NEON在Android中的使用舉例，neonandroid舉例

NEON在Android中的使用舉例，neonandroid舉例

1、  開啟Eclipse，File-->New-->AndroidApplication Project-->Application Name:Hello-Neon, Project Name: Hello-Neon,Package Name:com.hello_neon.android, Minimum Required SDK:API 9:Android 2.3(Gingerbread),Next-->去掉Create custom launcher icon的勾選，Next-->Next-->ActivityName:Hello_NeonProjectActivity,Finish.

2、  開啟Hello-Neon工程下的src-->com.hello_neon.android-->Hello_NeonProjectActivity.java，將其內容改為：

package com.hello_neon.android;import android.os.Bundle;import android.app.Activity;import android.widget.TextView;public class Hello_NeonProjectActivity 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");    }}

3、 儲存Hello_NeonProjectActivity.java檔案，開啟命令列視窗，將其定位到\bin\classes目錄下，輸入命令：javah –classpath D:\ProgramFiles\Android\android-sdk\platforms\android-9\android.jar;com.hello_neon.android.Hello_NeonProjectActivity ,會在\bin\classes目錄下產生com_hello_neon_android_Hello_NeonProjectActivity.h檔案(說明：*.jar也可以是其它版本)；

4、  選中Hello-Neon工程，點擊右鍵-->New-->Folder建立一個jni檔案夾，在此檔案夾下添加Android.mk、Application.mk、helloneon.c、helloneon-intrinsics.c、helloneon-intrinsics.h五個檔案，其中內容分別為：

Android.mk:

LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS)LOCAL_MODULE    := helloneon#填寫要編譯的源檔案路徑LOCAL_SRC_FILES := helloneon.c helloneon-intrinsics.c#預設包含的標頭檔路徑LOCAL_C_INCLUDES := \$(LOCAL_PATH) \$(LOCAL_PATH)/..#-g 後面的一系列項目添加了才能使用arm_neon-h標頭檔, -mfloat-abi=softfp -mfpu=neon 使用arm_neon.h必須LOCAL_CFLAGS := -g -mfloat-abi=softfp -mfpu=neon -march=armv7-a -mtune=cortex-a8LOCAL_LDLIBS := -lz -llogTARGET_ARCH_ABI := armeabi-v7a LOCAL_ARM_MODE := armifeq ($(TARGET_ARCH_ABI),armeabi-v7a)#採用NEON最佳化技術    LOCAL_ARM_NEON := true    #LOCAL_CFLAGS := -DHAVE_NEON=1endifLOCAL_STATIC_LIBRARIES := cpufeatures#產生動態調用庫include $(BUILD_SHARED_LIBRARY)$(call import-module,cpufeatures)

Application.mk:

APP_PROJECT_PATH := $(call my-dir)/..APP_PLATFORM := android-10#choose which library to compile against in your MakefileAPP_STL := stlport_static#APP_ABI這句指定了編譯的目標平台類型，可以針對不同平台進行最佳化,x86 or armeabi-v7a# Build both ARMv5TE and ARMv7-A machine code.APP_ABI := armeabi armeabi-v7aAPP_CPPFLAGS += -fexceptions#for using c++ features,you need to enable these in your MakefileAPP_CPP_FEATURES += exceptions rtti

helloneon.c:

#include <jni.h>#include <time.h>#include <stdio.h>#include <stdlib.h>#include <cpu-features.h>#include "helloneon-intrinsics.h"#define DEBUG 0#define HAVE_NEON#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 doublenow_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 voidfir_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    600static 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 */JNIEXPORT jstring JNICALL Java_com_hello_1neon_android_Hello_1NeonProjectActivity_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);}

helloneon-intrinsics.h:

#ifndef HELLONEON_INTRINSICS_H#define HELLONEON_INTRINSICS_Hvoid fir_filter_neon_intrinsics(short *output, const short* input, const short* kernel, int width, int kernelSize);#endif /* HELLONEON_INTRINSICS_H */

helloneon-intrinsics.c:

#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 */voidfir_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[nn] = (short)((sum + 0x8000) >> 16);    }#endif}

5、 利用NDK產生.so檔案：選中工程-->Properties-->Builders-->New-->選中Program-->OK,Name:Hello_Neon_Builder,Location: D:\ProgramFiles\Android\android-sdk\android-ndk-r9\ndk-build.cmd,Working Directory: E:\NEON\Eclipse\Hello-Neon -->Apply,選中Refresh,勾選Refreshresources upon completion, 勾選Specific resources,點擊Specify Resources…,勾選Hello-Neon工程下的libs檔案夾，Finish-->Apply,選中BuildOptions,勾選Allocate Console(necessary for input), After a “Clean”, During manualbuilds, During auto builds, Specify working set of relevant resources,點擊SpecifyResoures…,勾選Hello-Neon工程下的jni檔案夾，Finish-->Apply-->OK-->OK,會在libs檔案夾下產生libhelloneon.so檔案;

6、  選中Hello-Neon，-->Run As-->AndroidApplication,運行結果為：

FIRFilter benchmark:

C version       :282.84 ms

Neon version    :135985 ms(x2.07994 faster)

以上是.c檔案的操作步驟，若將.c檔案該為.cpp檔案，則需改動兩個檔案：

1、將Android.mk改為：

LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS)LOCAL_MODULE    := helloneon#填寫要編譯的源檔案路徑LOCAL_SRC_FILES := helloneon.cpp helloneon-intrinsics.cpp#預設包含的標頭檔路徑LOCAL_C_INCLUDES := \$(LOCAL_PATH) \$(LOCAL_PATH)/..#-g 後面的一系列項目添加了才能使用arm_neon-h標頭檔, -mfloat-abi=softfp -mfpu=neon 使用arm_neon.h必須LOCAL_CFLAGS := -g -mfloat-abi=softfp -mfpu=neon -march=armv7-a -mtune=cortex-a8LOCAL_LDLIBS := -lz -llogTARGET_ARCH_ABI := armeabi-v7a LOCAL_ARM_MODE := armifeq ($(TARGET_ARCH_ABI),armeabi-v7a)#採用NEON最佳化技術    LOCAL_ARM_NEON := true    #LOCAL_CFLAGS := -DHAVE_NEON=1endifLOCAL_STATIC_LIBRARIES := cpufeatures#產生動態調用庫include $(BUILD_SHARED_LIBRARY)$(call import-module,cpufeatures)

2、helloneon.c改為：

#include <jni.h>#include <time.h>#include <stdio.h>#include <stdlib.h>#include <cpu-features.h>#include "helloneon-intrinsics.h"#define DEBUG 0#define HAVE_NEON#ifdef __cplusplusextern "C" {#endif#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 doublenow_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 voidfir_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    600static 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 */JNIEXPORT jstring JNICALL Java_com_hello_1neon_android_Hello_1NeonProjectActivity_stringFromJNI(JNIEnv *env, jobject thiz){    char str[512] = {0};    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;    sprintf(str, "FIR Filter benchmark:\nC version          : %g ms\n", time_c);    strlcpy(buffer, str, sizeof buffer);    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;    sprintf(str, "%g ms (x%g faster)\n", time_neon, time_c / (time_neon < 1e-6 ? 1. : time_neon));    strlcat(buffer, str, sizeof buffer);    /* 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(buffer);}#ifdef __cplusplus}#endif

參考文獻：

1、  http://blog.csdn.net/fengbingchun/article/details/11580983

2、  android-ndk-r9-windows-x86_64中的hello-neon例子代碼

Android中Handler的使用方法

你可以直接建立自己的thread來完成一些工作。
Handler主要是用來跟UI主線程互動用。 比如：
1、你用handler發送一個message，然後在handler的線程中來接收、處理該訊息，以避免直接在UI主線程中處理事務導致影響UI主線程的其他處理工作。
2、你可以將handler對象傳給其他進程，以便在其他進程中通過handler給你發送事件。
3、通過handler的延時發送message，可以延時處理一些事務的處理
 
你好 ， android中的資源引用中舉例的這個語句setTitle(Rstringmain_title)為何錯了

這種錯誤很容易找到問題的，你看看String下有沒有資源main_title這個東西，或者有沒有把資源加到你的軟體中，有的話可以在R.java檔案中找到id