diff --git a/makefile b/makefile
index 1994bd5349..e875719e7a 100644
--- a/makefile
+++ b/makefile
@@ -1,4 +1,4 @@
-MAKEFLAGS = -s
+#MAKEFLAGS = -s
 
 arch = $(shell uname -m)
 ifeq ($(arch),i586)
@@ -43,7 +43,7 @@ ifeq ($(mode),stress-major)
 cflags += -O0 -g3 -DVM_STRESS -DVM_STRESS_MAJOR
 endif
 ifeq ($(mode),fast)
-fast = -Os -DNDEBUG
+cflags += -Os -DNDEBUG -DMONOLITHIC
 endif
 
 lflags = $(thread-lflags) -ldl
@@ -81,11 +81,13 @@ interpreter-depends = \
 	$(src)/machine.h
 
 interpreter-sources = \
-	$(src)/run.cpp \
+	$(src)/system.cpp \
+	$(src)/class-finder.cpp \
 	$(src)/machine.cpp \
-	$(src)/jnienv.cpp \
-	$(src)/builtin.cpp \
 	$(src)/heap.cpp \
+	$(src)/run.cpp \
+	$(src)/builtin.cpp \
+	$(src)/jnienv.cpp \
 	$(src)/main.cpp
 
 ifeq ($(arch),i386)
diff --git a/src/builtin.cpp b/src/builtin.cpp
index 29358142a3..50d685dfdc 100644
--- a/src/builtin.cpp
+++ b/src/builtin.cpp
@@ -3,6 +3,7 @@
 #include "run.h"
 
 namespace vm {
+
 namespace builtin {
 
 jstring
@@ -262,4 +263,5 @@ populate(Thread* t, object map)
 }
 
 } // namespace builtin
+
 } // namespace vm
diff --git a/src/builtin.h b/src/builtin.h
index b8fee910e4..3c03ffba8c 100644
--- a/src/builtin.h
+++ b/src/builtin.h
@@ -4,12 +4,14 @@
 #include "machine.h"
 
 namespace vm {
+
 namespace builtin {
 
 void
 populate(Thread* t, object map);
 
 } // namespace builtin
+
 } // namespace vm
 
 #endif//BUILTIN_H
diff --git a/src/class-finder.cpp b/src/class-finder.cpp
new file mode 100644
index 0000000000..4ff401a1ff
--- /dev/null
+++ b/src/class-finder.cpp
@@ -0,0 +1,167 @@
+
+
+#include "sys/mman.h"
+#include "sys/types.h"
+#include "sys/stat.h"
+#include "fcntl.h"
+
+
+
+#include "system.h"
+#include "class-finder.h"
+
+using namespace vm;
+
+namespace {
+
+const char*
+append(System* s, const char* a, const char* b, const char* c,
+       const char* d)
+{
+  unsigned al = strlen(a);
+  unsigned bl = strlen(b);
+  unsigned cl = strlen(c);
+  unsigned dl = strlen(d);
+  char* p = static_cast<char*>(s->allocate(al + bl + cl + dl + 1));
+  memcpy(p, a, al);
+  memcpy(p + al, b, bl);
+  memcpy(p + al + bl, c, cl);
+  memcpy(p + al + bl + cl, d, dl + 1);
+  return p;
+}
+
+const char**
+parsePath(System* s, const char* path)
+{
+  class Tokenizer {
+   public:
+    class Token {
+     public:
+      Token(const char* s, unsigned length): s(s), length(length) { }
+
+      const char* s;
+      unsigned length;
+    };
+
+    Tokenizer(const char* s, char delimiter): s(s), delimiter(delimiter) { }
+
+    bool hasMore() {
+      while (*s == delimiter) ++s;
+      return *s;
+    }
+
+    Token next() {
+      const char* p = s;
+      while (*s and *s != delimiter) ++s;
+      return Token(p, s - p);
+    }
+
+    const char* s;
+    char delimiter;
+  };
+
+  unsigned count = 0;
+  for (Tokenizer t(path, ':'); t.hasMore(); t.next()) ++ count;
+
+  const char** v = static_cast<const char**>
+    (s->allocate((count + 1) * sizeof(const char*)));
+
+  unsigned i = 0;
+  for (Tokenizer t(path, ':'); t.hasMore(); ++i) {
+    Tokenizer::Token token(t.next());
+    char* p = static_cast<char*>(s->allocate(token.length + 1));
+    memcpy(p, token.s, token.length);
+    p[token.length] = 0;
+    v[i] = p;
+  }
+
+  v[i] = 0;
+
+  return v;
+}
+
+class MyClassFinder: public ClassFinder {
+ public:
+  MyClassFinder(System* system, const char* path):
+    system(system),
+    path(parsePath(system, path))
+  { }
+
+  class Data: public ClassFinder::Data {
+   public:
+    Data(System* system, uint8_t* start, size_t length):
+      system(system),
+      start_(start),
+      length_(length)
+    { }
+
+    virtual const uint8_t* start() {
+      return start_;
+    }
+
+    virtual size_t length() {
+      return length_;
+    }
+
+    virtual void dispose() {
+      if (start_) {
+        munmap(start_, length_);
+      }
+      system->free(this);
+    }
+
+    System* system;
+    uint8_t* start_;
+    size_t length_;
+  };
+
+  virtual Data* find(const char* className) {
+    Data* d = new (system->allocate(sizeof(Data))) Data(system, 0, 0);
+
+    for (const char** p = path; *p; ++p) {
+      const char* file = append(system, *p, "/", className, ".class");
+      int fd = open(file, O_RDONLY);
+      system->free(file);
+
+      if (fd != -1) {
+        struct stat s;
+        int r = fstat(fd, &s);
+        if (r != -1) {
+          void* data = mmap(0, s.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+          if (data) {
+            d->start_ = static_cast<uint8_t*>(data);
+            d->length_ = s.st_size;
+            return d;
+          }
+        }
+      }
+    }
+    
+    system->free(d);
+    return 0;
+  }
+
+  virtual void dispose() {
+    for (const char** p = path; *p; ++p) {
+      system->free(*p);
+    }
+    system->free(path);
+
+    system->free(this);
+  }
+
+  System* system;
+  const char** path;
+};
+
+} // namespace
+
+namespace vm {
+
+ClassFinder*
+makeClassFinder(System* s, const char* path)
+{
+  return new (s->allocate(sizeof(MyClassFinder))) MyClassFinder(s, path);
+}
+
+} // namespace vm
diff --git a/src/class-finder.h b/src/class-finder.h
index d46061ab73..36f5d45eb9 100644
--- a/src/class-finder.h
+++ b/src/class-finder.h
@@ -2,6 +2,7 @@
 #define CLASS_FINDER_H
 
 #include "common.h"
+#include "system.h"
 
 namespace vm {
 
@@ -17,8 +18,12 @@ class ClassFinder {
 
   virtual ~ClassFinder() { }
   virtual Data* find(const char* className) = 0;
+  virtual void dispose() = 0;
 };
 
+ClassFinder*
+makeClassFinder(System* s, const char* path);
+
 } // namespace vm
 
 #endif//CLASS_FINDER_H
diff --git a/src/common.h b/src/common.h
index bf1b26b388..76d6473a60 100644
--- a/src/common.h
+++ b/src/common.h
@@ -1,6 +1,8 @@
 #ifndef COMMON_H
 #define COMMON_H
 
+
+
 #include "stdint.h"
 #include "stdlib.h"
 #include "stdarg.h"
@@ -27,6 +29,8 @@
 
 inline void* operator new(size_t, void* p) throw() { return p; }
 
+
+
 namespace vm {
 
 typedef void* object;
@@ -127,6 +131,6 @@ mask(T* p)
   return reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(p) & PointerMask);
 }
 
-}
+} // namespace vm
 
 #endif//COMMON_H
diff --git a/src/constants.h b/src/constants.h
index 799b931547..e381b2dc09 100644
--- a/src/constants.h
+++ b/src/constants.h
@@ -168,7 +168,7 @@ enum OpCode {
   ldc = 0x12,
   ldc_w = 0x13,
   ldc2_w = 0x14,
-  ldiv = 0x6d,
+  ldiv_ = 0x6d,
   lload = 0x16,
   lload_0 = 0x1e,
   lload_1 = 0x1f,
diff --git a/src/heap.cpp b/src/heap.cpp
index 0f055b65db..95b4c660a0 100644
--- a/src/heap.cpp
+++ b/src/heap.cpp
@@ -1374,99 +1374,99 @@ collect(Context* c)
   }
 }
 
+class MyHeap: public Heap {
+ public:
+  MyHeap(System* system): c(system) { }
+
+  virtual void collect(CollectionType type, Client* client) {
+    switch (type) {
+    case MinorCollection:
+      c.mode = ::MinorCollection;
+      break;
+
+    case MajorCollection:
+      c.mode = ::MajorCollection;
+      break;
+
+    default: abort(&c);
+    }
+
+    c.client = client;
+
+    ::collect(&c);
+  }
+
+  virtual bool needsMark(void** p) {
+    return *p and c.gen2.contains(p) and not c.gen2.contains(*p);
+  }
+
+  virtual void mark(void** p) {
+    if (Debug) {        
+      fprintf(stderr, "mark %p (%s) at %p (%s)\n",
+              *p, segment(&c, *p), p, segment(&c, p));
+    }
+
+    c.heapMap.set(p);
+  }
+
+  virtual void dispose() {
+    c.dispose();
+    c.system->free(this);
+  }
+
+  virtual void* follow(void* p) {
+    if (wasCollected(&c, p)) {
+      if (Debug) {
+        fprintf(stderr, "follow %p (%s) to %p (%s)\n",
+                p, segment(&c, p),
+                ::follow(&c, p), segment(&c, ::follow(&c, p)));
+      }
+
+      return ::follow(&c, p);
+    } else {
+      return p;
+    }
+  }
+
+  virtual Status status(void* p) {
+    p = mask(p);
+
+    if (p == 0) {
+      return Null;
+    } else if (c.nextGen1.contains(p)) {
+      return Reachable;
+    } else if (c.nextGen2.contains(p)
+               or (c.gen2.contains(p)
+                   and (c.mode == ::MinorCollection
+                        or c.gen2.indexOf(p) >= c.gen2Base)))
+    {
+      return Tenured;
+    } else if (wasCollected(&c, p)) {
+      return Reachable;
+    } else {
+      return Unreachable;
+    }
+  }
+
+  virtual CollectionType collectionType() {
+    if (c.mode == ::MinorCollection) {
+      return MinorCollection;
+    } else {
+      return MajorCollection;
+    }
+  }
+
+  Context c;
+};
+
 } // namespace
 
 namespace vm {
 
 Heap*
 makeHeap(System* system)
-{
-  class Heap: public vm::Heap {
-   public:
-    Heap(System* system): c(system) { }
-
-    virtual void collect(CollectionType type, Client* client) {
-      switch (type) {
-      case MinorCollection:
-        c.mode = ::MinorCollection;
-        break;
-
-      case MajorCollection:
-        c.mode = ::MajorCollection;
-        break;
-
-      default: abort(&c);
-      }
-
-      c.client = client;
-
-      ::collect(&c);
-    }
-
-    virtual bool needsMark(void** p) {
-      return *p and c.gen2.contains(p) and not c.gen2.contains(*p);
-    }
-
-    virtual void mark(void** p) {
-      if (Debug) {        
-        fprintf(stderr, "mark %p (%s) at %p (%s)\n",
-                *p, segment(&c, *p), p, segment(&c, p));
-      }
-
-      c.heapMap.set(p);
-    }
-
-    virtual void dispose() {
-      c.dispose();
-      c.system->free(this);
-    }
-
-    virtual void* follow(void* p) {
-      if (wasCollected(&c, p)) {
-        if (Debug) {
-          fprintf(stderr, "follow %p (%s) to %p (%s)\n",
-                  p, segment(&c, p),
-                  ::follow(&c, p), segment(&c, ::follow(&c, p)));
-        }
-
-        return ::follow(&c, p);
-      } else {
-        return p;
-      }
-    }
-
-    virtual Status status(void* p) {
-      p = mask(p);
-
-      if (p == 0) {
-        return Null;
-      } else if (c.nextGen1.contains(p)) {
-        return Reachable;
-      } else if (c.nextGen2.contains(p)
-                 or (c.gen2.contains(p)
-                     and (c.mode == ::MinorCollection
-                          or c.gen2.indexOf(p) >= c.gen2Base)))
-      {
-        return Tenured;
-      } else if (wasCollected(&c, p)) {
-        return Reachable;
-      } else {
-        return Unreachable;
-      }
-    }
-
-    virtual CollectionType collectionType() {
-      if (c.mode == ::MinorCollection) {
-        return MinorCollection;
-      } else {
-        return MajorCollection;
-      }
-    }
-
-    Context c;
-  };
-  
-  return new (system->allocate(sizeof(Heap))) Heap(system);
+{  
+  return new (system->allocate(sizeof(MyHeap))) MyHeap(system);
 }
 
 } // namespace vm
diff --git a/src/jnienv.cpp b/src/jnienv.cpp
index f6d22189a3..c373b9b03f 100644
--- a/src/jnienv.cpp
+++ b/src/jnienv.cpp
@@ -2,6 +2,7 @@
 #include "machine.h"
 
 namespace vm {
+
 namespace jni {
 
 jsize
@@ -51,4 +52,5 @@ populate(JNIEnvVTable* table)
 }
 
 } // namespace jni
+
 } // namespace vm
diff --git a/src/jnienv.h b/src/jnienv.h
index 6632b0510d..c9454e1598 100644
--- a/src/jnienv.h
+++ b/src/jnienv.h
@@ -4,12 +4,14 @@
 #include "machine.h"
 
 namespace vm {
+
 namespace jni {
 
 void
 populate(JNIEnvVTable* table);
 
 } // namespace jni
+
 } // namespace vm
 
 #endif//JNIENV_H
diff --git a/src/machine.h b/src/machine.h
index cf2bf9d015..e6c0952ceb 100644
--- a/src/machine.h
+++ b/src/machine.h
@@ -2008,6 +2008,12 @@ wait(Thread* t, object o, int64_t milliseconds)
   stress(t);
 }
 
+inline void
+vmWait(Thread* t, object o, int64_t milliseconds)
+{
+  wait(t, o, milliseconds);
+}
+
 inline void
 notify(Thread* t, object o)
 {
@@ -2025,6 +2031,12 @@ notify(Thread* t, object o)
   }
 }
 
+inline void
+vmNotify(Thread* t, object o)
+{
+  notify(t, o);
+}
+
 inline void
 notifyAll(Thread* t, object o)
 {
@@ -2042,6 +2054,12 @@ notifyAll(Thread* t, object o)
   }
 }
 
+inline void
+vmNotifyAll(Thread* t, object o)
+{
+  notifyAll(t, o);
+}
+
 void
 exit(Thread* t);
 
diff --git a/src/main.cpp b/src/main.cpp
index 120ad63106..8b2efc2168 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,13 +1,3 @@
-#include "sys/mman.h"
-#include "sys/types.h"
-#include "sys/stat.h"
-#include "sys/time.h"
-#include "time.h"
-#include "fcntl.h"
-#include "dlfcn.h"
-#include "errno.h"
-#include "pthread.h"
-
 #include "common.h"
 #include "system.h"
 #include "heap.h"
@@ -16,534 +6,21 @@
 
 using namespace vm;
 
-#ifdef __i386__
-
-extern "C" uint64_t
-cdeclCall(void* function, void* stack, unsigned stackSize,
-          unsigned returnType);
-
 namespace {
 
-inline uint64_t
-dynamicCall(void* function, uint32_t* arguments, uint8_t*,
-            unsigned, unsigned argumentsSize, unsigned returnType)
-{
-  return cdeclCall(function, arguments, argumentsSize, returnType);
-}
-
-} // namespace
-
-#elif defined __x86_64__
-
-extern "C" uint64_t
-amd64Call(void* function, void* stack, unsigned stackSize,
-          void* gprTable, void* sseTable, unsigned returnType);
-
-namespace {
-
-uint64_t
-dynamicCall(void* function, uint64_t* arguments, uint8_t* argumentTypes,
-            unsigned argumentCount, unsigned, unsigned returnType)
-{
-  const unsigned GprCount = 6;
-  uint64_t gprTable[GprCount];
-  unsigned gprIndex = 0;
-
-  const unsigned SseCount = 8;
-  uint64_t sseTable[SseCount];
-  unsigned sseIndex = 0;
-
-  uint64_t stack[argumentCount];
-  unsigned stackIndex = 0;
-
-  for (unsigned i = 0; i < argumentCount; ++i) {
-    switch (argumentTypes[i]) {
-    case FLOAT_TYPE:
-    case DOUBLE_TYPE: {
-      if (sseIndex < SseCount) {
-        sseTable[sseIndex++] = arguments[i];
-      } else {
-        stack[stackIndex++] = arguments[i];
-      }
-    } break;
-
-    default: {
-      if (gprIndex < GprCount) {
-        gprTable[gprIndex++] = arguments[i];
-      } else {
-        stack[stackIndex++] = arguments[i];
-      }
-    } break;
-    }
-  }
-
-  return amd64Call(function, stack, stackIndex * 8, (gprIndex ? gprTable : 0),
-                   (sseIndex ? sseTable : 0), returnType);
-}
-
-} // namespace
-
-#else
-#  error unsupported platform
-#endif
-
-namespace {
-
-void*
-run(void* t)
-{
-  static_cast<vm::System::Thread*>(t)->run();
-  return 0;
-}
-
-int64_t
-now()
-{
-  timeval tv = { 0, 0 };
-  gettimeofday(&tv, 0);
-  return (static_cast<int64_t>(tv.tv_sec) * 1000) +
-    (static_cast<int64_t>(tv.tv_usec) / 1000);
-}
-
-const char*
-append(vm::System* s, const char* a, const char* b, const char* c,
-       const char* d)
-{
-  unsigned al = strlen(a);
-  unsigned bl = strlen(b);
-  unsigned cl = strlen(c);
-  unsigned dl = strlen(d);
-  char* p = static_cast<char*>(s->allocate(al + bl + cl + dl + 1));
-  memcpy(p, a, al);
-  memcpy(p + al, b, bl);
-  memcpy(p + al + bl, c, cl);
-  memcpy(p + al + bl + cl, d, dl + 1);
-  return p;
-}
-
-const bool Verbose = false;
-
-class System: public vm::System {
- public:
-  class Thread: public vm::System::Thread {
-   public:
-    Thread(vm::System* s, vm::System::Runnable* r): s(s), r(r) { }
-
-    virtual void run() {
-      r->run(this);
-    }
-
-    virtual void join() {
-      int rv = pthread_join(thread, 0);
-      assert(s, rv == 0);
-    }
-
-    virtual void dispose() {
-      if (r) {
-        r->dispose();
-      }
-      s->free(this);
-    }
-
-    vm::System* s;
-    vm::System::Runnable* r;
-    pthread_t thread;
-  };
-
-  class Monitor: public vm::System::Monitor {
-   public:
-    Monitor(vm::System* s): s(s), context(0), depth(0) {
-      pthread_mutex_init(&mutex, 0);
-      pthread_cond_init(&condition, 0);      
-    }
-
-    virtual bool tryAcquire(void* context) {
-      if (this->context == context) {
-        ++ depth;
-        return true;
-      } else {
-        switch (pthread_mutex_trylock(&mutex)) {
-        case EBUSY:
-          return false;
-
-        case 0:
-          this->context = context;
-          ++ depth;
-          return true;
-
-        default:
-          vm::abort(s);
-        }
-      }
-    }
-
-    virtual void acquire(void* context) {
-      if (this->context != context) {
-        pthread_mutex_lock(&mutex);
-        this->context = context;
-      }
-      ++ depth;
-    }
-
-    virtual void release(void* context) {
-      if (this->context == context) {
-        if (-- depth == 0) {
-          this->context = 0;
-          pthread_mutex_unlock(&mutex);
-        }
-      } else {
-        vm::abort(s);
-      }
-    }
-
-    virtual void wait(void* context, int64_t time) {
-      if (this->context == context) {
-        unsigned depth = this->depth;
-        this->depth = 0;
-        this->context = 0;
-        if (time) {
-          int64_t then = now() + time;
-          timespec ts = { then / 1000, (then % 1000) * 1000 * 1000 };
-          int rv = pthread_cond_timedwait(&condition, &mutex, &ts);
-          assert(s, rv == 0);
-        } else {
-          int rv = pthread_cond_wait(&condition, &mutex);
-          assert(s, rv == 0);
-        }
-        this->context = context;
-        this->depth = depth;
-      } else {
-        vm::abort(s);
-      }
-    }
-
-    virtual void notify(void* context) {
-      if (this->context == context) {
-        int rv = pthread_cond_signal(&condition);
-        assert(s, rv == 0);
-      } else {
-        vm::abort(s);
-      }
-    }
-
-    virtual void notifyAll(void* context) {
-      if (this->context == context) {
-        int rv = pthread_cond_broadcast(&condition);
-        assert(s, rv == 0);
-      } else {
-        vm::abort(s);
-      }
-    }
-    
-    virtual void* owner() {
-      return context;
-    }
-
-    virtual void dispose() {
-      assert(s, context == 0);
-      pthread_mutex_destroy(&mutex);
-      pthread_cond_destroy(&condition);
-      s->free(this);
-    }
-
-    vm::System* s;
-    pthread_mutex_t mutex;
-    pthread_cond_t condition;
-    void* context;
-    unsigned depth;
-  };
-
-  class Library: public vm::System::Library {
-   public:
-    Library(vm::System* s, void* p, vm::System::Library* next):
-      s(s),
-      p(p),
-      next_(next)
-    { }
-
-    virtual void* resolve(const char* function) {
-      return dlsym(p, function);
-    }
-
-    virtual vm::System::Library* next() {
-      return next_;
-    }
-
-    virtual void dispose() {
-      if (Verbose) {
-        fprintf(stderr, "close %p\n", p);
-      }
-
-      dlclose(p);
-
-      if (next_) {
-        next_->dispose();
-      }
-      s->free(this);
-    }
-
-    vm::System* s;
-    void* p;
-    vm::System::Library* next_;
-  };
-
-  System(unsigned limit): limit(limit), count(0) {
-    pthread_mutex_init(&mutex, 0);
-  }
-
-  ~System() {
-    pthread_mutex_destroy(&mutex);
-  }
-
-  virtual bool success(Status s) {
-    return s == 0;
-  }
-
-  virtual void* tryAllocate(unsigned size) {
-    pthread_mutex_lock(&mutex);
-
-    if (Verbose) {
-      fprintf(stderr, "try %d; count: %d; limit: %d\n",
-              size, count, limit);
-    }
-
-    if (count + size > limit) {
-      pthread_mutex_unlock(&mutex);
-      return 0;
-    } else {
-      uintptr_t* up = static_cast<uintptr_t*>
-        (malloc(size + sizeof(uintptr_t)));
-      if (up == 0) {
-        pthread_mutex_unlock(&mutex);
-        vm::abort(this);
-      } else {
-        *up = size;
-        count += *up;
-      
-        pthread_mutex_unlock(&mutex);
-        return up + 1;
-      }
-    }
-  }
-
-  virtual void free(const void* p) {
-    pthread_mutex_lock(&mutex);
-
-    if (p) {
-      const uintptr_t* up = static_cast<const uintptr_t*>(p) - 1;
-      if (count < *up) {
-        abort();
-      }
-      count -= *up;
-
-      if (Verbose) {
-        fprintf(stderr, "free " LD "; count: %d; limit: %d\n",
-                *up, count, limit);
-      }
-
-      ::free(const_cast<uintptr_t*>(up));
-    }
-
-    pthread_mutex_unlock(&mutex);
-  }
-
-  virtual Status attach(vm::System::Thread** tp) {
-    Thread* t = new (vm::System::allocate(sizeof(Thread))) Thread(this, 0);
-    t->thread = pthread_self();
-    *tp = t;
-    return 0;
-  }
-
-  virtual Status start(Runnable* r) {
-    Thread* t = new (vm::System::allocate(sizeof(Thread))) Thread(this, r);
-    int rv = pthread_create(&(t->thread), 0, run, t);
-    assert(this, rv == 0);
-    return 0;
-  }
-
-  virtual Status make(vm::System::Monitor** m) {
-    *m = new (vm::System::allocate(sizeof(Monitor))) Monitor(this);
-    return 0;
-  }
-
-  virtual void sleep(int64_t milliseconds) {
-    timespec ts = { milliseconds / 1000, (milliseconds % 1000) * 1000 * 1000 };
-
-    nanosleep(&ts, 0);
-  }
-
-  virtual uint64_t call(void* function, uintptr_t* arguments, uint8_t* types,
-                        unsigned count, unsigned size, unsigned returnType)
-  {
-    return dynamicCall(function, arguments, types, count, size, returnType);
-  }
-
-  virtual Status load(vm::System::Library** lib,
-                      const char* name,
-                      vm::System::Library* next)
-  {
-    unsigned size = strlen(name) + 7;
-    char buffer[size];
-    snprintf(buffer, size, "lib%s.so", name);
- 
-    void* p = dlopen(buffer, RTLD_LAZY);
-    if (p) {
-      if (Verbose) {
-        fprintf(stderr, "open %s as %p\n", buffer, p);
-      }
-
-      *lib = new (vm::System::allocate(sizeof(Library)))
-        Library(this, p, next);
-      return 0;
-    } else {
-      return 1;
-    }
-  }
-
-  virtual void abort() {
-    ::abort();
-  }
-
-  pthread_mutex_t mutex;
-  unsigned limit;
-  unsigned count;
-};
-
-class ClassFinder: public vm::ClassFinder {
- public:
-  ClassFinder(vm::System* system, const char** path):
-    system(system),
-    path(path)
-  { }
-
-  class Data: public vm::ClassFinder::Data {
-   public:
-    Data(vm::System* system, uint8_t* start, size_t length):
-      system(system),
-      start_(start),
-      length_(length)
-    { }
-
-    virtual const uint8_t* start() {
-      return start_;
-    }
-
-    virtual size_t length() {
-      return length_;
-    }
-
-    virtual void dispose() {
-      if (start_) {
-        munmap(start_, length_);
-      }
-      system->free(this);
-    }
-
-    vm::System* system;
-    uint8_t* start_;
-    size_t length_;
-  };
-
-  virtual Data* find(const char* className) {
-    Data* d = new (system->allocate(sizeof(Data))) Data(system, 0, 0);
-
-    for (const char** p = path; *p; ++p) {
-      const char* file = append(system, *p, "/", className, ".class");
-      int fd = open(file, O_RDONLY);
-      system->free(file);
-
-      if (fd != -1) {
-        struct stat s;
-        int r = fstat(fd, &s);
-        if (r != -1) {
-          void* data = mmap(0, s.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
-          if (data) {
-            d->start_ = static_cast<uint8_t*>(data);
-            d->length_ = s.st_size;
-            return d;
-          }
-        }
-      }
-    }
-    
-    system->free(d);
-    return 0;
-  }
-
-  vm::System* system;
-  const char** path;
-};
-
-const char**
-parsePath(vm::System* s, const char* path)
-{
-  class Tokenizer {
-   public:
-    class Token {
-     public:
-      Token(const char* s, unsigned length): s(s), length(length) { }
-
-      const char* s;
-      unsigned length;
-    };
-
-    Tokenizer(const char* s, char delimiter): s(s), delimiter(delimiter) { }
-
-    bool hasMore() {
-      while (*s == delimiter) ++s;
-      return *s;
-    }
-
-    Token next() {
-      const char* p = s;
-      while (*s and *s != delimiter) ++s;
-      return Token(p, s - p);
-    }
-
-    const char* s;
-    char delimiter;
-  };
-
-  unsigned count = 0;
-  for (Tokenizer t(path, ':'); t.hasMore(); t.next()) ++ count;
-
-  const char** v = static_cast<const char**>
-    (s->allocate((count + 1) * sizeof(const char*)));
-
-  unsigned i = 0;
-  for (Tokenizer t(path, ':'); t.hasMore(); ++i) {
-    Tokenizer::Token token(t.next());
-    char* p = static_cast<char*>(s->allocate(token.length + 1));
-    memcpy(p, token.s, token.length);
-    p[token.length] = 0;
-    v[i] = p;
-  }
-
-  v[i] = 0;
-
-  return v;
-}
-
 int
 run(unsigned heapSize, const char* path, const char* class_, int argc,
     const char** argv)
 {
-  System s(heapSize);
+  System* s = makeSystem(heapSize);
+  ClassFinder* cf = makeClassFinder(s, path);
+  Heap* heap = makeHeap(s);
 
-  const char** pathv = parsePath(&s, path);
-  ClassFinder cf(&s, pathv);
-
-  Heap* heap = makeHeap(&s);
-
-  int exitCode = run(&s, heap, &cf, class_, argc, argv);
+  int exitCode = run(s, heap, cf, class_, argc, argv);
 
   heap->dispose();
-
-  for (const char** p = pathv; *p; ++p) {
-    s.free(*p);
-  }
-
-  s.free(pathv);
+  cf->dispose();
+  s->dispose();
 
   return exitCode;
 }
diff --git a/src/run.cpp b/src/run.cpp
index 11a685c55a..239373fac5 100644
--- a/src/run.cpp
+++ b/src/run.cpp
@@ -1656,7 +1656,7 @@ run(Thread* t)
     }
   } goto loop;
 
-  case vm::ldiv: {
+  case ldiv_: {
     int64_t b = popLong(t);
     int64_t a = popLong(t);
     
@@ -2386,4 +2386,4 @@ run(System* system, Heap* heap, ClassFinder* classFinder,
   return exitCode;
 }
 
-}
+} // namespace vm
diff --git a/src/run.h b/src/run.h
index 1e721dbfc6..069b38c0a6 100644
--- a/src/run.h
+++ b/src/run.h
@@ -16,6 +16,6 @@ int
 run(System* sys, Heap* heap, ClassFinder* classFinder,
     const char* className, int argc, const char** argv);
 
-}
+} // namespace vm
 
 #endif//RUN_H
diff --git a/src/system.cpp b/src/system.cpp
new file mode 100644
index 0000000000..7cdde23232
--- /dev/null
+++ b/src/system.cpp
@@ -0,0 +1,403 @@
+#include "sys/mman.h"
+#include "sys/types.h"
+#include "sys/stat.h"
+#include "sys/time.h"
+#include "time.h"
+#include "fcntl.h"
+#include "dlfcn.h"
+#include "errno.h"
+#include "pthread.h"
+#include "stdint.h"
+
+#ifdef __i386__
+
+extern "C" uint64_t
+cdeclCall(void* function, void* stack, unsigned stackSize,
+          unsigned returnType);
+
+namespace {
+
+inline uint64_t
+dynamicCall(void* function, uint32_t* arguments, uint8_t*,
+            unsigned, unsigned argumentsSize, unsigned returnType)
+{
+  return cdeclCall(function, arguments, argumentsSize, returnType);
+}
+
+} // namespace
+
+#elif defined __x86_64__
+
+extern "C" uint64_t
+amd64Call(void* function, void* stack, unsigned stackSize,
+          void* gprTable, void* sseTable, unsigned returnType);
+
+#include "system.h"
+
+namespace {
+
+uint64_t
+dynamicCall(void* function, uint64_t* arguments, uint8_t* argumentTypes,
+            unsigned argumentCount, unsigned, unsigned returnType)
+{
+  const unsigned GprCount = 6;
+  uint64_t gprTable[GprCount];
+  unsigned gprIndex = 0;
+
+  const unsigned SseCount = 8;
+  uint64_t sseTable[SseCount];
+  unsigned sseIndex = 0;
+
+  uint64_t stack[argumentCount];
+  unsigned stackIndex = 0;
+
+  for (unsigned i = 0; i < argumentCount; ++i) {
+    switch (argumentTypes[i]) {
+    case FLOAT_TYPE:
+    case DOUBLE_TYPE: {
+      if (sseIndex < SseCount) {
+        sseTable[sseIndex++] = arguments[i];
+      } else {
+        stack[stackIndex++] = arguments[i];
+      }
+    } break;
+
+    default: {
+      if (gprIndex < GprCount) {
+        gprTable[gprIndex++] = arguments[i];
+      } else {
+        stack[stackIndex++] = arguments[i];
+      }
+    } break;
+    }
+  }
+
+  return amd64Call(function, stack, stackIndex * 8, (gprIndex ? gprTable : 0),
+                   (sseIndex ? sseTable : 0), returnType);
+}
+
+} // namespace
+
+#else
+#  error unsupported platform
+#endif
+
+using namespace vm;
+
+namespace {
+
+void*
+run(void* t)
+{
+  static_cast<System::Thread*>(t)->run();
+  return 0;
+}
+
+int64_t
+now()
+{
+  timeval tv = { 0, 0 };
+  gettimeofday(&tv, 0);
+  return (static_cast<int64_t>(tv.tv_sec) * 1000) +
+    (static_cast<int64_t>(tv.tv_usec) / 1000);
+}
+
+const bool Verbose = false;
+
+class MySystem: public System {
+ public:
+  class Thread: public System::Thread {
+   public:
+    Thread(System* s, System::Runnable* r): s(s), r(r) { }
+
+    virtual void run() {
+      r->run(this);
+    }
+
+    virtual void join() {
+      int rv = pthread_join(thread, 0);
+      assert(s, rv == 0);
+    }
+
+    virtual void dispose() {
+      if (r) {
+        r->dispose();
+      }
+      s->free(this);
+    }
+
+    System* s;
+    System::Runnable* r;
+    pthread_t thread;
+  };
+
+  class Monitor: public System::Monitor {
+   public:
+    Monitor(System* s): s(s), context(0), depth(0) {
+      pthread_mutex_init(&mutex, 0);
+      pthread_cond_init(&condition, 0);      
+    }
+
+    virtual bool tryAcquire(void* context) {
+      if (this->context == context) {
+        ++ depth;
+        return true;
+      } else {
+        switch (pthread_mutex_trylock(&mutex)) {
+        case EBUSY:
+          return false;
+
+        case 0:
+          this->context = context;
+          ++ depth;
+          return true;
+
+        default:
+          sysAbort(s);
+        }
+      }
+    }
+
+    virtual void acquire(void* context) {
+      if (this->context != context) {
+        pthread_mutex_lock(&mutex);
+        this->context = context;
+      }
+      ++ depth;
+    }
+
+    virtual void release(void* context) {
+      if (this->context == context) {
+        if (-- depth == 0) {
+          this->context = 0;
+          pthread_mutex_unlock(&mutex);
+        }
+      } else {
+        sysAbort(s);
+      }
+    }
+
+    virtual void wait(void* context, int64_t time) {
+      if (this->context == context) {
+        unsigned depth = this->depth;
+        this->depth = 0;
+        this->context = 0;
+        if (time) {
+          int64_t then = now() + time;
+          timespec ts = { then / 1000, (then % 1000) * 1000 * 1000 };
+          int rv = pthread_cond_timedwait(&condition, &mutex, &ts);
+          assert(s, rv == 0);
+        } else {
+          int rv = pthread_cond_wait(&condition, &mutex);
+          assert(s, rv == 0);
+        }
+        this->context = context;
+        this->depth = depth;
+      } else {
+        sysAbort(s);
+      }
+    }
+
+    virtual void notify(void* context) {
+      if (this->context == context) {
+        int rv = pthread_cond_signal(&condition);
+        assert(s, rv == 0);
+      } else {
+        sysAbort(s);
+      }
+    }
+
+    virtual void notifyAll(void* context) {
+      if (this->context == context) {
+        int rv = pthread_cond_broadcast(&condition);
+        assert(s, rv == 0);
+      } else {
+        sysAbort(s);
+      }
+    }
+    
+    virtual void* owner() {
+      return context;
+    }
+
+    virtual void dispose() {
+      assert(s, context == 0);
+      pthread_mutex_destroy(&mutex);
+      pthread_cond_destroy(&condition);
+      s->free(this);
+    }
+
+    System* s;
+    pthread_mutex_t mutex;
+    pthread_cond_t condition;
+    void* context;
+    unsigned depth;
+  };
+
+  class Library: public System::Library {
+   public:
+    Library(System* s, void* p, System::Library* next):
+      s(s),
+      p(p),
+      next_(next)
+    { }
+
+    virtual void* resolve(const char* function) {
+      return dlsym(p, function);
+    }
+
+    virtual System::Library* next() {
+      return next_;
+    }
+
+    virtual void dispose() {
+      if (Verbose) {
+        fprintf(stderr, "close %p\n", p);
+      }
+
+      dlclose(p);
+
+      if (next_) {
+        next_->dispose();
+      }
+      s->free(this);
+    }
+
+    System* s;
+    void* p;
+    System::Library* next_;
+  };
+
+  MySystem(unsigned limit): limit(limit), count(0) {
+    pthread_mutex_init(&mutex, 0);
+  }
+
+  virtual bool success(Status s) {
+    return s == 0;
+  }
+
+  virtual void* tryAllocate(unsigned size) {
+    pthread_mutex_lock(&mutex);
+
+    if (Verbose) {
+      fprintf(stderr, "try %d; count: %d; limit: %d\n",
+              size, count, limit);
+    }
+
+    if (count + size > limit) {
+      pthread_mutex_unlock(&mutex);
+      return 0;
+    } else {
+      uintptr_t* up = static_cast<uintptr_t*>
+        (malloc(size + sizeof(uintptr_t)));
+      if (up == 0) {
+        pthread_mutex_unlock(&mutex);
+        sysAbort(this);
+      } else {
+        *up = size;
+        count += *up;
+      
+        pthread_mutex_unlock(&mutex);
+        return up + 1;
+      }
+    }
+  }
+
+  virtual void free(const void* p) {
+    pthread_mutex_lock(&mutex);
+
+    if (p) {
+      const uintptr_t* up = static_cast<const uintptr_t*>(p) - 1;
+      if (count < *up) {
+        abort();
+      }
+      count -= *up;
+
+      if (Verbose) {
+        fprintf(stderr, "free " LD "; count: %d; limit: %d\n",
+                *up, count, limit);
+      }
+
+      ::free(const_cast<uintptr_t*>(up));
+    }
+
+    pthread_mutex_unlock(&mutex);
+  }
+
+  virtual Status attach(System::Thread** tp) {
+    Thread* t = new (System::allocate(sizeof(Thread))) Thread(this, 0);
+    t->thread = pthread_self();
+    *tp = t;
+    return 0;
+  }
+
+  virtual Status start(Runnable* r) {
+    Thread* t = new (System::allocate(sizeof(Thread))) Thread(this, r);
+    int rv = pthread_create(&(t->thread), 0, run, t);
+    assert(this, rv == 0);
+    return 0;
+  }
+
+  virtual Status make(System::Monitor** m) {
+    *m = new (System::allocate(sizeof(Monitor))) Monitor(this);
+    return 0;
+  }
+
+  virtual void sleep(int64_t milliseconds) {
+    timespec ts = { milliseconds / 1000, (milliseconds % 1000) * 1000 * 1000 };
+
+    nanosleep(&ts, 0);
+  }
+
+  virtual uint64_t call(void* function, uintptr_t* arguments, uint8_t* types,
+                        unsigned count, unsigned size, unsigned returnType)
+  {
+    return dynamicCall(function, arguments, types, count, size, returnType);
+  }
+
+  virtual Status load(System::Library** lib,
+                      const char* name,
+                      System::Library* next)
+  {
+    unsigned size = strlen(name) + 7;
+    char buffer[size];
+    snprintf(buffer, size, "lib%s.so", name);
+ 
+    void* p = dlopen(buffer, RTLD_LAZY);
+    if (p) {
+      if (Verbose) {
+        fprintf(stderr, "open %s as %p\n", buffer, p);
+      }
+
+      *lib = new (System::allocate(sizeof(Library))) Library(this, p, next);
+      return 0;
+    } else {
+      return 1;
+    }
+  }
+
+  virtual void abort() {
+    ::abort();
+  }
+
+  virtual void dispose() {
+    pthread_mutex_destroy(&mutex);
+    ::free(this);
+  }
+
+  pthread_mutex_t mutex;
+  unsigned limit;
+  unsigned count;
+};
+
+} // namespace
+
+namespace vm {
+
+System*
+makeSystem(unsigned heapSize)
+{
+  return new (malloc(sizeof(MySystem))) MySystem(heapSize);
+}
+
+} // namespace vm
diff --git a/src/system.h b/src/system.h
index 789f615528..03a3d8275f 100644
--- a/src/system.h
+++ b/src/system.h
@@ -65,6 +65,7 @@ class System: public Allocator {
                         unsigned returnType) = 0;
   virtual Status load(Library**, const char* name, Library* next) = 0;
   virtual void abort() = 0;
+  virtual void dispose() = 0;
 
   virtual void* allocate(unsigned size) {
     void* p = tryAllocate(size);
@@ -82,6 +83,12 @@ abort(System* s)
   ::abort();
 }
 
+inline void NO_RETURN
+sysAbort(System* s)
+{
+  abort(s);
+}
+
 inline void
 expect(System* s, bool v)
 {
@@ -100,6 +107,9 @@ assert(System* s, bool v)
 }
 #endif
 
+System*
+makeSystem(unsigned heapSize);
+
 } // namespace vm
 
 #endif//SYSTEM_H