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Functionalities.md

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Smart Contract goals and restrictions

Goals

  1. Create ERC20-compatible (https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md) LAT token available for storage in Ethereum-compatible wallets and trading on cryptoexchanges
  2. Issue 400 000 000 tokens to the company pool address, including tokens for further distribution to contributors (more than 15000 contributors).
  3. Start issuing tokens from the reserve pool ("frozen tokens") on 22 August 2022. Tokens from the reserve pool will be issued every day in equal amounts (328,767.12328767126 tokens) and sent to the company pool address for 5 years starting from 22.08.2022 until all 600 000 000 tokens are issued.

Restrictions

  1. By “execution” or “calling” a function is meant a process of sending a signed transaction which will cause EVM (Ethereum Virtual Machine) to process block of code marked as a function with specified name. The transaction must be signed using a private key of an Ethereum-address (and entering the password for this key if necessary), the Ethereum-address used is called “executor” or “caller” of the function.
  2. All addresses (founder, token, minter, exchanger, helper) in smart contracts can be updated ONLY by founder and by no one else.
  3. The founder is set as the address of the smart contract deployer. After that, new founder can only be set by the previous founder (using function changeFounder)
  4. Only “minter” and “exchanger” can issue and burn tokens
  5. Only “helper” can initialize the issuance of tokens from the reserve pool to the company pool address and only starting from 22.08.2022.
  6. Only account owner can transfer tokens from his account, except cases when he entitles someone to do so by executing function "approve" with 2 arguments: address of spender (someone who will transfer tokens on your behalf) and number of tokens (spender will be allowed to spend only up to this amount in total).

Overview

Project contains 3 internal libraries:

  1. Token.sol – abstract contract for ERC20 token with necessary functions' declarations without any internal logic
  2. StandardToken.sol – implementation of ERC20 token with the necessary logic (described below)
  3. SafeMath.sol – contract providing all mathematical operations on uint256 with safety checks (basically overflow checks).

And 3 base parts:

  1. LATToken.sol - Smart contract of ERC20 token itself
  2. LATokenMinter.sol - Smart contract of minter – a contract which responsible for issuing tokens
  3. ExchangeContract.sol - Smart contract of exchanger – a contract which can automatically convert old tokens sent to it to the new tokens

Detailed view

Token.sol

No internal logic

StandardToken.sol

Function transfer

Transfers a specified number of tokens from caller to a specified address checking balances and creating the Transfer event.

Function transferFrom

Transfers a specified number of tokens from one specified address to another creating the Transfer event. There are checks for allowance (are you able to do such transfer) and for the balance (is there a sufficient balance at the address).

Function balanceOf

Returns the number of tokens for the specified address

Function approve

Sets allowance from caller to a specified address for a specified number of tokens creating Approval event.

Function approveAndCall

Sets allowance from caller to a specified address for a specified number of tokens creating Approval event and calling receiveApproval function on the smart contract receiving allowance.

Function allowance

Returns the amount of allowance given from one specified address to another.

SafeMath.sol

Function mul

Multiplies two numbers and checks if the result is correct

Function div

Divides the first number by the second number and checks if the result is correct

Function sub

Subtracts the second number from the first number and checks if the result is correct

Function add

Adds the second number to the first number and checks if the result is correct

LATToken.sol

At the deployment the contract saves deployer’s address as the founder’s address and sets totalSupply value to zero.

Variable founder

Contains address of wallet/smart contract which can execute “onlyFounder” function in the contract

Variable minter

Contains address of wallet/smart contract which can execute “onlyMinterAndExchanger” function in the contract

Variable exchanger

Contains address of wallet/smart contract which can execute “onlyMinterAndExchanger” function in the contract

Variable name

Contains the string “LAT Token” – used by wallets to show the name of token. Not used in contract internally

Variable decimals

Contains the number 18 – used by wallets to differentiate an integer and fractional part of a number in all places where the number of tokens is showed. Not used in contract internally

Variable symbol

Contains the string “LAT” – used by wallets and exchanges to show the token symbol. Not used in contract internally

Variable version

Contains the string “0.7.1” – used by wallets to show the token version. Not used in contract internally

Modifier onlyFounder

Applied to the function rejects all executions except those from the founder’s address

Modifier onlyMinterAndExchanger

Applied to the function rejects all executions except those from the minter’s or exchanger’s addresses

Function transfer

Expansion of a standard ERC20 transfer function – when transfer goes to the “exchanger” address it will not change the balance by itself, but will call “exchange” function of the exchanger’s contract passing the specified address and specified amount to it.

