There is no system-dependent floating point arithmetic used to my knowledge. The Bitcoin blockchain doesn't use the concept of floating point math, nor do the Bitcoin clients do that.
The Bitcoin blockchain has 1 Satoshi as smallest token. By definition of Satoshi Nakamote 100,000,000 of those tokens are 1BTC. I remember that this division in 108 token has been discussed a lot of times in this forum. Did you try to search for this?
The maximum supply of slightly less than 21.000.000BTC, to be accurate max is 2,099,999,997,690,000sat, is directly correlated to the initial block reward of 50BTC and halving this value of 5,000,000,000sat by binary bit-shifting. There will be times when an odd number of Satoshis has to be halved and that's no issue by a bit-shift then.