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September 2004
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2004.09.17 15:55 "Re: BigTIFF Tag Value Count issue", by Fernando Loygorri
> Some possible implementation languages do not even support unsigned > types. That's what I meant: Java is one of them. > Is there an alternative to using unsigned 64-bit values to access > large data? There is a standard class, BigInteger, that is of arbitrary size. Unfortunately, using objects like BigInteger instead of primitives like long is slower and clumsier. By using unsigned 64-bit values in BigTIFF instead of unsigned 32-bit values in TIFF, we increase the range by a factor of 2^32. By using signed 64-bit values in BigTIFF, which are equivalent to unsigned 63-bit values, the range would increase by a factor of 2^31, still a very respectable value. Just to clarify, I'm not proposing that negative 64-bit values should have any meaning. They should be outlawed by the spec. I'm proposing that the spec outlaw values with the most-significant bit set, and this only to accommodate languages like Java that have a 64-bit signed type but no 64-bit unsigned type. Regards, FGL