input/null: Add a null module that discards all data.

This is useful for testing purposes.

Makefile.am

@@ -77,7 +77,8 @@ libsigrok_la_SOURCES += \
 	src/input/raw_analog.c \
 	src/input/trace32_ad.c \
 	src/input/vcd.c \
-	src/input/wav.c
+	src/input/wav.c \
+	src/input/null.c
 
 # Output modules
 libsigrok_la_SOURCES += \

src/input/input.c

@@ -66,6 +66,7 @@ extern SR_PRIV struct sr_input_module input_trace32_ad;
 extern SR_PRIV struct sr_input_module input_vcd;
 extern SR_PRIV struct sr_input_module input_wav;
 extern SR_PRIV struct sr_input_module input_raw_analog;
+extern SR_PRIV struct sr_input_module input_null;
 /* @endcond */
 
 static const struct sr_input_module *input_module_list[] = {
@@ -76,6 +77,7 @@ static const struct sr_input_module *input_module_list[] = {
 	&input_vcd,
 	&input_wav,
 	&input_raw_analog,
+	&input_null,
 	NULL,
 };
 

src/input/null.c

@@ -0,0 +1,59 @@
+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright (C) 2018 Uwe Hermann <uwe@hermann-uwe.de>
+ *
+ * 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 2 of the License, or
+ * (at your option) 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 <config.h>
+#include <libsigrok/libsigrok.h>
+#include "libsigrok-internal.h"
+
+#define LOG_PREFIX "input/null"
+
+static int init(struct sr_input *in, GHashTable *options)
+{
+	(void)in;
+	(void)options;
+
+	return SR_OK;
+}
+
+static int receive(struct sr_input *in, GString *buf)
+{
+	(void)in;
+	(void)buf;
+
+	return SR_OK;
+}
+
+static int end(struct sr_input *in)
+{
+	(void)in;
+
+	return SR_OK;
+}
+
+SR_PRIV struct sr_input_module input_null = {
+	.id = "null",
+	.name = "Null",
+	.desc = "Null input (discards all input)",
+	.exts = NULL,
+	.options = NULL,
+	.init = init,
+	.receive = receive,
+	.end = end,
+	.reset = NULL,
+};