1

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

     2

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

     3

  <includes>

     4

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

     5

  </includes>

     6

  <variables>

     7

    <variable name="TestInput" type="SINT" initial="0"/>

     8

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

     9

  </variables>

    10

  <globals>

    11

<![CDATA[volatile long Lock=0;

    12

volatile char PtoC=1,CtoP=2;

    13

    14

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

    15

    16

int Simple_C_Call(int val){

    17

  return val+1;

    18

}

    19

    20

int Python_to_C_Call(char toC, char *fromC){

    21

  /* Code called by python should never touch to 

    22

     variables modified by PLC thread directly

    23

    24

     AtomicCompareExchange comes from 

    25

     beremiz' runtime implementation */

    26

    27

  int res = 0;

    28

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

    29

    PtoC=toC;

    30

    *fromC=CtoP;

    31

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

    32

    res=1;

    33

  }

    34

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

    35

  return res;

    36

}

    37

    38

int PLC_C_Call(char fromPLC, char *toPLC){

    39

  /* PLC also have to be realy carefull not to 

    40

     conflict with asynchronous python access */

    41

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

    42

      CtoP = fromPLC;

    43

      *toPLC = PtoC;

    44

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

    45

      return 1;

    46

  }

    47

  return 0;

    48

}]]>

    49

  </globals>

    50

  <initFunction>

    51

<![CDATA[]]>

    52

  </initFunction>

    53

  <cleanUpFunction>

    54

<![CDATA[]]>

    55

  </cleanUpFunction>

    56

  <retrieveFunction>

    57

<![CDATA[]]>

    58

  </retrieveFunction>

    59

  <publishFunction>

    60

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

    61

    TestInput = CtoP + PtoC + TestOutput;

    62

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

    63

}]]>

    64

  </publishFunction>

    65

</CodeFile>