff --git a/Transceiver52M/arm/Makefile.am b/Transceiver52M/arm/Makefile.am
new file mode 100644
index 0000000..6d34daa
--- /dev/null
+++ b/Transceiver52M/arm/Makefile.am
@@ -0,0 +1,21 @@
+if ARCH_ARM
+if ARCH_ARM_A15
+ARCH_FLAGS = -mfpu=neon-vfpv4
+else
+ARCH_FLAGS = -mfpu=neon
+endif
+
+AM_CFLAGS = -Wall $(ARCH_FLAGS) -std=gnu99 -I../common
+AM_CCASFLAGS = $(ARCH_FLAGS)
+
+noinst_LTLIBRARIES = libarch.la
+
+libarch_la_SOURCES = \
+	../common/convolve_base.c \
+	convert.c \
+	convert_neon.S \
+	convolve.c \
+	convolve_neon.S \
+	scale.c \
+	scale_neon.S
+endif
diff --git a/Transceiver52M/arm/convert.c b/Transceiver52M/arm/convert.c
new file mode 100644
index 0000000..a32eb55
--- /dev/null
+++ b/Transceiver52M/arm/convert.c
@@ -0,0 +1,96 @@
+/*
+ * NEON type conversions
+ * Copyright (C) 2012, 2013 Thomas Tsou <tom@tsou.cc>
+ *
+ * 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 Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <malloc.h>
+#include <string.h>
+#include "convert.h"
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+void neon_convert_ps_si16_4n(short *, float *, float *, int);
+void neon_convert_si16_ps_4n(float *, short *, int);
+
+#ifndef HAVE_NEON
+static void convert_si16_ps(float *out, short *in, int len)
+{
+	for (int i = 0; i < len; i++)
+		out[i] = in[i];
+}
+
+static void convert_ps_si16(short *out, float *in, float scale, int len)
+{
+	for (int i = 0; i < len; i++)
+		out[i] = in[i] * scale;
+}
+#else
+/* 4*N 16-bit signed integer conversion with remainder */
+static void neon_convert_si16_ps(float *restrict out,
+				 short *restrict in,
+				 int len)
+{
+	int start = len / 4 * 4;
+
+	neon_convert_si16_ps_4n(out, in, len >> 2);
+
+	for (int i = 0; i < len % 4; i++)
+		out[start + i] = (float) in[start + i];
+}
+
+/* 4*N 16-bit signed integer conversion with remainder */
+static void neon_convert_ps_si16(short *restrict out,
+				 float *restrict in,
+				 float *restrict scale,
+				 int len)
+{
+	int start = len / 4 * 4;
+
+	neon_convert_ps_si16_4n(out, in, scale, len >> 2);
+
+	for (int i = 0; i < len % 4; i++)
+		out[start + i] = (short) (in[start + i] * (*scale));
+}
+#endif
+
+void convert_float_short(short *out, float *in, float scale, int len)
+{
+#ifdef HAVE_NEON
+        float q[4] = { scale, scale, scale, scale };
+
+	if (len % 4)
+		neon_convert_ps_si16(out, in, q, len);
+	else
+		neon_convert_ps_si16_4n(out, in, q, len >> 2);
+#else
+	convert_ps_si16(out, in, scale, len);
+#endif
+}
+
+void convert_short_float(float *out, short *in, int len)
+{
+#ifdef HAVE_NEON
+	if (len % 4)
+		neon_convert_si16_ps(out, in, len);
+	else
+		neon_convert_si16_ps_4n(out, in, len >> 2);
+#else
+	convert_si16_ps(out, in, len);
+#endif
+}
diff --git a/Transceiver52M/arm/convert_neon.S b/Transceiver52M/arm/convert_neon.S
new file mode 100644
index 0000000..842ed9f
--- /dev/null
+++ b/Transceiver52M/arm/convert_neon.S
@@ -0,0 +1,51 @@
+/*
+ * NEON type conversions
+ * Copyright (C) 2012, 2013 Thomas Tsou <tom@tsou.cc>
+ *
+ * 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 Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+	.syntax unified
+	.text
+	.align 2
+	.global neon_convert_ps_si16_4n
+	.type neon_convert_ps_si16_4n, %function
+neon_convert_ps_si16_4n:
+	vld1.32          {q1}, [r2]
+.loop_fltint:
+	vld1.64       {d0-d1}, [r1]!
