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jasmin/jasmin-2.4/lib/jas/examples/README

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+This contains three examples of using the assembler
+from java and from the script
+
+Look up http://www.blackdown.org/~kbs/jas.html for more
+documentation. This only tells you how to run the examples.  The
+documentation is very Unix centric, I apologize.... I have not had
+time to set this up on the PC's yet.
+
+
+simple.java:
+simple.jas:
+
+  Unexciting program that generates a do nothing class.
+
+  Go up a directory and compile simple.java. Run the program,
+  which generates the bytecode. Disassemble the bytecode
+
+  % (cd ..; javac -d . examples/simple.java; java simple; javap -p -c out)
+
+  Same thing, but using the script instead of java directly.
+
+  % (cd ..;  java scm.driver examples/simple.jas; javap -p -c out)
+
+
+hworld.java:
+hworld.jas:
+
+  Print a string in a loop.
+
+  % (cd ..; javac -d . examples/hworld.java; java hworld; java out)
+
+  As before, but use script instead.
+
+  % (cd ..; java scm.driver examples/hworld.jas; java out)
+
+exprcomp.java:
+
+  Primitive runtime expression compiler. It translates arithmetic
+  expressions into bytecode and loads it on the fly as a class, which
+  is run to get the answer. test.inp is an example of the sort of
+  arithmetic expressions it translates.
+
+  % (cd ..; javac -d . examples/exprcomp.java; java exprcomp examples/test.inp)
+
+exprcomp.jas:
+
+   Primitive compiler for jas arithmetic expressions (in jas).
+   jas is fairly expressive, thats about the only point of this
+   exercise ;-) Unlike the java version, this gets written out
+   into a file which you'll have to run to get the results.
+
+  % (cd ..; java scm.driver examples/exprcomp.jas; java results)

jasmin/jasmin-2.4/lib/jas/examples/exprcomp.jas

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+;;; Simple arithmetic expression compiler for jas in jas.
+;;;
+;;; The compiler is defined in the function
+;;; compile-expression
+;;;
+;;; use as (for instance)
+;;; (compile-expression (quote (+ (* 2 (+ 1 3)) 1)))
+;;;
+;;; This will generate a standalone program called results.class
+;;; Run the bytecode interpreter on it as:
+;;;
+;;; % java results
+;;;
+;;; which will print the result of the expression
+
+(define compile-expression
+  (lambda (expr)
+    (real-compile-expression expr)
+    (dump-code)))
+
+;; The fun part...
+
+(define real-compile-expression
+  (lambda (expr)
+    (cond
+
+     ((num? expr)
+      (compile-number expr))
+
+     (1 (progn
+         (real-compile-expression (get-op1 expr))
+         (real-compile-expression (get-op2 expr))
+         (compile-op (get-op expr))
+         (set! cur-stack-height (- cur-stack-height 1)))))))
+
+;; Ah well. Back to boring bookkeeping.
+
+
+(define compile-number
+  (lambda (num)
+    (append-insn (bipush num))
+    (set! cur-stack-height (+ 1 cur-stack-height))
+    (cond
+     ((< max-stack-height cur-stack-height)
+      (set! max-stack-height cur-stack-height)))))
+
+(define compile-op
+  (lambda (op)
+    (cond
+     ((eq? op (quote +)) (append-insn (iadd)))
+     ((eq? op (quote -)) (append-insn (isub)))
+     ((eq? op (quote *)) (append-insn (imul)))
+     ((eq? op (quote /)) (append-insn (idiv))))))
+
+(define get-op1
+  (lambda (expr) (car (cdr expr))))
+(define get-op2
+  (lambda (expr) (car (cdr (cdr expr)))))
+(define get-op
+  (lambda (expr) (car expr)))
+
+(define append-insn
+  (lambda (insn)
+    (jas-code-addinsn my-code insn)))
+
+(define cur-stack-height 1)
+(define max-stack-height 1)
+
+(define my-code (make-code))
+(define my-init-code (make-code))
+
+                                        ; define the main() portion,
+                                        ; and the call to print out the
+                                        ; results.
+(define append-sequence
+  (lambda (code-part insn-list)
+    (mapcar (lambda (insn) (jas-code-addinsn code-part insn))
+            insn-list)))
+
+(append-sequence
+ my-init-code
+ (quote
+  ((aload_0)
+   (invokenonvirtual (make-method-cpe "java/lang/Object" "<init>" "()V"))
+   (return))))
+
+(define dump-code
+  (lambda ()
+    (define my-env (make-class-env))
+    (jas-class-setclass my-env (make-class-cpe "results"))
+    (jas-class-setsuperclass my-env (make-class-cpe "java/lang/Object"))
+    (jas-class-addmethod my-env acc-public "<init>" "()V" my-init-code ())
+    (append-sequence
+     my-code
+     (quote
+      ((getstatic
+        (make-field-cpe "java/lang/System" "out" "Ljava/io/PrintStream;"))
+       (swap)
+       (invokevirtual (make-method-cpe
+                       "java/io/PrintStream" "println" "(I)V"))
+       (return))))
+    (jas-code-stack-size my-code max-stack-height)
+    (jas-class-addmethod my-env
+                         (| acc-public acc-static)
+                         "main" "([Ljava/lang/String;)V" my-code ())
+    (jas-class-write my-env
+                     (make-outputstream "results.class"))))
+
+;;;
+;;; example usage of compiler.
+;;;
+;;; run the compiled class with
+;;; % java results
+;;; to get the answer.
+
+(compile-expression (quote (+ (* 2 (+ 1 3)) 1)))

