Timeline for Genesis TX varint
Current License: CC BY-SA 4.0
10 events
| when toggle format | what | by | license | comment | |
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| Jun 18, 2020 at 8:26 | history | edited | CommunityBot |
Commonmark migration
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| Jan 6, 2020 at 5:42 | comment | added | jtgrassie | I'm also ignoring the other type of varints you can find in Monero code! EPEE has another type it uses in its binary serialization. Not relevant to this question however. | |
| Jan 6, 2020 at 5:03 | comment | added | jtgrassie | A normal, max 8 bytes number is 2^64-1. With a varint you would have to remove 7 bits from your 64 bits because the most significant bit of each byte is used to signify another byte is needed. Thus (N-1) as in 8 bytes minus the last byte is 7. 7 bits used in the encoding. 64-7 = 57. Max 57 bit number is 2^57-1 - as I stated in previous comment. Checking the Monero source, it treats the last byte just as the others, so only 7 bits can be used from that also. If the 8th bit of that bytes is set, it's considered an overflow. So yes, in fact the max number would be 2^56-1. | |
| Jan 6, 2020 at 3:51 | comment | added | koe | If I'm understanding right, is it 2^57 instead of 2^56 because the MSB of the 8th byte is, unlike the previous 7 bytes, an information bit? | |
| Jan 6, 2020 at 3:23 | comment | added | jtgrassie | "Am I correct in thinking varints occupy up to 9 bytes of space, and can contain up to 63 bits of information?" <- No you are incorrect. Varints can be as small as 1 byte and in theory, any size as a maximum. It even states this in the part I quoted from the spec. In Monero the range used is 1 byte to 8 bytes, because they are typically decoded to unsigned 64 bit integers. As you lose N-1 bits due to the encoding, for an 8 byte varint the maximum decoded value would be 2^57-1 | |
| Jan 6, 2020 at 3:17 | comment | added | koe | Am I correct in thinking varints occupy up to 9 bytes of space, and can contain up to 63 bits of information? based on section 1.2 here tukaani.org/xz/xz-file-format.txt | |
| Jun 25, 2018 at 22:29 | vote | accept | W. Kadou | ||
| Jun 25, 2018 at 22:29 | comment | added | W. Kadou | Thanks a million, this did help me. Sorry for responding late | |
| Jun 15, 2018 at 12:00 | history | edited | jtgrassie | CC BY-SA 4.0 |
Added link to spec and quoted. And added breakdown.
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| Jun 14, 2018 at 22:59 | history | answered | jtgrassie | CC BY-SA 4.0 |