+	vmul.f32           q0, q1
+	vcvt.s32.f32       q2, q0
+	vqmovn.s32         d0, q2
+	vst1.64          {d0}, [r0]!
+	subs               r3, #1
+	bne          .loop_fltint
+	bx                 lr
+	.size neon_convert_ps_si16_4n, .-neon_convert_ps_si16_4n
+	.text
+	.align 2
+	.global neon_convert_si16_ps_4n
+	.type neon_convert_si16_ps_4n, %function
+neon_convert_si16_ps_4n:
+.loop_intflt:
+	vld1.64          {d0}, [r1]!
+	vmovl.s16          q1, d0
+	vcvt.f32.s32       q0, q1
+	vst1.64          {q0}, [r0]!
+	subs               r2, #1
+	bne          .loop_intflt
+        bx                 lr
+	.size neon_convert_si16_ps_4n, .-neon_convert_si16_ps_4n
+	.section .note.GNU-stack,"",%progbits
diff --git a/Transceiver52M/arm/convolve.c b/Transceiver52M/arm/convolve.c
new file mode 100644
index 0000000..2b42090
--- /dev/null
+++ b/Transceiver52M/arm/convolve.c
@@ -0,0 +1,139 @@
+/*
+ * NEON Convolution
+ * Copyright (C) 2012, 2013 Thomas Tsou <tom@tsou.cc>
+ *
+ * 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 Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <malloc.h>
+#include <string.h>
+#include <stdio.h>
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+/* Forward declarations from base implementation */
+int _base_convolve_real(float *x, int x_len,
+			float *h, int h_len,
+			float *y, int y_len,
+			int start, int len,
+			int step, int offset);
+
+int _base_convolve_complex(float *x, int x_len,
+			   float *h, int h_len,
+			   float *y, int y_len,
+			   int start, int len,
+			   int step, int offset);
+
+int bounds_check(int x_len, int h_len, int y_len,
+		 int start, int len, int step);
+
+#ifdef HAVE_NEON
+/* Calls into NEON assembler */
+void neon_conv_real4(float *x, float *h, float *y, int len);
+void neon_conv_real8(float *x, float *h, float *y, int len);
+void neon_conv_real12(float *x, float *h, float *y, int len);
+void neon_conv_real16(float *x, float *h, float *y, int len);
+void neon_conv_real20(float *x, float *h, float *y, int len);
+void mac_cx_neon4(float *x, float *h, float *y, int len);
+
+/* Complex-complex convolution */
+static void neon_conv_cmplx_4n(float *x, float *h, float *y, int h_len, int len)
+{
+	for (int i = 0; i < len; i++)
+		mac_cx_neon4(&x[2 * i], h, &y[2 * i], h_len >> 2);
+}
+#endif
+
+/* API: Aligned complex-real */
+int convolve_real(float *x, int x_len,
+		  float *h, int h_len,
+		  float *y, int y_len,
+		  int start, int len,
+		  int step, int offset)
+{
+	void (*conv_func)(float *, float *, float *, int) = NULL;
+
+	if (bounds_check(x_len, h_len, y_len, start, len, step) < 0)
+		return -1;
+
+	memset(y, 0, len * 2 * sizeof(float));
+
+#ifdef HAVE_NEON
+	if (step <= 4) {
+		switch (h_len) {
+		case 4:
+			conv_func = neon_conv_real4;
+			break;
+		case 8:
+			conv_func = neon_conv_real8;
+			break;
+		case 12:
+			conv_func = neon_conv_real12;
+			break;
+		case 16:
+			conv_func = neon_conv_real16;
+			break;
+		case 20:
+			conv_func = neon_conv_real20;
+			break;
+		}
+	}
+#endif
+	if (conv_func) {
+		conv_func(&x[2 * (-(h_len - 1) + start)],
+			  h, y, len);
+	} else {
+		_base_convolve_real(x, x_len,
+				    h, h_len,
+				    y, y_len,
+				    start, len, step, offset);
+	}
+
+	return len;
+}
+
+
+/* API: Aligned complex-complex */
+int convolve_complex(float *x, int x_len,
+		     float *h, int h_len,
+		     float *y, int y_len,
+		     int start, int len,
+		     int step, int offset)
+{
+	void (*conv_func)(float *, float *, float *, int, int) = NULL;
+
+	if (bounds_check(x_len, h_len, y_len, start, len, step) < 0)
+		return -1;
+
+	memset(y, 0, len * 2 * sizeof(float));
+
+#ifdef HAVE_NEON
+	if (step <= 4 && !(h_len % 4))
+		conv_func = neon_conv_cmplx_4n;
+#endif
+	if (conv_func) {
+		conv_func(&x[2 * (-(h_len - 1) + start)],
+			  h, y, h_len, len);
+	} else {
+		_base_convolve_complex(x, x_len,
+				       h, h_len,
+				       y, y_len,
+				       start, len, step, offset);
+	}
+
+	return len;
+}
diff --git a/Transceiver52M/arm/convolve_neon.S b/Transceiver52M/arm/convolve_neon.S
new file mode 100644
index 0000000..637d150
--- /dev/null
+++ b/Transceiver52M/arm/convolve_neon.S
@@ -0,0 +1,277 @@
+/*
+ * NEON Convolution
+ * Copyright (C) 2012, 2013 Thomas Tsou <tom@tsou.cc>
+ *
+ * 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 Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+	.syntax unified
+	.text
+	.align 2
+	.global neon_conv_real4
+	.type neon_conv_real4, %function
+neon_conv_real4:
+	push            {r4, lr}
+	vpush       {q4-q7}
+	vld2.32     {q0-q1}, [r1]
+	ldr              r4, =8
+.neon_conv_loop4:
+	vld2.32     {q2-q3}, [r0], r4
+	vmul.f32         q4,   q2, q0
+	vmul.f32         q5,   q3, q0
+	vpadd.f32       d12,   d8, d9
+	vpadd.f32       d13,  d10, d11
+	vpadd.f32       d14,  d12, d13
+	vst1.64       {d14}, [r2]!
+	subs             r3,   r3, #1
+	bne          .neon_conv_loop4
+	vpop       {q4-q7}
+	pop             {r4, pc}
+	.size neon_conv_real4, .-neon_conv_real4
+	.align 2
+	.p2align 4,,15
+	.global neon_conv_real8
+	.type neon_conv_real8, %function
+neon_conv_real8:
+	push         {r4-r5, lr}
+	vpush        {q4-q7}
+	vld2.32     {q0-q1}, [r1]!
+	vld2.32     {q2-q3}, [r1]
+	add              r4, r0, #32
+	ldr              r5, =8
+.neon_conv_loop8:
+	vld2.32     {q4-q5}, [r0], r5
+	vld2.32     {q6-q7}, [r4], r5
+	vmul.f32         q8,   q4, q0
+	vmul.f32         q9,   q5, q0
+	vmul.f32        q10,   q6, q2
+	vmul.f32        q11,   q7, q2
+
+	vadd.f32        q12,   q8, q10
+	vadd.f32        q13,   q9, q11
+
+	vpadd.f32       d22,  d24, d25
+	vpadd.f32       d23,  d26, d27
+	vpadd.f32       d24,  d22, d23
+	vst1.64       {d24}, [r2]!
