Add UD21x18 and SD21x18 types

src/casting/Uint128.sol

@@ -14,7 +14,7 @@ import { UD60x18 } from "../ud60x18/ValueType.sol";
 /// @notice Thrown when trying to cast a uint128 that doesn't fit in SD1x18.
 error PRBMath_IntoSD1x18_Overflow(uint128 x);
 
-/// @notice Thrown when trying to cast a uint128 that doesn't fit in SD1x18.
+/// @notice Thrown when trying to cast a uint128 that doesn't fit in SD21x18.
 error PRBMath_IntoSD21x18_Overflow(uint128 x);
 
 /// @notice Thrown when trying to cast a uint128 that doesn't fit in UD2x18.
@@ -33,7 +33,7 @@ library PRBMathCastingUint128 {
         result = SD1x18.wrap(int64(uint64(x)));
     }
 
-    /// @notice Casts a uint256 number to SD21x18.
+    /// @notice Casts a uint128 number to SD21x18.
     /// @dev Requirements:
     /// - x must be less than or equal to `uMAX_SD21x18`.
     function intoSD21x18(uint128 x) internal pure returns (SD21x18 result) {
@@ -60,7 +60,6 @@ library PRBMathCastingUint128 {
     }
 
     /// @notice Casts a uint128 number to UD21x18.
-    /// @dev There is no overflow check because the domain of uint128 is a subset of UD21x18.
     function intoUD21x18(uint128 x) internal pure returns (UD21x18 result) {
         result = UD21x18.wrap(x);
     }

src/casting/Uint256.sol

@@ -8,8 +8,8 @@ import { SD21x18 } from "../sd21x18/ValueType.sol";
 import { uMAX_SD59x18 } from "../sd59x18/Constants.sol";
 import { SD59x18 } from "../sd59x18/ValueType.sol";
 import { uMAX_UD2x18 } from "../ud2x18/Constants.sol";
-import { uMAX_UD21x18 } from "../ud21x18/Constants.sol";
 import { UD2x18 } from "../ud2x18/ValueType.sol";
+import { uMAX_UD21x18 } from "../ud21x18/Constants.sol";
 import { UD21x18 } from "../ud21x18/ValueType.sol";
 import { UD60x18 } from "../ud60x18/ValueType.sol";
 
@@ -62,6 +62,8 @@ library PRBMathCastingUint256 {
     }
 
     /// @notice Casts a uint256 number to UD2x18.
+    /// @dev Requirements:
+    /// - x must be less than or equal to `uMAX_UD2x18`.
     function intoUD2x18(uint256 x) internal pure returns (UD2x18 result) {
         if (x > uint256(uMAX_UD2x18)) {
             revert PRBMath_IntoUD2x18_Overflow(x);
@@ -70,6 +72,8 @@ library PRBMathCastingUint256 {
     }
 
     /// @notice Casts a uint256 number to UD2x18.
+    /// @dev Requirements:
+    /// - x must be less than or equal to `uMAX_UD21x18`.
     function intoUD21x18(uint256 x) internal pure returns (UD21x18 result) {
         if (x > uint256(uMAX_UD21x18)) {
             revert PRBMath_IntoUD21x18_Overflow(x);

src/sd1x18/Casting.sol

@@ -53,26 +53,26 @@ function intoUD60x18(SD1x18 x) pure returns (UD60x18 result) {
     result = UD60x18.wrap(uint64(xInt));
 }
 
-/// @notice Casts an SD1x18 number into uint256.
+/// @notice Casts an SD1x18 number into uint128.
 /// @dev Requirements:
 /// - x must be positive.
-function intoUint256(SD1x18 x) pure returns (uint256 result) {
+function intoUint128(SD1x18 x) pure returns (uint128 result) {
     int64 xInt = SD1x18.unwrap(x);
     if (xInt < 0) {
-        revert CastingErrors.PRBMath_SD1x18_ToUint256_Underflow(x);
+        revert CastingErrors.PRBMath_SD1x18_ToUint128_Underflow(x);
     }
-    result = uint256(uint64(xInt));
+    result = uint128(uint64(xInt));
 }
 
-/// @notice Casts an SD1x18 number into uint128.
+/// @notice Casts an SD1x18 number into uint256.
 /// @dev Requirements:
 /// - x must be positive.
-function intoUint128(SD1x18 x) pure returns (uint128 result) {
+function intoUint256(SD1x18 x) pure returns (uint256 result) {
     int64 xInt = SD1x18.unwrap(x);
     if (xInt < 0) {
-        revert CastingErrors.PRBMath_SD1x18_ToUint128_Underflow(x);
+        revert CastingErrors.PRBMath_SD1x18_ToUint256_Underflow(x);
     }
-    result = uint128(uint64(xInt));
+    result = uint256(uint64(xInt));
 }
 
