From eef2c848e86f7370d7cda57e837fdab7e9a5cd6a Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Wed, 25 Dec 2024 00:06:54 -0600
Subject: [PATCH] implement long

---
 .gitignore           |   3 +-
 c/class_file.c       |  12 ++-
 c/class_file.h       |   7 +-
 c/class_resolver.c   |   3 +-
 c/debug_class_file.c |  17 ++--
 c/execute.c          | 209 ++++++++++++++++++++++++++++++++++---------
 c/frame.c            |  67 +++++++++-----
 c/frame.h            |  18 ++++
 c/main.c             |   2 +
 class_file.py        |  38 ++++----
 gen_decoder.py       |   9 +-
 p/Long.java          |  57 ++++++++++++
 12 files changed, 337 insertions(+), 105 deletions(-)
 create mode 100644 p/Long.java

diff --git a/.gitignore b/.gitignore
index 17c1e98..fdeb6ca 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,4 +6,5 @@
 *.class
 *.out
 main
-print_class
\ No newline at end of file
+print_class
+__pycache__
\ No newline at end of file
diff --git a/c/class_file.c b/c/class_file.c
index 332aa81..540e9c8 100644
--- a/c/class_file.c
+++ b/c/class_file.c
@@ -142,8 +142,14 @@ struct class_file * class_file_parse(const uint8_t * buf)
       break;
     case CONSTANT_Long:                 [[fallthrough]];
     case CONSTANT_Double:
-      constant->_long.high_bytes = parse_u4(&buf);
-      constant->_long.low_bytes = parse_u4(&buf);
+      {
+        uint64_t high_bytes = parse_u4(&buf);
+        uint64_t low_bytes = parse_u4(&buf);
+        constant->_long.bytes = high_bytes << 32 | low_bytes;
+        // long and double use two constant pool entries
+        class_file->constant_pool[i + 1].tag = 0;
+        i += 1;
+      }
       break;
     case CONSTANT_NameAndType:
       constant->nameandtype.name_index = parse_u2(&buf);
@@ -170,9 +176,7 @@ struct class_file * class_file_parse(const uint8_t * buf)
       constant->module.name_index = parse_u2(&buf);
       break;
     default:
-      #ifdef DEBUG
       assert(false);
-      #endif
       break;
     }
   }
diff --git a/c/class_file.h b/c/class_file.h
index b621f41..5f53b0b 100644
--- a/c/class_file.h
+++ b/c/class_file.h
@@ -2,6 +2,7 @@
 
 #include <stdint.h>
 
+typedef uint64_t u8;
 typedef uint32_t u4;
 typedef uint16_t u2;
 typedef uint8_t u1;
@@ -58,13 +59,11 @@ struct constant_Float_info {
 };
 
 struct constant_Long_info {
-  u4 high_bytes;
-  u4 low_bytes;
+  u8 bytes;
 };
 
 struct constant_Double_info {
-  u4 high_bytes;
-  u4 low_bytes;
+  u8 bytes;
 };
 
 struct constant_NameAndType_info {
diff --git a/c/class_resolver.c b/c/class_resolver.c
index d8fa8d4..0c96f5c 100644
--- a/c/class_resolver.c
+++ b/c/class_resolver.c
@@ -181,7 +181,8 @@ struct method_info * class_resolver_lookup_method(struct class_entry * class_ent
                                                  method_name_length,
                                                  method_descriptor,
                                                  method_descriptor_length);
-  assert(e != nullptr);
+  if (e == nullptr)
+    return nullptr;
 
   return (struct method_info *)e->value;
 }
diff --git a/c/debug_class_file.c b/c/debug_class_file.c
index 2f4eb2d..4f10a56 100644
--- a/c/debug_class_file.c
+++ b/c/debug_class_file.c
@@ -2,6 +2,7 @@
 #include <assert.h>
 #include <stdint.h>
 #include <string.h>
+#include <inttypes.h>
 
