--- a/ProjectController.py	Wed Nov 09 10:59:00 2022 +0800
+++ b/ProjectController.py	Wed Nov 09 17:29:59 2022 +0800
@@ -370,6 +370,8 @@
     def GetDefaultTargetName(self):
         if wx.Platform == '__WXMSW__':
             return "Win32"
+        elif wx.Platform == '__WXMAC__':
+            return "OSX"
         else:
             return "Linux"
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/OSX/XSD	Wed Nov 09 17:29:59 2022 +0800
@@ -0,0 +1,6 @@
+
+                  <xsd:element name="OSX">
+                    <xsd:complexType>
+                      %(toolchain_gcc)s
+                    </xsd:complexType>
+                  </xsd:element>

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/OSX/__init__.py	Wed Nov 09 17:29:59 2022 +0800
@@ -0,0 +1,40 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# This file is part of Beremiz, a Integrated Development Environment for
+# programming IEC 61131-3 automates supporting plcopen standard and CanFestival.
+#
+# Copyright (C) 2007: Edouard TISSERANT and Laurent BESSARD
+#
+# See COPYING file for copyrights details.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+
+
+from ..toolchain_gcc import toolchain_gcc
+
+
+class OSX_target(toolchain_gcc):
+    dlopen_prefix = "./"
+    extension = ".dynlib"
+
+    def getBuilderCFLAGS(self):
+        return toolchain_gcc.getBuilderCFLAGS(self) + \
+                ["-fPIC", "-Wno-deprecated-declarations",
+                 "-Wno-parentheses-equality", "-Wno-varargs"]
+
+    def getBuilderLDFLAGS(self):
+        return toolchain_gcc.getBuilderLDFLAGS(self) + ["-shared"]

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/OSX/plc_OSX_main.c	Wed Nov 09 17:29:59 2022 +0800
@@ -0,0 +1,295 @@
+/**
+ * Mac OSX specific code
+ **/
+
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <locale.h>
+#include <semaphore.h>
+#include <dispatch/dispatch.h>
+
+static sem_t Run_PLC;
+
+long AtomicCompareExchange(long *atomicvar, long compared, long exchange)
+{
+    return __sync_val_compare_and_swap(atomicvar, compared, exchange);
+}
+
+long long AtomicCompareExchange64(long long *atomicvar, long long compared,
+                                  long long exchange)
+{
+    return __sync_val_compare_and_swap(atomicvar, compared, exchange);
+}
+
+void PLC_GetTime(IEC_TIME * CURRENT_TIME)
+{
+    struct timespec tmp;
+    clock_gettime(CLOCK_REALTIME, &tmp);
+    CURRENT_TIME->tv_sec = tmp.tv_sec;
+    CURRENT_TIME->tv_nsec = tmp.tv_nsec;
+}
+
+dispatch_queue_t queue;
+dispatch_source_t PLC_timer;
+
+static inline void PLC_timer_cancel(void *arg)
+{
+    dispatch_release(PLC_timer);
+    dispatch_release(queue);
+    exit(0);
+}
+
+static inline void PLC_timer_notify(void *arg)
+{
+    PLC_GetTime(&__CURRENT_TIME);
+    sem_post(&Run_PLC);
+}
+
+void PLC_SetTimer(unsigned long long next, unsigned long long period)
+{
+    if (next == period && next == 0) {
+        dispatch_suspend(PLC_timer);
+    } else {
+        dispatch_time_t start;
+        start = dispatch_time(DISPATCH_TIME_NOW, next);
+        dispatch_source_set_timer(PLC_timer, start, period, 0);
+        dispatch_resume(PLC_timer);
+    }
+}
+
+void catch_signal(int sig)
+{
+    signal(SIGINT, catch_signal);
+    printf("Got Signal %d\n", sig);
+    dispatch_source_cancel(PLC_timer);
+    exit(0);
+}
+
+static unsigned long __debug_tick;
+
+pthread_t PLC_thread;
+static pthread_mutex_t python_wait_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t python_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t debug_wait_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t debug_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+int PLC_shutdown = 0;
+
+int ForceSaveRetainReq(void)
+{
+    return PLC_shutdown;
+}
+
+void PLC_thread_proc(void *arg)
+{
+    while (!PLC_shutdown) {
+        sem_wait(&Run_PLC);
+        __run();
+    }
+    pthread_exit(0);
+}
+
+#define maxval(a,b) ((a>b)?a:b)
+int startPLC(int argc, char **argv)
+{
+    setlocale(LC_NUMERIC, "C");
