Binance Smart Chain tokens: What are tTotal, rTotal, tSupply, rSupply, rOwned, tOwned which I see everywhere?

Question

Looking at all the latest shitcoins' Smart Contract code on Binance Smart Chain, there's a lot of common,recurring themes because most of each project's code is mostly copy-pasted. The code is also completely uncommented, which makes it a pain to understand what's what.

Most of these contacts use two different types of variables for their internal token calculations, 1 called t and one called r. For example, on TrustPad's smart contract (available here: bscscan link):

    mapping(address => uint256) private _rOwned;
    mapping(address => uint256) private _tOwned;
    mapping(address => mapping(address => uint256)) private _allowances;
uint256 private constant MAX = ~uint256(0);
uint256 private constant _tTotal = 100 * (10 ** 6) * (10 ** 9);
uint256 private _rTotal = (MAX - (MAX % _tTotal));
uint256 private _tFeeTotal;
uint256 private _tFeePercent = 2;

Anybody got any idea what the r and t mean, and why they maintain _tOwned and _rOwned, _tTotal and _rTotal, etc?

Same question (though no answers): https://ethereum.stackexchange.com/questions/97782/why-do-some-contracts-use-multiple-balance-and-supply-variables — Richard Horrocks, May 09 '21 at 09:24
Haven't looked into it, but probably something along the lines of "Automatic x% Distribution to Holders and Burn on Each Transaction"... — Richard Horrocks, May 09 '21 at 09:26
@RichardHorrocks You're right that it has something to do with the mehcanic most of these coins called "reflection to holders", which incidentally starts with an r, but what's the t they also maintain for variables? t for tax? No idea! — Dimitris Sfounis, May 09 '21 at 09:28

score 16 · Accepted Answer · answered May 14 '21 at 07:22

It' a bit of an algorithm, or really just some math, to to the balance of an account. Instead of using the default "tokenSupply".

Constants
Fee is 1% (assuming no burn, just a general 1% fee)
tTotal is totalSupply and literally never changes
rTotal starts at 127366483000000 and continuously subtracts or adds
currentRate
Example:
You buy 100 Token as tAmount
>>>
Current Totals:
rTotal = 127366483000000
tTotal = 10000
currentRate = rTotal / tTotal
= 12736648300
Formula to get amount you will receive
> rTransferAmount = [rAmount] - [rFee]
[rAmount] = tAmount * currentRate
> 1273664830000 = 100 * 12736648300
[rFee] = tFee * currrentRate
> 127366483 = .01 * 12736648300
>>> 1273537463517 = [rAmount] - [rFee] = rTransferAmount
rTotal is updated to = rTotal - rTransferAmount
balanceOf():
= rAmount / currentRate
>
rAmount[me] is rAmount
rAmount = 1273537463517
currentRate = 12735374635.17
Balance: 100
...Someone else makes a transfer from x0 supply to buy 100 Tokens
rTotal = 126092945536483
tTotal = 10000
currentRate = rTotal / tTotal
= 12609294553.6483
Formula to get amount you will receive
> rTransferAmount = [rAmount] - [rFee]
rAmount = tAmount * currentRate
> 1260929455364.83 = 100 * 12609294553.6483
rFee = tFee * currrentRate
> 126092945.536483 = .01 * 12609294553.6483
>>> rTransferAmount = 1260803362419.293517
They now have 100
...Now check [me] balance after previous purchase
balanceOf():
= rAmount / currentRate
rAmount[me] is rAmount
rAmount = 1273537463517
currentRate = 12609294553.6483
Balance: 100.9998979799010304029995929297
...Now lets buy 100 more directly after checking balance
...this is the next transaction after the previous one
rTotal = 124832142174063.706483
tTotal = 10000
currentRate = rTotal / tTotal
= 12483214217.4063706483
Formula to get amount you will receive
> rTransferAmount = [rAmount] - [rFee]
rAmount = tAmount * currentRate
> 1248321421740.63706483 = 100 * 12483214217.4063706483
rFee = tFee * currrentRate
> 124832142.174063706483 = .01 * 12483214217.4063706483
>>> rTransferAmount = 1248196589598.463001123517
We now take our previous rAmount and add the rTransferAmount to update our rAmount
> rOwned[me] = rOwned[me] + rTransferAmount 
> 2521734053115.463001123517 = 1273537463517 + 1248196589598.463001123517
...Now check [me] balance after previous purchase
balanceOf():
= rAmount / currentRate
rAmount[me] is rAmount
rAmount = 2521734053115.463001123517
currentRate = 12483214217.4063706483
Balance: 202.00999591909607202719956134358
... now lets sell 100
rTotal = 123583945584465.243481876483
tTotal = 10000
currentRate = rTotal / tTotal
= 12358394558.4465243481876483
Formula to get amount you will receive
> rTransferAmount = [rAmount] - [rFee]
rAmount = tAmount * currentRate
> 1235839455844.65243481876483 = 100 * 12358394558.4465243481876483
rFee = tFee * currrentRate
> 123583945.584465243481876483 = .01 * 12358394558.4465243481876483
>>> rTransferAmount = 1235715871899.067969575282953517
We now take our previous rAmount and add the rTransferAmount to update our rAmount
(we are subtracting because we are selling)
> rOwned[me] = rOwned[me] - rTransferAmount 
> 1286018181216.395031548234046483 = 2521734053115.463001123517 - 1235715871899.067969575282953517
rTotal is updated to = rTotal - rTransferAmount 
122348229712566.17551230120004648 = 123583945584465.243481876483 - 1235715871899.067969575282953517
...Now check [me] balance after previous purchase
balanceOf():
= rAmount / currentRate
rAmount[me] is rAmount
rAmount = 1286018181216.395031548234046483
currentRate = 12358394558.4465243481876483
Balance: 104.06029481697096470326753341015

