2004.09.16 19:12 "[Tiff] BigTIFF Tag Value Count issue", by Joris Van Damme

2004.09.17 16:13 "Re: [Tiff] BigTIFF Tag Value Count issue", by Joris Van Damme

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.

I have the same problem in Delphi. But I decided to just not care. What are the odds of a file growing beyond 2^63-1 bytes? I'll have a very long beard by the time that happens.

Plus, depending on the api you use... I'm not even sure that me using signed 64bit values will actually ever be a problem. I use windows api to set file pointer and such, and they just take a pointer to the higher 32bit value, so I give it to them. I don't care they see this as unsigned, the api functions don't care I see this as signed.

If you're unsure about that, another option is to always check whether the 64bit value is negative, and if it is, error out.

And even if it is a problem, adjusting the spec to compensate for our implementation trouble, is, I think, not very good practice. The major factor in spec design should be logic, instead, and this logically is an unsigned value and there is no logical reason to discriminate bit 63.

Joris Van Damme
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