}
}
-static const char gVertexShader[] = "attribute vec4 vPosition;\n"
+static const char gVertexShader[] =
+ "attribute vec4 vPosition;\n"
"void main() {\n"
" gl_Position = vPosition;\n"
"}\n";
-static const char gFragmentShader[] = "precision mediump float;\n"
+static const char gFragmentShader[] =
+ "precision mediump float;\n"
"void main() {\n"
" gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);\n"
"}\n";
--- /dev/null
+APP_PROJECT_PATH := $(call my-dir)/project
+APP_MODULES := helloneon cpufeatures
+APP_ABI := armeabi armeabi-v7a
--- /dev/null
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+ package="com.example.neon"
+ android:versionCode="1"
+ android:versionName="1.0">
+ <application android:label="@string/app_name">
+ <activity android:name=".HelloNeon"
+ android:label="@string/app_name">
+ <intent-filter>
+ <action android:name="android.intent.action.MAIN" />
+ <category android:name="android.intent.category.LAUNCHER" />
+ </intent-filter>
+ </activity>
+ </application>
+</manifest>
--- /dev/null
+# This file is used to override default values used by the Ant build system.
+#
+# This file must be checked in Version Control Systems, as it is
+# integral to the build system of your project.
+
+# This file is only used by the Ant script.
+
+# You can use this to override default values such as
+# 'source.dir' for the location of your java source folder and
+# 'out.dir' for the location of your output folder.
+
+# You can also use it define how the release builds are signed by declaring
+# the following properties:
+# 'key.store' for the location of your keystore and
+# 'key.alias' for the name of the key to use.
+# The password will be asked during the build when you use the 'release' target.
+
+# The name of your application package as defined in the manifest.
+# Used by the 'uninstall' rule.
+application.package=com.example.neon
--- /dev/null
+# This file is automatically generated by Android Tools.
+# Do not modify this file -- YOUR CHANGES WILL BE ERASED!
+#
+# This file must be checked in Version Control Systems.
+#
+# To customize properties used by the Ant build system use,
+# "build.properties", and override values to adapt the script to your
+# project structure.
+
+# Project target.
+target=android-3
--- /dev/null
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := helloneon
+
+LOCAL_SRC_FILES := helloneon.c
+
+ifeq ($(TARGET_ARCH_ABI),armeabi-v7a)
+ LOCAL_CFLAGS := -DHAVE_NEON=1
+ LOCAL_SRC_FILES += helloneon-intrinsics.c.neon
+endif
+
+LOCAL_C_INCLUDES := sources/cpufeatures
+
+LOCAL_STATIC_LIBRARIES := cpufeatures
+
+LOCAL_LDLIBS := -llog
+
+include $(BUILD_SHARED_LIBRARY)
+
+include sources/cpufeatures/Android.mk
--- /dev/null
+#include "helloneon-intrinsics.h"
+#include <arm_neon.h>
+
+/* this source file should only be compiled by Android.mk when targeting
+ * the armeabi-v7a ABI, and should be built in NEON mode
+ */
+void
+fir_filter_neon_intrinsics(short *output, const short* input, const short* kernel, int width, int kernelSize)
+{
+#if 1
+ int nn, offset = -kernelSize/2;
+
+ for (nn = 0; nn < width; nn++)
+ {
+ int mm, sum = 0;
+ int32x4_t sum_vec = vdupq_n_s32(0);
+ for(mm = 0; mm < kernelSize/4; mm++)
+ {
+ int16x4_t kernel_vec = vld1_s16(kernel + mm*4);
+ int16x4_t input_vec = vld1_s16(input + (nn+offset+mm*4));
+ sum_vec = vmlal_s16(sum_vec, kernel_vec, input_vec);
+ }
+