 /// @notice Casts an SD1x18 number into uint40.

src/sd1x18/Errors.sol

@@ -3,23 +3,23 @@ pragma solidity >=0.8.19;
 
 import { SD1x18 } from "./ValueType.sol";
 
-/// @notice Thrown when trying to cast a SD1x18 number that doesn't fit in UD2x18.
+/// @notice Thrown when trying to cast an SD1x18 number that doesn't fit in UD2x18.
 error PRBMath_SD1x18_ToUD2x18_Underflow(SD1x18 x);
 
-/// @notice Thrown when trying to cast a SD1x18 number that doesn't fit in UD21x18.
+/// @notice Thrown when trying to cast an SD1x18 number that doesn't fit in UD21x18.
 error PRBMath_SD1x18_ToUD21x18_Underflow(SD1x18 x);
 
-/// @notice Thrown when trying to cast a SD1x18 number that doesn't fit in UD60x18.
+/// @notice Thrown when trying to cast an SD1x18 number that doesn't fit in UD60x18.
 error PRBMath_SD1x18_ToUD60x18_Underflow(SD1x18 x);
 
-/// @notice Thrown when trying to cast a SD1x18 number that doesn't fit in uint128.
+/// @notice Thrown when trying to cast an SD1x18 number that doesn't fit in uint128.
 error PRBMath_SD1x18_ToUint128_Underflow(SD1x18 x);
 
-/// @notice Thrown when trying to cast a SD1x18 number that doesn't fit in uint256.
+/// @notice Thrown when trying to cast an SD1x18 number that doesn't fit in uint256.
 error PRBMath_SD1x18_ToUint256_Underflow(SD1x18 x);
 
-/// @notice Thrown when trying to cast a SD1x18 number that doesn't fit in uint40.
+/// @notice Thrown when trying to cast an SD1x18 number that doesn't fit in uint40.
 error PRBMath_SD1x18_ToUint40_Overflow(SD1x18 x);
 
-/// @notice Thrown when trying to cast a SD1x18 number that doesn't fit in uint40.
+/// @notice Thrown when trying to cast an SD1x18 number that doesn't fit in uint40.
 error PRBMath_SD1x18_ToUint40_Underflow(SD1x18 x);

src/sd1x18/ValueType.sol

@@ -19,8 +19,8 @@ using {
     Casting.intoUD2x18,
     Casting.intoUD21x18,
     Casting.intoUD60x18,
-    Casting.intoUint256,
     Casting.intoUint128,
+    Casting.intoUint256,
     Casting.intoUint40,
     Casting.unwrap
 } for SD1x18 global;

src/sd21x18/Casting.sol

@@ -6,6 +6,7 @@ import "./Errors.sol" as CastingErrors;
 import { SD1x18 } from "../sd1x18/ValueType.sol";
 import { uMAX_SD1x18, uMIN_SD1x18 } from "../sd1x18/Constants.sol";
 import { SD59x18 } from "../sd59x18/ValueType.sol";
+import { uMAX_UD2x18 } from "../ud2x18/Constants.sol";
 import { UD2x18 } from "../ud2x18/ValueType.sol";
 import { UD21x18 } from "../ud21x18/ValueType.sol";
 import { UD60x18 } from "../ud60x18/ValueType.sol";
@@ -34,11 +35,15 @@ function intoSD59x18(SD21x18 x) pure returns (SD59x18 result) {
 
 /// @notice Casts an SD21x18 number into UD2x18.
 /// - x must be positive.
+/// - x must be less than or equal to `uMAX_UD2x18`.
 function intoUD2x18(SD21x18 x) pure returns (UD2x18 result) {
     int128 xInt = SD21x18.unwrap(x);
     if (xInt < 0) {
         revert CastingErrors.PRBMath_SD21x18_ToUD2x18_Underflow(x);
     }
+    if (xInt > int128(uint128(uMAX_UD2x18))) {
+        revert CastingErrors.PRBMath_SD21x18_ToUD2x18_Overflow(x);
+    }
     result = UD2x18.wrap(uint64(uint128(xInt)));
 }
 
@@ -63,17 +68,6 @@ function intoUD60x18(SD21x18 x) pure returns (UD60x18 result) {
     result = UD60x18.wrap(uint128(xInt));
 }
 
-/// @notice Casts an SD21x18 number into uint256.
-/// @dev Requirements:
-/// - x must be positive.
-function intoUint256(SD21x18 x) pure returns (uint256 result) {
-    int128 xInt = SD21x18.unwrap(x);
-    if (xInt < 0) {
-        revert CastingErrors.PRBMath_SD21x18_ToUint256_Underflow(x);
-    }
-    result = uint256(uint128(xInt));
-}
-
 /// @notice Casts an SD21x18 number into uint128.
 /// @dev Requirements:
 /// - x must be positive.
@@ -85,19 +79,15 @@ function intoUint128(SD21x18 x) pure returns (uint128 result) {
     result = uint128(xInt);
 }
 
