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Windows API vs. Linux API

ibwood (22)
Hi all,

I am trying to transfer some c++ code, originally made in windows, into linux language. I knew it would not be easy, since the two APIs are completely different. I just know there are alternative ways to do this. The following serial communication types are what I need different methods for:

HANDLE - as in handling a node for communication. I am using serial ports.

DCB - just a length.. not sure why it pertains to serial port communication.. unless the program receives specific serial code.

COMMTIMEOUTS - set the timeout parameters for the serial port, for WriteFile and ReadFile (read or write data to serial port).

WriteFile/ReadFile - I'm not sure if there is something similar..

DWORD - just a length equal to 4 bytes, or 32 bits. I didn't think this type was all that important, so I replaced with an "unsigned long" type instead.

I will post the code too, since it helps to see what I'm doing. Essentially I just need to know how serial port communication works under a Linux API.

NOTE: may be confusing. Linux API mixed with windows API, and another language, called ROS (robot operating system).

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#define PI = 3.14159265358979323846264338327950288419716

 #include "ros/ros.h"
 #include "std_msgs/String.h"

 #include <sstream>
 #include <cmath>
 #include <iostream>

 #include <stdio.h>
 #include <string.h>
 #include <fcntl.h>
 #include <errno.h>
 #include <termios.h>
 #include <unistd.h>

 using namespace std;


 int fd1;
 int wr,rd;

 int i,j;
 char parseChar[1];
 char stringIn[50];

 char INBUFFER[500];
 char OUTBUFFER[20];

 unsigned long numSentS         = 0;
 unsigned long bytes_read	= 0;		//Number of bytes read from port
 unsigned long bytes_written	= 0;		//Number of bytes written to the port
 HANDLE	comport1	= NULL;		//Handle COM port
 HANDLE	comport2	= NULL;
 HANDLE	comport3	= NULL;

 int numSent;
 int bStatus;
 DCB		comSettings;		//Contains various port settings
 COMMTIMEOUTS	CommTimeouts;
	
 //Open COM port
 if ((comport1 = 
     Createfile("HCS12",			//open HCS12 access:
		GENERIC_READ | GENERIC_WRITE,	//for reading and writing
		0,				//exclusive access
		NULL,				//no security attributes
		OPEN_EXISTING,
		FILE_ATTRIBUTE_NORMAL,
		NULL)) == INVALID_HANDLE_VALUE)
 {
	cout << "error: cannot open port /dev/HCS12" << endl;
 }
	
 if ((comport2 = 
      Createfile("Driver1&2",			//open Driver1&2 access:
 		GENERIC_READ | GENERIC_WRITE,	//for reading and writing
		0,				//exclusive access
		NULL,				//no security attributes
		OPEN_EXISTING,
		FILE_ATTRIBUTE_NORMAL,
		NULL)) == INVALID_HANDLE_VALUE)
 {
	cout << "error: cannot open port /dev/Driver1&2" << endl;
 }

 if ((comport3 = 
      Createfile("Driver3&4",			//open Driver3&4 access:
 		GENERIC_READ | GENERIC_WRITE,	//for reading and writing
		0,				//exclusive access
		NULL,				//no security attributes
		OPEN_EXISTING,
		FILE_ATTRIBUTE_NORMAL,
		NULL)) == INVALID_HANDLE_VALUE)
 {
	cout << "error: cannot open port /dev/Driver3&4" << endl;
 }	

 //set timeouts in milliseconds
 CommTimeouts.ReadIntervalTimeout		= 0;
 CommTimeouts.ReadTotalTimeoutMultiplier 	= 0;
 CommTimeouts.ReadTotalTimeoutConstant		= 100;
 CommTimeouts.WriteTotalTimeoutMultiplier	= 0;
 CommTimeouts.WriteTotalTimeoutConstant		= 100;
 bstatus = SetCommTimeouts (comport, &CommTimeouts);

 if (bStatus != 0)
 {
	cout << "byte status error!" << endl;
 }
	
 //set Port parameters
 GetCommState(comport, &comSettings);
 comSettings.BaudRate = 115200;
 comSettings.StopBits = ONESTOPBIT;
 comSettings.ByteSize = 8;
 comSettings.Parity   = NOPARITY;
 comSettings.fParity  = FALSE;
 bStatus = SetCommState(comport, &comSettings);
	
 if (bStatus == 0)
 {
 	cout << "byte status error!!" << endl;
 }

 int main(int argc, char **argv)
 {

	// initalize node
	ros::init(argc, argv, "joyTalker");
	ros::NodeHandle joyTalker;