 #include "class_file.h"
 #include "bytes.h"
@@ -50,14 +51,12 @@ void print_constant(struct constant * constant)
            *(float *)(&constant->_float.bytes));
     break;
   case CONSTANT_Long:
-    printf("CONSTANT_Long high_bytes=%d low_bytes=%d\n",
-           constant->_long.high_bytes,
-           constant->_long.low_bytes);
+    printf("CONSTANT_Long bytes=%" PRId64 "\n",
+           constant->_long.bytes);
     break;
   case CONSTANT_Double:
-    printf("CONSTANT_Double high_bytes=%d low_bytes=%d\n",
-           constant->_long.high_bytes,
-           constant->_long.low_bytes);
+    printf("CONSTANT_Double bytes=%f\n",
+           *(double *)(&constant->_double.bytes));
     break;
   case CONSTANT_NameAndType:
     printf("CONSTANT_NameAndType %d %d\n",
@@ -221,8 +220,10 @@ void print_class_file(struct class_file * class_file)
 
   printf("constants:\n");
   for (int i = 0; i < class_file->constant_pool_count - 1; i++) {
-    printf("% 3d: ", i + 1);
-    print_constant(&class_file->constant_pool[i]);
+    if (class_file->constant_pool[i].tag != 0) {
+      printf("% 3d: ", i + 1);
+      print_constant(&class_file->constant_pool[i]);
+    }
   }
 
   printf("access_flags %04x\n", class_file->access_flags);
diff --git a/c/execute.c b/c/execute.c
index 708e2d2..2b8e65b 100644
--- a/c/execute.c
+++ b/c/execute.c
@@ -321,7 +321,9 @@ void op_f2i(struct vm * vm)
 
 void op_f2l(struct vm * vm)
 {
-  assert(!"op_f2l");
+  float value = operand_stack_pop_f32(vm->current_frame);
+  int64_t result = (int64_t)value;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_fadd(struct vm * vm)
@@ -599,7 +601,9 @@ void op_i2f(struct vm * vm)
 
 void op_i2l(struct vm * vm)
 {
-  assert(!"op_i2l");
+  int32_t value = operand_stack_pop_u32(vm->current_frame);
+  int64_t result = (int64_t)value;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_i2s(struct vm * vm)
@@ -629,9 +633,9 @@ void op_iaload(struct vm * vm)
 
 void op_iand(struct vm * vm)
 {
-  int32_t value2 = operand_stack_pop_u32(vm->current_frame);
-  int32_t value1 = operand_stack_pop_u32(vm->current_frame);
-  int32_t result = value1 & value2;
+  uint32_t value2 = operand_stack_pop_u32(vm->current_frame);
+  uint32_t value1 = operand_stack_pop_u32(vm->current_frame);
+  uint32_t result = value1 & value2;
   operand_stack_push_u32(vm->current_frame, result);
 }
 
@@ -954,7 +958,7 @@ void op_ior(struct vm * vm)
 {
   uint32_t value2 = operand_stack_pop_u32(vm->current_frame);
   uint32_t value1 = operand_stack_pop_u32(vm->current_frame);
-  int32_t result = value1 | value2;
+  uint32_t result = value1 | value2;
   operand_stack_push_u32(vm->current_frame, result);
 }
 
@@ -1072,7 +1076,7 @@ void op_ixor(struct vm * vm)
 {
   uint32_t value2 = operand_stack_pop_u32(vm->current_frame);
   uint32_t value1 = operand_stack_pop_u32(vm->current_frame);
-  int32_t result = value1 ^ value2;
+  uint32_t result = value1 ^ value2;
   operand_stack_push_u32(vm->current_frame, result);
 }
 
