Where the block production speed is written in the zcash code, I got confused I don’t understand at all how the calculation takes place.
Hi @Pirat I assume you are referring to the Zcash difficulty adjustment? The block target time since Sapling is 75 seconds, the difficulty adjustment is defined in section 7.6.3 of the protocol spec: https://zips.z.cash/protocol/protocol.pdf#diffadjustment
[Edit for accuracy by @daira: since Blossom, not Sapling. Also changed the link to a stable URL.]
And where in the code it is written
I found only Sapling time and where is the original time?
The original time can be seen in History: https://github.com/zcash/zcash/commit/f2c48e15e5867426ab1f888b28fe1fc556f020e4#diff-bc9415451d733499187a3fe59e0fd7e6
The line you’ve highlighted is the block interval in seconds from the Blossom network upgrade onwards (75 seconds). The line right above it is the block interval from the launch of Zcash through to just before the Blossom NU (150 seconds).
The canonical place to look in the code for the block interval at some block height is here: