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Reading pool price

How to interpret pool data from the on-chain methods

Computing the price of a pool

Let's say you wanted to determine the human-readable price of the ETH-USDC pool on mainnet.
These two tokens are:
  • ETH: 0x049d36570d4e46f48e99674bd3fcc84644ddd6b96f7c741b1562b82f9e004dc7 (Voyager)
  • USDC: 0x053c91253bc9682c04929ca02ed00b3e423f6710d2ee7e0d5ebb06f3ecf368a8 (Voyager)
First, let's determine which token is token0 and which token is token1. We can do this by comparing the integer values of the addresses. In this case, 0x053c91253bc9682c04929ca02ed00b3e423f6710d2ee7e0d5ebb06f3ecf368a8 > 0x049d36570d4e46f48e99674bd3fcc84644ddd6b96f7c741b1562b82f9e004dc7, so USDC is token1 and ETH is token0.
Next, we need to decide which pool to read. Let's use the pool with the 0.05% fee and the 0.1% tick spacing, since it's the most popular ETH/USDC pool. The easiest way to get the fee and tick spacing parameters is to read the URL from the website when you add liquidity to this pool:
https://app.ekubo.org/positions/new?baseCurrency=ETH&quoteCurrency=USDC&fee=170141183460469235273462165868118016&tickSpacing=1000
The second easiest way is to compute the value. Fee is a 0.128 fixed point number, so to compute the fee, we can do floor(0.05% * 2**128). The result is 170141183460469235273462165868118016. The tick spacing of 0.01% is represented as an exponent of 1.000001, so it can be computed as log base 1.000001 of 1.001, which is roughly equal to 1000. The extension is 0 because it is not used for this pool.
Input the values into the Core contract on Voyager to read the pool price. If you're following along, you'll get a value that looks like this:
{
"sqrt_ratio": "0x029895c9cbfca44f2c46e6e9b5459b",
"tick": {
"mag": "0x0135566d",
"sign": "0x01"
},
"call_points": {
"after_initialize_pool": "0x00",
"before_swap": "0x00",
"after_swap": "0x00",
"before_update_position": "0x00",
"after_update_position": "0x00"
}
}
Let's compute the price from this result. The value sqrt_ratio is a 64.128 fixed point number. To convert it to a price, first divide it by 2**128, then square it to get the price. Since USDC is token1, this value is the price of the pool in USDC/ETH. (0x029895c9cbfca44f2c46e6e9b5459b / 2**128)**2 == 1.56914... ×10^-9. To adjust for display, we have to account for the decimal difference between the USDC and ETH tokens. Because USDC has 6 decimals and ETH has 18 decimals, we need to scale it up by 10**(18-6) to be human readable. 1.56914e-9 * 1e12 == 1.56914e3 == 1569.14 USDC/ETH.
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