Initial Commit - Copy from Altus Metrum AltOS

ao-tools/lib/cc-telemetry.c

@@ -0,0 +1,92 @@
+/*
+ * Copyright © 2011 Keith Packard <keithp@keithp.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 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 "cc.h"
+#include <string.h>
+
+static int
+parse_byte(char *data, uint8_t *byte)
+{
+	char	d[3];
+	int x;
+	d[0] = data[0];
+	d[1] = data[1];
+	d[2] = '\0';
+
+	if (sscanf(d, "%x", &x) != 1)
+		return FALSE;
+	*byte = x;
+	return TRUE;
+}
+
+int
+cc_telemetry_parse(const char *input_line, union ao_telemetry_all *telemetry)
+{
+	uint8_t	*byte;
+	char *data;
+	uint8_t hex[35];
+	int i;
+
+	if (strncmp(input_line, "TELEM", 5) != 0)
+		return FALSE;
+
+	data = strchr (input_line, ' ');
+	if (!data)
+		return FALSE;
+	data++;
+	byte = hex;
+	for (i = 0; i < 35; i++) {
+		if (!parse_byte(data, byte))
+			return FALSE;
+		data += 2;
+		byte++;
+	}
+	if (hex[0] != 34)
+		return FALSE;
+	memcpy(telemetry, hex+1, 34);
+	return TRUE;
+}
+
+uint8_t
+cc_telemetry_cksum(const union ao_telemetry_all *telemetry)
+{
+	const uint8_t	*x = (const uint8_t *) telemetry;
+	int i;
+	uint8_t	sum = 0x5a;
+	for (i = 0; i < 34; i++)
+		sum += x[i];
+	return sum;
+}
+
+void
+cc_telemetry_unparse(const union ao_telemetry_all *telemetry, char output_line[CC_TELEMETRY_BUFSIZE])
+{
+	uint8_t hex[36];
+	int i;
+	int p;
+
+	hex[0] = 34;
+	memcpy(hex+1, telemetry, 34);
+	hex[35] = cc_telemetry_cksum(telemetry);
+	strcpy(output_line, "TELEM ");
+	p = strlen(output_line);
+	for (i = 0; i < 36; i++) {
+		sprintf(output_line + p, "%02x", hex[i]);
+		p += 2;
+	}
+}