You bit-negated a 32 bit value - of course printf gave you all the significant digits. Only you can know which digits are safe to throw away.

I recommend the following:

perl -e '$a = 127; printf "original:%04x, bit-negative version:%04x\n"
+, $a, (~$a)&0xffff;'
original:007f, bit-negative version:ff80
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