	// Publish to topic joyChatter
	ros::Publisher pub = joyTalker.advertise<std_msgs::String>("joyChatter", 1000);

	ros::Rate r(10);

	// set settings for serial port 
	system("stty -F /dev/ttyUSB0 115200 cs8 -cstopb -parity -icanon hupcl -crtscts min 1 time 1");
	
	// attempt to open serial port
	fd1=open("/dev/ttyUSB0",O_RDWR | O_NOCTTY | O_NDELAY);
	
	if (fd1 == -1 ) // if error
	{
		perror("open_port: Unable to open /dev/ttyUSB0 – ");
	}
	
	else // if no error
	{
		fcntl(fd1, F_SETFL,0);
		printf("Test Port 1 has been sucessfully opened and %d is the file description\n",fd1);
	}

	while (joyTalker.ok())
	{
		parseChar[0]=0;	  

		for(j=0;j<50;j++)
		{
			stringIn[j]=0;
		}

		i=0;

		while(parseChar[0] != 10)
		{
			if(i==50)
			{
				break;
			}

			rd=read(fd1,parseChar,1);
			//printf("%s ",parseChar);
			if ((parseChar[0] > 43) && (parseChar[0] < 58) || (parseChar[0]==32))
                        {
				stringIn[i]=parseChar[0];
				i++;
			}
			
			bStatus = WriteFile(comport,		//Handle
				    	    &INBUFFER,		//Incoming data
				    	    500,		//Number of bytes to read
				    	    &bytes_read, 	//Number of bytes read
				            NULL);
				
			if (bStatus != 0)
			{
				cout << "byte status error!!!" << endl;
			}
			
			void kinematics (int x, int y, int z)
			{
				const double r=0.125, R=0.55, ratio=127;
				double motorspeed[4] = 0;

				motorspeed[0] = ((x/sqrt(2))+y+(R*tan((z/ratio)*(2*PI))))/(2*PI*r);
				motorspeed[1] = (-(x/sqrt(2))+y+(R*tan((z/ratio)*(2*PI))))/(2*PI*r);
				motorspeed[2] = ((x/sqrt(2))+y-(R*tan((z/ratio)*(2*PI))))/(2*PI*r);
				motorspeed[3] = (-(x/sqrt(2))+y-(R*tan((z/ratio)*(2*PI))))/(2*PI*r);		

				numSent = sprintf(stringIn, "%3d,%3d\n", motorspeed[0], motorspeed[1]);
				status[0] = Serial_SendBlock(stringIn, numSent, &numSentS);
			
				numSent = sprintf(stringIn, "%3d,%3d\n", motorspeed[2], motorspeed[3]);
				status[0] = Serial_SendBlock(stringIn, numSent, &numSentS);
			}

		}

		printf("got this string %s\n",stringIn);

		// convert message to string for ROS node communication
		std_msgs::String msg;
		std::stringstream ss;
		ss << stringIn;
		ROS_INFO("%s", ss.str().c_str());
		msg.data = ss.str();
		// publish data under topic joyChatter
		pub.publish(msg);

		ros::spinOnce();
	}
 
	
 return 0;
 }
jsmith (5804)
Serial ports in linux are accessed by opening /dev/tty<something> as if it were a normal disk file.
ibwood (22)
Yeah I figured that out just yesterday. Anyways I have modified my code to look like linux programming:

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#define PI = 3.14159265358979323846264338327950288419716

 #include "ros/ros.h"
 #include "std_msgs/String.h"

