Initial implementation

README.md

@@ -0,0 +1,64 @@
+## Conv
+
+On-chain repository for MCD rates.
+
+`Conv` stores all per-second MCD rates for annualized BPSs in a single on-chain repository.
+
+It allows to convert BPS into `RAY` accumulators and _vice versa_.
+
+### Motivation
+
+Useful for validation using human-friendly notation, which drastically reduces the cognitive overhead when checking rates.
+
+Requirements:
+- The rates need to have full precision compared to rates currently used in MCD (https://ipfs.io/ipfs/QmVp4mhhbwWGTfbh2BzwQB9eiBrQBKiqcPRZCaAxNUaar6)
+- Read cost should be reasonable, allowing other components of the system to use it without too much overhead.
+- The contract needs to be deployable efficiently (low priority, one time cost).
+
+### Design
+
+We explored several ways to store or calculate rates onchain and arrive at this approach, for details see [this](https://github.com/dewiz-xyz/conv-research).
+
+The contract makes use of optimized storage to ease the cost of deployment. Each rate is stored as `rate - RAY`, so only the relevant part of the rate takes space in storage. Each rate is stored in 8 bytes, so every storage position fits exactly four rates.
+
+On reads, the function `btor(bps)` will fetch the correct storage slot, fetch the desired rate within it, add one RAY and return the result.
+
+The contract also includes a conversion function `rtob(ray)` that calculates the annualized BPS rate from the per-second rate.
+
+### Limitations
+
+- Since rates are stored in 8 bytes, the max BPS that can be used without reimplementing this contract is **7891**.
+- EIP-170: Due to contract size limits on Ethereum mainnet, the ceiling for rates is 6k. On L2s that do not enforce the limit this does not apply.
+- Gas cost of deployment: With the current 30M block gas ceiling on Ethereum mainnet, up to ~5.5k rates can be stored.
+
+## Deployments
+
+- **5000bps Ethereum Mainnet**: tbd
+
+## Usage
+
+### Build
+
+```shell
+$ forge build
+```
+
+### Test
+
+```shell
+$ forge test
+```
+
+### Gas Snapshots
+
+```shell
+$ forge snapshot
+```
+
+### Deploy
+
+```shell
+$ forge script script/ConvDeploy.s.sol:ConvDeployScript \
+    --rpc-url $ETH_RPC_URL \
+    --broadcast
+```

foundry.toml

@@ -6,7 +6,7 @@ libs = ["lib"]
 solc = '0.8.24'
 
 optimizer = true
-optimizer_runs = 1
+optimizer_runs = 200
 
 [fuzz]
 runs = 256000

script/ConvDeploy.s.sol

@@ -0,0 +1,36 @@
+// SPDX-FileCopyrightText: 2025 Dai Foundation <www.daifoundation.org>
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+pragma solidity ^0.8.24;
+
+import {Script} from "forge-std/Script.sol";
+import {ScriptTools} from "dss-test/ScriptTools.sol";
+import {Conv} from "src/Conv.sol";
+
+contract ConvDeployScript is Script {
+    using ScriptTools for string;
+
+    string constant NAME = "conv-deploy";
+
+    function run() external {
+        vm.startBroadcast();
+
+        Conv conv = new Conv();
+
+        vm.stopBroadcast();
+
+        ScriptTools.exportContract(NAME, "conv", address(conv));
+    }
+}