@@ -1093,47 +1097,79 @@ void op_l2d(struct vm * vm)
 
 void op_l2f(struct vm * vm)
 {
-  assert(!"op_l2f");
+  int64_t value = operand_stack_pop_u64(vm->current_frame);
+  float result = (float)value;
+  operand_stack_push_f32(vm->current_frame, result);
 }
 
 void op_l2i(struct vm * vm)
 {
-  assert(!"op_l2i");
+  int64_t value = operand_stack_pop_u64(vm->current_frame);
+  int32_t result = (int32_t)value;
+  operand_stack_push_u32(vm->current_frame, result);
 }
 
 void op_ladd(struct vm * vm)
 {
-  assert(!"op_ladd");
+  int64_t value2 = operand_stack_pop_u64(vm->current_frame);
+  int64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  int64_t result = value1 + value2;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_laload(struct vm * vm)
 {
-  assert(!"op_laload");
+  int32_t index = operand_stack_pop_u32(vm->current_frame);
+  int32_t * arrayref = (int32_t *)operand_stack_pop_u32(vm->current_frame);
+  assert(arrayref[0] > 0 && index < arrayref[0]);
+  int64_t * longarray = (int64_t *)&arrayref[1];
+  int64_t value = longarray[index];
+  operand_stack_push_u64(vm->current_frame, value);
 }
 
 void op_land(struct vm * vm)
 {
-  assert(!"op_land");
+  uint64_t value2 = operand_stack_pop_u64(vm->current_frame);
+  uint64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  uint64_t result = value1 & value2;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_lastore(struct vm * vm)
 {
-  assert(!"op_lastore");
+  int64_t value = operand_stack_pop_u64(vm->current_frame);
+  int32_t index = operand_stack_pop_u32(vm->current_frame);
+  int32_t * arrayref = (int32_t *)operand_stack_pop_u32(vm->current_frame);
+  assert(arrayref[0] > 0 && index < arrayref[0]);
+  int64_t * longarray = (int64_t *)&arrayref[1];
+  longarray[index] = value;
 }
 
 void op_lcmp(struct vm * vm)
 {
-  assert(!"op_lcmp");
+  int64_t value2 = operand_stack_pop_u64(vm->current_frame);
+  int64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  bool greater = value1 > value2;
+  bool equal = value1 == value2;
+  int32_t value;
+  if (equal) {
+    value = 0;
+  } else if (greater) {
+    value = 1;
+  } else { // less than
+    value = -1;
+  }
+  operand_stack_push_u32(vm->current_frame, value);
 }
 
 void op_lconst_0(struct vm * vm)
 {
-  assert(!"op_lconst_0");
+  operand_stack_push_u64(vm->current_frame, 0);
 }
 
 void op_lconst_1(struct vm * vm)
 {
-  assert(!"op_lconst_1");
+  operand_stack_push_u64(vm->current_frame, 1);
 }
 
 void op_ldc(struct vm * vm, uint32_t index)
@@ -1148,7 +1184,12 @@ void op_ldc(struct vm * vm, uint32_t index)
 
 void op_ldc2_w(struct vm * vm, uint32_t index)
 {
-  assert(!"op_ldc2_w");
+  struct constant * constant = &vm->current_thread.current_class->constant_pool[index - 1];
+  #ifdef DEBUG
+  assert(constant->tag == CONSTANT_Long || constant->tag == CONSTANT_Double);
+  #endif
+  int64_t value = constant->_long.bytes;
+  operand_stack_push_u64(vm->current_frame, value);
 }
 
 void op_ldc_w(struct vm * vm, uint32_t index)
@@ -1158,42 +1199,65 @@ void op_ldc_w(struct vm * vm, uint32_t index)
 
 void op_ldiv(struct vm * vm)
 {
-  assert(!"op_ldiv");
+  int64_t value2 = operand_stack_pop_u64(vm->current_frame);
+  int64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  int64_t result = value1 / value2;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_lload(struct vm * vm, uint32_t index)
 {
-  assert(!"op_lload");
+  uint32_t low = vm->current_frame->local_variable[index];
+  uint32_t high = vm->current_frame->local_variable[index + 1];
+  operand_stack_push_u32(vm->current_frame, low);
+  operand_stack_push_u32(vm->current_frame, high);
 }
 
 void op_lload_0(struct vm * vm)
 {
-  assert(!"op_lload_0");
+  uint32_t low = vm->current_frame->local_variable[0];
+  uint32_t high = vm->current_frame->local_variable[0 + 1];
+  operand_stack_push_u32(vm->current_frame, low);
+  operand_stack_push_u32(vm->current_frame, high);
 }
 