+	subs             r3,   r3, #1
+	bne          .neon_conv_loop8
+	vpop       {q4-q7}
+	pop          {r4-r5, pc}
+	.size neon_conv_real8, .-neon_conv_real8
+	.align 2
+	.global neon_conv_real12
+	.type neon_conv_real12, %function
+neon_conv_real12:
+	push         {r4-r6, lr}
+	vpush       {q4-q7}
+	vld2.32     {q0-q1}, [r1]!
+	vld2.32     {q2-q3}, [r1]!
+	vld2.32     {q4-q5}, [r1]!
+	add              r4, r0, #32
+	add              r5, r0, #64
+	ldr              r6, =8
+.neon_conv_loop12:
+	vld2.32     {q6-q7}, [r0], r6
+	vld2.32     {q8-q9}, [r4], r6
+	vld2.32   {q10-q11}, [r5], r6
+#ifdef HAVE_NEON_FMA
+	vfma.f32         q1,   q6, q0
+	vfma.f32         q3,   q7, q0
+	vfma.f32         q1,   q8, q2
+	vfma.f32         q3,   q9, q2
+	vfma.f32         q1,  q10, q4
+	vfma.f32         q3,  q11, q4
+#else
+	vmul.f32        q12,   q6, q0
+	vmul.f32        q13,   q7, q0
+	vmul.f32        q14,   q8, q2
+	vmul.f32        q15,   q9, q2
+	vmul.f32         q1,  q10, q4
+	vmul.f32         q3,  q11, q4
+
+	vadd.f32         q5,  q12, q14
+	vadd.f32         q6,  q13, q15
+	vadd.f32         q1,   q5, q1
+	vadd.f32         q3,   q6, q3
+#endif
+	vpadd.f32        d2,   d2, d3
+	vpadd.f32        d3,   d6, d7
+	vpadd.f32        d6,   d2, d3
+	vst1.64        {d6}, [r2]!
+	subs             r3,   r3, #1
+	bne          .neon_conv_loop12
+	vpop         {q4-q7}
+	pop          {r4-r6, pc}
+	.size neon_conv_real12, .-neon_conv_real12
+	.align 2
+	.global neon_conv_real16
+	.type neon_conv_real16, %function
+neon_conv_real16:
+	push         {r4-r7, lr}
+	vpush        {q4-q7}
+	vld2.32     {q0-q1}, [r1]!
+	vld2.32     {q2-q3}, [r1]!
+	vld2.32     {q4-q5}, [r1]!
+	vld2.32     {q6-q7}, [r1]
+	add              r4, r0, #32
+	add              r5, r0, #64
+	add              r6, r0, #96
+	ldr              r7, =8
+.neon_conv_loop16:
+	vld2.32     {q8-q9}, [r0], r7
+	vld2.32   {q10-q11}, [r4], r7
+	vld2.32   {q12-q13}, [r5], r7
+	vld2.32   {q14-q15}, [r6], r7
+#ifdef HAVE_NEON_FMA
+	vmul.f32         q1,   q8, q0
+	vmul.f32         q3,   q9, q0
+	vfma.f32         q1,  q10, q2
+	vfma.f32         q3,  q11, q2
+	vfma.f32         q1,  q12, q4
+	vfma.f32         q3,  q13, q4
+	vfma.f32         q1,  q14, q6
+	vfma.f32         q3,  q15, q6
+#else
+	vmul.f32         q1,   q8, q0
+	vmul.f32         q3,   q9, q0
+	vmul.f32         q5,  q10, q2
+	vmul.f32         q7,  q11, q2
+	vmul.f32         q8,  q12, q4
+	vmul.f32         q9,  q13, q4
+	vmul.f32        q10,  q14, q6
+	vmul.f32        q11,  q15, q6
+
+	vadd.f32         q1,   q1, q5
+	vadd.f32         q3,   q3, q7
+	vadd.f32         q5,   q8, q10
+	vadd.f32         q7,   q9, q11
+	vadd.f32         q1,   q1, q5
+	vadd.f32         q3,   q3, q7
+#endif
+	vpadd.f32        d2,   d2, d3
+	vpadd.f32        d3,   d6, d7
+	vpadd.f32        d6,   d2, d3
+	vst1.64        {d6}, [r2]!