script/GasMetering.s.sol

@@ -0,0 +1,146 @@
+// SPDX-FileCopyrightText: 2025 Dai Foundation <www.daifoundation.org>
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+pragma solidity ^0.8.24;
+
+import {Script} from "forge-std/Script.sol";
+import {console} from "forge-std/console.sol";
+import {Conv} from "src/Conv.sol";
+
+contract GasMeteringScript is Script {
+    function run() external {
+        Conv conv;
+
+        uint256 gasBefore = gasleft();
+        conv = new Conv();
+        console.log("Deploy: ", gasBefore - gasleft());
+
+        for (uint256 i; i <= 5_000; i += 123) {
+            gasBefore = gasleft();
+            conv.btor(i);
+            console.log("btor", i, ":", gasBefore - gasleft());
+        }
+
+        uint256[] memory rates = new uint256[](101);
+
+        rates[0] = 1000000000000000000000000000;
+        rates[1] = 1000000000315522921573372069;
+        rates[2] = 1000000000627937192491029810;
+        rates[3] = 1000000000937303470807876289;
+        rates[4] = 1000000001243680656318820312;
+        rates[5] = 1000000001547125957863212448;
+        rates[6] = 1000000001847694957439350562;
+        rates[7] = 1000000002145441671308778766;
+        rates[8] = 1000000002440418608258400030;
+        rates[9] = 1000000002732676825177582095;
+        rates[10] = 1000000003022265980097387650;
+        rates[11] = 1000000003309234382829738808;
+        rates[12] = 1000000003593629043335673582;
+        rates[13] = 1000000003875495717943815211;
+        rates[14] = 1000000004154878953532704765;
+        rates[15] = 1000000004431822129783699001;
+        rates[16] = 1000000004706367499604668374;
+        rates[17] = 1000000004978556227818707070;
+        rates[18] = 1000000005248428428206454010;
+        rates[19] = 1000000005516023198985389892;
+        rates[20] = 1000000005781378656804591712;
+        rates[21] = 1000000006044531969328866955;
+        rates[22] = 1000000006305519386481930552;
+        rates[23] = 1000000006564376270414306730;
+        rates[24] = 1000000006821137124257914908;
+        rates[25] = 1000000007075835619725814915;
+        rates[26] = 1000000007328504623612325153;
+        rates[27] = 1000000007579176223245671878;
+        rates[28] = 1000000007827881750942464045;
+        rates[29] = 1000000008074651807510602798;
+        rates[30] = 1000000008319516284844715115;
+        rates[31] = 1000000008562504387655836125;
+        rates[32] = 1000000008803644654374843395;
+        rates[33] = 1000000009042964977267059505;
+        rates[34] = 1000000009280492621793477151;
+        rates[35] = 1000000009516254245252215861;
+        rates[36] = 1000000009750275914732082986;
+        rates[37] = 1000000009982583124408477109;
+        rates[38] = 1000000010213200812210332586;
+        rates[39] = 1000000010442153375885353361;
+        rates[40] = 1000000010669464688489416886;
+        rates[41] = 1000000010895158113324739488;
+        rates[42] = 1000000011119256518350177948;
+        rates[43] = 1000000011341782290085893805;
+        rates[44] = 1000000011562757347033522598;
+        rates[45] = 1000000011782203152631966084;
+        rates[46] = 1000000012000140727767957524;
+        rates[47] = 1000000012216590662859635112;
+        rates[48] = 1000000012431573129530493155;
+        rates[49] = 1000000012645107891890261872;
+        rates[50] = 1000000012857214317438491659;
+        rates[51] = 1000000013067911387605883890;
+        rates[52] = 1000000013277217707947715318;
+        rates[53] = 1000000013485151518003044532;
+        rates[54] = 1000000013691730700832764691;
+        rates[55] = 1000000013896972792248974855;
+        rates[56] = 1000000014100894989747580713;
+        rates[57] = 1000000014303514161155502800;
+        rates[58] = 1000000014504846853003364537;
+        rates[59] = 1000000014704909298634052283;
+        rates[60] = 1000000014903717426057083481;
+        rates[61] = 1000000015101286865558285606;
+        rates[62] = 1000000015297632957073876761;
+        rates[63] = 1000000015492770757337647112;
+        rates[64] = 1000000015686715046809567945;
+        rates[65] = 1000000015879480336393800741;
+        rates[66] = 1000000016071080873953741499;
+        rates[67] = 1000000016261530650631414500;
+        rates[68] = 1000000016450843406978224029;
+        rates[69] = 1000000016639032638903781446;
+        rates[70] = 1000000016826111603449247521;
+        rates[71] = 1000000017012093324391365593;
+        rates[72] = 1000000017196990597683109018;
+        rates[73] = 1000000017380815996736626004;
+        rates[74] = 1000000017563581877553935633;
+        rates[75] = 1000000017745300383710610088;
+        rates[76] = 1000000017925983451197469286;
+        rates[77] = 1000000018105642813125114801;
+        rates[78] = 1000000018284290004295939569;
+        rates[79] = 1000000018461936365648068049;
+        rates[80] = 1000000018638593048575507813;
+        rates[81] = 1000000018814271019128627481;
+        rates[82] = 1000000018988981062098917230;
+        rates[83] = 1000000019162733784991836346;
+        rates[84] = 1000000019335539621891407188;
+        rates[85] = 1000000019507408837220076029;
+        rates[86] = 1000000019678351529397228463;
+        rates[87] = 1000000019848377634399619849;
+        rates[88] = 1000000020017496929226859581;
+        rates[89] = 1000000020185719035274971385;
+        rates[90] = 1000000020353053421620940223;
+        rates[91] = 1000000020519509408221049399;
+        rates[92] = 1000000020685096169025709028;
+        rates[93] = 1000000020849822735013378765;
+        rates[94] = 1000000021013697997146093523;
+        rates[95] = 1000000021176730709249010667;
+        rates[96] = 1000000021338929490816310513;
+        rates[97] = 1000000021500302829745698932;
+        rates[98] = 1000000021660859085003681151;
+        rates[99] = 1000000021820606489223699321;
+        rates[100] = 1000000021979553151239153027;
+
+        for (uint256 i; i < rates.length; i++) {
+            gasBefore = gasleft();
+            conv.rtob(rates[i]);
+            console.log("rtob", rates[i], ":", gasBefore - gasleft());
+        }
+    }
+}