From 9497e4407c51d191447811f180dd37d7db83cdf6 Mon Sep 17 00:00:00 2001
From: Raph Levien <raph@google.com>
Date: Thu, 28 Nov 2013 11:20:32 -0800
Subject: [PATCH] Neon detection

Use runtime check to detect Neon. Also add some copyright headers.
---
 cpp/src/fm_op_kernel.cc  | 12 ------------
 cpp/src/neon_fm_kernel.s | 16 ++++++++++++++++
 cpp/src/neon_ladder.s    | 16 ++++++++++++++++
 cpp/src/resofilter.cc    |  7 ++-----
 cpp/src/synth.h          | 15 +++++++++++++++
 lab/ladder/sawtest.py    | 16 ++++++++++++++++
 6 files changed, 65 insertions(+), 17 deletions(-)

diff --git a/cpp/src/fm_op_kernel.cc b/cpp/src/fm_op_kernel.cc
index 6f2aa69..1a7e10b 100644
--- a/cpp/src/fm_op_kernel.cc
+++ b/cpp/src/fm_op_kernel.cc
@@ -16,20 +16,12 @@
 
 #include <math.h>
 
-#ifdef HAVE_NEON
-#include <cpu-features.h>
-#endif
-
 #include "synth.h"
 
 #include "sin.h"
 #include "fm_op_kernel.h"
 
 #ifdef HAVE_NEON
-static bool hasNeon() {
-  return true;
-  return (android_getCpuFeatures() & ANDROID_CPU_ARM_FEATURE_NEON) != 0;
-}
 
 extern "C"
 void neon_fm_kernel(const int *in, const int *busin, int *out, int count,
@@ -37,10 +29,6 @@ void neon_fm_kernel(const int *in, const int *busin, int *out, int count,
 
 const int32_t __attribute__ ((aligned(16))) zeros[N] = {0};
 
-#else
-static bool hasNeon() {
-  return false;
-}
 #endif
 
 void FmOpKernel::compute(int32_t *output, const int32_t *input,
diff --git a/cpp/src/neon_fm_kernel.s b/cpp/src/neon_fm_kernel.s
index 0dc2a47..1efba5c 100644
--- a/cpp/src/neon_fm_kernel.s
+++ b/cpp/src/neon_fm_kernel.s
@@ -1,3 +1,19 @@
+@ Copyright 2013 Google Inc.
+@ 
+@ Licensed under the Apache License, Version 2.0 (the "License");
+@ you may not use this file except in compliance with the License.
+@ You may obtain a copy of the License at
+@ 
+@      http://www.apache.org/licenses/LICENSE-2.0
+@ 
+@ Unless required by applicable law or agreed to in writing, software
+@ distributed under the License is distributed on an "AS IS" BASIS,
+@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@ See the License for the specific language governing permissions and
+@ limitations under the License.
+
+@ NEON assembly implementation of FM operator kernel
+
 	.text
 
 	.align	2
diff --git a/cpp/src/neon_ladder.s b/cpp/src/neon_ladder.s
index 9a9a6dc..565e50c 100644
--- a/cpp/src/neon_ladder.s
+++ b/cpp/src/neon_ladder.s
@@ -1,3 +1,19 @@
+@ Copyright 2013 Google Inc.
+@ 
+@ Licensed under the Apache License, Version 2.0 (the "License");
+@ you may not use this file except in compliance with the License.
+@ You may obtain a copy of the License at
+@ 
+@      http://www.apache.org/licenses/LICENSE-2.0
+@ 
+@ Unless required by applicable law or agreed to in writing, software
+@ distributed under the License is distributed on an "AS IS" BASIS,
+@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@ See the License for the specific language governing permissions and
+@ limitations under the License.
+
+@ NEON assembly implementation of ladder filter core
+
     .text
 
     .align  2
diff --git a/cpp/src/resofilter.cc b/cpp/src/resofilter.cc
index f0419ef..80aaffc 100644
--- a/cpp/src/resofilter.cc
+++ b/cpp/src/resofilter.cc
@@ -197,12 +197,9 @@ void ResoFilter::process(const int32_t **inbufs, const int32_t *control_in,
   float overdrive = control_in[2] * (1.0 / (1 << 24));
   const int32_t *ibuf = inbufs[0];
   int32_t *obuf = outbufs[0];
-  bool useneon = false;
-#ifdef HAVE_NEON
-  useneon = true;  // TODO: detect
-#endif
+  bool useneon = hasNeon();
 
-  if (overdrive == 0) {
+  if (overdrive < 0.01) {
     if (useneon) {
 #ifdef HAVE_NEON
       AlignedBuf<float, 20> a_neon;
diff --git a/cpp/src/synth.h b/cpp/src/synth.h
index 2d310d8..1addd5d 100644
--- a/cpp/src/synth.h
+++ b/cpp/src/synth.h
@@ -21,6 +21,7 @@
 // See http://stackoverflow.com/questions/126279/c99-stdint-h-header-and-ms-visual-studio
 #include <stdint.h>
 
+// TODO(raph): move from fixed to variable N
 #define LG_N 6
 #define N (1 << LG_N)
 
@@ -50,4 +51,18 @@ inline static T max(const T& a, const T& b) {
     return a > b ? a : b;
 }
 
+#ifdef HAVE_NEON
+#include <cpu-features.h>
+
+static inline bool hasNeon() {
+  return (android_getCpuFeatures() & ANDROID_CPU_ARM_FEATURE_NEON) != 0;
+}
+#else
+static inline bool hasNeon() {
+  return false;
+}
+#endif
+
+
+
 #endif  // __SYNTH_H
diff --git a/lab/ladder/sawtest.py b/lab/ladder/sawtest.py
index 1224ade..99c9749 100644
--- a/lab/ladder/sawtest.py
+++ b/lab/ladder/sawtest.py
@@ -1,3 +1,19 @@
+# Copyright 2013 Google Inc.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# 
+#      http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Script for generating sound samples for comparing ladder filters
+
 import argparse
 import struct
 import numpy as np