<?xml version="1.0" encoding="UTF-8" standalone="no"?>

<CFile xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.w3.org/2001/XMLSchema" xsi:schemaLocation="cext_xsd.xsd">

<includes>

<![CDATA[#include "stdio.h"]]>

</includes>

<variables>

<variable name="TestInput" type="SINT" class="input"/>

<variable name="TestOutput" type="SINT" class="output"/>

</variables>

<globals>

<![CDATA[volatile long Lock=0;

volatile char PtoC=1,CtoP=2;

extern long AtomicCompareExchange(long*,long, long);

int Simple_C_Call(int val){

return val+1;

}

int Python_to_C_Call(char toC, char *fromC){

/* Code called by python should never touch to

variables modified by PLC thread directly

AtomicCompareExchange comes from

beremiz' runtime implementation */

int res = 0;

if(!AtomicCompareExchange((long*)&Lock, 0, 1)){

PtoC=toC;

*fromC=CtoP;

AtomicCompareExchange((long*)&Lock, 1, 0);

res=1;

}

printf("C code called by Python: toC %d fromC %d\n",toC,*fromC);

return res;

}

int PLC_C_Call(char fromPLC, char *toPLC){

/* PLC also have to be realy carefull not to

conflict with asynchronous python access */

if(!AtomicCompareExchange((long*)&Lock, 0, 1)){

CtoP = fromPLC;

*toPLC = PtoC;

AtomicCompareExchange((long*)&Lock, 1, 0);

return 1;

}

return 0;

}]]>

</globals>

<initFunction>

<![CDATA[]]>

</initFunction>

<cleanUpFunction>

<![CDATA[]]>

</cleanUpFunction>

<retrieveFunction>

<![CDATA[]]>

</retrieveFunction>

<publishFunction>

<![CDATA[if(!AtomicCompareExchange((long*)&Lock, 0, 1)){

TestInput = CtoP + PtoC + TestOutput;

AtomicCompareExchange((long*)&Lock, 1, 0);

}]]>

</publishFunction>

</CFile>