+	subs             r3,   r3, #1
+	bne          .neon_conv_loop16
+	vpop       {q4-q7}
+	pop          {r4-r7, pc}
+	.size neon_conv_real16, .-neon_conv_real16
+	.align 2
+	.global neon_conv_real20
+	.type neon_conv_real20, %function
+neon_conv_real20:
+	push         {r4-r8, lr}
+	vpush        {q4-q7}
+	vld2.32     {q0-q1}, [r1]!
+	vld2.32     {q2-q3}, [r1]!
+	vld2.32     {q4-q5}, [r1]!
+	vld2.32     {q6-q7}, [r1]!
+	vld2.32     {q8-q9}, [r1]
+	add              r4, r0, #32
+	add              r5, r0, #64
+	add              r6, r0, #96
+	add              r7, r0, #128
+	ldr              r8, =8
+.neon_conv_loop20:
+	vld2.32   {q10-q11}, [r0], r8
+	vld2.32   {q12-q13}, [r4], r8
+	vld2.32   {q14-q15}, [r5], r8
+#ifdef HAVE_NEON_FMA
+	vmul.f32         q1,  q10, q0
+	vfma.f32         q1,  q12, q2
+	vfma.f32         q1,  q14, q4
+	vmul.f32         q3,  q11, q0
+	vfma.f32         q3,  q13, q2
+	vfma.f32         q3,  q15, q4
+
+	vld2.32   {q12-q13}, [r6], r8
+	vld2.32   {q14-q15}, [r7], r8
+
+	vfma.f32         q1,  q12, q6
+	vfma.f32         q3,  q13, q6
+	vfma.f32         q1,  q14, q8
+	vfma.f32         q3,  q15, q8
+#else
+	vmul.f32         q1,  q10, q0
+	vmul.f32         q3,  q12, q2
+	vmul.f32         q5,  q14, q4
+	vmul.f32         q7,  q11, q0
+	vmul.f32         q9,  q13, q2
+	vmul.f32        q10,  q15, q4
+	vadd.f32         q1,   q1, q3
+	vadd.f32         q3,   q7, q9
+	vadd.f32         q9,   q1, q5
+	vadd.f32        q10,   q3, q10
+
+	vld2.32   {q12-q13}, [r6], r8
+	vld2.32   {q14-q15}, [r7], r8
+
+	vmul.f32         q1,  q12, q6
+	vmul.f32         q3,  q13, q6
+	vmul.f32         q5,  q14, q8
+	vmul.f32         q7,  q15, q8
+	vadd.f32        q12,   q1, q9
+	vadd.f32        q14,   q3, q10
+	vadd.f32         q1,  q12, q5
+	vadd.f32         q3,  q14, q7
+#endif
+	vpadd.f32        d2,   d2, d3
+	vpadd.f32        d3,   d6, d7
+	vpadd.f32        d6,   d2, d3
+	vst1.64        {d6}, [r2]!
+	subs             r3,   r3, #1
+	bne          .neon_conv_loop20
+	vpop       {q4-q7}
+	pop          {r4-r8, pc}
+	.size neon_conv_real20, .-neon_conv_real20
+	.align 2
+	.global mac_cx_neon4
+	.type mac_cx_neon4, %function
+mac_cx_neon4:
+	push           {r4, lr}
+	ldr             r4, =32
+	veor           q14, q14
+	veor           q15, q15
+.neon_conv_loop_mac4:
+	vld2.32     {q0-q1}, [r0], r4
+	vld2.32     {q2-q3}, [r1]!
