Prevent overflows in ao value conversion.

Also makes ROFF fields unsigned, needed for ROFF=0x80000000

src/rec/aiRecord.dbd

@@ -176,8 +176,8 @@ recordtype(ai) {
 		pp(TRUE)
 		interest(2)
 	}
-	field(ROFF,DBF_LONG) {
-		prompt("Raw Offset, obsolete")
+	field(ROFF,DBF_ULONG) {
+		prompt("Raw Offset")
 		pp(TRUE)
 		interest(2)
 	}

src/rec/aoRecord.c

@@ -469,10 +469,20 @@ static void convert(aoRecord *prec, double value)
     }
     value -= prec->aoff;
     if (prec->aslo != 0) value /= prec->aslo;
-    if (value >= 0.0)
-        prec->rval = (epicsInt32)(value + 0.5) - prec->roff;
-    else
-        prec->rval = (epicsInt32)(value - 0.5) - prec->roff;
+
+    /* Apply raw offset and limits, round to 32-bit integer */
+    value -= prec->roff;
+    if (value >= 0.0) {
+        if (value >= (0x7fffffff - 0.5))
+            prec->rval = 0x7fffffff;
+        else
+            prec->rval = (epicsInt32)(value + 0.5);
+    } else {
+        if (value > (0.5 - 0x80000000))
+            prec->rval = (epicsInt32)(value - 0.5);
+        else
+            prec->rval = 0x80000000;
+    }
 }
 
 

src/rec/aoRecord.dbd

@@ -82,8 +82,8 @@ recordtype(ao) {
 		interest(1)
 		size(16)
 	}
-	field(ROFF,DBF_LONG) {
-		prompt("Raw Offset, obsolete")
+	field(ROFF,DBF_ULONG) {
+		prompt("Raw Offset")
 		pp(TRUE)
 		interest(2)
 	}