+ sum += vgetq_lane_s32(sum_vec, 0);
+ sum += vgetq_lane_s32(sum_vec, 1);
+ sum += vgetq_lane_s32(sum_vec, 2);
+ sum += vgetq_lane_s32(sum_vec, 3);
+
+ if(kernelSize & 3)
+ {
+ for(mm = kernelSize - (kernelSize & 3); mm < kernelSize; mm++)
+ sum += kernel[mm] * input[nn+offset+mm];
+ }
+
+ output[nn] = (short)((sum + 0x8000) >> 16);
+ }
+#else /* for comparison purposes only */
+ int nn, offset = -kernelSize/2;
+ for (nn = 0; nn < width; nn++) {
+ int sum = 0;
+ int mm;
+ for (mm = 0; mm < kernelSize; mm++) {
+ sum += kernel[mm]*input[nn+offset+mm];
+ }
+ output[n] = (short)((sum + 0x8000) >> 16);
+ }
+#endif
+}
--- /dev/null
+#ifndef HELLONEON_INTRINSICS_H
+#define HELLONEON_INTRINSICS_H
+
+void fir_filter_neon_intrinsics(short *output, const short* input, const short* kernel, int width, int kernelSize);
+
+#endif /* HELLONEON_INTRINSICS_H */
--- /dev/null
+#include <jni.h>
+#include <time.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <cpu-features.h>
+#include "helloneon-intrinsics.h"
+
+#define DEBUG 0
+
+#if DEBUG
+#include <android/log.h>
+# define D(x...) __android_log_print(ANDROID_LOG_INFO,"helloneon",x)
+#else
+# define D(...) do {} while (0)
+#endif
+
+/* return current time in milliseconds */
+static double
+now_ms(void)
+{
+ struct timespec res;
+ clock_gettime(CLOCK_REALTIME, &res);
+ return 1000.0*res.tv_sec + (double)res.tv_nsec/1e6;
+}
+
+
+/* this is a FIR filter implemented in C */
+static void
+fir_filter_c(short *output, const short* input, const short* kernel, int width, int kernelSize)
+{
+ int offset = -kernelSize/2;
+ int nn;
+ for (nn = 0; nn < width; nn++) {
+ int sum = 0;
+ int mm;
+ for (mm = 0; mm < kernelSize; mm++) {
+ sum += kernel[mm]*input[nn+offset+mm];
+ }
+ output[nn] = (short)((sum + 0x8000) >> 16);
+ }
+}
+
+#define FIR_KERNEL_SIZE 32
+#define FIR_OUTPUT_SIZE 2560
+#define FIR_INPUT_SIZE (FIR_OUTPUT_SIZE + FIR_KERNEL_SIZE)
+#define FIR_ITERATIONS 600
+
+static const short fir_kernel[FIR_KERNEL_SIZE] = {
+ 0x10, 0x20, 0x40, 0x70, 0x8c, 0xa2, 0xce, 0xf0, 0xe9, 0xce, 0xa2, 0x8c, 070, 0x40, 0x20, 0x10,
+ 0x10, 0x20, 0x40, 0x70, 0x8c, 0xa2, 0xce, 0xf0, 0xe9, 0xce, 0xa2, 0x8c, 070, 0x40, 0x20, 0x10 };
+
+static short fir_output[FIR_OUTPUT_SIZE];
+static short fir_input_0[FIR_INPUT_SIZE];
+static const short* fir_input = fir_input_0 + (FIR_KERNEL_SIZE/2);
+static short fir_output_expected[FIR_OUTPUT_SIZE];
+
+/* This is a trivial JNI example where we use a native method
+ * to return a new VM String. See the corresponding Java source
+ * file located at:
+ *
+ * apps/samples/hello-neon/project/src/com/example/neon/HelloNeon.java
+ */
+jstring
+Java_com_example_neon_HelloNeon_stringFromJNI( JNIEnv* env,
+ jobject thiz )
+{
+ char* str;
+ uint64_t features;
+ char buffer[512];
+ char tryNeon = 0;
+ double t0, t1, time_c, time_neon;
+
+ /* setup FIR input - whatever */
+ {
+ int nn;
+ for (nn = 0; nn < FIR_INPUT_SIZE; nn++) {
+ fir_input_0[nn] = (5*nn) & 255;
+ }
+ fir_filter_c(fir_output_expected, fir_input, fir_kernel, FIR_OUTPUT_SIZE, FIR_KERNEL_SIZE);
+ }
+
+ /* Benchmark small FIR filter loop - C version */
+ t0 = now_ms();
+ {
+ int count = FIR_ITERATIONS;
+ for (; count > 0; count--) {
+ fir_filter_c(fir_output, fir_input, fir_kernel, FIR_OUTPUT_SIZE, FIR_KERNEL_SIZE);
+ }
+ }
+ t1 = now_ms();
+ time_c = t1 - t0;
+
+ asprintf(&str, "FIR Filter benchmark:\nC version : %g ms\n", time_c);
