feat: AMM

l1-contracts/src/core/libraries/ConstantsGen.sol

@@ -18,7 +18,7 @@ library Constants {
   uint256 internal constant ARGS_LENGTH = 16;
   uint256 internal constant MAX_NOTE_HASHES_PER_CALL = 16;
   uint256 internal constant MAX_NULLIFIERS_PER_CALL = 16;
-  uint256 internal constant MAX_PRIVATE_CALL_STACK_LENGTH_PER_CALL = 4;
+  uint256 internal constant MAX_PRIVATE_CALL_STACK_LENGTH_PER_CALL = 5;
   uint256 internal constant MAX_ENQUEUED_CALLS_PER_CALL = 16;
   uint256 internal constant MAX_L2_TO_L1_MSGS_PER_CALL = 2;
   uint256 internal constant MAX_PUBLIC_DATA_UPDATE_REQUESTS_PER_CALL = 64;
@@ -202,7 +202,7 @@ library Constants {
   uint256 internal constant TOTAL_FEES_LENGTH = 1;
   uint256 internal constant TOTAL_MANA_USED_LENGTH = 1;
   uint256 internal constant HEADER_LENGTH = 25;
-  uint256 internal constant PRIVATE_CIRCUIT_PUBLIC_INPUTS_LENGTH = 491;
+  uint256 internal constant PRIVATE_CIRCUIT_PUBLIC_INPUTS_LENGTH = 499;
   uint256 internal constant PUBLIC_CIRCUIT_PUBLIC_INPUTS_LENGTH = 867;
   uint256 internal constant PRIVATE_CONTEXT_INPUTS_LENGTH = 38;
   uint256 internal constant FEE_RECIPIENT_LENGTH = 2;

noir-projects/aztec-nr/aztec/src/macros/functions/interfaces.nr

@@ -131,7 +131,7 @@ pub comptime fn stub_fn(f: FunctionDefinition) -> Quoted {
             $args
             let selector = dep::aztec::protocol_types::abis::function_selector::FunctionSelector::from_field($fn_selector);
             $call_interface_name {
-                target_contract: self.target_contract,
+                target_contract: self.addr,
                 selector,
                 name: $fn_name_str,
                 $args_hash

noir-projects/aztec-nr/aztec/src/macros/mod.nr

@@ -71,35 +71,35 @@ comptime fn generate_contract_interface(m: Module) -> Quoted {
 
     quote {
         pub struct $module_name {
-            target_contract: dep::aztec::protocol_types::address::AztecAddress
+            addr: dep::aztec::protocol_types::address::AztecAddress
         }
 
         impl $module_name {
             $fn_stubs_quote
 
             pub fn at(
-                target_contract: aztec::protocol_types::address::AztecAddress
+                addr: aztec::protocol_types::address::AztecAddress
             ) -> Self {
-                Self { target_contract }
+                Self { addr }
             }
 
             pub fn interface() -> Self {
-                Self { target_contract: aztec::protocol_types::address::AztecAddress::zero() }
+                Self { addr: aztec::protocol_types::address::AztecAddress::zero() }
             }
 
             $storage_layout_getter
         }
 
         #[contract_library_method]
         pub fn at(
-            target_contract: aztec::protocol_types::address::AztecAddress
+            addr: aztec::protocol_types::address::AztecAddress
         ) -> $module_name {
-            $module_name { target_contract }
+            $module_name { addr }
         }
 
         #[contract_library_method]
         pub fn interface() -> $module_name {
-            $module_name { target_contract: aztec::protocol_types::address::AztecAddress::zero() }
+            $module_name { addr: aztec::protocol_types::address::AztecAddress::zero() }
         }
 
         $library_storage_layout_getter

noir-projects/noir-contracts/Nargo.toml

@@ -1,5 +1,6 @@
 [workspace]
 members = [
+    "contracts/amm_contract",
     "contracts/app_subscription_contract",
     "contracts/auth_contract",
     "contracts/auth_registry_contract",

noir-projects/noir-contracts/contracts/amm_contract/Nargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "amm_contract"
+authors = [""]
+compiler_version = ">=0.25.0"
+type = "contract"
+
+[dependencies]
+aztec = { path = "../../../aztec-nr/aztec" }
+token = { path = "../token_contract" }

noir-projects/noir-contracts/contracts/amm_contract/src/config.nr

@@ -0,0 +1,29 @@
+use dep::aztec::protocol_types::{address::AztecAddress, traits::{Deserialize, Serialize}};
+
+global CONFIG_LENGTH: u32 = 3;
+
+/// We store the tokens of the pool in a struct such that to load it from SharedImmutable asserts only a single
+/// merkle proof.
+/// (Once we actually do the optimization. WIP in https://github.com/AztecProtocol/aztec-packages/pull/8022).
+pub struct Config {
+    pub token0: AztecAddress,
+    pub token1: AztecAddress,
+    pub liquidity_token: AztecAddress,
+}
+
+// Note: I could not get #[derive(Serialize)] to work so I had to implement it manually.
+impl Serialize<CONFIG_LENGTH> for Config {
+    fn serialize(self: Self) -> [Field; CONFIG_LENGTH] {
+        [self.token0.to_field(), self.token1.to_field(), self.liquidity_token.to_field()]
+    }
+}
+
+impl Deserialize<CONFIG_LENGTH> for Config {
+    fn deserialize(fields: [Field; CONFIG_LENGTH]) -> Self {
+        Self {
+            token0: AztecAddress::from_field(fields[0]),
+            token1: AztecAddress::from_field(fields[1]),
+            liquidity_token: AztecAddress::from_field(fields[2]),
+        }
+    }
+}

