ArduinoISP.ino does not properly handle word-based address for EEPROM read/write

[x0urc3]

Steps to reproduce
Reading and writing EEPROM using Adafruit ArduinoISP.ino will cause Bad EEPROM data. The official Arduino ArduinoISP.ino does not have similar issue. See avrdudes/avrdude/issues/990

Possible solution
The read and write EEPROM function does not handle word-based address. The high address byte is 0x00 in both function.

Adafruit_Learning_System_Guides/ArduinoISP/ArduinoISP/ArduinoISP.ino

Lines 550 to 557 in 0090edd

	char eeprom_read_page(int length) {
	// here again we have a word address
	for (int x = 0; x < length; x++) {
	byte ee = spi_transaction(0xA0, 0x00, _addr*2+x, 0xFF);
	Serial.write( ee);
	}
	return STK_OK;
	}

Adafruit_Learning_System_Guides/ArduinoISP/ArduinoISP/ArduinoISP.ino

Lines 487 to 496 in 0090edd

	byte write_eeprom(int length) {
	// here is a word address, so we use here*2
	// this writes byte-by-byte,
	// page writing may be faster (4 bytes at a time)
	for (int x = 0; x < length; x++) {
	spi_transaction(0xC0, 0x00, _addr*2+x, buff[x]);
	delay(45);
	}
	return STK_OK;
	}

[TheKitty]

Please submit a pull request if at all possible.

[mcuee]

FYI, Arduino's example has the fix back in Dec 2011.
arduino/arduino-examples@ea98fc8

Specific fix here.
rsbohn/ArduinoISP@bc480b0