add utag filter

modules/database/src/std/filters/Makefile

@@ -16,6 +16,7 @@ dbRecStd_SRCS += dbnd.c
 dbRecStd_SRCS += arr.c
 dbRecStd_SRCS += sync.c
 dbRecStd_SRCS += decimate.c
+dbRecStd_SRCS += utag.c
 
 HTMLS += filters.html
 

modules/database/src/std/filters/filters.dbd.pod

@@ -285,3 +285,5 @@ once every minute:
  ...
 
 =cut
+
+registrar(utagInitialize)

modules/database/src/std/filters/utag.c

@@ -0,0 +1,99 @@
+/*************************************************************************\
+* Copyright (c) 2020 Michael Davidsaver
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+
+#include <stdlib.h>
+
+#include <caeventmask.h>
+#include <chfPlugin.h>
+#include <dbCommon.h>
+#include <epicsStdio.h>
+#include <epicsExport.h>
+
+typedef struct {
+    epicsInt32 mask, value;
+    int first;
+} utagPvt;
+
+static const
+chfPluginArgDef opts[] = {
+    chfInt32(utagPvt, mask, "M", 0, 1),
+    chfInt32(utagPvt, value, "V", 0, 1),
+    chfPluginArgEnd
+};
+
+static void * allocPvt(void)
+{
+    utagPvt *pvt;
+    pvt = calloc(1, sizeof(utagPvt));
+    pvt->mask = 0xffffffff;
+    return pvt;
+}
+
+static void freePvt(void *pvt)
+{
+    free(pvt);
+}
+
+static int parse_ok(void *raw)
+{
+    utagPvt *pvt = (utagPvt*)raw;
+    pvt->first = 1;
+    return 0;
+}
+
+static db_field_log* filter(void* raw, dbChannel *chan, db_field_log *pfl)
+{
+    utagPvt *pvt = (utagPvt*)raw;
+    epicsInt32 utag = pfl->type==dbfl_type_rec ? dbChannelRecord(chan)->utag : pfl->utag;
+    int drop = (utag&pvt->mask)!=pvt->value;
+
+    if(pfl->ctx!=dbfl_context_event || pfl->mask&DBE_PROPERTY) {
+        /* never drop for reads, or property events */
+
+    } else if(pvt->first) {
+        /* never drop first */
+        pvt->first = 0;
+
+    } else if(drop) {
+        db_delete_field_log(pfl);
+        pfl = NULL;
+    }
+
+    return pfl;
+}
+
+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 *raw, int level, const unsigned short indent)
+{
+    utagPvt *pvt = (utagPvt*)raw;
+    printf("%*sutag : mask=0x%08x value=0x%08x\n", indent, "", (epicsUInt32)pvt->mask, (epicsUInt32)pvt->value);
+}
+
+static const
+chfPluginIf pif = {
+    allocPvt,
+    freePvt,
+    NULL, /* parse_error */
+    parse_ok, /* parse_ok */
+    NULL, /* channel_open */
+    channelRegisterPre,
+    NULL, /* channelRegisterPost */
+    channel_report,
+    NULL, /* channel_close */
+};
+
+static
+void utagInitialize(void)
+{
+    chfPluginRegister("utag", &pif, opts);
+}
+epicsExportRegistrar(utagInitialize);