Repurpose into gRPC service

Repurpose repository into a spiritual successor of the previous
binding.  The backend code is retained behind a new gRPC API
defined in protos/radio.proto.  The simpler synchronous gRPC API
had been used for expediency, this may warrant revisiting to
rework into an async or callback API based server instead.  As
well, authentication has been left until some consensus on an
approach can be worked out.

Bug-AGL: SPEC-4665

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I28b122ce6e0ecfc7504aa08b90394cb1b9e22976
(cherry picked from commit dd23c157bdba1b25bbb50cdb99a60aa597735f43)

1 files changed, 243 insertions, 0 deletions

diff --git a/src/rtl_fm_helper.c b/src/rtl_fm_helper.c
new file mode 100644
index 0000000..c7df4b9
--- /dev/null
+++ b/src/rtl_fm_helper.c
@@ -0,0 +1,243 @@
+/*
+ * Copyright (C) 2018 Konsulko Group
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include <glib.h>
+
+#include "rtl_fm.h"
+#include "radio_output.h"
+
+#ifdef DEBUG
+#define LOG_FILE	"/tmp/helper.log"
+FILE *_log;
+#define LOG(...) \
+	do { \
+		if(!_log) _log = fopen(LOG_FILE, "w");	\
+		fprintf(_log, __VA_ARGS__);		\
+		fflush(_log);				\
+	} while(0)
+#else
+#define LOG(...) do { } while(0)
+#endif
+
+// Structure to describe FM band plans, all values in Hz.
+typedef struct {
+	const char *name;
+	uint32_t min;
+	uint32_t max;
+	uint32_t step;
+} fm_band_plan_t;
+
+static fm_band_plan_t known_fm_band_plans[5] = {
+	{ .name = "US", .min = 87900000, .max = 107900000, .step = 200000 },
+	{ .name = "JP", .min = 76000000, .max = 95000000, .step = 100000 },
+	{ .name = "EU", .min = 87500000, .max = 108000000, .step = 50000 },
+	{ .name = "ITU-1", .min = 87500000, .max = 108000000, .step = 50000 },
+	{ .name = "ITU-2", .min = 87900000, .max = 107900000, .step = 50000 }
+};
+
+static unsigned int bandplan;
+static char line[64];
+
+static void rtl_output_callback(int16_t *result, int result_len, void *ctx)
+{
+	radio_output_write((char*) result, result_len * 2);
+}
+
+static void rtl_freq_callback(uint32_t freq, void *ctx)
+{
+	// Note, need to flush output to ensure parent sees it
+	printf("F=%u\n", freq);
+	fflush(stdout);
+	LOG("F=%u\n", freq);
+}
+
+static void rtl_scan_callback(uint32_t freq, void *ctx)
+{
+	// Note, need to flush output to ensure parent sees it
+	printf("S=%u\n", freq);
+	fflush(stdout);
+	LOG("S=%u\n", freq);
+}
+
+static void read_config(void)
+{
+	GKeyFile* conf_file;
+	int conf_file_present = 0;
+	char *value_str;
+
+	// Load settings from configuration file if it exists
+	conf_file = g_key_file_new();
+	if(conf_file &&
+	   g_key_file_load_from_dirs(conf_file,
+				     "AGL.conf",
+				     (const gchar**) g_get_system_config_dirs(),
+				     NULL,
+				     G_KEY_FILE_KEEP_COMMENTS,
+				     NULL) == TRUE) {
+		conf_file_present = 1;
+
+		// Set band plan if it is specified
+		value_str = g_key_file_get_string(conf_file,
+						  "radio",
+						  "fmbandplan",
+						  NULL);
+		if(value_str) {
+			unsigned int i;
+			for(i = 0;
+			    i < sizeof(known_fm_band_plans) / sizeof(fm_band_plan_t);
+			    i++) {
+				if(!strcasecmp(value_str, known_fm_band_plans[i].name)) {
