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/**

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 * Linux specific code

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 **/

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#include <stdio.h>

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#include <string.h>

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#include <time.h>

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#include <signal.h>

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#include <stdlib.h>

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#include <errno.h>

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#include <pthread.h>

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#include <locale.h>

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#include <semaphore.h>

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static unsigned long __debug_tick;

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static pthread_t PLC_thread;

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static pthread_mutex_t python_wait_mutex = PTHREAD_MUTEX_INITIALIZER;

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static pthread_mutex_t python_mutex = PTHREAD_MUTEX_INITIALIZER;

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static pthread_mutex_t debug_wait_mutex = PTHREAD_MUTEX_INITIALIZER;

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static pthread_mutex_t debug_mutex = PTHREAD_MUTEX_INITIALIZER;

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static int PLC_shutdown = 0;

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long AtomicCompareExchange(long* atomicvar,long compared, long exchange)

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{

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    return __sync_val_compare_and_swap(atomicvar, compared, exchange);

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}

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long long AtomicCompareExchange64(long long* atomicvar, long long compared, long long exchange)

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{

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    return __sync_val_compare_and_swap(atomicvar, compared, exchange);

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}

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void PLC_GetTime(IEC_TIME *CURRENT_TIME)

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{

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    struct timespec tmp;

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    clock_gettime(CLOCK_REALTIME, &tmp);

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    CURRENT_TIME->tv_sec = tmp.tv_sec;

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    CURRENT_TIME->tv_nsec = tmp.tv_nsec;

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}

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static long long period_ns = 0;

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struct timespec next_abs_time;

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static void inc_timespec(struct timespec *ts, unsigned long long value_ns)

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{

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    long long next_ns = ((long long) ts->tv_sec * 1000000000) + ts->tv_nsec + value_ns;

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#ifdef __lldiv_t_defined

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    lldiv_t next_div = lldiv(next_ns, 1000000000);

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    ts->tv_sec = next_div.quot;

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    ts->tv_nsec = next_div.rem;

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#else

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    ts->tv_sec = next_ns / 1000000000;

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    ts->tv_nsec = next_ns % 1000000000;

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#endif

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}

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void PLC_SetTimer(unsigned long long next, unsigned long long period)

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{

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    /*

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    printf("SetTimer(%lld,%lld)\n",next, period);

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    */

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    period_ns = period;

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    clock_gettime(CLOCK_MONOTONIC, &next_abs_time);

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    inc_timespec(&next_abs_time, next);

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    // interrupt clock_nanpsleep

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    pthread_kill(PLC_thread, SIGUSR1);

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}

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void catch_signal(int sig)

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{

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//  signal(SIGTERM, catch_signal);

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  signal(SIGINT, catch_signal);

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  printf("Got Signal %d\n",sig);

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  exit(0);

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}

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void PLCThreadSignalHandler(int sig)

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{

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    if (sig == SIGUSR2)

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        pthread_exit(NULL);

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}

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int ForceSaveRetainReq(void) {

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    return PLC_shutdown;

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}

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void PLC_thread_proc(void *arg)

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{

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    while (!PLC_shutdown) {

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        // Sleep until next PLC run

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        // TODO check result of clock_nanosleep and wait again or exit eventually

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        int res = clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &next_abs_time, NULL);

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        if(res==EINTR){

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            continue;

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        }

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        if(res!=0){

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            printf("PLC thread died with error %d \n", res);

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            return;

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        }

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        PLC_GetTime(&__CURRENT_TIME);

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        __run();

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        inc_timespec(&next_abs_time, period_ns);

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    }

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    pthread_exit(0);

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}

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#define maxval(a,b) ((a>b)?a:b)

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int startPLC(int argc,char **argv)

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{

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    PLC_shutdown = 0;

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    pthread_mutex_init(&debug_wait_mutex, NULL);

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    pthread_mutex_init(&debug_mutex, NULL);

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    pthread_mutex_init(&python_wait_mutex, NULL);

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    pthread_mutex_init(&python_mutex, NULL);

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    pthread_mutex_lock(&debug_wait_mutex);

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    pthread_mutex_lock(&python_wait_mutex);

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    if(  __init(argc,argv) == 0 ){

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        /* Signal to wakeup PLC thread when period changes */

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        signal(SIGUSR1, PLCThreadSignalHandler);

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        /* Signal to end PLC thread */

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        signal(SIGUSR2, PLCThreadSignalHandler);

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        /* install signal handler for manual break */

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        signal(SIGINT, catch_signal);

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        /* initialize next occurence and period */

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        period_ns = common_ticktime__;

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        clock_gettime(CLOCK_MONOTONIC, &next_abs_time);

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        pthread_create(&PLC_thread, NULL, (void*) &PLC_thread_proc, NULL);

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    }else{

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        return 1;

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    }

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    return 0;

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}

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int TryEnterDebugSection(void)

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{

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    if (pthread_mutex_trylock(&debug_mutex) == 0){

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        /* Only enter if debug active */

