chore: Prune old contracts (#304)

Prune exchange-libs
deploy migrations at specific address
remove exchange-libs, moving LibMath into Utils
Remove staking order-utils multisig and remaining asset-proxy

contracts/utils/src/reference_functions.ts

@@ -1,4 +1,4 @@
-import { BigNumber, SafeMathRevertErrors } from '@0x/utils';
+import { BigNumber, LibMathRevertErrors, SafeMathRevertErrors } from '@0x/utils';
 
 const MAX_UINT256 = new BigNumber(2).pow(256).minus(1);
 
@@ -52,3 +52,77 @@ export function safeDiv(a: BigNumber, b: BigNumber): BigNumber {
     }
     return a.dividedToIntegerBy(b);
 }
+
+// LibMath
+
+/**
+ * Checks if rounding error >= 0.1% when rounding down.
+ */
+export function isRoundingErrorFloor(numerator: BigNumber, denominator: BigNumber, target: BigNumber): boolean {
+    if (denominator.eq(0)) {
+        throw new LibMathRevertErrors.DivisionByZeroError();
+    }
+    if (numerator.eq(0) || target.eq(0)) {
+        return false;
+    }
+    const remainder = numerator.times(target).mod(denominator);
+    // Need to do this separately because solidity evaluates RHS of the comparison expression first.
+    const rhs = safeMul(numerator, target);
+    const lhs = safeMul(remainder, new BigNumber(1000));
+    return lhs.gte(rhs);
+}
+
+/**
+ * Checks if rounding error >= 0.1% when rounding up.
+ */
+export function isRoundingErrorCeil(numerator: BigNumber, denominator: BigNumber, target: BigNumber): boolean {
+    if (denominator.eq(0)) {
+        throw new LibMathRevertErrors.DivisionByZeroError();
+    }
+    if (numerator.eq(0) || target.eq(0)) {
+        return false;
+    }
+    let remainder = numerator.times(target).mod(denominator);
+    remainder = safeSub(denominator, remainder).mod(denominator);
+    // Need to do this separately because solidity evaluates RHS of the comparison expression first.
+    const rhs = safeMul(numerator, target);
+    const lhs = safeMul(remainder, new BigNumber(1000));
+    return lhs.gte(rhs);
+}
+
+/**
+ * Calculates partial value given a numerator and denominator rounded down.
+ *      Reverts if rounding error is >= 0.1%
+ */
+export function safeGetPartialAmountFloor(numerator: BigNumber, denominator: BigNumber, target: BigNumber): BigNumber {
+    if (isRoundingErrorFloor(numerator, denominator, target)) {
+        throw new LibMathRevertErrors.RoundingError(numerator, denominator, target);
+    }
+    return safeDiv(safeMul(numerator, target), denominator);
+}
+
+/**
+ * Calculates partial value given a numerator and denominator rounded down.
+ *      Reverts if rounding error is >= 0.1%
+ */
+export function safeGetPartialAmountCeil(numerator: BigNumber, denominator: BigNumber, target: BigNumber): BigNumber {
+    if (isRoundingErrorCeil(numerator, denominator, target)) {
+        throw new LibMathRevertErrors.RoundingError(numerator, denominator, target);
+    }
+    return safeDiv(safeAdd(safeMul(numerator, target), safeSub(denominator, new BigNumber(1))), denominator);
+}
+
+/**
+ * Calculates partial value given a numerator and denominator rounded down.
+ */
+export function getPartialAmountFloor(numerator: BigNumber, denominator: BigNumber, target: BigNumber): BigNumber {
+    return safeDiv(safeMul(numerator, target), denominator);
+}
+
+/**
+ * Calculates partial value given a numerator and denominator rounded down.
+ */
+export function getPartialAmountCeil(numerator: BigNumber, denominator: BigNumber, target: BigNumber): BigNumber {
+    const sub = safeSub(denominator, new BigNumber(1)); // This is computed first to simulate Solidity's order of operations
+    return safeDiv(safeAdd(safeMul(numerator, target), sub), denominator);
+}