From 9b460d38bc2685bca7f530b7749c0e0381f6264c Mon Sep 17 00:00:00 2001
From: Keith Packard <keithp@keithp.com>
Date: Sat, 9 Mar 2013 20:39:31 -0800
Subject: [PATCH] ao-tools/lib: Add cc_telemetry_unparse

This takes a telemetry structure and generates a string version

Signed-off-by: Keith Packard <keithp@keithp.com>
---
 ao-tools/lib/cc-telemetry.c | 30 ++++++++++++++++++++++++++++++
 ao-tools/lib/cc-telemetry.h | 12 ++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/ao-tools/lib/cc-telemetry.c b/ao-tools/lib/cc-telemetry.c
index 99da2680..88da7f03 100644
--- a/ao-tools/lib/cc-telemetry.c
+++ b/ao-tools/lib/cc-telemetry.c
@@ -60,3 +60,33 @@ cc_telemetry_parse(const char *input_line, union ao_telemetry_all *telemetry)
 	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;
+	}
+}
+		
diff --git a/ao-tools/lib/cc-telemetry.h b/ao-tools/lib/cc-telemetry.h
index e849cd3b..9a5be49f 100644
--- a/ao-tools/lib/cc-telemetry.h
+++ b/ao-tools/lib/cc-telemetry.h
@@ -237,7 +237,19 @@ union ao_telemetry_all {
 	struct ao_telemetry_baro		baro;
 };
 
+#define CC_TELEMETRY_HEADER	"TELEM"
+
+/* "TELEM " 1 byte length 32 data bytes 1 rssi 1 status 1 checksum 1 null */
+
+#define CC_TELEMETRY_BUFSIZE	(6 + (1 + 32 + 3) * 2 + 1)
+
 int
 cc_telemetry_parse(const char *input_line, union ao_telemetry_all *telemetry);
 
+uint8_t
+cc_telemetry_cksum(const union ao_telemetry_all *telemetry);
+
+void
+cc_telemetry_unparse(const union ao_telemetry_all *telemetry, char output_line[CC_TELEMETRY_BUFSIZE]);
+
 #endif
-- 
2.30.2