altosui: Clean up eeprom parsing a bit

Export basic parsing and checksum functions for shared use.
Create 'erased' function to check a chunk of eeprom data for data.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/altosui/AltosEepromChunk.java b/altosui/AltosEepromChunk.java
index 1e42077f..fb632a3f 100644
--- a/altosui/AltosEepromChunk.java
+++ b/altosui/AltosEepromChunk.java
@@ -52,6 +52,13 @@ public class AltosEepromChunk {
 		return data[offset] | (data[offset + 1] << 8);
 	}
 
+	boolean erased(int start, int len) {
+		for (int i = 0; i < len; i++)
+			if (data[start+i] != 0xff)
+				return false;
+		return true;
+	}
+
 	public AltosEepromChunk(AltosSerial serial_line, int block)
 		throws TimeoutException, InterruptedException {