jasmin/jasmin-2.4/lib/jas/examples/exprcomp.java

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+// Primitive runtime code generation of expressions. This is a jas
+// implementation of the example in Aho Sethi Ullman.
+// 
+// You pass to it statements of the form
+// a = 1*2 + 3*5;
+// Only integer operations are allowed, and variables
+// are magically created by using them in the LHS of a statement.
+//
+// You can print out the value of expressions with the println keyword:
+// println(a + 10);
+//
+// It compiles this into a bytearray, and then loads it as 
+// a new class.
+//
+// Unfortunately, this trick cannot be used in an applet --- security
+// restrictions prevent ClassLoaders from being placed on the
+// stack. So much for writing regexp compilers that can do codegen instead of
+// state tables.
+//
+// The grammar is simple, so code generation is part of the parsing
+// step. Operator precedence is directly handled by the grammar.
+//
+// Grammar + production rules:
+//
+// start -> list EOF
+// list -> id = expr ;  { emit(istore, id.index); } list
+//        | println expr ;  { emit(<println sequence>); } list
+//        | lambda
+// expr -> term moreterms
+// moreterms -> + term { emit(iadd) } moreterms
+//           |  - term { emit(isub) } moreterms
+//           |  lambda
+// term -> factor morefactors
+// morefactors -> * factor { emit(imul) } morefactors
+//              | / factor { emit(idiv) } morefactors
+//              | lambda
+// factor -> ( expr )
+//          | number { emit(iconst, number.value) }
+//          | id { emit(iload, id.index); }
+
+import java.util.*;
+import java.io.*;
+import jas.*;
+import sun.tools.java.RuntimeConstants;
+
+public class exprcomp implements RuntimeConstants
+{
+  StreamTokenizer inp;
+  CodeAttr myCode;
+  short cur_stack_height;
+  short max_stack_height;
+  short max_vars;
+  Hashtable vars;
+
+  public exprcomp(StreamTokenizer inp)
+    throws jasError
+  {
+    inp.eolIsSignificant(false);
+    this.inp = inp;
+    myCode = new CodeAttr();
+                                // Add initializations
+    myCode.addInsn(new Insn(opc_aload_0));
+    myCode.addInsn(new Insn(opc_invokenonvirtual,
+                            new MethodCP("java/lang/Object",
+                                         "<init>", "()V")));
+    cur_stack_height = max_stack_height = 1;
+    vars = new Hashtable();
+    max_vars = 1;
+  }
+  public void write(DataOutputStream out)
+    throws IOException, jasError
+  {
+    ClassEnv clazz = new ClassEnv();
+    myCode.setStackSize(max_stack_height);
+    myCode.setVarSize(max_vars);
+                                // add initializer to class
+    clazz.addMethod
+      ((short) ACC_PUBLIC, "<init>", "()V", myCode, null);
+    clazz.setClassAccess((short) ACC_PUBLIC);
+    clazz.setClass(new ClassCP("results"));
+    clazz.setSuperClass(new ClassCP("java/lang/Object"));
+    clazz.write(out);
+  }
+
+  public void parse()
+    throws IOException, parseError, jasError
+  {
+    inp.nextToken();
+    while(inp.ttype != inp.TT_EOF)
+      {
+        if (inp.ttype != inp.TT_WORD)
+          {
+            throw new parseError("Expected an id at line " + inp.lineno());
+          }
+        if (inp.sval.equals("println"))
+          {
+            match(inp.TT_WORD);
+            expr();
+            match(';');
+            emit(new Insn(opc_getstatic,
+                          new FieldCP("java/lang/System",
+                                      "out", "Ljava/io/PrintStream;")));
+            emit(new Insn(opc_swap));
+            emit(new Insn(opc_invokevirtual,
+                          new MethodCP("java/io/PrintStream",
+                                       "println", "(I)V")));
+          }
+        else
+          {                     // search, maybe add into var list
+            Integer idx;
+            if ((idx = (Integer) vars.get(inp.sval)) == null)
+              {
+                idx = new Integer(max_vars++);
+                vars.put(inp.sval.intern(), idx);
+              }
+            match(inp.TT_WORD); match('='); expr(); match(';');
+            emit(new Insn(opc_istore, idx.intValue()));
+          }
+      }
+    emit(new Insn(opc_return));
+  }
+
+  void expr()
+    throws IOException, parseError, jasError
+  {
+    term();
+    while (true)
+      {
+        switch(inp.ttype)
+          {
+          case '+':
+            match('+'); term(); emit(new Insn(opc_iadd)); break;
+          case '-':
+            match('-'); term(); emit(new Insn(opc_isub)); break;
+          default: return;
+          }
+        cur_stack_height--;
+      }
+  }
+
+  void term()
+    throws IOException, parseError, jasError
+  {
+    factor();
+    while (true)
+      {
+        switch(inp.ttype)
+          {
+          case '*': match('*'); factor(); emit(new Insn(opc_imul)); break;
+          case '/': match('/'); factor(); emit(new Insn(opc_idiv)); break;
+          default: return;
+          }
+        cur_stack_height --;
+      }
+  }
+  void factor()
+    throws IOException, parseError, jasError
+  {
+    switch(inp.ttype)
+      {
+      case '(': match('('); expr(); match(')'); break;
+      case inp.TT_NUMBER:
+        int val = (int)(inp.nval);
+        emit(new Insn(opc_bipush, (short)val));
+        match(inp.TT_NUMBER);
+        break;
+      case inp.TT_WORD:
+        Integer idx;
+        if ((idx = (Integer) vars.get(inp.sval)) == null)
+          {
+            throw new parseError
+              ("Unknown variable " + inp.sval + " at line " + inp.lineno());
+          }
+        emit(new Insn(opc_iload, idx.intValue()));
+        match(inp.TT_WORD);
+        break;
+      default:
+        throw new parseError("Syntax error at line " + inp.lineno());
+      }
+    cur_stack_height++;
+    if (max_stack_height < cur_stack_height)
+      max_stack_height = cur_stack_height;
+  }
+  void match(int val)
+    throws IOException, parseError
+  {
+    if (inp.ttype != val)
+      { throw new parseError
+          ("line " + inp.lineno() + ": expected " + val + " but got " + inp); }
+    inp.nextToken();
+  }
+
+  void emit(Insn insn)
+  {
+    myCode.addInsn(insn);
+  }
+
+  public static void main(String argv[])
+    throws Exception
+  {
+    exprcomp compiler =
+      new exprcomp(new StreamTokenizer(new FileInputStream(argv[0])));
+    compiler.parse();
+    ByteArrayOutputStream data = new ByteArrayOutputStream();
+    compiler.write(new DataOutputStream(data));
+    dynaloader dl = new dynaloader(data.toByteArray());
+    dl.exec();
+  }
+}
+
+class dynaloader extends ClassLoader
+{
+  Hashtable cache;
+  Class ex;
+
+  dynaloader(byte[] data)
+    throws ClassFormatError
+  {
+    cache = new Hashtable();
+    ex = defineClass(data, 0, data.length);
+    cache.put("results", ex);
+    resolveClass(ex);
+  }
+
+  void exec() throws Exception { ex.newInstance(); }
+  public synchronized Class loadClass(String name, boolean resolve)
+    throws ClassNotFoundException
+  {
+    Class c = (Class) cache.get(name);
+    if (c == null)
+      {
+        c = findSystemClass(name);
+        cache.put(name, c);
+      }
+    if (resolve) resolveClass(c);
+    return c;
+  }
+}
+
+
+class parseError extends Exception
+{ parseError(String s) { super(s); } }