+ strlcpy(buffer, str, sizeof buffer);
+ free(str);
+
+ strlcat(buffer, "Neon version : ", sizeof buffer);
+
+ if (android_getCpuFamily() != ANDROID_CPU_FAMILY_ARM) {
+ strlcat(buffer, "Not an ARM CPU !\n", sizeof buffer);
+ goto EXIT;
+ }
+
+ features = android_getCpuFeatures();
+ if ((features & ANDROID_CPU_ARM_FEATURE_ARMv7) == 0) {
+ strlcat(buffer, "Not an ARMv7 CPU !\n", sizeof buffer);
+ goto EXIT;
+ }
+
+ /* HAVE_NEON is defined in Android.mk ! */
+#ifdef HAVE_NEON
+ if ((features & ANDROID_CPU_ARM_FEATURE_NEON) == 0) {
+ strlcat(buffer, "CPU doesn't support NEON !\n", sizeof buffer);
+ goto EXIT;
+ }
+
+ /* Benchmark small FIR filter loop - Neon version */
+ t0 = now_ms();
+ {
+ int count = FIR_ITERATIONS;
+ for (; count > 0; count--) {
+ fir_filter_neon_intrinsics(fir_output, fir_input, fir_kernel, FIR_OUTPUT_SIZE, FIR_KERNEL_SIZE);
+ }
+ }
+ t1 = now_ms();
+ time_neon = t1 - t0;
+ asprintf(&str, "%g ms (x%g faster)\n", time_neon, time_c / (time_neon < 1e-6 ? 1. : time_neon));
+ strlcat(buffer, str, sizeof buffer);
+ free(str);
+
+ /* check the result, just in case */
+ {
+ int nn, fails = 0;
+ for (nn = 0; nn < FIR_OUTPUT_SIZE; nn++) {
+ if (fir_output[nn] != fir_output_expected[nn]) {
+ if (++fails < 16)
+ D("neon[%d] = %d expected %d", nn, fir_output[nn], fir_output_expected[nn]);
+ }
+ }
+ D("%d fails\n", fails);
+ }
+#else /* !HAVE_NEON */
+ strlcat(buffer, "Program not compiled with ARMv7 support !\n", sizeof buffer);
+#endif /* !HAVE_NEON */
+EXIT:
+ return (*env)->NewStringUTF(env, buffer);
+}
--- /dev/null
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+ <string name="app_name">HelloNeon</string>
+</resources>
--- /dev/null
+package com.example.neon;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.widget.TextView;
+
+public class HelloNeon extends Activity
+{
+ /** Called when the activity is first created. */
+ @Override
+ public void onCreate(Bundle savedInstanceState)
+ {
+ super.onCreate(savedInstanceState);
+ /* Create a TextView and set its content.
+ * the text is retrieved by calling a native
+ * function.
+ */
+ TextView tv = new TextView(this);
+ tv.setText( stringFromJNI() );
+ setContentView(tv);
+ }
+
+ /* A native method that is implemented by the
+ * 'helloneon' native library, which is packaged
+ * with this application.
+ */
+ public native String stringFromJNI();
+
+ /* this is used to load the 'helloneon' library on application
+ * startup. The library has already been unpacked into
+ * /data/data/com.example.neon/lib/libhelloneon.so at
+ * installation time by the package manager.
+ */
+ static {
+ System.loadLibrary("helloneon");
+ }
+}
--- /dev/null
+#!/bin/sh
+#
+# This is used to cleanup the project directories before making a commit or
+# a clean release. This will get rid of auto-generated files in the
+# apps/<name>/project directories.
+#
+for projectPath in `find apps/*/project` ; do
+ rm -rf $projectPath/bin
+ rm -rf $projectPath/gen
+ rm -f $projectPath/build.xml
+ rm -f $projectPath/local.properties
+done
}
...
+
+Sample code:
+------------
+
+Look at the source code for the "hello-neon" sample in this NDK for an example
+on how to use the 'cpufeatures' library and Neon intrinsics at the same time.
+
+This implements a tiny benchmark for a FIR filter loop using a C version, and
+a NEON-optimized one for devices that support it.
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