+					bandplan = i;
+					break;
+				}
+			}
+		}
+	}
+	fprintf(stderr, "Using FM Bandplan: %s\n", known_fm_band_plans[bandplan].name);
+
+	if(conf_file_present) {
+		GError *error = NULL;
+		int n;
+
+		// Allow over-riding scanning parameters just in case a demo
+		// setup needs to do so to work reliably.
+		n = g_key_file_get_integer(conf_file,
+					   "radio",
+					   "scan_squelch_level",
+					   &error);
+		if(!error) {
+			fprintf(stderr, "Scanning squelch level set to %d\n", n);
+			rtl_fm_scan_set_squelch_level(n);
+		}
+
+		error = NULL;
+		n = g_key_file_get_integer(conf_file,
+					   "radio",
+					   "scan_squelch_limit",
+					   &error);
+		if(!error) {
+			fprintf(stderr, "Scanning squelch limit set to %d\n", n);
+			rtl_fm_scan_set_squelch_limit(n);
+		}
+
+		g_key_file_free(conf_file);
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	int rc;
+	bool detect = false;
+	bool done = false;
+	bool started = false;
+	uint32_t frequency;
+
+	LOG("started\n");
+
+	read_config();
+	frequency = known_fm_band_plans[bandplan].min;
+
+	if(argc == 2 && strcmp(argv[1], "--detect") == 0) {
+		detect = true;
+	}
+
+	rc = rtl_fm_init(frequency, 200000, 48000, rtl_output_callback, NULL);
+	if(rc < 0) {
+		fprintf(stderr, "No RTL USB adapter?\n");
+		exit(1);
+	}
+	if(detect) {
+		rtl_fm_cleanup();
+		exit(0);
+	}
+
+	rtl_fm_set_freq_callback(rtl_freq_callback, NULL);
+
+	while(!done) {
+		LOG("Reading command\n");
+		if (fgets(line, sizeof(line), stdin) == NULL)
+			break;
+		if(line[0] == '\0' || line[0] == '\n')
+			continue;
+		if(strcmp(line, "START\n") == 0) {
+			LOG("START received\n");
+			if(!started) {
+				LOG("Starting\n");
+				radio_output_start();
+				rtl_fm_start();
+				started = true;
+			}
+		} else if(strcmp(line, "STOP\n") == 0) {
+			LOG("STOP received\n");
+			if(started) {
+				LOG("Stopping\n");
+				radio_output_stop();
+				rtl_fm_stop();
+				started = false;
+			}
+		} else if(strncmp(line, "F=", 2) == 0) {
+			uint32_t n;
+			if(sscanf(line, "F=%u\n", &n) == 1) {
+				LOG("F=%d received\n", n);
+				rtl_fm_scan_stop();
+				rtl_fm_set_freq(n);
+			}
+		} else if(strcmp(line, "S=UP\n") == 0) {
+			LOG("S=UP received\n");
+			if(!started)
+				continue;
+			LOG("Calling rtl_fm_scan_start\n");
+			rtl_fm_scan_start(0,
+					  rtl_scan_callback,
+					  NULL,
+					  known_fm_band_plans[bandplan].step,
+					  known_fm_band_plans[bandplan].min,
+					  known_fm_band_plans[bandplan].max);
+		} else if(strcmp(line, "S=DOWN\n") == 0) {
+			LOG("S=DOWN received\n");
+			if(!started)
+				continue;
+			LOG("Calling rtl_fm_scan_start\n");
+			rtl_fm_scan_start(1,
+					  rtl_scan_callback,
+					  NULL,
+					  known_fm_band_plans[bandplan].step,
+					  known_fm_band_plans[bandplan].min,
+					  known_fm_band_plans[bandplan].max);
+		} else if(strcmp(line, "S=STOP\n") == 0) {
+			LOG("S=STOP received\n");
+			if(started) {
+				LOG("Calling rtl_fm_scan_stop\n");
+				rtl_fm_scan_stop();
+			}
+		} else if(line[0] == 'q' || line[0] == 'Q')
+			break;
+	}
+	if(started) {
+		radio_output_stop();
+		rtl_fm_stop();
+	}
+	rtl_fm_cleanup();
+	LOG("done");
+	return 0;
+}