 #include <sstream>
 #include <cmath>
 #include <iostream>

 #include <stdio.h>
 #include <string.h>
 #include <fcntl.h>
 #include <errno.h>
 #include <termios.h>
 #include <unistd.h>

 using namespace std;


 int fd;
 int wr,rd;

 int i,j;
 char parseChar[1];
 char stringIn[50];

 // unsigned long bytes_read	= 0;		//Number of bytes read from port
 // unsigned long bytes_written	= 0;		//Number of bytes written to the port

 int numSent;
 int bStatus;
 struct termios options;		//Contains various port settings
	
 // set settings for serial port 

 system("stty -F /dev/ttyUSB0 115200 cs8 -cstopb -parity -icanon hupcl -crtscts min 1 time 1");

	

 // attempt to open serial port

 fd = open("/dev/ttyUSB0",O_RDWR | O_NOCTTY | O_NDELAY);


 //check for errors opening port	

 if (fd == -1 )

 {

	printf("open_port: Unable to open /dev/ttyUSB0");

 }

 
 else // if no error

 {

 	fcntl(fd, F_SETFL,0);

	printf("Test Port ttyUSB0 has been successfully opened and %d is the file description\n",fd1);

 }

 //get current settings of serial ports
 tcgetattr(fd1, &options);
 tcgetattr(fd2, &options);
 tcgetattr(fd3, &options);

 //set the read and write speeds
 cfsetispeed(&options, B115200);
 cfsetospeed(&options, B115200);

 //set parity
 options.c_cflag &= ~CSIZE;
 options.c_cflag |= CS8;

 if (bStatus != 0)
 {
	cout << "byte status error!" << endl;
 }

 void kinematics (int x, int y, int z)		
 {
	const double r=0.125, R=0.55, ratio=127;
	int motorspeed[4], numSent=0;

	motorspeed[0] = ((x/sqrt(2))+y+(R*tan((z/ratio)*(2*PI))))/(2*PI*r);
	motorspeed[1] = (-(x/sqrt(2))+y+(R*tan((z/ratio)*(2*PI))))/(2*PI*r);
	motorspeed[2] = ((x/sqrt(2))+y-(R*tan((z/ratio)*(2*PI))))/(2*PI*r);
	motorspeed[3] = (-(x/sqrt(2))+y-(R*tan((z/ratio)*(2*PI))))/(2*PI*r);

	fd = open("/dev/Driver1&2",O_RDWR | O_NOCTTY | O_NDELAY);
		
	if (fd == -1 )

	{

		perror("open_port: Unable to open /dev/Driver1&2");

	}				

	numSent = sprintf(stringIn, "%3d,%3d\n", motorspeed[0], motorspeed[1]);
	status[0] = Serial_SendBlock(stringIn, numSent, &numSentS);
			        
	fd = open("/dev/Driver3&4",O_RDWR | O_NOCTTY | O_NDELAY);
	
	if (fd == -1 )

	{

		perror("open_port: Unable to open /dev/Driver3&4");

	}

	numSent = sprintf(stringIn, "%3d,%3d\n", motorspeed[2], motorspeed[3]);
	status[0] = Serial_SendBlock(stringIn, numSent, &numSentS);
 }

 int main(int argc, char **argv)
 {
	int x, y, z;

	// initalize node
	ros::init(argc, argv, "joyTalker");
	ros::NodeHandle joyTalker;

	// Publish to topic joyChatter
	ros::Publisher pub = joyTalker.advertise<std_msgs::String>("joyChatter", 1000);

	ros::Rate r(10);

	while (joyTalker.ok())
	{
		parseChar[0]=0;	  

		for(j=0;j<50;j++)
		{
			stringIn[j]=0;
		}

		i=0;

		while(parseChar[0] != 10)
		{
			if(i==50)
			{
				break;
			}

			rd = read(fd,parseChar,1);
			//printf("%s ",parseChar);
			if ((parseChar[0] > 43) && ((parseChar[0] < 58) || (parseChar[0]==32)))
                        {
				stringIn[i]=parseChar[0];
				i++;
			}
				
			if (wr != 0)
			{
				cout << "byte status error!!!" << endl;
			}
			
			kinematics(x, y, z);
		}

		printf("got this string %s\n",stringIn);

