Uniswap

Peripheral EOSIO smart contracts for interacting with Uniswap V2

Quickstart

#include "uniswap.hpp"

// Inputs
const uint64_t amount_in = 10000;
const uint64_t reserve_in = 45851931234;
const uint64_t reserve_out = 125682033533;
const uint8_t fee = 30;

// Calculation
const uint64_t out = uniswap::get_amount_out( amount_in, reserve_in, reserve_out, fee );
// => 27328

Pseudocode Price Formula

function get_amount_out( amount_in, reserve_in, reserve_out, fee ) {
    amount_in_with_fee = amount_in * (10000 - fee);
    numerator = amount_in_with_fee * reserve_out;
    denominator = reserve_in * 10000 + amount_in_with_fee;
    amount_out = numerator / denominator;
    return amount_out;
}

Table of Content

• STATIC get_amount_out
• STATIC get_amount_in
• STATIC quote

STATIC get_amount_out

Given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset

params

• {uint64_t} amount_in - amount input
• {uint64_t} reserve_in - reserve input
• {uint64_t} reserve_out - reserve output
• {uint8_t} [fee=30] - (optional) trade fee (pips 1/100 of 1%)

example

// Inputs
const uint64_t amount_in = 10000;
const uint64_t reserve_in = 45851931234;
const uint64_t reserve_out = 125682033533;
const uint8_t fee = 30;

// Calculation
const uint64_t amount_out = uniswap::get_amount_out( amount_in, reserve_in, reserve_out, fee );
// => 27328

STATIC get_amount_in

Given an output amount of an asset and pair reserves, returns a required input amount of the other asset.

params

• {uint64_t} amount_in - amount input
• {uint64_t} reserve_in - reserve input
• {uint64_t} reserve_out - reserve output
• {uint8_t} [fee=30] - (optional) trade fee (pips 1/100 of 1%)

example

// Inputs
const uint64_t amount_out = 27328;
const uint64_t reserve_in = 45851931234;
const uint64_t reserve_out = 125682033533;
const uint8_t fee = 30;

// Calculation
const uint64_t amount_in = uniswap::get_amount_in( amount_out, reserve_in, reserve_out, fee );
// => 10000

STATIC quote

Given some amount of an asset and pair reserves, returns an equivalent amount of the other asset

params

• {uint64_t} amount_a - amount A
• {uint64_t} reserve_a - reserve A
• {uint64_t} reserve_b - reserve B

example

// Inputs
const uint64_t amount_a = 10000;
const uint64_t reserve_a = 45851931234;
const uint64_t reserve_b = 125682033533;

// Calculation
const uint64_t amountB = uniswap::quote( amount_a, reserve_a, reserve_b );
// => 27410