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VarInt decoding pseudocode #4316

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merged 5 commits into from Nov 3, 2020
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VarInt decoding pseudocode #4316

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VarInt decoding pseudocode
MikeBishop Oct 29, 2020
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MikeBishop Oct 30, 2020
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MikeBishop Oct 30, 2020
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MikeBishop Oct 30, 2020
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MikeBishop Oct 30, 2020
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12 changes: 6 additions & 6 deletions draft-ietf-quic-transport.md
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Expand Up @@ -7491,12 +7491,12 @@ sequence of bytes to read from.

~~~
ReadVarint(data):
first_byte = data.peek()
prefix = first_byte >> 6
num_bytes = 1 << prefix
mask = (1 << (num_bytes * 8 - 2)) - 1

return data.read(num_bytes) & mask
v = data.next_byte()
length = (1 << (v >> 6))
v = v & 0x3f
repeat length-1 times:
v = (v << 8) + data.next_byte()
return v
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v is also in network byte-order, no?

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Yes, but I'm not sure that's necessary to mention. We haven't changed it over the course of the algorithm.

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How could it not be in network byte order? Unless next_byte does something other than read the next byte.

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What I meant is that we might want to say that the value still needs to converted into host byte order before it can be used.

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Doesn't this do that? I mean, the operations here are numeric, so unless << means "divide by 2^n", we're good, right?

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Yeah -- there's nothing here that is endian-specific.

~~~
{: #alg-varint title="Sample Variable-Length Integer Decoding Algorithm"}

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