updated readme

README

@@ -1,12 +1,78 @@
-Erjang Readme
+Erjang - a JVM-based Erlang VM
 
--- 
+  Wiki Pages: www.erjang.org
+  Discussion: http://groups.google.com/group/erjang
+  Source: http://github.com/krestenkrab/erjang
 
-At this stage nothing works, so don't get your hopes up. 
-You cannot even compile "hello world".
+--
+
+BUILDING
+
+
+You should be able to do "ant jar", and thereafter run the sample
+with 
+
+  prompt% ant jar
+  ...
+  prompt% ./ring_test.sh 
+  ...
+  loading io
+  loading timer
+  loading ring
+  loading erlang
+  io:format "~p Starting message~n" [{1259,922511,63000}]
+  io:format "~p Around ring ~p times ~n" [{1259,922512,434000},10000]
+  io:format "~p Around ring ~p times ~n" [{1259,922513,600000},20000]
+  io:format "~p Around ring ~p times ~n" [{1259,922514,763000},30000]
+  io:format "~p Around ring ~p times ~n" [{1259,922515,930000},40000]
+  io:format "~p Around ring ~p times ~n" [{1259,922517,117000},50000]
+  ....
+
+The source for the few samples are in src/main/erl.
+
+--
+
+RUNNING
+
+When running, it writes files named ".erj/module-${CRC}.jar".  These
+files are written in response to erlang:compile_module(Module,Binary).
+
+These files also serve as a cache of files translated from beam -> jar.
+If something goes astray, it may help to remove the .erj directory
+forcing Erjang to recompile next time it runs.
+
+--
+
+PREREQUISITES
+
+I have only been testing this with Erlang/OTP R13B02.
+
+While we are still bootstrapping, the compiler uses a remote
+erlang process to parse beam files (using beam_disasm), so you 
+need to have this running:
+
+  prompt% cd src/main/erl
+  prompt% erl -sname beam_loader@localhost -s beam_loader
+
+Otherwise you will get errors like this:
+
+Exception in thread "main" java.lang.Error: java.io.IOException: Cannot connect to peer node
+	at erjang.beam.Compiler.<clinit>(Compiler.java:55)
+	at erjang.EModule.load_module(EModule.java:429)
+	at erjang.Erj.main(Erj.java:61)
+
+Eventually this will obviously be self-hosted in Erjang.
+
+
+To run the tests, you need an OTP distribution, and go edit src/test/java/erjang/TestAll.java
+to tell it where your OTP_HOME is.
+
+
+
+Cheers!
 
 Kresten Krab Thorup
-krab@trifork.com
+krab _at_ trifork dot com
 
 
 

src/main/java/erjang/EModule.java

@@ -74,7 +74,7 @@ public int compare(Field o1, Field o2) {
 		 * @throws IllegalAccessException
 		 * @throws IllegalArgumentException
 		 */
-		synchronized boolean add_import(Field ref) throws Exception {
+		synchronized boolean add_import(final Field ref) throws Exception {
 			resolve_points.add(ref);
 			if (resolved_value != null) {
 				//System.out.println("binding "+fun+" "+resolved_value+" -> "+ref);
@@ -86,8 +86,19 @@ synchronized boolean add_import(Field ref) throws Exception {
 							public EObject invoke(EProc proc, EObject[] args) 
 								throws Pausable
 							{
-								System.out.println("undefined "+fun);
-								throw new ErlangUndefined(fun.module, fun.function, ESmall.make(fun.arity));
+								EFun found = null;
+								try {
+									ERT.load(fun.module);
+									found = EModule.resolve(fun);
+								} catch (Throwable ex) {
+									System.out.println("unable to load module for "+fun);
+								}
+
+								if (found == null) {
+									throw new ErlangUndefined(fun.module, fun.function, ESmall.make(fun.arity));
+								} else {
+									return found.invoke(proc, args);
+								}
 							}
 						});
 				ref.set(null, h);

src/main/java/erjang/EModuleLoader.java

@@ -77,6 +77,10 @@ protected Class<?> findClass(String name) throws ClassNotFoundException {
 
 		if (name.startsWith("kilim.S_")) {
 			InputStream resource = super.getResourceAsStream(name.replace('.', '/')  + ".class");
+
+			if (resource == null) {
+				throw new ClassNotFoundException(name, new Error("while loading "+this.getURLs()[0]));
+			}
 
 			try {
 				byte[] bb = new byte[resource.available()];

src/main/java/erjang/Erj.java

@@ -27,11 +27,6 @@
  */
 public class Erj {
 
-	public static String PRELOADED = "src/main/erl/preloaded/ebin";
-	public static String[] MODULES = new String[] { "erl_prim_loader",
-			"erlang", "init", "otp_ring0", "prim_file", "prim_inet",
-			"prim_zip", "zlib" };
-
 	@SuppressWarnings("unchecked")
 	public static void main(String[] args) 
 		throws Exception {
@@ -49,15 +44,7 @@ public static void main(String[] args)
 		EAtom module = EAtom.intern(m);
 		EAtom fun = EAtom.intern(f);
 
-		EModule[] modules = new EModule[MODULES.length];
-
-		for (int i = 0; i < modules.length; i++) {
-
-			String mod = MODULES[i];
-
-			ERT.load(EAtom.intern(mod));
-		}		
-
+		// TODO: remove this hack, it prevents loading real modules for these
 		EModule.load_module(EAtom.intern("io"), new File("target/classes").toURL());
 		EModule.load_module(EAtom.intern("timer"), new File("target/classes").toURL());