+
+    PLC_shutdown = 0;
+
+    sem_init(&Run_PLC, 0, 0);
+
+    pthread_create(&PLC_thread, NULL, (void *)&PLC_thread_proc, NULL);
+
+    pthread_mutex_init(&debug_wait_mutex, NULL);
+    pthread_mutex_init(&debug_mutex, NULL);
+    pthread_mutex_init(&python_wait_mutex, NULL);
+    pthread_mutex_init(&python_mutex, NULL);
+
+    pthread_mutex_lock(&debug_wait_mutex);
+    pthread_mutex_lock(&python_wait_mutex);
+
+    queue = dispatch_queue_create("timerQueue", 0);
+    PLC_timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
+
+    dispatch_set_context(PLC_timer, &PLC_timer);
+    dispatch_source_set_event_handler_f(PLC_timer, PLC_timer_notify);
+    dispatch_source_set_cancel_handler_f(PLC_timer, PLC_timer_cancel);
+
+    if (__init(argc, argv) == 0) {
+        PLC_SetTimer(common_ticktime__, common_ticktime__);
+
+        /* install signal handler for manual break */
+        signal(SIGINT, catch_signal);
+    } else {
+        return 1;
+    }
+    return 0;
+}
+
+int TryEnterDebugSection(void)
+{
+    if (pthread_mutex_trylock(&debug_mutex) == 0) {
+        /* Only enter if debug active */
+        if (__DEBUG) {
+            return 1;
+        }
+        pthread_mutex_unlock(&debug_mutex);
+    }
+    return 0;
+}
+
+void LeaveDebugSection(void)
+{
+    pthread_mutex_unlock(&debug_mutex);
+}
+
+int stopPLC()
+{
+    /* Stop the PLC */
+    PLC_shutdown = 1;
+    sem_post(&Run_PLC);
+    PLC_SetTimer(0, 0);
+    pthread_join(PLC_thread, NULL);
+    sem_destroy(&Run_PLC);
+    dispatch_source_cancel(PLC_timer);
+    __cleanup();
+    pthread_mutex_destroy(&debug_wait_mutex);
+    pthread_mutex_destroy(&debug_mutex);
+    pthread_mutex_destroy(&python_wait_mutex);
+    pthread_mutex_destroy(&python_mutex);
+    return 0;
+}
+
+extern unsigned long __tick;
+
+int WaitDebugData(unsigned long *tick)
+{
+    int res;
+    if (PLC_shutdown)
+        return 1;
+    /* Wait signal from PLC thread */
+    res = pthread_mutex_lock(&debug_wait_mutex);
+    *tick = __debug_tick;
+    return res;
+}
+
+/* Called by PLC thread when debug_publish finished
+ * This is supposed to unlock debugger thread in WaitDebugData*/
+void InitiateDebugTransfer()
+{
+    /* remember tick */
+    __debug_tick = __tick;
+    /* signal debugger thread it can read data */
+    pthread_mutex_unlock(&debug_wait_mutex);
+}
+
+int suspendDebug(int disable)
+{
+    /* Prevent PLC to enter debug code */
+    pthread_mutex_lock(&debug_mutex);
+    /*__DEBUG is protected by this mutex */
+    __DEBUG = !disable;
+    if (disable)
+        pthread_mutex_unlock(&debug_mutex);
+    return 0;
+}
+
+void resumeDebug(void)
+{
+    __DEBUG = 1;
+    /* Let PLC enter debug code */
+    pthread_mutex_unlock(&debug_mutex);
+}
+
+/* from plc_python.c */
+int WaitPythonCommands(void)
+{
+    /* Wait signal from PLC thread */
+    return pthread_mutex_lock(&python_wait_mutex);
+}
+
+/* Called by PLC thread on each new python command*/
+void UnBlockPythonCommands(void)
+{
+    /* signal python thread it can read data */
+    pthread_mutex_unlock(&python_wait_mutex);
+}
+
+int TryLockPython(void)
+{
+    return pthread_mutex_trylock(&python_mutex) == 0;
+}
+
+void UnLockPython(void)
+{
+    pthread_mutex_unlock(&python_mutex);
+}
+
+void LockPython(void)
+{
+    pthread_mutex_lock(&python_mutex);
+}
+
+struct RT_to_nRT_signal_s {
+    pthread_cond_t WakeCond;
+    pthread_mutex_t WakeCondLock;
+};
+
+typedef struct RT_to_nRT_signal_s RT_to_nRT_signal_t;
+
+#define _LogAndReturnNull(text) \
+    {\
+    	char mstr[256] = text " for ";\
+        strncat(mstr, name, 255);\
+        LogMessage(LOG_CRITICAL, mstr, strlen(mstr));\
+        return NULL;\
+    }
+
+void *create_RT_to_nRT_signal(char *name)
+{
+    RT_to_nRT_signal_t *sig =
+        (RT_to_nRT_signal_t *) malloc(sizeof(RT_to_nRT_signal_t));
+
+    if (!sig)
+        _LogAndReturnNull("Failed allocating memory for RT_to_nRT signal");
+
+    pthread_cond_init(&sig->WakeCond, NULL);