jasmin/jasmin-2.4/lib/jas/examples/hworld.jas

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+;; create a container
+
+(define my-class (make-class-env))
+
+
+;; specify class hierarchy
+
+(jas-class-setaccess my-class acc-public)
+(jas-class-setclass my-class (make-class-cpe "out"))
+(jas-class-setsuperclass my-class (make-class-cpe "java/lang/Object"))
+
+
+;; write a convenience function to append insns as a list.
+(define append-code
+  (lambda (code-part insn-list)
+    (mapcar (lambda (insn) (jas-code-addinsn code-part insn))
+            insn-list)))
+
+;; Define code for initializer
+;;
+(define init-it (make-code))
+(append-code
+ init-it
+ (quote
+  ((aload_0)
+   (invokenonvirtual (make-method-cpe "java/lang/Object" "<init>" "()V"))
+   (return))))
+
+;; this is the code that comprises
+;; the actual task, ie the code for
+;; main(String argv[]).
+;; print a string 5 times
+
+(define doit (make-code))
+(append-code
+ doit
+ (quote
+  (
+
+                                        ; store references in local
+                                        ; variables to avoid field/cp
+                                        ; lookup
+   (getstatic
+    (make-field-cpe "java/lang/System" "out" "Ljava/io/PrintStream;"))
+   (astore_1)
+   (ldc (make-string-cpe "Hello World"))
+   (astore_2)
+   (bipush 5)
+   (istore_3)                           ; store loop index in var reg 3
+
+                                        ; loop 5 times, printing out
+                                        ; the string.
+
+   (make-label "loop")
+                                        ; push arguments to function
+                                        ; on stack and call it
+
+   (aload_1) (aload_2)
+   (invokevirtual
+    (make-method-cpe "java/io/PrintStream" "println" "(Ljava/lang/String;)V"))
+
+                                        ; decrement loop index
+
+   (iinc 3 -1)
+   (iload_3)
+   (ifne (make-label "loop"))
+   (return))))
+
+;; set stack/var size
+
+(jas-code-stack-size doit 3)
+(jas-code-var-size doit 4)
+
+;; fill up the class with the methods
+
+;; first the initializer.
+(jas-class-addmethod my-class acc-public "<init>" "()V" init-it ())
+
+;; define the printing code as a static main(String argv[]) method
+
+(jas-class-addmethod my-class
+                     (| acc-static acc-public)
+                     "main" "([Ljava/lang/String;)V" doit ())
+
+;; write it out.
+
+(jas-class-write my-class (make-outputstream "out.class"))

