Most of the warnings are due to -Wunused-but-set-variable, one is due to
-Wdiscarded-qualifiers.
There are couple due to -Wparentheses. Those are noteworthy as the
default precedence w/o the missing paranthesis is not what we want.

e.g.,
We have : 4 - count & 0x03
We want : 4 - (count & 0x03)
We get  : (4 - count) & 0x03

This is because '-' operator has higher precedence than '&' and they
have left-to-right associativity.

Luckily, for the case (count & 0x03), the incorrect precedence also
results in the same result, so it should not affect anything.