 void op_lload_1(struct vm * vm)
 {
-  assert(!"op_lload_1");
+  uint32_t low = vm->current_frame->local_variable[1];
+  uint32_t high = vm->current_frame->local_variable[1 + 1];
+  operand_stack_push_u32(vm->current_frame, low);
+  operand_stack_push_u32(vm->current_frame, high);
 }
 
 void op_lload_2(struct vm * vm)
 {
-  assert(!"op_lload_2");
+  uint32_t low = vm->current_frame->local_variable[2];
+  uint32_t high = vm->current_frame->local_variable[2 + 1];
+  operand_stack_push_u32(vm->current_frame, low);
+  operand_stack_push_u32(vm->current_frame, high);
 }
 
 void op_lload_3(struct vm * vm)
 {
-  assert(!"op_lload_3");
+  uint32_t low = vm->current_frame->local_variable[3];
+  uint32_t high = vm->current_frame->local_variable[3 + 1];
+  operand_stack_push_u32(vm->current_frame, low);
+  operand_stack_push_u32(vm->current_frame, high);
 }
 
 void op_lmul(struct vm * vm)
 {
-  assert(!"op_lmul");
+  int64_t value2 = operand_stack_pop_u64(vm->current_frame);
+  int64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  int64_t result = value1 * value2;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_lneg(struct vm * vm)
 {
-  assert(!"op_lneg");
+  int64_t value = operand_stack_pop_u64(vm->current_frame);
+  int64_t result = -value;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_lookupswitch(struct vm * vm)
@@ -1203,67 +1267,107 @@ void op_lookupswitch(struct vm * vm)
 
 void op_lor(struct vm * vm)
 {
-  assert(!"op_lor");
+  uint64_t value2 = operand_stack_pop_u64(vm->current_frame);
+  uint64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  uint64_t result = value1 | value2;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_lrem(struct vm * vm)
 {
-  assert(!"op_lrem");
+  int64_t value2 = operand_stack_pop_u64(vm->current_frame);
+  int64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  int64_t result = value1 % value2;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_lreturn(struct vm * vm)
 {
-  assert(!"op_lreturn");
+  assert(vm->current_frame->return_type == 'J');
+  vm_method_return(vm);
 }
 
 void op_lshl(struct vm * vm)
 {
-  assert(!"op_lshl");
+  int32_t value2 = operand_stack_pop_u32(vm->current_frame);
+  int64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  int s = value2 & 0b111111;
+  int64_t result = value1 << s;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_lshr(struct vm * vm)
 {
-  assert(!"op_lshr");
+  int32_t value2 = operand_stack_pop_u32(vm->current_frame);
+  int64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  int s = value2 & 0b111111;
+  int64_t result = value1 >> s;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_lstore(struct vm * vm, uint32_t index)
 {
-  assert(!"op_lstore");
+  uint32_t high = operand_stack_pop_u32(vm->current_frame);
+  uint32_t low = operand_stack_pop_u32(vm->current_frame);
+  vm->current_frame->local_variable[index + 1] = high;
+  vm->current_frame->local_variable[index] = low;
 }
 
 void op_lstore_0(struct vm * vm)
 {
-  assert(!"op_lstore_0");
+  uint32_t high = operand_stack_pop_u32(vm->current_frame);
+  uint32_t low = operand_stack_pop_u32(vm->current_frame);
+  vm->current_frame->local_variable[0 + 1] = high;
+  vm->current_frame->local_variable[0] = low;
 }
 
 void op_lstore_1(struct vm * vm)
 {
-  assert(!"op_lstore_1");
+  uint32_t high = operand_stack_pop_u32(vm->current_frame);
+  uint32_t low = operand_stack_pop_u32(vm->current_frame);
+  vm->current_frame->local_variable[1 + 1] = high;
+  vm->current_frame->local_variable[1] = low;
 }
 