Function issueTokens

This function can be executed only by minter or exchanger. It adds the specified number of tokens to the balance of the specified address and to the “totalSupply” variable and creates the Issuance event

Function burnTokens

This function can be executed only by minter or exchanger. It subtracts the specified number of tokens from the balance of the specified address and from “totalSupply” variable and creates the Burn event

Function changeMinter

This function can be executed only by the founder. It replaces the current minter’s address with the specified new address

Function changeExchanger

This function can be executed only by the founder. It replaces the current exchanger’s address with the specified new address

Function changeFounder

This function can be executed only by the founder. It replaces the current founder’s address with the specified new address

LATokenMinter.sol

At the deployment the contract saves the deployer’s address as a founder’s address and saves specified token’s and helper’s addresses.

Variable founder

Contains the address of a wallet/smart contract which can execute “onlyFounder” function in the contract

Variable helper

Contains the address of a wallet/smart contract which can execute “onlyHelper” (harvest) function in the contract

Variable token

Contains the address of LATToken contract, used for issuance of tokens

Variable teamPoolInstant

Contains the address of a wallet/smart contract which will receive 400 000 000 tokens after deployment and executing “fundTeamInstant”

Variable teamPoolForFrozenTokens

Contains the address of a wallet/smart contract which will receive 600 000 000 tokens during 5 years starting from 22 August 2022

Variable teamInstantSent

Flag to prevent multiple execution of “fundTeamInstant” – by default it contains “false” value, right after the execution of “fundTeamInstant” it will contain “true” value.

Variable startTime

Unix timestamp with the starting date of the frozen tokens issuance

Variable endTime

Unix timestamp with the end date of the frozen tokens issuance, it should be equal: startTime + 5 * 365 days

Variable numberOfDays

Number of days during which the frozen tokens will be issued. Should be equal - 5 * 365.

Variable unfrozePerDay

Number of tokens issued each day after 22 August 2022. Should be equal to 600 000 000 / (5 * 365) = 328,767.12328767126 LAT

Variable alreadyHarvestedTokens

Number of tokens already unfrozen and issued to “teamPoolForFrozenTokens” address

Modifier onlyFounder

Applied to the function rejects all the executions except those from the founder’s address

Modifier onlyHelper

Applied to the function rejects all executions except those from the helper

Function fundTeamInstant

The function can be executed only once (checked by teamInstantSent flag). It issues 400 000 000 LAT to the address “teamPoolInstant”.

Function harvest

This function should be called once a day after 22 August of 2022. By each execution it calculates the number of unfrozen tokens, subtracts from it the number of already issued tokens (“alreadyHarvestedTokens”), sends unharvested unfrozen tokens to “teamPoolForFrozenTokens” and adds the number of issued tokens to “alreadyHarvestedTokens” variable.

Function changeTokenAddress

This function can be executed only by the founder. It replaces the current token’s address by the specified new address

Function changeHelper

This function can be executed only by the founder. It replaces the current helper’s address by the specified new address

Function changeTeamPoolInstant

This function can be executed only by the founder. It replaces the current teamPoolInstant address by the specified new address

Function changeTeamPoolForFrozenTokens

This function can be executed only by the founder. It replaces the current teamPoolForFrozenTokens address by the specified new address

Function changeFounder

This function can be executed only by founder. It replaces the current founder address by the specified new address

ExchangeContract.sol

At the deployment the contract saves the deployer’s address as a founder address, saves a specified previous token’s and the next token’s addresses, saves a previous token price (prevCourse) and the next token price (nextCourse).

Variable founder

Contains the address of wallet/smart contract which can execute “onlyFounder” functions in the contract

Variable prevTokenAddress

Contains the address of a smart contract of the token which will be replaced by the next token

Variable nextTokenAddress

Contains the address of a smart contract of the token which is replacing a previous token

Variable prevCourse

Contains the price of a previous token

Variable nextCourse

Contains a price of the next token

Modifier onlyFounder

Applied to the function rejects all executions except those from the founder’s address

Modifier onlyPreviousToken

Applied to the function rejects all executions except those from the previous token address

Function exchange

This function can be called only by the previous token. It should be called automatically if someone wants to send tokens to the exchanger address. It calculates the number of next tokens by dividing the number of previous tokens someone wants to exchange by the previous token price and multiplying it by the next token price. After that it burns a specified number of previous tokens and issues the calculated number of the next tokens to the specified address (with all balance checks).

Function changeCourse

Saves new prices of the previous and next tokens

Function changeFounder

This function can be executed only by the founder. It replaces the current founder’s address by the specified new address