Merged Michael Davidsaver's array-opt branch

documentation/RELEASE_NOTES.html

@@ -15,6 +15,22 @@ EPICS Base 3.15.0.x releases are not intended for use in production systems.</p>
 <h2 align="center">Changes between 3.15.0.1 and 3.15.0.2</h2>
 <!-- Insert new items immediately below here ... -->
 
+<h3>Array field double-buffering</h3>
+
+<p>Array data can now be moved, without copying, into and out of the VAL field
+of the waveform, aai, and aao record types by replacing the pointer in BPTR.
+The basic rules which device support must follow are:</p>
+
+<ol>
+    <li>BPTR, and the memory it is currently pointing to, can only be accessed
+      while the record is locked.</li>
+    <li>NELM may not be changed; NORD should be updated whenever the number of
+      valid data elements changes.</li>
+    <li>When BPTR is replaced it must always point to a block of memory large
+      enough to hold the maximum number of elements, as given by the NELM and
+      FTVL fields.</li>
+</ol>
+
 <h3>Spin-locks API added</h3>
 
 <p>The new header file epicsSpin.h adds a portable spin-locks API which is

src/ioc/db/dbAccess.c

@@ -780,6 +780,7 @@ long dbGet(DBADDR *paddr, short dbrType,
     void *pbuffer, long *options, long *nRequest, void *pflin)
 {
     char *pbuf = pbuffer;
+    void *pfieldsave;
     db_field_log *pfl = (db_field_log *)pflin;
     short field_type;
     long no_elements;
@@ -815,6 +816,13 @@ long dbGet(DBADDR *paddr, short dbrType,
         return S_db_badDbrtype;
     }
 
+    /* For array field, the rset function
+     * get_array_info() is allowed to modify
+     * paddr->pfield.  So we store the original
+     * value and restore it later.
+     */
+    pfieldsave = paddr->pfield;
+
     /* check for array */
     if ((!pfl || pfl->type == dbfl_type_rec) &&
         paddr->special == SPC_DBADDR &&
@@ -860,7 +868,8 @@ long dbGet(DBADDR *paddr, short dbrType,
             sprintf(message, "dbGet: Missing conversion for [%d][%d]\n",
                     field_type, dbrType);
             recGblDbaddrError(S_db_badDbrtype, paddr, message);
-            return S_db_badDbrtype;
+            status = S_db_badDbrtype;
+            goto done;
         }
         /* convert database field  and place it in the buffer */
         if (n <= 0) {
@@ -880,6 +889,8 @@ long dbGet(DBADDR *paddr, short dbrType,
             status = convert(&localAddr, pbuf, n, no_elements, offset);
         }
     }
+done:
+    paddr->pfield = pfieldsave;
     return status;
 }
 

src/std/filters/arr.c

@@ -104,7 +104,9 @@ static db_field_log* filter(void* pvt, dbChannel *chan, db_field_log *pfl) {
         if (chan->addr.special == SPC_DBADDR &&
             nSource > 1 &&
             (prset = dbGetRset(&chan->addr)) &&
-            prset->get_array_info) {
+            prset->get_array_info)
+        {
+            void *pfieldsave = chan->addr.pfield;
             prec = dbChannelRecord(chan);
             dbScanLock(prec);
             prset->get_array_info(&chan->addr, &nSource, &offset);
@@ -126,6 +128,7 @@ static db_field_log* filter(void* pvt, dbChannel *chan, db_field_log *pfl) {
                 pfl->u.r.field = pdst;
             }
             dbScanUnlock(prec);
+            chan->addr.pfield = pfieldsave;
         }
 
     /* Extract from buffer */

src/std/rec/aaiRecord.c

@@ -183,7 +183,6 @@ static long cvt_dbaddr(DBADDR *paddr)
 {
     aaiRecord *prec = (aaiRecord *)paddr->precord;
 
-    paddr->pfield         = prec->bptr;
     paddr->no_elements    = prec->nelm;
     paddr->field_type     = prec->ftvl;
     paddr->field_size     = dbValueSize(prec->ftvl);
@@ -195,6 +194,7 @@ static long get_array_info(DBADDR *paddr, long *no_elements, long *offset)
 {
     aaiRecord *prec = (aaiRecord *)paddr->precord;
 
+    paddr->pfield = prec->bptr;
     *no_elements =  prec->nord;
     *offset = 0;
     return 0;
@@ -308,7 +308,7 @@ static void monitor(aaiRecord *prec)
     }
 
     if (monitor_mask)
-        db_post_events(prec, prec->bptr, monitor_mask);
+        db_post_events(prec, &prec->val, monitor_mask);
 }
 
 static long readValue(aaiRecord *prec)

src/std/rec/aaoRecord.c

@@ -183,7 +183,6 @@ static long cvt_dbaddr(DBADDR *paddr)
 {
     aaoRecord *prec = (aaoRecord *)paddr->precord;
 
-    paddr->pfield         = prec->bptr;
     paddr->no_elements    = prec->nelm;
     paddr->field_type     = prec->ftvl;
     paddr->field_size     = dbValueSize(prec->ftvl);
@@ -195,6 +194,7 @@ static long get_array_info(DBADDR *paddr, long *no_elements, long *offset)
 {
     aaoRecord *prec = (aaoRecord *)paddr->precord;
 
+    paddr->pfield = prec->bptr;
     *no_elements =  prec->nord;
     *offset = 0;
     return 0;
@@ -308,7 +308,7 @@ static void monitor(aaoRecord *prec)
     }
 
     if (monitor_mask)
-        db_post_events(prec, prec->bptr, monitor_mask);
+        db_post_events(prec, &prec->val, monitor_mask);
 }
 
 static long writeValue(aaoRecord *prec)

src/std/rec/waveformRecord.c

@@ -163,7 +163,6 @@ static long cvt_dbaddr(DBADDR *paddr)
 {
     waveformRecord *prec = (waveformRecord *) paddr->precord;
 
-    paddr->pfield = prec->bptr;
     paddr->no_elements = prec->nelm;
     paddr->field_type = prec->ftvl;
     paddr->field_size = dbValueSize(prec->ftvl);
@@ -176,6 +175,7 @@ static long get_array_info(DBADDR *paddr, long *no_elements, long *offset)
 {
     waveformRecord *prec = (waveformRecord *) paddr->precord;
 
+    paddr->pfield = prec->bptr;
     *no_elements = prec->nord;
     *offset = 0;
 
@@ -300,7 +300,7 @@ static void monitor(waveformRecord *prec)
     }
 
     if (monitor_mask) {
-        db_post_events(prec, prec->bptr, monitor_mask);
+        db_post_events(prec, &prec->val, monitor_mask);
     }
 }