Add sync plugin that uses the db state

src/ioc/db/Makefile

@@ -91,4 +91,5 @@ dbCore_SRCS += dbState.c
 dbCore_SRCS += ts.c
 dbCore_SRCS += dbnd.c
 dbCore_SRCS += arr.c
+dbCore_SRCS += sync.c
 

src/ioc/db/filters/filters.dbd

@@ -1,3 +1,4 @@
 registrar(tsInitialize)
 registrar(dbndInitialize)
 registrar(arrInitialize)
+registrar(syncInitialize)

src/ioc/db/filters/sync.c

@@ -0,0 +1,170 @@
+/*************************************************************************\
+* Copyright (c) 2010 Brookhaven National Laboratory.
+* Copyright (c) 2010 Helmholtz-Zentrum Berlin
+*     fuer Materialien und Energie GmbH.
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+
+/*
+ *  Author: Ralph Lange <Ralph.Lange@bessy.de>
+ */
+
+#include <stdio.h>
+
+#include "epicsExport.h"
+#include "freeList.h"
+#include "db_field_log.h"
+#include "chfPlugin.h"
+#include "dbState.h"
+
+#define STATE_NAME_LENGTH 20
+
+static const
+chfPluginEnumType modeEnum[] = { {"before", 0}, {"first", 1},
+                                 {"last", 2}, {"after", 3},
+                                 {"while", 4}, {"unless", 5},
+                                 {NULL,0} };
+typedef enum syncMode {
+    syncModeBefore=0,
+    syncModeFirst=1,
+    syncModeLast=2,
+    syncModeAfter=3,
+    syncModeWhile=4,
+    syncModeUnless=5
+} syncMode;
+
+typedef struct myStruct {
+    syncMode mode;
+    char state[STATE_NAME_LENGTH];
+    dbStateId id;
+    db_field_log *lastfl;
+    int laststate:1;
+} myStruct;
+
+static void *myStructFreeList;
+
+static const
+chfPluginArgDef opts[] = {
+    chfEnum   (myStruct, mode,  "m", 1, 1, modeEnum),
+    chfString (myStruct, state, "s", 1, 0),
+    chfPluginArgEnd
+};
+
+static void * allocPvt(void)
+{
+    myStruct *my = (myStruct*) freeListCalloc(myStructFreeList);
+    return (void *) my;
+}
+
+static void freePvt(void *pvt)
+{
+    freeListFree(myStructFreeList, pvt);
+}
+
+static int parse_ok(void *pvt)
+{
+    myStruct *my = (myStruct*) pvt;
+
+    if (!(my->id = dbStateFind(my->state)))
+        return -1;
+
+    return 0;
+}
+
+static db_field_log* filter(void* pvt, dbChannel *chan, db_field_log *pfl) {
+    if (pfl->ctx == dbfl_context_read)
+        return pfl;
+
+    db_field_log *passfl = NULL;
+    myStruct *my = (myStruct*) pvt;
+    int actstate = dbStateGet(my->id);
+
+    switch (my->mode) {
+    case syncModeBefore:
+        if (actstate && !my->laststate) {
+            passfl = my->lastfl;
+            my->lastfl = NULL;
+        }
+        break;
+    case syncModeFirst:
+        if (actstate && !my->laststate) {
+            passfl = pfl;
+            pfl = NULL;
+        }
+        break;
+    case syncModeLast:
+        if (!actstate && my->laststate) {
+            passfl = my->lastfl;
+            my->lastfl = NULL;
+        }
+        break;
+    case syncModeAfter:
+        if (!actstate && my->laststate) {
+            passfl = pfl;
+            pfl = NULL;
+        }
+        break;
+    case syncModeWhile:
+        if (actstate) {
+            passfl = pfl;
+        }
+        goto no_shift;
+    case syncModeUnless:
+        if (!actstate) {
+            passfl = pfl;
+        }
+        goto no_shift;
+    }
+
+    if (my->lastfl)
+        db_delete_field_log(my->lastfl);
+    my->lastfl = pfl;
+    my->laststate = actstate;
+
+    no_shift:
+    return passfl;
+}
+
+static void channelRegisterPre(dbChannel *chan, void *pvt,
+                               chPostEventFunc **cb_out, void **arg_out, db_field_log *probe)
+{
+    *cb_out = filter;
+    *arg_out = pvt;
+}
+
+static void channel_report(dbChannel *chan, void *pvt, int level, const unsigned short indent)
+{
+    myStruct *my = (myStruct*) pvt;
+    printf("%*s  plugin sync, mode=%s, state=%s\n", indent, "",
+           chfPluginEnumString(modeEnum, my->mode, "n/a"), my->state);
+}
+
+static chfPluginIf pif = {
+    allocPvt,
+    freePvt,
+
+    NULL, /* parse_error, */
+    parse_ok,
+
+    NULL, /* channel_open, */
+    channelRegisterPre,
+    NULL, /* channelRegisterPost, */
+    channel_report,
+    NULL /* channel_close */
+};
+
+static void syncInitialize(void)
+{
+    static int firstTime = 1;
+
+    if (!firstTime) return;
+    firstTime = 0;
+
+    if (!myStructFreeList)
+        freeListInitPvt(&myStructFreeList, sizeof(myStruct), 64);
+
+    chfPluginRegister("sync", &pif, opts);
+}
+
+epicsExportRegistrar(syncInitialize);