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        if(__DEBUG){

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            return 1;

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        }

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        pthread_mutex_unlock(&debug_mutex);

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    }

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    return 0;

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}

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void LeaveDebugSection(void)

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{

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    pthread_mutex_unlock(&debug_mutex);

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}

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int stopPLC()

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{

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    /* Stop the PLC */

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    PLC_shutdown = 1;

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    /* Order PLCThread to exit */

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    pthread_kill(PLC_thread, SIGUSR2);

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    pthread_join(PLC_thread, NULL);

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    __cleanup();

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    pthread_mutex_destroy(&debug_wait_mutex);

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    pthread_mutex_destroy(&debug_mutex);

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    pthread_mutex_destroy(&python_wait_mutex);

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    pthread_mutex_destroy(&python_mutex);

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    return 0;

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}

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extern unsigned long __tick;

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int WaitDebugData(unsigned long *tick)

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{

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    int res;

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    if (PLC_shutdown) return 1;

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    /* Wait signal from PLC thread */

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    res = pthread_mutex_lock(&debug_wait_mutex);

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    *tick = __debug_tick;

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    return res;

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}

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/* Called by PLC thread when debug_publish finished

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 * This is supposed to unlock debugger thread in WaitDebugData*/

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void InitiateDebugTransfer()

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{

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    /* remember tick */

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    __debug_tick = __tick;

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    /* signal debugger thread it can read data */

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    pthread_mutex_unlock(&debug_wait_mutex);

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}

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int suspendDebug(int disable)

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{

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    /* Prevent PLC to enter debug code */

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    pthread_mutex_lock(&debug_mutex);

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    /*__DEBUG is protected by this mutex */

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    __DEBUG = !disable;

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    if (disable)

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        pthread_mutex_unlock(&debug_mutex);

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    return 0;

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}

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void resumeDebug(void)

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{

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    __DEBUG = 1;

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    /* Let PLC enter debug code */

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    pthread_mutex_unlock(&debug_mutex);

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}

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/* from plc_python.c */

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int WaitPythonCommands(void)

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{

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    /* Wait signal from PLC thread */

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    return pthread_mutex_lock(&python_wait_mutex);

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}

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/* Called by PLC thread on each new python command*/

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void UnBlockPythonCommands(void)

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{

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    /* signal python thread it can read data */

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    pthread_mutex_unlock(&python_wait_mutex);

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}

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int TryLockPython(void)

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{

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    return pthread_mutex_trylock(&python_mutex) == 0;

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}

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void UnLockPython(void)

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{

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    pthread_mutex_unlock(&python_mutex);

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}

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void LockPython(void)

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{

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    pthread_mutex_lock(&python_mutex);

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}

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struct RT_to_nRT_signal_s {

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    int used;

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    pthread_cond_t WakeCond;

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    pthread_mutex_t WakeCondLock;

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};

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typedef struct RT_to_nRT_signal_s RT_to_nRT_signal_t;

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#define _LogAndReturnNull(text) \

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    {\

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        char mstr[256] = text " for ";\

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        strncat(mstr, name, 255);\

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        LogMessage(LOG_CRITICAL, mstr, strlen(mstr));\

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        return NULL;\

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    }

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void *create_RT_to_nRT_signal(char* name){

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    RT_to_nRT_signal_t *sig = (RT_to_nRT_signal_t*)malloc(sizeof(RT_to_nRT_signal_t));

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    if(!sig)

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        _LogAndReturnNull("Failed allocating memory for RT_to_nRT signal");

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    sig->used = 1;

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    pthread_cond_init(&sig->WakeCond, NULL);

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    pthread_mutex_init(&sig->WakeCondLock, NULL);

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    return (void*)sig;

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}

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void delete_RT_to_nRT_signal(void* handle){

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    RT_to_nRT_signal_t *sig = (RT_to_nRT_signal_t*)handle;

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    pthread_mutex_lock(&sig->WakeCondLock);

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    sig->used = 0;

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    pthread_cond_signal(&sig->WakeCond);

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    pthread_mutex_unlock(&sig->WakeCondLock);

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}

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int wait_RT_to_nRT_signal(void* handle){

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    int ret;

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    RT_to_nRT_signal_t *sig = (RT_to_nRT_signal_t*)handle;

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    pthread_mutex_lock(&sig->WakeCondLock);

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    ret = pthread_cond_wait(&sig->WakeCond, &sig->WakeCondLock);

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    if(!sig->used) ret = -EINVAL;

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    pthread_mutex_unlock(&sig->WakeCondLock);

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    if(!sig->used){

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        pthread_cond_destroy(&sig->WakeCond);

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        pthread_mutex_destroy(&sig->WakeCondLock);

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        free(sig);

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    }

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    return ret;

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}

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int unblock_RT_to_nRT_signal(void* handle){

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    RT_to_nRT_signal_t *sig = (RT_to_nRT_signal_t*)handle;

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    return pthread_cond_signal(&sig->WakeCond);

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}

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void nRT_reschedule(void){

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    sched_yield();

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}