If BufferRegister is in lower-case, then gen_decoder_prefix will
return nil. When the return value is nil, other functions like
gen_decoder() will backtrace due to a "undefined method "+" for nil"
error. Therefore, this input should NOT be case-sensitive.
Also, if for some reason the user supplies an invalid BufferRegister,
the function should be aware of that and warn the user about the
bad input.
sinn3r
192279544b