This is in general ill-defined, a compiler might generate code that sometimes
does byte access to a particular byte, anmd sometimes gets the entire word
in which the byte resides.
This is often a nasty issue, and is one of the few things in this area that
Ada does not properly address.
If you have a memory mapped byte, you really want a way of saying
"when I read this byte, do a byte read, it will not work to do a word read"
pragma Atomic in Ada (volatile gets close in C, but is not close enough) will
ensure a byte store in practice, but may not ensure byte reads.
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