[edgar-bonet]

In sim_core.c, there are two instances where an address is determined to be a valid I/O address with this test:

if (addr > 31 && addr < 31 + MAX_IOs)

However, the range of valid I/O addresses is 32 – (MAX_IOs+31) inclusive. Thus, the upper bound in the above test should be included.

This pull request fixes the error. This could be done by replacing < with <= in the second comparison. Instead, I chose to write

if (addr >= 32 && addr < MAX_IOs + 32)

because:

1. index ranges defined as left-closed, right-open intervals, like [a, b), are more idiomatic in C than their reversed counterparts

2. this is stylistically more consistent with the test if (addr < MAX_IOs + 32) in _avr_set_ram().