+    pthread_mutex_init(&sig->WakeCondLock, NULL);
+
+    return (void *)sig;
+}
+
+void delete_RT_to_nRT_signal(void *handle)
+{
+    RT_to_nRT_signal_t *sig = (RT_to_nRT_signal_t *) handle;
+
+    pthread_cond_destroy(&sig->WakeCond);
+    pthread_mutex_destroy(&sig->WakeCondLock);
+
+    free(sig);
+}
+
+int wait_RT_to_nRT_signal(void *handle)
+{
+    int ret;
+    RT_to_nRT_signal_t *sig = (RT_to_nRT_signal_t *) handle;
+    pthread_mutex_lock(&sig->WakeCondLock);
+    ret = pthread_cond_wait(&sig->WakeCond, &sig->WakeCondLock);
+    pthread_mutex_unlock(&sig->WakeCondLock);
+    return ret;
+}
+
+int unblock_RT_to_nRT_signal(void *handle)
+{
+    RT_to_nRT_signal_t *sig = (RT_to_nRT_signal_t *) handle;
+    return pthread_cond_signal(&sig->WakeCond);
+}
+
+void nRT_reschedule(void)
+{
+    sched_yield();
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/OSX/plc_OSX_main_retain.c	Wed Nov 09 17:29:59 2022 +0800
@@ -0,0 +1,352 @@
+/*
+  This file is part of Beremiz, a Integrated Development Environment for
+  programming IEC 61131-3 automates supporting plcopen standard and CanFestival.
+
+  See COPYING.runtime
+
+  Copyright (C) 2018: Sergey Surkov <surkov.sv@summatechnology.ru>
+  Copyright (C) 2018: Andrey Skvortsov <andrej.skvortzov@gmail.com>
+
+*/
+
+#ifndef HAVE_RETAIN
+#include <stdio.h>
+#include <stdint.h>
+#include <unistd.h>
+#include "iec_types.h"
+
+int GetRetainSize(void);
+
+/* Retain buffer.  */
+FILE *retain_buffer;
+const char rb_file[] = "retain_buffer_file";
+const char rb_file_bckp[] = "retain_buffer_file.bak";
+
+/* Retain header struct.  */
+struct retain_info_t {
+    uint32_t retain_size;
+    uint32_t hash_size;
+    uint8_t *hash;
+    uint32_t header_offset;
+    uint32_t header_crc;
+};
+
+/* Init retain info structure.  */
+struct retain_info_t retain_info;
+
+/* CRC lookup table and initial state.  */
+static const uint32_t crc32_table[256] = {
+    0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F,
+        0xE963A535, 0x9E6495A3,
+    0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD,
+        0xE7B82D07, 0x90BF1D91,
+    0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB,
+        0xF4D4B551, 0x83D385C7,
+    0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
+        0xFA0F3D63, 0x8D080DF5,
+    0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447,
+        0xD20D85FD, 0xA50AB56B,
+    0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75,
+        0xDCD60DCF, 0xABD13D59,
+    0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423,
+        0xCFBA9599, 0xB8BDA50F,
+    0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11,
+        0xC1611DAB, 0xB6662D3D,
+    0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F,
+        0x9FBFE4A5, 0xE8B8D433,
+    0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
+        0x91646C97, 0xE6635C01,
+    0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B,
+        0x8208F4C1, 0xF50FC457,
+    0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49,
+        0x8CD37CF3, 0xFBD44C65,
+    0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7,
+        0xA4D1C46D, 0xD3D6F4FB,
+    0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5,
+        0xAA0A4C5F, 0xDD0D7CC9,
+    0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3,
+        0xB966D409, 0xCE61E49F,
+    0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81,
+        0xB7BD5C3B, 0xC0BA6CAD,
+    0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF,
+        0x04DB2615, 0x73DC1683,
+    0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D,
+        0x0A00AE27, 0x7D079EB1,
+    0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
+        0x196C3671, 0x6E6B06E7,
+    0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9,
+        0x17B7BE43, 0x60B08ED5,
+    0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767,
+        0x3FB506DD, 0x48B2364B,
+    0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55,
+        0x316E8EEF, 0x4669BE79,