Example assumes a 1% fee with reflect and nothing else. Usually there is a fee that reflects and burns

Thanks for this answer, friend. Any reason you started rTotal at 127366483000000? — Dimitris Sfounis, May 14 '21 at 08:35
@DimitrisSfounis rTotal is fixed & pre-determined constant _rTotal = (MAX - (MAX % _tTotal)); — hack3r-0m, May 22 '21 at 18:05
@bob-linux: if you buy 100 token, and the total fee is 1%....and I think you will get 99 token in the end...am I correct? and when you calculate the balance, it seems that you don't care about how many token holders out there... why? — mc-tor, Jul 17 '21 at 09:57
I also have some doubts and there is not too much information on the internet. I think that is also because all of these coins are a clone of a previous one with same code, so the variable names are spread across all repos. — Alexander Herranz, Nov 04 '21 at 22:24
Not exactly true: _rTotal is always decreasing in order to divide less between holders. — Alexander Herranz, Nov 14 '21 at 03:04
"Not exactly true: _rTotal is always decreasing in order to divide less between holders." I forget this post, but i do believe you were right. it is always decreasing- i think — Bob Linux, Nov 21 '23 at 06:58

score 3 · Answer 2 · answered Jan 19 '22 at 22:06

Well _rTotal is simply Total Reflections and _rOwned refers to number of reflection a user owns. think of this way: we could set initial _rTotal to 100 to represent 100% and if your _rOwned value is 10, you own 10% of total reflections. in the constructor method you see after deployment of the contract, the whole reflections are transfered to the owner of the contract.

_rOwned[_msgSender()] = _rTotal;

using 100 as total reflection has a problem: solidity only supports integers and doesn't support floating point numbers, so we gotta somehow do it another way

If i am right, the reason they set _rTotal to a huge number is to make reflection very accurate and support as much floating points as possible (if i am wrong, correct me in comments), so if you own something like 0.00812301283120398912312836% of reflections, it should work accurately.

I hope i could explain it in a simple way

score 1 · Answer 3 · answered Apr 04 '22 at 16:58

tTotal, which belongs to t-space, represents tokens in circulation or total supply of a token. On the other hand, rTotal, which belongs to r-space, is a reflected value of tTotal. The term “reflected” cannot be easily explained in words but one interpretation of rTotal is token supply in reserve.

• tAmount: token amount that sender pays/transfers including tFee 　• tFee: transfer fee (note: 10% was chosen arbitrarily) 　• tTransferAmount: tokens that will get transferred to recipient 　• tOwned[user]: User’s balance represented in t-space (only used by non-stakers) 　• rOwned[user]: User’s balance represented in r-space

https://reflect-contract-doc.netlify.app/

Binance Smart Chain tokens: What are tTotal, rTotal, tSupply, rSupply, rOwned, tOwned which I see everywhere?

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