Speed up hts_parse_decimal() handling of oversized exponents#2045
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The loop to apply exponent values could be made to run for a very long time (although not forever) if the exponent value in the number passed to the function was very large. As in both the +ve and -ve exponent cases this will eventually result in `n` becoming zero, it's possible to short-cut the rest of the loop as the final value will no longer change. (While the -ve case is obvious, the +ve one is a bit more complicated due to wrap-around. However, as each multiplication by 10 adds a factor of 2 (as 10 = 5 + 2), after at most 64 enough 2's will have accumulated in the product to make it divide exactly into 2^64 and the result will be zero.) Note that this does not try to add overflow detection, which would require more extensive changes and is left to future work. Signed-off-by: Rob Davies <rmd+git@sanger.ac.uk>
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The loop to apply exponent values could be made to run for a very long time (although not forever) if the exponent value in the number passed to the function was very large. As in both the +ve and -ve exponent cases this will eventually result in
nbecoming zero (the former through overflow), it's possible to short-cut the rest of the loop as the final value will no longer change.Note that this does not try to add overflow detection, which would require more extensive changes and is left to future work.