value: add new format for parsing simple text values

lib/formats/CMakeLists.txt

@@ -69,6 +69,7 @@ list(APPEND FORMAT_SRC
     csv.cpp
     raw.cpp
     msg.cpp
+    value.cpp
 )
 
 add_library(formats STATIC ${FORMAT_SRC})

lib/formats/value.cpp

@@ -0,0 +1,114 @@
+/** Bare text values.
+ *
+ * @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
+ * @copyright 2014-2019, Institute for Automation of Complex Power Systems, EONERC
+ * @license GNU General Public License (version 3)
+ *
+ * VILLASnode
+ *
+ * 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 3 of the License, or
+ * 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, see <http://www.gnu.org/licenses/>.
+ *********************************************************************************/
+
+#include <villas/io.h>
+#include <villas/formats/csv.h>
+#include <villas/plugin.h>
+#include <villas/sample.h>
+#include <villas/signal.h>
+
+using namespace villas::utils;
+
+int value_sprint(struct io *io, char *buf, size_t len, size_t *wbytes, struct sample *smps[], unsigned cnt)
+{
+	unsigned i;
+	size_t off = 0;
+	struct signal *sig;
+	struct sample *smp = smps[0];
+
+	assert(cnt == 1);
+	assert(smp->length <= 1);
+
+	buf[0] = '\0';
+
+	for (i = 0; i < smp->length; i++) {
+		sig = (struct signal *) vlist_at_safe(smp->signals, i);
+		if (!sig)
+			break;
+
+		off += signal_data_print_str(&smp->data[i], sig, buf, len);
+		off += snprintf(buf + off, len - off, "\n");
+	}
+
+	if (wbytes)
+		*wbytes = off;
+
+	return i;
+}
+
+int value_sscan(struct io *io, const char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt)
+{
+	unsigned i = 0, ret;
+	struct sample *smp = smps[0];
+
+	const char *ptr = buf;
+	char *end;
+
+	assert(cnt == 1);
+
+	printf("Reading: %s", buf);
+
+	if (smp->capacity >= 1) {
+		struct signal *sig = (struct signal *) vlist_at_safe(io->signals, i);
+		if (!sig)
+			goto out;
+
+		ret = signal_data_parse_str(&smp->data[i], sig, ptr, &end);
+		if (ret || end == ptr) /* There are no valid values anymore. */
+			goto out;
+
+		i++;
+		ptr = end;
+	}
+
+out:	smp->flags = 0;
+	smp->signals = io->signals;
+	smp->length = i;
+	if (smp->length > 0)
+		smp->flags |= (int) SampleFlags::HAS_DATA;
+
+	if (rbytes)
+		*rbytes = ptr - buf;
+
+	return i;
+}
+
+static struct plugin p;
+__attribute__((constructor(110))) static void UNIQUE(__ctor)() {
+	if (plugins.state == State::DESTROYED)
+		vlist_init(&plugins);
+
+	p.name = "value";
+	p.description = "A bare text value without any headers";
+	p.type = PluginType::FORMAT;
+	p.format.sprint = value_sprint;
+	p.format.sscan	= value_sscan;
+	p.format.size 	= 0;
+	p.format.flags	= (int) SampleFlags::HAS_DATA | (int) IOFlags::NEWLINES;
+
+	vlist_push(&plugins, &p);
+}
+
+__attribute__((destructor(110))) static void UNIQUE(__dtor)() {
+	if (plugins.state != State::DESTROYED)
+		vlist_remove_all(&plugins, &p);
+}