The new file type I is essentially Intel HEX that, on download, inserts
comments next to data records with the resolved effective address and an
ASCII dump of that same record. On upload the `I` format is permissive
with respect to check sum errors, eg, after manipulated an Intel HEX file
for debugging.
The paged read in pickit2.c has two errors:
- It drops load extended address commands unless a paged read happens at a
64k byte boundary; this is invalid when reading files with holes
- It wrongly assumed that flash memory is byte addressed
The fix is to carry out a load extended address command, if needed, at the
beginning of each paged flash read with the correct word address. Although the
pickit2_paged_load() has independent parameters page_size, addr and n_bytes,
AVRDUDE only ever calls paged read/write functions with page_size and n_bytes
both set to mem->page_size and addr aligned with a page boundary. Therefore, it
is sufficient to set the load extended address at the beginning of each page
read.