-/// @notice Casts an SD21x18 number into uint64.
+/// @notice Casts an SD21x18 number into uint256.
 /// @dev Requirements:
 /// - x must be positive.
-/// - x must be less than or equal to `MAX_UINT64`.
-function intoUint64(SD21x18 x) pure returns (uint64 result) {
+function intoUint256(SD21x18 x) pure returns (uint256 result) {
     int128 xInt = SD21x18.unwrap(x);
     if (xInt < 0) {
-        revert CastingErrors.PRBMath_SD21x18_ToUint64_Underflow(x);
-    }
-    if (xInt > int128(uint128(Common.MAX_UINT64))) {
-        revert CastingErrors.PRBMath_SD21x18_ToUint64_Overflow(x);
+        revert CastingErrors.PRBMath_SD21x18_ToUint256_Underflow(x);
     }
-    result = uint64(uint128(xInt));
+    result = uint256(uint128(xInt));
 }
 
 /// @notice Casts an SD21x18 number into uint40.
@@ -115,6 +105,21 @@ function intoUint40(SD21x18 x) pure returns (uint40 result) {
     result = uint40(uint128(xInt));
 }
 
+/// @notice Casts an SD21x18 number into uint64.
+/// @dev Requirements:
+/// - x must be positive.
+/// - x must be less than or equal to `MAX_UINT64`.
+function intoUint64(SD21x18 x) pure returns (uint64 result) {
+    int128 xInt = SD21x18.unwrap(x);
+    if (xInt < 0) {
+        revert CastingErrors.PRBMath_SD21x18_ToUint64_Underflow(x);
+    }
+    if (xInt > int128(uint128(Common.MAX_UINT64))) {
+        revert CastingErrors.PRBMath_SD21x18_ToUint64_Overflow(x);
+    }
+    result = uint64(uint128(xInt));
+}
+
 /// @notice Alias for {wrap}.
 function sd21x18(int128 x) pure returns (SD21x18 result) {
     result = SD21x18.wrap(x);

src/sd21x18/Errors.sol

@@ -3,35 +3,38 @@ pragma solidity >=0.8.19;
 
 import { SD21x18 } from "./ValueType.sol";
 
-/// @notice Thrown when trying to cast a SD21x18 number that doesn't fit in SD1x18.
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in SD1x18.
 error PRBMath_SD21x18_IntoSD1x18_Overflow(SD21x18 x);
 
-/// @notice Thrown when trying to cast a SD21x18 number that doesn't fit in SD1x18.
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in SD1x18.
 error PRBMath_SD21x18_IntoSD1x18_Underflow(SD21x18 x);
 
-/// @notice Thrown when trying to cast a SD21x18 number that doesn't fit in UD2x18.
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in UD2x18.
+error PRBMath_SD21x18_ToUD2x18_Overflow(SD21x18 x);
+
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in UD2x18.
 error PRBMath_SD21x18_ToUD2x18_Underflow(SD21x18 x);
 
-/// @notice Thrown when trying to cast a SD21x18 number that doesn't fit in UD21x18.
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in UD21x18.
 error PRBMath_SD21x18_ToUD21x18_Underflow(SD21x18 x);
 
-/// @notice Thrown when trying to cast a SD21x18 number that doesn't fit in UD60x18.
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in UD60x18.
 error PRBMath_SD21x18_ToUD60x18_Underflow(SD21x18 x);
 
-/// @notice Thrown when trying to cast a SD21x18 number that doesn't fit in uint256.
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in uint256.
 error PRBMath_SD21x18_ToUint256_Underflow(SD21x18 x);
 
-/// @notice Thrown when trying to cast a SD21x18 number that doesn't fit in uint128.
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in uint128.
 error PRBMath_SD21x18_ToUint128_Underflow(SD21x18 x);
 
-/// @notice Thrown when trying to cast a SD21x18 number that doesn't fit in uint64.
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in uint64.
 error PRBMath_SD21x18_ToUint64_Overflow(SD21x18 x);
 
-/// @notice Thrown when trying to cast a SD21x18 number that doesn't fit in uint64.
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in uint64.
 error PRBMath_SD21x18_ToUint64_Underflow(SD21x18 x);
 
-/// @notice Thrown when trying to cast a SD21x18 number that doesn't fit in uint40.
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in uint40.
 error PRBMath_SD21x18_ToUint40_Overflow(SD21x18 x);
 