jasmin/jasmin-2.4/lib/jas/examples/hworld.java

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+import jas.*;
+import java.io.*;
+import sun.tools.java.RuntimeConstants;
+
+//
+// This is program that makes calls into the jas package
+// to generate a class that prints a string afew times.
+//
+
+class hworld implements RuntimeConstants
+{
+  public static void main(String argv[])
+    throws jasError, IOException
+  {
+
+                                // class hierarchy
+    ClassEnv nclass = new ClassEnv();
+    nclass.setClass(new ClassCP("out"));
+    nclass.setSuperClass(new ClassCP("java/lang/Object"));
+    nclass.setClassAccess((short)ACC_PUBLIC);
+
+                                // Initialization code
+
+    CodeAttr init = new CodeAttr();
+    init.addInsn(new Insn(opc_aload_0));
+    init.addInsn(new Insn(opc_invokenonvirtual,
+                          new MethodCP("java/lang/Object", "<init>", "()V")));
+    init.addInsn(new Insn(opc_return));
+
+
+                                // Actual code to print string
+    CodeAttr doit = new CodeAttr();
+
+                                // store refs in local variables
+    doit.addInsn(new Insn(opc_getstatic,
+                          new FieldCP("java/lang/System",
+                                      "out",
+                                      "Ljava/io/PrintStream;")));
+    doit.addInsn(new Insn(opc_astore_1));
+    doit.addInsn(new Insn(opc_ldc,
+                          new StringCP("Hello World")));
+    doit.addInsn(new Insn(opc_astore_2));
+
+                                // Loop index in var reg 3
+    doit.addInsn(new Insn(opc_bipush, 5));
+    doit.addInsn(new Insn(opc_istore_3));
+
+                                // Start the loop
+    Label loop = new Label("loop");
+    doit.addInsn(loop);
+    doit.addInsn(new Insn(opc_aload_1));
+    doit.addInsn(new Insn(opc_aload_2));
+    doit.addInsn(new Insn(opc_invokevirtual,
+                          new MethodCP("java/io/PrintStream",
+                                       "println",
+                                       "(Ljava/lang/String;)V")));
+    doit.addInsn(new IincInsn(3, -1));
+    doit.addInsn(new Insn(opc_iload_3));
+    doit.addInsn(new Insn(opc_ifne, loop));
+    doit.addInsn(new Insn(opc_return));
+
+                                // set the right sizes for code
+    doit.setStackSize((short)3); doit.setVarSize((short)4);
+
+                                // Add the init code to the class.
+    nclass.addMethod((short)ACC_PUBLIC, "<init>", "()V", init, null);
+
+                                // Add the printing code
+    nclass.addMethod((short)(ACC_PUBLIC|ACC_STATIC), "main",
+                     "([Ljava/lang/String;)V", doit, null);
+
+                                // write it all out
+    nclass.write(new DataOutputStream
+                 (new FileOutputStream("out.class")));
+  }
+}
+
+    

jasmin/jasmin-2.4/lib/jas/examples/simple.jas

@@ -0,0 +1,30 @@
+;; script to create a class that does nothing.
+
+
+                                        ; make-class-env creates
+                                        ; a ClassEnv object which is
+                                        ; used to store information about
+                                        ; an object.
+(define my-class (make-class-env))
+
+                                        ; make-code creates a code object
+                                        ; which contains the body of a
+                                        ; method.
+
+(define init-code (make-code))
+(jas-code-addinsn init-code
+                  (aload_0))
+(jas-code-addinsn init-code
+                  (invokenonvirtual
+                   (make-method-cpe "java/lang/Object" "<init>" "()V")))
+(jas-code-addinsn init-code
+                  (return))
+
+                                        ; fill up the class with goodies
+(jas-class-setsuperclass my-class (make-class-cpe "java/lang/Object"))
+(jas-class-setclass my-class (make-class-cpe "out"))
+(jas-class-setaccess my-class acc-public)
+(jas-class-addmethod my-class acc-public "<init>" "()V" init-code ())
+
+                                        ; and write it all out
+(jas-class-write my-class (make-outputstream "out.class"))

jasmin/jasmin-2.4/lib/jas/examples/simple.java

@@ -0,0 +1,45 @@
+import jas.*;
+import java.io.*;
+import sun.tools.java.RuntimeConstants;
+
+//
+// This is program that makes calls into the jas package
+// to generate a class that does nothing at all.
+//
+
+class simple implements RuntimeConstants
+{
+  public static void main(String argv[])
+    throws jasError, IOException
+  {
+
+                                // CodeAttr's contain the body of
+                                // a method.
+
+    CodeAttr init = new CodeAttr();
+    init.addInsn(new Insn(opc_aload_0));
+    init.addInsn(new Insn(opc_invokenonvirtual,
+                          new MethodCP("java/lang/Object", "<init>", "()V")));
+    init.addInsn(new Insn(opc_return));
+
+
+                                // ClassEnv's are used as a container
+                                // to hold all information about a class.
+
+    ClassEnv nclass = new ClassEnv();
+    nclass.setClass(new ClassCP("out"));
+    nclass.setSuperClass(new ClassCP("java/lang/Object"));
+
+
+
+                                // Add the init code to the class.
+    nclass.addMethod((short)ACC_PUBLIC, "<init>", "()V", init, null);
+
+
+                                // write it all out
+    nclass.write(new DataOutputStream
+                 (new FileOutputStream("out.class")));
+  }
+}
+
+    

jasmin/jasmin-2.4/lib/jas/examples/test.inp

@@ -0,0 +1,8 @@
+a = 10;
+println a;
+
+b = a + 5;
+
+println (b);
+println(a*b +2);
+