noir-projects/noir-contracts/contracts/amm_contract/src/lib.nr

@@ -0,0 +1,96 @@
+/// Given an input amount of an asset and pair balances, returns the maximum output amount of the other asset.
+pub fn get_amount_out(amount_in: U128, balance_in: U128, balance_out: U128) -> U128 {
+    assert(amount_in > U128::zero(), "INSUFFICIENT_INPUT_AMOUNT");
+    assert((balance_in > U128::zero()) & (balance_out > U128::zero()), "INSUFFICIENT_LIQUIDITY");
+
+    // The expression below is:
+    //    (amount_in * 997 * balance_out) / (balance_in * 10000 + amount_in * 997)
+    // which is equivalent to:
+    //    balance_out * ((amount_in * 0.997) / (balance_in + amount_in * 0.997))
+    // resulting in an implicit 0.3% fee on the amount in, as the fee tokens are not taken into consideration.
+
+    let amount_in_with_fee = amount_in * U128::from_integer(997);
+    let numerator = amount_in_with_fee * balance_out;
+    let denominator = balance_in * U128::from_integer(1000) + amount_in_with_fee;
+    numerator / denominator
+}
+
+/// Given an output amount of an asset and pair balances, returns a required input amount of the other asset.
+pub fn get_amount_in(amount_out: U128, balance_in: U128, balance_out: U128) -> U128 {
+    assert(amount_out > U128::zero(), "INSUFFICIENT_OUTPUT_AMOUNT");
+    assert((balance_in > U128::zero()) & (balance_out > U128::zero()), "INSUFFICIENT_LIQUIDITY");
+
+    // The expression below is:
+    //    (balance_in * amount_out * 1000) / (balance_out - amout_out * 997) + 1
+    // which is equivalent to:
+    //    balance_in * (amount_out / (balance_in + amount_in)) *  1/0.997 + 1
+    // resulting in an implicit 0.3% fee on the amount in, as the fee tokens are not taken into consideration. The +1
+    // at the end ensures the rounding error favors the pool.
+
+    let numerator = balance_in * amount_out * U128::from_integer(1000);
+    let denominator = (balance_out - amount_out) * U128::from_integer(997);
+    (numerator / denominator) + U128::from_integer(1)
+}
+
+/// Given the desired amounts and balances of token0 and token1 returns the optimal amount of token0 and token1 to be added to the pool.
+pub fn get_amounts_to_add(
+    amount0_max: U128,
+    amount1_max: U128,
+    amount0_min: U128,
+    amount1_min: U128,
+    balance0: U128,
+    balance1: U128,
+) -> (U128, U128) {
+    // When adding tokens, both balances must grow by the same ratio, which means that their spot price is unchanged.
+    // Since any swaps would affect these ratios, liquidity providers supply a range of minimum and maximum balances
+    // they are willing to supply for each token (which translates to minimum and maximum relative prices of the
+    // tokens, preventing loss of value outside of this range due to e.g. front-running).
+
+    if (balance0 == U128::zero()) | (balance1 == U128::zero()) {
+        // The token balances should only be zero when initializing the pool. In this scenario there is no prior ratio
+        // to follow so we simply transfer the full maximum balance - it is up to the caller to make sure that the ratio
+        // they've chosen results in a a reasonable spot price.
+        (amount0_max, amount1_max)
+    } else {
+        // There is a huge number of amount combinations that respect the minimum and maximum for each token, but we'll
+        // only consider the two scenarios in which one of the amounts is the maximum amount.
+
+        // First we calculate the token1 amount that'd need to be supplied if we used the maximum amount for token0.
+        let amount1_equivalent = get_equivalent_amount(amount0_max, balance0, balance1);
+        if (amount1_equivalent <= amount1_max) {
+            assert(amount1_equivalent >= amount1_min, "AMOUNT_1_BELOW_MINIMUM");
+            (amount0_max, amount1_equivalent)
+        } else {
+            // If the max amount for token0 results in a token1 amount larger than the maximum, then we try with the
+            // maximum token1 amount, hoping that it'll result in a token0 amount larger than the minimum.
+            let amount0_equivalent = get_equivalent_amount(amount1_max, balance1, balance0);
+            // This should never happen, as it'd imply that the maximum is lower than the minimum.
+            assert(amount0_equivalent <= amount0_max);
+
+            assert(amount0_equivalent >= amount0_min, "AMOUNT_0_BELOW_MINIMUM");
+            (amount0_equivalent, amount1_max)
+        }
+    }
+}
+
+/// Returns the amount of tokens to return to a liquidity provider when they remove liquidity from the pool.
+pub fn get_amounts_on_remove(
+    to_burn: U128,
+    total_supply: U128,
+    balance0: U128,
+    balance1: U128,
+) -> (U128, U128) {
+    // Since the liquidity token tracks ownership of the pool, the liquidity provider gets a proportional share of each
+    // token.
+    (to_burn * balance0 / total_supply, to_burn * balance1 / total_supply)
+}
+
+/// Given some amount of an asset and pair balances, returns an equivalent amount of the other asset. Tokens should be
+/// added and removed from the Pool respecting this ratio.
+fn get_equivalent_amount(amount0: U128, balance0: U128, balance1: U128) -> U128 {
+    assert((balance0 > U128::zero()) & (balance1 > U128::zero()), "INSUFFICIENT_LIQUIDITY");
+
+    // This is essentially the Rule of Three, since we're computing proportional ratios. Note we divide at the end to
+    // avoid introducing too much error due to truncation.
+    (amount0 * balance1) / balance0
+}