+    0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703,
+        0x220216B9, 0x5505262F,
+    0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31,
+        0x2CD99E8B, 0x5BDEAE1D,
+    0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F,
+        0x72076785, 0x05005713,
+    0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D,
+        0x7CDCEFB7, 0x0BDBDF21,
+    0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B,
+        0x6FB077E1, 0x18B74777,
+    0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69,
+        0x616BFFD3, 0x166CCF45,
+    0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7,
+        0x4969474D, 0x3E6E77DB,
+    0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5,
+        0x47B2CF7F, 0x30B5FFE9,
+    0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693,
+        0x54DE5729, 0x23D967BF,
+    0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1,
+        0x5A05DF1B, 0x2D02EF8D,
+};
+
+uint32_t retain_crc;
+
+/* Calculate CRC32 for len bytes from pointer buf with init starting value.  */
+uint32_t GenerateCRC32Sum(const void *buf, unsigned int len, uint32_t init)
+{
+    uint32_t crc = ~init;
+    unsigned char *current = (unsigned char *)buf;
+    while (len--)
+        crc = crc32_table[(crc ^ *current++) & 0xFF] ^ (crc >> 8);
+    return ~crc;
+}
+
+/* Calc CRC32 for retain file byte by byte.  */
+int CheckFileCRC(FILE * file_buffer)
+{
+    /* Set the magic constant for one-pass CRC calc according to ZIP CRC32.  */
+    const uint32_t magic_number = 0x2144df1c;
+
+    /* CRC initial state.  */
+    uint32_t calc_crc32 = 0;
+    char data_block = 0;
+
+    while (!feof(file_buffer)) {
+        if (fread(&data_block, sizeof(data_block), 1, file_buffer))
+            calc_crc32 =
+                GenerateCRC32Sum(&data_block, sizeof(char), calc_crc32);
+    }
+
+    /* Compare crc result with a magic number.  */
+    return (calc_crc32 == magic_number) ? 1 : 0;
+}
+
+/* Compare current hash with hash from file byte by byte.  */
+int CheckFilehash(void)
+{
+    int k, ret;
+    int offset = sizeof(retain_info.retain_size);
+
+    rewind(retain_buffer);
+    fseek(retain_buffer, offset, SEEK_SET);
+
+    uint32_t size;
+    ret = fread(&size, sizeof(size), 1, retain_buffer);
+    if (size != retain_info.hash_size)
+        return 0;
+
+    for (k = 0; k < retain_info.hash_size; k++) {
+        uint8_t file_digit;
+        ret = fread(&file_digit, sizeof(char), 1, retain_buffer);
+        if (file_digit != *(retain_info.hash + k))
+            return 0;
+    }
+
+    return 1;
+}
+
+void InitRetain(void)
+{
+    int i;
+
+    /* Get retain size in bytes */
+    retain_info.retain_size = GetRetainSize();
+
+    /* Hash stored in retain file as array of char in hex digits
+       (that's why we divide strlen in two).  */
+    retain_info.hash_size = PLC_ID ? strlen(PLC_ID) / 2 : 0;
+    //retain_info.hash_size = 0;
+    retain_info.hash = malloc(retain_info.hash_size);
+
+    /* Transform hash string into byte sequence.  */
+    for (i = 0; i < retain_info.hash_size; i++) {
+        int byte = 0;
+        sscanf((PLC_ID + i * 2), "%02X", &byte);
+        retain_info.hash[i] = byte;
+    }
+
+    /* Calc header offset.  */
+    retain_info.header_offset = sizeof(retain_info.retain_size) +
+        sizeof(retain_info.hash_size) + retain_info.hash_size;
+
+    /*  Set header CRC initial state.  */
+    retain_info.header_crc = 0;
+
+    /* Calc crc for header.  */
+    retain_info.header_crc = GenerateCRC32Sum(&retain_info.retain_size,
+                                              sizeof(retain_info.retain_size),
+                                              retain_info.header_crc);
+
+    retain_info.header_crc = GenerateCRC32Sum(&retain_info.hash_size,
+                                              sizeof(retain_info.hash_size),
+                                              retain_info.header_crc);
+
+    retain_info.header_crc = GenerateCRC32Sum(retain_info.hash,
