13:50:11 <m-relay> <r​ucknium:monero.social> If I use https://docs.getmonero.org/rpc-library/monerod-rpc/#get_block_header_by_height with `fill_pow_hash` = true, I can get a `pow_hash` of each block. How would I convert the hex `pow_hash` value into an integer, for example to get the value of `H` in this formula: https://monero.stackexchange.com/a/12046 ?
13:50:54 <m-relay> <r​ucknium:monero.social> And why do the zeros of `pow_hash` appear at the end of the hex string? In bitcoin, the zeros appear at the beginning.
13:52:52 <moneromooo> parse_hash256
13:54:46 <m-relay> <r​ucknium:monero.social> Thank you.
13:55:38 <moneromooo> If you want true 256 bit divisions, use boost bigint. Or div256_64 for short divisors. 
13:56:16 <sech1> it's a sequence of bytes (2 hex characters per byte)
13:56:21 <sech1> zeroes are in the end because LSB encoded
13:57:12 <sech1> so the first byte is the least significant byte, the last byte is the most significant byte (bits 248-255)
16:23:19 <m-relay> <r​ucknium:monero.social> This is what I have done:
16:23:29 <m-relay> <r​ucknium:monero.social> 1) Start with the original `pow_hash`, which has 64 hexadecimal "characters".
16:23:40 <m-relay> <r​ucknium:monero.social> 2) Convert this to individual "byte" elements by concatenating the pairs of hexadecimal elements, so we have 32 byte elements.
16:23:49 <m-relay> <r​ucknium:monero.social> 3) Reverse the ordering of the 32 byte elements, i.e. the put the first element last, then the second element in the penultimate place, etc.
16:23:59 <m-relay> <r​ucknium:monero.social> 4) Concatenate these bytes together, add a `0x` at the beginning, and use a function to convert this hexadecimal form into an arbitrary-precision integer.
16:24:37 <m-relay> <r​ucknium:monero.social> Is this correct? It seems to work. A large sample of blocks pass the appropriate difficulty hurdle.
16:49:50 <m-relay> <s​needlewoods_xmr:matrix.org> seems correct to me (for block: 3472006 the pow_hash: aa6f70cf7b1e67e60028e19b03ac2f8f5661c61017cd41377dee7c0000000000, integer value: 51393878524106522740461043578110141991369175320009076927949205418)
16:58:08 <DataHoarder> it's a 256-bit hash in little endian wire format :)
17:18:28 <sech1> Yes, this is correct
18:34:51 <m-relay> <r​ucknium:monero.social> Thanks, all. I am learning one byte at a time :)