我正在开发一个程序，该程序从 USB 操纵杆获取轴值并通过 TCP 发送它。我所做的是首先让 TCP 程序正常工作，这样我就可以发送按预期工作的消息。然后我编写了另一个程序来从操纵杆获取值并将它们打印到屏幕上，这也按预期工作。
我最近尝试将这两个独立的程序合并为一个，这样我就有了一个server程序和一个client程序。那就是我的问题开始的地方，我在编译期间没有收到任何错误。程序似乎不再从操纵杆获取值并将它们存储在变量axis[0]中。
现在我的过程是在server.c连接了操纵杆的计算机上启动文件。然后我将client.c在应该接收值的计算机上启动文件。在此过程中，我有几个printf陈述可以告诉我脚本到目前为止的进展情况。当我执行server.c脚本时，它告诉我操纵杆被检测到并且有 6 个轴和 12 个按钮。然后它将循环等待，直到尝试来自客户端的连接。
client.c程序执行后会打印出The value is -1093458243. 在它下面它将打印出Incoming connection from 192.168.254.15 - sending welcome.客户端程序然后退出，这就是所有发生的事情。
那行The value is:应该是-32768和32767之间的数字。所以它从某个地方得到了一个垃圾值。我迷路了，一整天都在尝试解决这个问题，但没有运气。我已经包含了几个代码示例、工作 TCPserver和client脚本以及工作joystick脚本以及我尝试将两者结合起来的代码。任何人都可以在我的代码中发现任何错误，或者给我一些指示吗？
这是组合代码server.c：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
//joysick libraries
#include <sys/ioctl.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/joystick.h>
//Joysick device
#define JOY_DEV "/dev/input/js0"
//TCP Port number
#define PORTNUM 2343
int main(int argc, char *argv[])
{
//TCP connect
struct sockaddr_in dest; /* socket info about the machine connecting to us */
struct sockaddr_in serv; /* socket info about our server */
int mysocket; /* socket used to listen for incoming connections */
socklen_t socksize = sizeof(struct sockaddr_in);
memset(&serv, 0, sizeof(serv)); /* zero the struct before filling the fields */
serv.sin_family = AF_INET; /* set the type of connection to TCP/IP */
serv.sin_addr.s_addr = htonl(INADDR_ANY); /* set our address to any interface */
serv.sin_port = htons(PORTNUM); /* set the server port number */
mysocket = socket(AF_INET, SOCK_STREAM, 0);
/* bind serv information to mysocket */
bind(mysocket, (struct sockaddr *)&serv, sizeof(struct sockaddr));
/* start listening, allowing a queue of up to 1 pending connection */
listen(mysocket, 1);
int consocket = accept(mysocket, (struct sockaddr *)&dest, &socksize);
//TCP variable
char msg1[10];
//Joystick variables
int xAxis;
int yAxis;
int xSpeed;
int ySpeed;
//Joystick initialize
int joy_fd, *axis=NULL, num_of_axis=0, num_of_buttons=0, x;
char *button=NULL, name_of_joystick[80];
struct js_event js;
if( ( joy_fd = open( JOY_DEV , O_RDONLY)) == -1 )
{
printf( "Couldn't open joystick\n" );
return -1;
}
//Get number of axes, buttons and name of joystick. Print results to screen
ioctl( joy_fd, JSIOCGAXES, &num_of_axis );
ioctl( joy_fd, JSIOCGBUTTONS, &num_of_buttons );
ioctl( joy_fd, JSIOCGNAME(80), &name_of_joystick );
axis = (int *) calloc( num_of_axis, sizeof( int ) );
button = (char *) calloc( num_of_buttons, sizeof( char ) );
printf("Joystick detected: %s\n\t%d axis\n\t%d buttons\n\n"
, name_of_joystick
, num_of_axis
, num_of_buttons );
//Use non blocking mode for joystick
fcntl( joy_fd, F_SETFL, O_NONBLOCK ); /* use non-blocking mode */
while(1) {
//Test to read joystick state
/* read the joystick state */
read(joy_fd, &js, sizeof(struct js_event));
/* see what to do with the event */
switch (js.type & ~JS_EVENT_INIT)
{
case JS_EVENT_AXIS:
axis [ js.number ] = js.value;
break;
case JS_EVENT_BUTTON:
button [ js.number ] = js.value;
break;
}
//Give msg1 variable the value of axis[0]
sprintf(msg1, "%d", axis[0]);
//char msg1 = axis[0];
//TCP send
while(consocket)
{
printf("Value is: %6d\n", axis[0]);
printf("Incoming connection from %s - sending welcome\n", inet_ntoa(dest.sin_addr));
send(consocket, msg1, strlen(msg1), 0);
consocket = accept(mysocket, (struct sockaddr *)&dest, &socksize);
}
close(consocket);
close(mysocket);
return EXIT_SUCCESS;
//Print joystick state to screen
printf("Value is: %d", axis[0]);
//printf(" \r");
//fflush(stdout);
}
//Joystick close
close( joy_fd ); /* too bad we never get here */
return 0;
//TCP message
//printf("Please enter info\n");
//fgets(msg1, 20, stdin);
}
