Update specs, implement nanotime

docs/specs/java_JVM.tex

@@ -1,5 +1,5 @@
 % !TEX root = ./java_JVM.tex
-\input source_header.tex
+\input java_header.tex
 \usepackage{titlesec}
 
 \setcounter{secnumdepth}{4}
@@ -38,10 +38,10 @@
 
 \begin{document}
 	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-	\docheader{Java}{Source}{}{Martin Henz, Yap Hock Chuan Roland, Chuan Hao Chang}
+	\docheader{2024}{Java}{JVM}{Martin Henz, Yap Hock Chuan Roland, Chuan Hao Chang}
 	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-\input source_intro.tex
+\input java_intro.tex
 
 This JVM follows the Java SE8 Edition \href{https://docs.oracle.com/javase/specs/jvms/se8/html/index.html}{JVM Specification}.
 

src/jvm/README.md

@@ -50,9 +50,7 @@ export const functions = {
 A build script has been provided to create a module of the Java standard library as a hashmap of base64 strings.
 
 ```sh
-node dist/jvm/utils/build.js /path/to/classfile/directory
+npx tsx src/jvm/utils/build path/to/classfiles
 ```
 
-It has been configured to only include modules with package name starting with `java`, `sun/misc`, `modules`.
-
-You can then import the strings using `import(java-slang/dist/jvm/utils/classfiles)`.
+Java packages are deployed as a submodule of the Source Academy modules repository ([link](https://github.com/source-academy/java-packages)).

src/jvm/stdlib/java/lang/System.ts

@@ -181,6 +181,16 @@ const functions = {
   'identityHashCode(Ljava/lang/Object;)I': (thread: Thread) => {
     logger.warn('System.identityHashCode(Ljava/lang/Object;)I not implemented')
     thread.returnStackFrame(0)
+  },
+
+  /**
+   * Returns the current time in nanoseconds.
+   * Accuracy is only in millis since browsers do not support hrtime.
+   * @param thread
+   */
+  'nanoTime()J': (thread: Thread) => {
+    const time = BigInt(Date.now()) * BigInt(1000000)
+    thread.returnStackFrame64(time)
   }
 }