Add sr_analog_to_float().

Makefile.am

@@ -35,6 +35,7 @@ libsigrok_la_SOURCES = \
 	src/hwdriver.c \
 	src/trigger.c \
 	src/soft-trigger.c \
+	src/analog.c \
 	src/strutil.c \
 	src/log.c \
 	src/version.c \

include/libsigrok/proto.h

@@ -26,6 +26,11 @@
  * Header file containing API function prototypes.
  */
 
+/*--- analog.c --------------------------------------------------------------*/
+
+SR_API int sr_analog_to_float(const struct sr_datafeed_analog2 *analog,
+		float *buf);
+
 /*--- backend.c -------------------------------------------------------------*/
 
 SR_API int sr_init(struct sr_context **ctx);

src/analog.c

@@ -0,0 +1,66 @@
+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright (C) 2014 Bert Vermeulen <bert@biot.com>
+ *
+ * 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
+ * (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 <string.h>
+#include "libsigrok.h"
+#include "libsigrok-internal.h"
+
+#define LOG_PREFIX "analog"
+
+SR_API int sr_analog_to_float(const struct sr_datafeed_analog2 *analog,
+		float *buf)
+{
+	float offset;
+	unsigned int b, i;
+	gboolean bigendian;
+
+#ifdef WORDS_BIGENDIAN
+	bigendian = TRUE;
+#else
+	bigendian = FALSE;
+#endif
+	if (!analog->encoding->is_float) {
+		/* TODO */
+		sr_err("Only floating-point analog data supported so far.");
+		return SR_ERR;
+	}
+
+	if (analog->encoding->unitsize == sizeof(float)
+			&& analog->encoding->is_bigendian == bigendian
+			&& (analog->encoding->scale.p == analog->encoding->scale.q)
+			&& analog->encoding->scale.p / (float)analog->encoding->scale.q == 0) {
+		/* The data is already in the right format. */
+		memcpy(buf, analog->data, analog->num_samples * sizeof(float));
+	} else {
+		for (i = 0; i < analog->num_samples; i += analog->encoding->unitsize) {
+			for (b = 0; b < analog->encoding->unitsize; b++) {
+				if (analog->encoding->is_bigendian == bigendian)
+					buf[i + b] = ((float *)analog->data)[i * analog->encoding->unitsize + b];
+				else
+					buf[i + (analog->encoding->unitsize - b)] = ((float *)analog->data)[i * analog->encoding->unitsize + b];
+			}
+			if (analog->encoding->scale.p != analog->encoding->scale.q)
+				buf[i] = (buf[i] * analog->encoding->scale.p) / analog->encoding->scale.q;
+			offset = ((float)analog->encoding->scale.p / (float)analog->encoding->scale.q);
+			buf[i] += offset;
+		}
+	}
+
+	return SR_OK;
+}