-/// @notice Thrown when trying to cast a SD21x18 number that doesn't fit in uint40.
+/// @notice Thrown when trying to cast an SD21x18 number that doesn't fit in uint40.
 error PRBMath_SD21x18_ToUint40_Underflow(SD21x18 x);

src/sd21x18/ValueType.sol

@@ -3,7 +3,7 @@ pragma solidity >=0.8.19;
 
 import "./Casting.sol" as Casting;
 
-/// @notice The signed 1.18-decimal fixed-point number representation, which can have up to 1 digit and up to 18
+/// @notice The signed 21.18-decimal fixed-point number representation, which can have up to 21 digits and up to 18
 /// decimals. The values of this are bound by the minimum and the maximum values permitted by the underlying Solidity
 /// type int128. This is useful when end users want to use int128 to save gas, e.g. with tight variable packing in contract
 /// storage.
@@ -19,8 +19,8 @@ using {
     Casting.intoUD2x18,
     Casting.intoUD21x18,
     Casting.intoUD60x18,
-    Casting.intoUint256,
     Casting.intoUint128,
+    Casting.intoUint256,
     Casting.intoUint40,
     Casting.unwrap
 } for SD21x18 global;

src/sd59x18/Casting.sol

@@ -9,6 +9,7 @@ import { uMAX_SD21x18, uMIN_SD21x18 } from "../sd21x18/Constants.sol";
 import { SD21x18 } from "../sd21x18/ValueType.sol";
 import { uMAX_UD2x18 } from "../ud2x18/Constants.sol";
 import { UD2x18 } from "../ud2x18/ValueType.sol";
+import { uMAX_UD21x18 } from "../ud21x18/Constants.sol";
 import { UD21x18 } from "../ud21x18/ValueType.sol";
 import { UD60x18 } from "../ud60x18/ValueType.sol";
 import { SD59x18 } from "./ValueType.sol";
@@ -67,12 +68,15 @@ function intoUD2x18(SD59x18 x) pure returns (UD2x18 result) {
 /// @notice Casts an SD59x18 number into UD21x18.
 /// @dev Requirements:
 /// - x must be positive.
+/// - x must be less than or equal to `uMAX_UD21x18`.
 function intoUD21x18(SD59x18 x) pure returns (UD21x18 result) {
     int256 xInt = SD59x18.unwrap(x);
     if (xInt < 0) {
         revert CastingErrors.PRBMath_SD59x18_IntoUD21x18_Underflow(x);
     }
-
+    if (xInt > int256(uint256(uMAX_UD21x18))) {
+        revert CastingErrors.PRBMath_SD59x18_IntoUD21x18_Overflow(x);
+    }
     result = UD21x18.wrap(uint128(uint256(xInt)));
 }
 

src/sd59x18/Errors.sol

@@ -36,43 +36,46 @@ error PRBMath_SD59x18_Gm_NegativeProduct(SD59x18 x, SD59x18 y);
 /// @notice Thrown when taking the geometric mean of two numbers and multiplying them overflows SD59x18.
 error PRBMath_SD59x18_Gm_Overflow(SD59x18 x, SD59x18 y);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in SD1x18.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in SD1x18.
 error PRBMath_SD59x18_IntoSD1x18_Overflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in SD1x18.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in SD1x18.
 error PRBMath_SD59x18_IntoSD1x18_Underflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in SD21x18.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in SD21x18.
 error PRBMath_SD59x18_IntoSD21x18_Overflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in SD21x18.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in SD21x18.
 error PRBMath_SD59x18_IntoSD21x18_Underflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in UD2x18.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in UD2x18.
 error PRBMath_SD59x18_IntoUD2x18_Overflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in UD2x18.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in UD2x18.
 error PRBMath_SD59x18_IntoUD2x18_Underflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in UD21x18.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in UD21x18.
+error PRBMath_SD59x18_IntoUD21x18_Overflow(SD59x18 x);
+
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in UD21x18.
 error PRBMath_SD59x18_IntoUD21x18_Underflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in UD60x18.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in UD60x18.
 error PRBMath_SD59x18_IntoUD60x18_Underflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in uint128.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in uint128.
 error PRBMath_SD59x18_IntoUint128_Overflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in uint128.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in uint128.
 error PRBMath_SD59x18_IntoUint128_Underflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in uint256.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in uint256.
 error PRBMath_SD59x18_IntoUint256_Underflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in uint40.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in uint40.
 error PRBMath_SD59x18_IntoUint40_Overflow(SD59x18 x);
 
-/// @notice Thrown when trying to cast a SD59x18 number that doesn't fit in uint40.
+/// @notice Thrown when trying to cast an SD59x18 number that doesn't fit in uint40.
 error PRBMath_SD59x18_IntoUint40_Underflow(SD59x18 x);
 
 /// @notice Thrown when taking the logarithm of a number less than or equal to zero.