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buffer: align chunks on 8-byte boundary #1126

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buffer: align chunks on 8-byte boundary #1126

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6 changes: 6 additions & 0 deletions lib/buffer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,12 @@ function palloc(that, length) {
var buf = sliceOnto(allocPool, that, start, end);
poolOffset = end;

// Ensure aligned slices
if (poolOffset & 0x7) {
poolOffset |= 0x7;
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I'm curious, why is this line needed if the condition already succeeded?

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  1. poolOffset = 1
  2. poolOffset & 0x7 === 1
  3. poolOffset |= 0x7 => 0x7
  4. poolOffset++ => 0x8
  5. Voila, poolOffset is aligned!

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@mscdex in other words, I'm just setting all bits that are lower than alignment value and increment the number to align it.

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A less convoluted way of writing that is poolOffset = (poolOffset & ~7) + 8 :-)

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I used something like this: poolOffset += 8 - poolOffset % 8; :)

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Yeah, I do this to for variable-size alignment or just non-power-of-two.

poolOffset++;
}

return buf;
}

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