 void op_lstore_2(struct vm * vm)
 {
-  assert(!"op_lstore_2");
+  uint32_t high = operand_stack_pop_u32(vm->current_frame);
+  uint32_t low = operand_stack_pop_u32(vm->current_frame);
+  vm->current_frame->local_variable[2 + 1] = high;
+  vm->current_frame->local_variable[2] = low;
 }
 
 void op_lstore_3(struct vm * vm)
 {
-  assert(!"op_lstore_3");
+  uint32_t high = operand_stack_pop_u32(vm->current_frame);
+  uint32_t low = operand_stack_pop_u32(vm->current_frame);
+  vm->current_frame->local_variable[3 + 1] = high;
+  vm->current_frame->local_variable[3] = low;
 }
 
 void op_lsub(struct vm * vm)
 {
-  assert(!"op_lsub");
+  int64_t value2 = operand_stack_pop_u64(vm->current_frame);
+  int64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  int64_t result = value1 - value2;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_lushr(struct vm * vm)
 {
-  assert(!"op_lushr");
+  int32_t value2 = operand_stack_pop_u32(vm->current_frame);
+  uint64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  int s = value2 & 0b111111;
+  uint64_t result = value1 >> s;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_lxor(struct vm * vm)
 {
-  assert(!"op_lxor");
+  uint64_t value2 = operand_stack_pop_u64(vm->current_frame);
+  uint64_t value1 = operand_stack_pop_u64(vm->current_frame);
+  uint64_t result = value1 ^ value2;
+  operand_stack_push_u64(vm->current_frame, result);
 }
 
 void op_monitorenter(struct vm * vm)
@@ -1283,16 +1387,38 @@ void op_multianewarray(struct vm * vm, uint32_t index, uint32_t dimensions)
 
 void op_new(struct vm * vm, uint32_t index)
 {
+  struct constant * class_constant = &vm->current_thread.current_class->constant_pool[index - 1];
+  #ifdef DEBUG
+  assert(class_constant->tag == CONSTANT_Class);
+  #endif
+  struct constant * class_name_constant = &vm->current_thread.current_class->constant_pool[class_constant->class.name_index - 1];
+  #ifdef DEBUG
+  assert(class_name_constant->tag == CONSTANT_Utf8);
+  #endif
+
+  struct class_entry * class_entry = class_resolver_lookup_class(vm->class_hash_table.length,
+                                                                 vm->class_hash_table.entry,
+                                                                 class_name_constant->utf8.bytes,
+                                                                 class_name_constant->utf8.length);
+  assert(class_entry != nullptr);
+
   /* On successful resolution of the class, it is initialized if it has not
      already been initialized (§5.5).
 
      (new) Upon execution of a new instruction, the class to be initialized is
      the class referenced by the instruction. */
 
-  /*
   if (!vm_initialize_class(vm, class_entry))
     return;
-  */
+
+  /* Memory for a new instance of that class is allocated from the
+     garbage-collected heap, and the instance variables of the new object are
+     initialized to their default initial values (§2.3, §2.4). The objectref, a
+     reference to the instance, is pushed onto the operand stack. */
+
+  int fields_count = class_entry->class_file->fields_count;
+  (void)fields_count;
+  //int32_t * arrayref = memory_allocate();
 
   assert(!"op_new");
 }
@@ -1363,7 +1489,8 @@ void op_pop(struct vm * vm)
 
 void op_pop2(struct vm * vm)
 {
-  assert(!"op_pop2");
+  operand_stack_pop_u32(vm->current_frame);
+  operand_stack_pop_u32(vm->current_frame);
 }
 
 void op_putfield(struct vm * vm, uint32_t index)
diff --git a/c/frame.c b/c/frame.c
index 235494d..2533041 100644
--- a/c/frame.c
+++ b/c/frame.c
@@ -60,10 +60,20 @@ static int descriptor_nargs(struct constant * descriptor_constant)
   int i = 1;
   int nargs = 0;
   while (i < descriptor_constant->utf8.length) {
-    if (descriptor_constant->utf8.bytes[i] == ')')
+    uint8_t byte = descriptor_constant->utf8.bytes[i];
+    if (byte == ')')
       break;
-    if (descriptor_constant->utf8.bytes[i] != '[')
+    switch (byte) {
+    case '[':
+      break;
+    case 'D': [[fallthrough]];
+    case 'J':
+      nargs += 2;
+      break;
+    default:
       nargs += 1;
+      break;
+    }
     i += 1;
   }
   assert(i + 2 == descriptor_constant->utf8.length);
@@ -92,28 +102,28 @@ bool vm_initialize_class(struct vm * vm, struct class_entry * class_entry)
   struct class_file * class_file = class_entry->class_file;
 