这是旧的工作server.c文件：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#define PORTNUM 2343
int main(int argc, char *argv[])
{
char msg1[] = "Hello World !\n";
struct sockaddr_in dest; /* socket info about the machine connecting to us */
struct sockaddr_in serv; /* socket info about our server */
int mysocket; /* socket used to listen for incoming connections */
socklen_t socksize = sizeof(struct sockaddr_in);
memset(&serv, 0, sizeof(serv)); /* zero the struct before filling the fields */
serv.sin_family = AF_INET; /* set the type of connection to TCP/IP */
serv.sin_addr.s_addr = htonl(INADDR_ANY); /* set our address to any interface */
serv.sin_port = htons(PORTNUM); /* set the server port number */
mysocket = socket(AF_INET, SOCK_STREAM, 0);
/* bind serv information to mysocket */
bind(mysocket, (struct sockaddr *)&serv, sizeof(struct sockaddr));
/* start listening, allowing a queue of up to 1 pending connection */
listen(mysocket, 1);
int consocket = accept(mysocket, (struct sockaddr *)&dest, &socksize);
while(consocket)
{
printf("Incoming connection from %s - sending welcome\n", inet_ntoa(dest.sin_addr));
send(consocket, msg1, strlen(msg1), 0);
consocket = accept(mysocket, (struct sockaddr *)&dest, &socksize);
}
close(consocket);
close(mysocket);
return EXIT_SUCCESS;
}
这是client.c文件：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#define MAXRCVLEN 500
#define PORTNUM 2343
int main(int argc, char *argv[])
{
char buffer[MAXRCVLEN + 1]; /* +1 so we can add null terminator */
int len, mysocket;
struct sockaddr_in dest;
mysocket = socket(AF_INET, SOCK_STREAM, 0);
memset(&dest, 0, sizeof(dest)); /* zero the struct */
dest.sin_family = AF_INET;
dest.sin_addr.s_addr = inet_addr("192.168.254.16"); /* set destination IP number */
dest.sin_port = htons(PORTNUM); /* set destination port number */
connect(mysocket, (struct sockaddr *)&dest, sizeof(struct sockaddr));
len = recv(mysocket, buffer, MAXRCVLEN, 0);
/* We have to null terminate the received data ourselves */
buffer[len] = '\0';
printf("Received %s (%d bytes).\n", buffer, len);
close(mysocket);
return EXIT_SUCCESS;
}
这是joystick获取值并将它们打印到屏幕上的文件：
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/joystick.h>
#include <wiringPi.h>
#define JOY_DEV "/dev/input/js0"
int main()
{
int xAxis;
int yAxis;
int xSpeed;
int ySpeed;
FILE *fp;
fp = fopen("/dev/servoblaster","w");
if (fp == NULL) {
printf("Error opening file");
exit(0);
}
int joy_fd, *axis=NULL, num_of_axis=0, num_of_buttons=0, x;
char *button=NULL, name_of_joystick[80];
struct js_event js;
if( ( joy_fd = open( JOY_DEV , O_RDONLY)) == -1 )
{
printf( "Couldn't open joystick\n" );
return -1;
}
ioctl( joy_fd, JSIOCGAXES, &num_of_axis );
ioctl( joy_fd, JSIOCGBUTTONS, &num_of_buttons );
ioctl( joy_fd, JSIOCGNAME(80), &name_of_joystick );
axis = (int *) calloc( num_of_axis, sizeof( int ) );
button = (char *) calloc( num_of_buttons, sizeof( char ) );
printf("Joystick detected: %s\n\t%d axis\n\t%d buttons\n\n"
, name_of_joystick
, num_of_axis
, num_of_buttons );
fcntl( joy_fd, F_SETFL, O_NONBLOCK ); /* use non-blocking mode */
while( 1 ) /* infinite loop */
{
/* read the joystick state */
read(joy_fd, &js, sizeof(struct js_event));
/* see what to do with the event */
switch (js.type & ~JS_EVENT_INIT)
{
case JS_EVENT_AXIS:
axis [ js.number ] = js.value;
break;
case JS_EVENT_BUTTON:
button [ js.number ] = js.value;
break;
}
/* print the results */
//printf( "X: %6d Y: %6d ", axis[0], axis[1] );
int xAxis = axis[0] / 327;
int yAxis = axis[1] / 327;
int ySpeed = 150-0.3*yAxis;
int xSpeed = 150-0.3*xAxis;
printf( "X is equal to: %d Y is equal to: %d Y speed is: %d ", xAxis, yAxis, ySpeed);
fprintf(fp, "2=%d\n", ySpeed);
fprintf(fp, "1=%d\n", xSpeed);
printf(" \r");
fflush(stdout);
}
close( joy_fd ); /* too bad we never get here */
return 0;
}