hand-optimize

Author: dcodeIO

lib/loader/index.js

@@ -37,20 +37,26 @@ const ARRAY_SIZE = 16;
 const BIGINT = typeof BigUint64Array !== "undefined";
 const THIS = Symbol();
 
-const STRING_CHUNKSIZE = 1024;
+const STRING_SMALLSIZE = 192; // break-even point in V8
+const STRING_CHUNKSIZE = 1024; // mitigate stack overflow
+const utf16 = new TextDecoder("utf-16le"); // != wtf16
 
 /** Gets a string from memory. */
 function getStringImpl(buffer, ptr) {
   let len = new Uint32Array(buffer)[ptr + SIZE_OFFSET >>> 2] >>> 1;
   const wtf16 = new Uint16Array(buffer, ptr, len);
-  if (len <= STRING_CHUNKSIZE) return String.fromCharCode.apply(String, wtf16);
-  let str = "";
-  let off = 0;
-  do {
-    str += String.fromCharCode.apply(String, wtf16.subarray(off, off += STRING_CHUNKSIZE));
-    len -= STRING_CHUNKSIZE;
-  } while (len > STRING_CHUNKSIZE);
-  return str + String.fromCharCode.apply(String, wtf16.subarray(off, off + len));
+  if (len <= STRING_SMALLSIZE) return String.fromCharCode.apply(String, wtf16);
+  try {
+    return utf16.decode(wtf16, { fatal: true });
+  } catch {
+    let str = "";
+    let off = 0;
+    while (len > STRING_CHUNKSIZE) {
+      str += String.fromCharCode.apply(String, wtf16.subarray(off, off += STRING_CHUNKSIZE));
+      len -= STRING_CHUNKSIZE;
+    }
+    return str + String.fromCharCode.apply(String, wtf16.subarray(off, off + len));
+  }
 }
 
 /** Prepares the base module prior to instantiation. */

lib/loader/umd/index.js

@@ -44,22 +44,34 @@ var loader = (function(exports) {
   const ARRAY_SIZE = 16;
   const BIGINT = typeof BigUint64Array !== "undefined";
   const THIS = Symbol();
-  const STRING_CHUNKSIZE = 1024;
+  const STRING_SMALLSIZE = 192; // break-even point in V8
+  
+  const STRING_CHUNKSIZE = 1024; // mitigate stack overflow
+  
+  const utf16 = new TextDecoder("utf-16le"); // != wtf16
+  
   /** Gets a string from memory. */
 
   function getStringImpl(buffer, ptr) {
     let len = new Uint32Array(buffer)[ptr + SIZE_OFFSET >>> 2] >>> 1;
     const wtf16 = new Uint16Array(buffer, ptr, len);
-    if (len <= STRING_CHUNKSIZE) return String.fromCharCode.apply(String, wtf16);
-    let str = "";
-    let off = 0;
+    if (len <= STRING_SMALLSIZE) return String.fromCharCode.apply(String, wtf16);
 
-    do {
-      str += String.fromCharCode.apply(String, wtf16.subarray(off, off += STRING_CHUNKSIZE));
-      len -= STRING_CHUNKSIZE;
-    } while (len > STRING_CHUNKSIZE);
+    try {
+      return utf16.decode(wtf16, {
+        fatal: true
+      });
+    } catch {
+      let str = "";
+      let off = 0;
 
-    return str + String.fromCharCode.apply(String, wtf16.subarray(off, off + len));
+      while (len > STRING_CHUNKSIZE) {
+        str += String.fromCharCode.apply(String, wtf16.subarray(off, off += STRING_CHUNKSIZE));
+        len -= STRING_CHUNKSIZE;
+      }
+  
+      return str + String.fromCharCode.apply(String, wtf16.subarray(off, off + len));
+    }
   }
   /** Prepares the base module prior to instantiation. */