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c2ec13c7e9
As I mentioned in the previous commit, I'm going to want PuTTY to be able to run sensibly when compiled with 64-bit Visual Studio, including handling bignums in 64-bit chunks for speed. Unfortunately, 64-bit VS does not provide any type we can use as BignumDblInt in that situation (unlike 64-bit gcc and clang, which give us __uint128_t). The only facilities it provides are compiler intrinsics to access an add-with-carry operation and a 64x64->128 multiplication (the latter delivering its product in two separate 64-bit output chunks). Hence, here's a substantial rework of the bignum code to make it implement everything in terms of _those_ primitives, rather than depending throughout on having BignumDblInt available to use ad-hoc. BignumDblInt does still exist, for the moment, but now it's an internal implementation detail of sshbn.h, only declared inside a new set of macros implementing arithmetic primitives, and not accessible to any code outside sshbn.h (which confirms that I really did catch all uses of it and remove them). The resulting code is surprisingly nice-looking, actually. You'd expect more hassle and roundabout circumlocutions when you drop down to using a more basic set of primitive operations, but actually, in many cases it's turned out shorter to write things in terms of the new BignumADC and BignumMUL macros - because almost all my uses of BignumDblInt were implementing those operations anyway, taking several lines at a time, and now they can do each thing in just one line. The biggest headache was Poly1305: I wasn't able to find any sensible way to adapt the existing Python script that generates the various per-int-size implementations of arithmetic mod 2^130-5, and so I had to rewrite it from scratch instead, with nothing in common with the old version beyond a handful of comments. But even that seems to have worked out nicely: the new version has much more legible descriptions of the high-level algorithms, by virtue of having a 'Multiprecision' type which wraps up the division into words, and yet Multiprecision's range analysis allows it to automatically drop out special cases such as multiplication by 5 being much easier than multiplication by another multi-word integer. |
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| .. | ||
| cygtermd | ||
| encodelib.py | ||
| kh2reg.py | ||
| logparse.pl | ||
| logrewrap.pl | ||
| make1305.py | ||
| nice-ibeam.cur | ||
| samplekex.py | ||