feat: keep assembly

foundry/src/lib/LibPrefixLengthEncodedByteArray.sol

@@ -1,8 +1,17 @@
 // SPDX-License-Identifier: UNLICENSED
 pragma solidity ^0.8.0;
 
-error LibPrefixLengthEncodedByteArray__InvalidEncoding();
+/**
-
+ * @title Propellerheads PrefixLengthEncoded Byte Array Library
+ * @author PropellerHeads Developers
+ * @dev Provide a gas efficient encoding for bytes array.
+ *
+ * Array of bytes are encoded as a single bytes like this :
+ *       16 bits      ??bits       16bits        ??bits ...
+ *   [length(elem1)]  [elem1]  [length(elem2)]  [elem2] ...
+ *
+ * This is much more efficient and compact than default solidity encoding.
+ */
 library LibPrefixLengthEncodedByteArray {
     /**
      * @dev Pop the first element of an array and returns it with the remaining data.
@@ -12,45 +21,35 @@ library LibPrefixLengthEncodedByteArray {
         pure
         returns (bytes calldata elem, bytes calldata res)
     {
-        // Handle empty input
+        assembly {
-        if (encoded.length == 0) {
+            switch iszero(encoded.length)
-            return (encoded[:0], encoded[:0]);
+            case 1 {
+                elem.offset := 0
+                elem.length := 0
+                res.offset := 0
+                res.length := 0
+            }
+            default {
+                let l := shr(240, calldataload(encoded.offset))
+                elem.offset := add(encoded.offset, 2)
+                elem.length := l
+                res.offset := add(elem.offset, l)
+                res.length := sub(sub(encoded.length, l), 2)
+            }
         }
-
-        // Ensure we have at least 2 bytes for length prefix
-        if (encoded.length < 2) revert LibPrefixLengthEncodedByteArray__InvalidEncoding();
-        // Extract the length prefix (first 2 bytes)
-        uint16 length = uint16(bytes2(encoded[:2]));
-        
-        // Check if length is valid
-        if (2 + length > encoded.length) revert LibPrefixLengthEncodedByteArray__InvalidEncoding();
-        
-        // Extract the element (after length prefix)
-        elem = encoded[2:2+length];
-        
-        // Extract the remaining data
-        res = encoded[2+length:];
-        
-        return (elem, res);
     }
 
     /**
      * @dev Gets the size of the encoded array.
      */
     function size(bytes calldata encoded) internal pure returns (uint256 s) {
-        uint256 offset = 0;
+        assembly {
-
+            let offset := encoded.offset
-        while (offset < encoded.length) {
+            let end := add(encoded.offset, encoded.length)
-            // Ensure we have at least 2 bytes for length prefix
+            for {} lt(offset, end) {} {
-            if (offset + 2 > encoded.length) revert LibPrefixLengthEncodedByteArray__InvalidEncoding();
+                offset := add(offset, add(shr(240, calldataload(offset)), 2))
-            
+                s := add(s, 1)
-            uint16 length = uint16(bytes2(encoded[offset:offset + 2]));
+            }
-            
-            // Check if length is valid
-            if (offset + 2 + length > encoded.length) revert LibPrefixLengthEncodedByteArray__InvalidEncoding();
-            
-            offset += length + 2;
-            s++;
         }
     }