+                                              retain_info.hash_size,
+                                              retain_info.header_crc);
+}
+
+void CleanupRetain(void)
+{
+    /* Free hash memory.  */
+    free(retain_info.hash);
+}
+
+int CheckRetainFile(const char *file)
+{
+    retain_buffer = fopen(file, "rb");
+    if (retain_buffer) {
+        /* Check CRC32 and hash.  */
+        if (CheckFileCRC(retain_buffer))
+            if (CheckFilehash())
+                return 1;
+        fclose(retain_buffer);
+        retain_buffer = NULL;
+    }
+    return 0;
+}
+
+int CheckRetainBuffer(void)
+{
+    retain_buffer = NULL;
+    if (!retain_info.retain_size)
+        return 1;
+
+    /* Check latest retain file.  */
+    if (CheckRetainFile(rb_file))
+        return 1;
+
+    /* Check if we have backup.  */
+    if (CheckRetainFile(rb_file_bckp))
+        return 1;
+
+    /* We don't have any valid retain buffer - nothing to remind.  */
+    return 0;
+}
+
+#ifndef FILE_RETAIN_SAVE_PERIOD_S
+#define FILE_RETAIN_SAVE_PERIOD_S 1.0
+#endif
+
+static double CalcDiffSeconds(IEC_TIME * t1, IEC_TIME * t2)
+{
+    IEC_TIME dt = {
+        t1->tv_sec - t2->tv_sec,
+        t1->tv_nsec - t2->tv_nsec
+    };
+
+    if ((dt.tv_nsec < -1000000000) || ((dt.tv_sec > 0) && (dt.tv_nsec < 0))) {
+        dt.tv_sec--;
+        dt.tv_nsec += 1000000000;
+    }
+    if ((dt.tv_nsec > +1000000000) || ((dt.tv_sec < 0) && (dt.tv_nsec > 0))) {
+        dt.tv_sec++;
+        dt.tv_nsec -= 1000000000;
+    }
+    return dt.tv_sec + 1e-9 * dt.tv_nsec;
+}
+
+int RetainSaveNeeded(void)
+{
+    int ret = 0;
+    static IEC_TIME last_save;
+    IEC_TIME now;
+    double diff_s;
+
+    /* no retain */
+    if (!retain_info.retain_size)
+        return 0;
+
+    /* periodic retain flush to avoid high I/O load */
+    PLC_GetTime(&now);
+
+    diff_s = CalcDiffSeconds(&now, &last_save);
+
+    if ((diff_s > FILE_RETAIN_SAVE_PERIOD_S) || ForceSaveRetainReq()) {
+        ret = 1;
+        last_save = now;
+    }
+    return ret;
+}
+
+void ValidateRetainBuffer(void)
+{
+    if (!retain_buffer)
+        return;
+
+    /* Add retain data CRC to the end of buffer file.  */
+    fseek(retain_buffer, 0, SEEK_END);
+    fwrite(&retain_crc, sizeof(uint32_t), 1, retain_buffer);
+
+    /* Sync file buffer and close file.  */
+#ifdef __WIN32
+    fflush(retain_buffer);
+#else
+    fsync(fileno(retain_buffer));
+#endif
+
+    fclose(retain_buffer);
+    retain_buffer = NULL;
+}
+
+void InValidateRetainBuffer(void)
+{
+    if (!RetainSaveNeeded())
+        return;
+
+    /* Rename old retain file into *.bak if it exists.  */
+    rename(rb_file, rb_file_bckp);
+
+    /* Set file CRC initial value.  */
+    retain_crc = retain_info.header_crc;
+
+    /* Create new retain file.  */
+    retain_buffer = fopen(rb_file, "wb+");
+    if (!retain_buffer) {
+        fprintf(stderr, "Failed to create retain file : %s\n", rb_file);
+        return;
+    }
+
+    /* Write header to the new file.  */
+    fwrite(&retain_info.retain_size,
+           sizeof(retain_info.retain_size), 1, retain_buffer);
+    fwrite(&retain_info.hash_size,
+           sizeof(retain_info.hash_size), 1, retain_buffer);
+    fwrite(retain_info.hash,
+           sizeof(char), retain_info.hash_size, retain_buffer);
+}
+
+void Retain(unsigned int offset, unsigned int count, void *p)
+{
+    if (!retain_buffer)
+        return;
+
+    /* Generate CRC 32 for each data block.  */
+    retain_crc = GenerateCRC32Sum(p, count, retain_crc);
+
+    /* Save current var in file.  */
+    fseek(retain_buffer, retain_info.header_offset + offset, SEEK_SET);
+    fwrite(p, count, 1, retain_buffer);
+}
+
+void Remind(unsigned int offset, unsigned int count, void *p)
+{
+    int ret;
+    /* Remind variable from file.  */
+    fseek(retain_buffer, retain_info.header_offset + offset, SEEK_SET);
+    ret = fread((void *)p, count, 1, retain_buffer);
+}
+#endif                          // !HAVE_RETAIN