		// convert message to string for ROS node communication
		std_msgs::String msg;
		std::stringstream ss;
		ss << stringIn;
		ROS_INFO("%s", ss.str().c_str());
		msg.data = ss.str();
		// publish data under topic joyChatter
		pub.publish(msg);

		ros::spinOnce();
	}
 
	
 return 0;
 }


These are the errors that come up. I am unsure how to fix them. I thought tcgetattr, cfsetispeed, and cfsetospeed were all predefined in linux. Unless I'm simply missing the library for them.

/home/mars/ros/omnibot/src/joyTalker.cpp:61: error: expected constructor, destructor, or type conversion before ‘(’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:64: error: expected constructor, destructor, or type conversion before ‘=’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:67: error: expected unqualified-id before ‘if’
/home/mars/ros/omnibot/src/joyTalker.cpp:72: error: expected unqualified-id before ‘else’
/home/mars/ros/omnibot/src/joyTalker.cpp:79: error: expected constructor, destructor, or type conversion before ‘(’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:80: error: expected constructor, destructor, or type conversion before ‘(’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:81: error: expected constructor, destructor, or type conversion before ‘(’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:84: error: expected constructor, destructor, or type conversion before ‘(’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:85: error: expected constructor, destructor, or type conversion before ‘(’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:88: error: expected constructor, destructor, or type conversion before ‘.’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:89: error: expected constructor, destructor, or type conversion before ‘.’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:91: error: expected unqualified-id before ‘if’
/home/mars/ros/omnibot/src/joyTalker.cpp: In function ‘void kinematics(int, int, int)’:
/home/mars/ros/omnibot/src/joyTalker.cpp:101: error: expected primary-expression before ‘=’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:101: error: expected primary-expression before ‘=’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:102: error: expected primary-expression before ‘=’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:102: error: expected primary-expression before ‘=’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:103: error: expected primary-expression before ‘=’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:103: error: expected primary-expression before ‘=’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:104: error: expected primary-expression before ‘=’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:104: error: expected primary-expression before ‘=’ token
/home/mars/ros/omnibot/src/joyTalker.cpp:114: error: ‘status’ was not declared in this scope
/home/mars/ros/omnibot/src/joyTalker.cpp:114: error: ‘numSentS’ was not declared in this scope
/home/mars/ros/omnibot/src/joyTalker.cpp:114: error: ‘Serial_SendBlock’ was not declared in this scope


bigearsbilly (143)
it looks like you have statements outside of functions,
where definitions and declarations go.
line 36 onwards.


you cannot do it.
put your initialisation stuff in main at least.
ibwood (22)
Ok. Once again the edited code:

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 #define PI = 3.14159265358979323846264338327950288419716

 #include "ros/ros.h"
 #include "std_msgs/String.h"

 #include <sstream>
 #include <cmath>
 #include <iostream>

 #include <sys/ioctl.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <stdio.h>
 #include <limits.h>
 #include <string.h>
 #include <fcntl.h>
 #include <errno.h>
 #include <termios.h>
 #include <unistd.h>

 using namespace std;

 const double r=0.125, R=0.55, ratio=127;	// initialize constants

 int main(int argc, char **argv)
 {
	unsigned ms1, ms2, ms3, ms4;			//motor speeds of omnimaxbot	
	int i, j, wr, rd, x=0, y=0, z=0, fd, numSent=0;
 	char parseChar[1], stringIn[50];

 	// unsigned long bytes_read	= 0;		//Number of bytes read from port
 	// unsigned long bytes_written	= 0;		//Number of bytes written to the port

 	int bStatus;
 	struct termios options;		//Contains various port settings

	

 	// attempt to open serial port

 	fd = open("/dev/HCS12",O_RDWR | O_NOCTTY | O_NDELAY);

