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Fixing possible overflow during multiplication #1381
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| ret[i + j + 1] = res; | ||
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| // Only single overflow possible there | ||
| carry2 = (o1 | o2 | o3) as u64; |
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We are multiplying two 64bit numbers - the result will fit in 128bits.
Those operations are adding the possible carry (so two 64bits, split into couple of parts) - the result will fit in 64bits + 1 carry.
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but you then add result to the next word, don't you ?..
let (res, o3) = res.overflowing_add(ret[i + j + 1]);
which can be also overflow
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though forget it, i think overflow tests are made for each word there
NikVolf
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A5-grumble 🔥
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It was haunting me since I finished working on uint. In a following code there can be only one overflow, but cannot be sure when it will occur.
Most probably closes #1380