transform: Add a "scale" transform module.

Makefile.am

@@ -71,7 +71,8 @@ libsigrok_la_SOURCES += \
 # Transform modules
 libsigrok_la_SOURCES += \
 	src/transform/transform.c \
-	src/transform/nop.c
+	src/transform/nop.c \
+	src/transform/scale.c
 
 # SCPI support
 libsigrok_la_SOURCES += \

src/transform/scale.c

@@ -0,0 +1,121 @@
+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright (C) 2015 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include <string.h>
+#include "libsigrok.h"
+#include "libsigrok-internal.h"
+
+#define LOG_PREFIX "transform/scale"
+
+struct context {
+	double factor;
+};
+
+static int init(struct sr_transform *t, GHashTable *options)
+{
+	struct context *ctx;
+
+	if (!t || !t->sdi || !options)
+		return SR_ERR_ARG;
+
+	t->priv = ctx = g_malloc0(sizeof(struct context));
+
+	ctx->factor = g_variant_get_double(g_hash_table_lookup(options, "factor"));
+
+	return SR_OK;
+}
+
+static int receive(const struct sr_transform *t,
+		struct sr_datafeed_packet *packet_in,
+		struct sr_datafeed_packet **packet_out)
+{
+	struct context *ctx;
+	const struct sr_datafeed_analog *analog;
+	struct sr_channel *ch;
+	GSList *l;
+	float *fdata;
+	int i, num_channels, c;
+
+	if (!t || !t->sdi || !packet_in || !packet_out)
+		return SR_ERR_ARG;
+	ctx = t->priv;
+
+	switch (packet_in->type) {
+	case SR_DF_ANALOG:
+		analog = packet_in->payload;
+		fdata = (float *)analog->data;
+		num_channels = g_slist_length(analog->channels);
+		for (i = 0; i < analog->num_samples; i++) {
+			/* For now scale all values in all channels. */
+			for (l = analog->channels, c = 0; l; l = l->next, c++) {
+				ch = l->data;
+				(void)ch;
+				fdata[i * num_channels + c] *= ctx->factor;
+			}
+		}
+		break;
+	default:
+		sr_spew("Unsupported packet type %d, ignoring.", packet_in->type);
+		break;
+	}
+
+	/* Return the in-place-modified packet. */
+	*packet_out = packet_in;
+
+	return SR_OK;
+}
+
+static int cleanup(struct sr_transform *t)
+{
+	struct context *ctx;
+
+	if (!t || !t->sdi)
+		return SR_ERR_ARG;
+	ctx = t->priv;
+
+	g_free(ctx);
+	t->priv = NULL;
+
+	return SR_OK;
+}
+
+static struct sr_option options[] = {
+	{ "factor", "Factor", "Factor by which to scale the analog values", NULL, NULL },
+	ALL_ZERO
+};
+
+static const struct sr_option *get_options(void)
+{
+	/* Default to a scaling factor of 1.0. */
+	if (!options[0].def)
+		options[0].def = g_variant_ref_sink(g_variant_new_double(1.0));
+
+	return options;
+}
+
+SR_PRIV struct sr_transform_module transform_scale = {
+	.id = "scale",
+	.name = "Scale",
+	.desc = "Scale analog values by a specified factor",
+	.options = get_options,
+	.init = init,
+	.receive = receive,
+	.cleanup = cleanup,
+};

src/transform/transform.c

@@ -40,10 +40,12 @@
 
 /** @cond PRIVATE */
 extern SR_PRIV struct sr_transform_module transform_nop;
+extern SR_PRIV struct sr_transform_module transform_scale;
 /* @endcond */
 
 static const struct sr_transform_module *transform_module_list[] = {
 	&transform_nop,
+	&transform_scale,
 	NULL,
 };