SCPIServer.cpp

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* scpi-server-tools                                                                                                    *
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* Copyright (c) 2012-2022 Andrew D. Zonenberg and contributors                                                         *
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#include "SCPIServer.h"
#include <log.h>

using namespace std;

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Construction / destruction

SCPIServer::SCPIServer(ZSOCKET sock)
	: m_socket(sock)
{
	LogVerbose("Client connected to SCPI socket\n");

	if(!m_socket.DisableNagle())
		LogWarning("Failed to disable Nagle on socket, performance may be poor\n");
}

SCPIServer::~SCPIServer()
{
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Low level (line oriented) I/O functions

/**
	@brief Sends a SCPI reply (terminated by newline)

	@param cmd	Reply to send
 */
bool SCPIServer::SendReply(const string& cmd)
{
	string tempbuf = cmd + "\n";
	return m_socket.SendLooped((unsigned char*)tempbuf.c_str(), tempbuf.length());
}

/**
	@brief Reads a SCPI command (terminated by newline or semicolon)

	@param str	Output command
 */
bool SCPIServer::RecvCommand(string& str)
{
	int sockid = m_socket;

	char tmp = ' ';
	str = "";
	while(true)
	{
		if(1 != recv(sockid, &tmp, 1, MSG_WAITALL))
			return false;

		if( (tmp == '\n') || ( (tmp == ';') ) )
			break;
		else
			str += tmp;
	}

	return true;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// SCPI command parsing

/**
	@brief Crack an inbound SCPI query into its component parts

	@param line		The inbound SCPI command
	@param subject	The object that the command operates on (for example, outputs C2 if line is C2:OFFS)
	@param cmd		The main text of the command (for example, outputs OFFS if line is C2:OFFS)
	@param query	Outputs true if the command is a query, false if not
	@param args		List of arguments after the main command
 */
void SCPIServer::ParseLine(
	const string& line,
	string& subject,
	string& cmd,
	bool& query,
	vector<string>& args)
{
	//Reset fields
	query = false;
	subject = "";
	cmd = "";
	args.clear();

	string tmp;
	bool reading_cmd = true;
	for(size_t i=0; i<line.length(); i++)
	{
		//If there's no colon in the command, the first block is the command.
		//If there is one, the first block is the subject and the second is the command.
		//If more than one, treat it as freeform text in the command.
		if( (line[i] == ':') && subject.empty() )
		{
			subject = tmp;
			tmp = "";
			continue;
		}

		//Detect queries
		if(line[i] == '?')
		{
			query = true;
			continue;
		}

		//Comma delimits arguments, space delimits command-to-args
		if(!(isspace(line[i]) && cmd.empty()) && line[i] != ',')
		{
			tmp += line[i];
			continue;
		}

		//merge multiple delimiters into one delimiter
		if(tmp == "")
			continue;

		//Save command or argument
		if(reading_cmd)
			cmd = tmp;
		else
			args.push_back(tmp);

		reading_cmd = false;
		tmp = "";
	}

	//Stuff left over at the end? Figure out which field it belongs in
	if(tmp != "")
	{
		if(cmd != "")
			args.push_back(tmp);
		else
			cmd = tmp;
	}
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Main event loop

void SCPIServer::MainLoop()
{
	//Main command loop
	string line;
	string cmd;
	bool query;
	string subject;
	vector<string> args;
	while(true)
	{
		//Get the inbound command
		if(!RecvCommand(line))
			break;
		LogTrace((line + "\n").c_str());
		ParseLine(line, subject, cmd, query, args);

		//Process the command
		if(query)
			OnQuery(line, subject, cmd);
		else if(cmd == "EXIT")
			break;
		else
			OnCommand(line, subject, cmd, args);
	}
}