You can see the https://fundlan.com/bitcoin-source-cod/ bitcoin open source code on the GitHub site (https://github.com/bitcoin/bitcoin).

Bitcoin mining source code
Bitcoin is mined by a pool of globally distributed computers running the Bitcoin software that verifies transaction records, adds them to the blockchain, and awards Bitcoin units in exchange.

Cryptocurrency mining involves solving complex arithmetic challenges, and the first computer or set of computers to resolve such issues is remunerated in the form of Bitcoins.

The Bitcoin source code has a mining process implemented within it. There is an open-source reference RPC miner written by a Bitcoin developer for advanced users who know Python.

Such a miner will be a very basic form of a CPU bitcoin miner. Mining is, however, very resource-intensive and needs to be supported by powerful hardware for it to be effective.