+
+	vmul.f32       q10,  q0, q2
+	vmul.f32       q11,  q1, q3
+	vmul.f32       q12,  q0, q3
+	vmul.f32       q13,  q2, q1
+	vsub.f32        q8, q10, q11
+	vadd.f32        q9, q12, q13
+
+	vadd.f32        q14, q8
+	vadd.f32        q15, q9
+	subs             r3, #1
+	bne       .neon_conv_loop_mac4
+
+	vld1.64          d0, [r2]
+	vpadd.f32       d28, d28, d29
+	vpadd.f32       d30, d30, d31
+	vpadd.f32        d1, d28, d30
+	vadd.f32         d1, d0
+	vst1.64          d1, [r2]
+        pop             {r4, pc}
+	.size mac_cx_neon4, .-mac_cx_neon4
+	.section .note.GNU-stack,"",%progbits
diff --git a/Transceiver52M/arm/scale.c b/Transceiver52M/arm/scale.c
new file mode 100644
index 0000000..2de13ff
--- /dev/null
+++ b/Transceiver52M/arm/scale.c
@@ -0,0 +1,56 @@
+/*
+ * NEON scaling
+ * Copyright (C) 2012,2013 Thomas Tsou <tom@tsou.cc>
+ *
+ * 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 Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <malloc.h>
+#include <string.h>
+#include <scale.h>
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+void neon_scale_4n(float *, float *, float *, int);
+
+static void scale_ps(float *out, float *in, float *scale, int len)
+{
+	float ai, aq, bi, bq;
+
+	bi = scale[0];
+	bq = scale[1];
+
+	for (int i = 0; i < len; i++) {
+		ai = in[2 * i + 0];
+		aq = in[2 * i + 1];
+
+		out[2 * i + 0] = ai * bi - aq * bq;
+		out[2 * i + 1] = ai * bq + aq * bi;
+	}
+}
+
+void scale_complex(float *out, float *in, float* scale, int len)
+{
+#ifdef HAVE_NEON
+	if (len % 4)
+		scale_ps(out, in, scale, len);
+	else
+		neon_scale_4n(in, scale, out, len >> 2);
+#else
+	scale_ps(out, in, scale, len);
+#endif
+}
diff --git a/Transceiver52M/arm/scale_neon.S b/Transceiver52M/arm/scale_neon.S
new file mode 100644
index 0000000..a66fbe5
--- /dev/null
+++ b/Transceiver52M/arm/scale_neon.S
@@ -0,0 +1,50 @@
+/*
+ * ARM NEON Scaling
+ * Copyright (C) 2013 Thomas Tsou <tom@tsou.cc>
+ *
+ * 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 Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+	.syntax unified
+	.text
+	.align 2
+	.global neon_scale_4n
+	.type neon_scale_4n, %function
+neon_scale_4n:
+	push            {r4, lr}
+	ldr              r4, =32
+
+	vld1.64          d0, [r1]
+	vmov.32          s4, s1
+	vmov.32          s1, s0
+	vmov.64          d1, d0
+	vmov.32          s5, s4
+	vmov.64          d3, d2
+.loop_mul_const:
+	vld2.32     {q2-q3}, [r0], r4
+
+	vmul.f32         q8, q0,  q2
+	vmul.f32         q9, q1,  q3
+	vmul.f32        q10, q0,  q3
+	vmul.f32        q11, q1,  q2
+	vsub.f32         q8, q8,  q9
+	vadd.f32         q9, q10, q11
+
+	vst2.32     {q8-q9}, [r2]!
+	subs             r3, #1
+	bne              .loop_mul_const
+	pop             {r4, pc}
+	.size neon_scale_4n, .-neon_scale_4n
+	.section .note.GNU-stack,"",%progbits
diff --git a/Transceiver52M/common/scale.h b/Transceiver52M/common/scale.h
new file mode 100644
index 0000000..da867e7
--- /dev/null
+++ b/Transceiver52M/common/scale.h
@@ -0,0 +1,6 @@
+#ifndef _SCALE_H_
+#define _SCALE_H_
+
+void scale_complex(float *out, float *in, float *scale, int len);
+
+#endif /* _SCALE_H_ */
diff --git a/Transceiver52M/sigProcLib.cpp b/Transceiver52M/sigProcLib.cpp
index 595efa3..5a1ab77 100644
--- a/Transceiver52M/sigProcLib.cpp
+++ b/Transceiver52M/sigProcLib.cpp
@@ -22,15 +22,20 @@
 
 */
 
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
 #include "sigProcLib.h"
 #include "GSMCommon.h"
 
-using namespace GSM;
-
 extern "C" {
 #include "convolve.h"
+#include "scale.h"
 }
 
+using namespace GSM;
+
 #define TABLESIZE 1024
 
 /** Lookup tables for trigonometric approximation */
@@ -958,6 +963,13 @@ complex peakDetect(const signalVector &rxBurst,
 void scaleVector(signalVector &x,
 		 complex scale)
 {
+#ifdef HAVE_NEON
+  int len = x.size();
+
+  scale_complex((float *) x.begin(),
+                (float *) x.begin(),
+                (float *) &scale, len);
+#else
   signalVector::iterator xP = x.begin();
   signalVector::iterator xPEnd = x.end();
   if (!x.isRealOnly()) {
@@ -972,6 +984,7 @@ void scaleVector(signalVector &x,
       xP++;
     }
   }
+#endif
 }
 
 /** in-place conjugation */
diff --git a/Transceiver52M/x86/Makefile.am b/Transceiver52M/x86/Makefile.am
index 0621b17..e880351 100644
--- a/Transceiver52M/x86/Makefile.am
+++ b/Transceiver52M/x86/Makefile.am
@@ -1,3 +1,4 @@
+if !ARCH_ARM
 AM_CFLAGS = -Wall -std=gnu99 -march=native -I../common
 
 noinst_LTLIBRARIES = libarch.la
@@ -6,3 +7,4 @@ libarch_la_SOURCES = \
 	../common/convolve_base.c \
 	convert.c \
 	convolve.c
+endif
diff --git a/configure.ac b/configure.ac
index 848f887..ae4ea3b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -68,6 +68,25 @@ AC_ARG_WITH(singledb, [
         [enable single daughterboard use on USRP1])
 ])
 
+AC_ARG_WITH(neon, [
+    AS_HELP_STRING([--with-neon],
+        [enable ARM NEON support])
+])
+
+AC_ARG_WITH(neon-vfpv4, [
+    AS_HELP_STRING([--with-neon-vfpv4],
+        [enable ARM NEON FMA support])
+])
+
+AS_IF([test "x$with_neon" = "xyes"], [
+    AC_DEFINE(HAVE_NEON, 1, Support ARM NEON)
+])
+
+AS_IF([test "x$with_neon_vfpv4" = "xyes"], [
+    AC_DEFINE(HAVE_NEON, 1, Support ARM NEON)
+    AC_DEFINE(HAVE_NEON_FMA, 1, Support ARM NEON with FMA)
+])
+
 AS_IF([test "x$with_usrp1" = "xyes"], [
     PKG_CHECK_MODULES(USRP, usrp >= 3.3)
 ])
@@ -85,6 +104,8 @@ AS_IF([test "x$with_singledb" = "xyes"], [
 AX_EXT
 
 AM_CONDITIONAL(USRP1, [test "x$with_usrp1" = "xyes"])
+AM_CONDITIONAL(ARCH_ARM, [test "x$with_neon" = "xyes" || test "x$with_neon_vfpv4" = "xyes"])
+AM_CONDITIONAL(ARCH_ARM_A15, [test "x$with_neon_vfpv4" = "xyes"])
 
 PKG_CHECK_MODULES(LIBUSB, libusb-1.0)
 
@@ -94,8 +115,9 @@ AC_CONFIG_FILES([\
     CommonLibs/Makefile \
     GSM/Makefile \
     Transceiver52M/Makefile \
+    Transceiver52M/arm/Makefile \
     Transceiver52M/x86/Makefile \
     sqlite3/Makefile \
-]) 
+])
 
 AC_OUTPUT