fix sqrt with bits > limb_bits #17919
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Signed-off-by: tison <wander4096@gmail.com>
tisonkun
commented
Nov 7, 2023
| @@ -1380,7 +1380,7 @@ pub const Mutable = struct { | |||
| var u = b: { | |||
| const start = buf_index; | |||
| const shift = (a.bitCountAbs() + 1) / 2; | |||
| buf_index += 1 + ((shift - 1) / limb_bits + 1); | |||
| buf_index += 1 + ((shift / limb_bits) + 1); | |||
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1- The initial value of m is 1, it takes at lest one limb_bit.shift / limb_bits- For each the shift bits == limb_bits, it takes one more limb_bit.1- The sentinel.
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and this is how we calculate in the next shiftLeft:
r.normalize(a.limbs.len + (shift / limb_bits) + 1);notice that we don't shift - 1 here.
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Actually I'm thinking of that we may not need the so-called sentinel + 1 in both code place. But this is safe while may be waste one usize space.
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This fixes #17858.
Offset by one issue.