I want to customize the available algorithms in a customizable miner. Let's say, I want to customize SHA256 in the way that it starts to generate Hash from Nonce value 10k instead of 1. Even after change, how can I integrate it into miner (e.g XMRig)?
In CPU miner program, you can setup nonce from 10k start to hash out a block header data. But,
In ASIC miner program, the chip is setup to search any nonces which produce a small hash value. the chip automatically brute force try nonces in all range of 0x00 to 0xffffffff. And asic chip is working extreme fast, 10k times trials cost no much time. eg. my asic miner, 25 minutes period, hash out 13,000 block headers (work), produce 6965 nonces which produce small hash values, start 00000000. (pass 1st test).
I understand your idea about algorithems. But, now, asic chip is widely used in mining device. the nonce is not issue for successful in mining bitcoin. It is a better (or optimalized) block header (work) which may enhance your chance to solve a bitcoin. Your algorithms should focus on how to get better block headers (works) to reduce your workloads against big pools or avoid to repeat hashing the same block headers which has been hashed out by fast miners in your pool.
Other ways is to build a 1PH/s + hashrate miner. see my other post.