JavaScript调用C库

本文介绍: 本文介绍通过ffi方式调用C动态库系统：ubuntu16.04 64bit。

本文介绍通过ffi方式调用C动态库
系统：ubuntu16.04 64bit

一、环境安装

安装js运行环境
- V17.3.0 地址：https://nodejs.org/dist
- wget https://nodejs.org/dist/v17.6.0/node-v17.6.0-linux-x64.tar.xz
- 解压tar xvf node-v17.6.0-linux-x64.tar.xz
- sudo mv node-v17.6.0-linux-x64 /usr/local/nodejs
- 添加环境变量 vi ~/.bashrc (添加后重启终端窗口)
```
export PATH=$PATH:/usr/local/nodejs/bin
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/nodejs/lib
```
安装ffi相关
- 设置源：npm config set registry https://registry.npmmirror.com （淘宝）
- npm config set python /usr/bin/python3 (python>3.6.0)
- npm install node-gyp
- npm install ffi-napi
- npm install ref-napi
- npm install ref-array-napi
- npm install ref-struct-napi

二、测试代码

c代码test.c–>编译出动态库libtest.so

#include <stdio.h>
typedef struct {
    int id;
    char* name;
    double height;
    int score[10];
    int score_size;
}userStruct;
typedef void (*callback)(int val);
static char char_point[64] = "";
int api_int(int a, int b) {
    return a + b;
}

double api_double(double a, double b) {
    return a + b;
}

char* api_char_point(char* a, char* b){
    memset(char_point, 0, sizeof(char_point));
    sprintf(char_point, "%s %s", a, b);
    return char_point;
}

int api_int_array(int* a, int size){
    int i = 0; 
    for(i = 0; i < size; i++){
        a[i] = i;
    }
    return 0;
}

int api_struct(userStruct user){
    int i = 0;
    char buf[128] = "";
    printf("C Print score_size:%dn", user.score_size);
    for(i = 0; i < user.score_size; i++){
        printf("C Print i:%d, score:%dn",i, user.score[i]);
        sprintf(buf, "%s %d", buf, user.score[i]);
    }
    printf("C Print id:%d name:%s height:%f socre:%sn", user.id, user.name, user.height, buf);
    return 0;
}
void api_callback(callback cb){
    cb(1);
}

js代码 test.js

const ffi = require('ffi-napi');
const ref = require('ref-napi');
const refArray = require('ref-array-napi')
const StructType = require('ref-struct-napi');
const IntArray10 = refArray(ref.types.int, 10);
const userStruct = StructType({
    id: 'int',
    name: 'string',
    height: 'double',
    score: IntArray10,
    score_size: 'int'
});

const rockeyInterface = {
    'api_int':['int', ['int', 'int']],
    'api_double':['double', ['double', 'double']],
    'api_char_point':['string', ['string', 'string']],
    'api_int_array':['int', ['pointer', 'int']],
    'api_struct':['int', [userStruct]],
    'api_callback':['void', ['pointer']]
}

let libtest = new ffi.Library('./libtest.so', rockeyInterface);
//int test
console.log("int result:", libtest.api_int(1, 2));
//double test
console.log("double Result:", libtest.api_double(1.1, 1.2));
//char* test
console.log("char* result:", libtest.api_char_point('hello', 'world'));
//int array test
let arraySize = 10;
let arrayBuf = Buffer.alloc(arraySize* Int32Array.BYTES_PER_ELEMENT);
console.log(typeof arrayBuf);
console.log(arrayBuf.length);
if(libtest.api_int_array(arrayBuf, arraySize) == 0){
    let arrayResult = new Int32Array(arrayBuf.buffer);
    console.log("int array result:", arrayResult);
}
//struct test
let user = new userStruct();
user.id = 101;
user.name = 'hsl';
user.height = 1.78;
user.score_size = 10;
user.score = new IntArray10();
for(var i = 0; i < user.score_size; i++){
    user.score[i] = i+1;
}
let ret = libtest.api_struct(user);
console.log("struct result:", ret);

//callback test
const callback = ffi.Callback('int', ['int'], function(value){
    console.log("callback result:", value);
});
libtest.api_callback(callback);

运行：node test.js

附：

python3升级
	下载：wget https://www.python.org/ftp/python/3.7.9/Python-3.7.9.tgz
	tar xvf Python-3.7.9.tgz
	cd Python-3.7.9
	./configure
	make && sudo make install
	sudo rm /usr/bin/python3
	sudo ln -s /usr/local/bin/python3 /usr/bin/python3