	// set settings for serial port 

 	system("stty -F /dev/HCS12 115200 cs8 -cstopb -parity -icanon hupcl -crtscts min 1 time 1");


 	// check for errors opening port	

 	if (fd == -1 )

 	{

		printf("open_port: Unable to open /dev/HCS12");

 	}

 
 	else // if no error

 	{

 		fcntl(fd, F_SETFL,0);

		printf("Test Port HCS12 has been successfully opened and %d is the file description\n",fd);

 	}

 	// get current settings of serial ports
 	tcgetattr(fd, &options);

 	// set the read and write speeds
 	cfsetispeed(&options, B115200);
 	cfsetospeed(&options, B115200);

 	// set parity
 	options.c_cflag &= ~CSIZE;
 	options.c_cflag |= CS8;

 	if (bStatus != 0)
 	{
		cout << "byte status error!" << endl;
 	}

	// initalize node
	ros::init(argc, argv, "joyTalker");
	ros::NodeHandle joyTalker;

	// Publish to topic joyChatter
	ros::Publisher pub = joyTalker.advertise<std_msgs::String>("joyChatter", 1000);

	ros::Rate r(10);

	while (joyTalker.ok())
	{
		parseChar[0]=0;	  

		for(j=0; j<50; j++)
		{
			stringIn[j]=0;
		}

		i=0;

		while(parseChar[0] != 10)
		{
			if(i==50)	// exceeds the allowable size
			{
				break;
			}

			rd = read(fd,parseChar,1);
			// printf("%s ",parseChar);
			if ((parseChar[0] > 43) && ((parseChar[0] < 58) || (parseChar[0]==32)))
                        {
				stringIn[i]=parseChar[0];
				i++;
			}
				
			if (wr != 0)
			{
				cout << "byte status error!!!" << endl;
			}
			
			// kinematics of the omnimaxbot
			ms1 = ((x/sqrt(2))+y+(R*tan((z/ratio)*(2*PI))))/((2*PI)*r);
			ms2 = (-(x/sqrt(2))+y+(R*tan((z/ratio)*(2*PI))))/((2*PI)*r);
			ms3 = ((x/sqrt(2))+y-(R*tan((z/ratio)*(2*PI))))/((2*PI)*r);
			ms4 = (-(x/sqrt(2))+y-(R*tan((z/ratio)*(2*PI))))/((2*PI)*r);
	
			fd = open("/dev/Driver1&2",O_RDWR | O_NOCTTY | O_NDELAY);
		
			if (fd == -1 )

			{

				perror("open_port: Unable to open /dev/Driver1&2");

			}				
	
			// send to ROS node for communication
			numSent = sprintf(stringIn, "%3d,%3d\n", ms1, ms2);
			// status[0] = Serial_SendBlock(stringIn, numSent, &numSentS);
			        
			fd = open("/dev/Driver3&4",O_RDWR | O_NOCTTY | O_NDELAY);
	
			if (fd == -1 )

			{

				perror("open_port: Unable to open /dev/Driver3&4");

			}
	
			// send to ROS node for communication
			numSent = sprintf(stringIn, "%3d,%3d\n", ms3, ms4);
			// status[0] = Serial_SendBlock(stringIn, numSent, &numSentS);
		}

		printf("got this string %s\n",stringIn);

		// convert message to string for ROS node communication
		std_msgs::String msg;
		std::stringstream ss;
		ss << stringIn;
		ROS_INFO("%s", ss.str().c_str());
		msg.data = ss.str();
		// publish data under topic joyChatter
		pub.publish(msg);

		ros::spinOnce();
	}
 
	
 return 0;
 }


There is only one type of error I need to deal with now. Here it is:

"error: expected primary-expression before ‘=’ token"

from lines 138-141
ibwood (22)
sorry that's lines 126-129. Didn't put my title block into the code.
Kyon (912)
You create ms1, ms2, ms3 and ms4 from the type unsigned. I'm not sure, but this might not be legit. Try unsigned int or unsigned short / long int, which ever of the three you want.
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