   int constantvalue_name_index = find_constantvalue_name_index(class_file);
-  assert(constantvalue_name_index != 0);
+  if (constantvalue_name_index != 0) {
+    for (int i = 0; i < class_file->fields_count; i++) {
+      struct field_info * field_info = &class_file->fields[i];
+      if (!(field_info->access_flags & FIELD_ACC_STATIC))
+        continue;
 
-  for (int i = 0; i < class_file->fields_count; i++) {
-    struct field_info * field_info = &class_file->fields[i];
-    if (!(field_info->access_flags & FIELD_ACC_STATIC))
-      continue;
+      for (int j = 0; j < field_info->attributes_count; j++) {
+        if (field_info->attributes[j].attribute_name_index == constantvalue_name_index) {
+          struct attribute_info * attribute = &field_info->attributes[j];
+          struct constant * constantvalue = &class_file->constant_pool[attribute->constantvalue->constantvalue_index - 1];
+          assert(constantvalue->tag == CONSTANT_Integer); // also need to support CONSTANT_String
 
-    for (int j = 0; j < field_info->attributes_count; j++) {
-      if (field_info->attributes[j].attribute_name_index == constantvalue_name_index) {
-        struct attribute_info * attribute = &field_info->attributes[j];
-        struct constant * constantvalue = &class_file->constant_pool[attribute->constantvalue->constantvalue_index - 1];
-        assert(constantvalue->tag == CONSTANT_Integer); // also need to support CONSTANT_String
-
-        struct constant * name_constant = &class_file->constant_pool[field_info->name_index - 1];
-        assert(name_constant->tag == CONSTANT_Utf8);
-        struct field_entry * field_entry = class_resolver_lookup_field(class_entry,
-                                                                       name_constant->utf8.bytes,
-                                                                       name_constant->utf8.length);
-        assert(field_entry != nullptr);
-        field_entry->value = constantvalue->integer.bytes;
-        printf("  constantvalue: %d\n", field_entry->value);
-        break;
+          struct constant * name_constant = &class_file->constant_pool[field_info->name_index - 1];
+          assert(name_constant->tag == CONSTANT_Utf8);
+          struct field_entry * field_entry = class_resolver_lookup_field(class_entry,
+                                                                         name_constant->utf8.bytes,
+                                                                         name_constant->utf8.length);
+          assert(field_entry != nullptr);
+          field_entry->value = constantvalue->integer.bytes;
+          printf("  constantvalue: %d\n", field_entry->value);
+          break;
+        }
       }
     }
   }
@@ -232,8 +242,17 @@ void vm_method_return(struct vm * vm)
   case 'S': [[fallthrough]];
   case 'I': [[fallthrough]];
   case 'F':
-    uint32_t value = operand_stack_pop_u32(old_frame);
-    operand_stack_push_u32(vm->current_frame, value);
+    {
+      uint32_t value = operand_stack_pop_u32(old_frame);
+      operand_stack_push_u32(vm->current_frame, value);
+    }
+    break;
+  case 'D': [[fallthrough]];
+  case 'J':
+    {
+      uint64_t value = operand_stack_pop_u64(old_frame);
+      operand_stack_push_u64(vm->current_frame, value);
+    }
     break;
   case 'V':
     break;
diff --git a/c/frame.h b/c/frame.h
index 8a2b35c..24040ea 100644
--- a/c/frame.h
+++ b/c/frame.h
@@ -109,6 +109,24 @@ static inline float operand_stack_pop_f32(struct frame * frame)
   return f;
 }
 
+static inline void operand_stack_push_u64(struct frame * frame, uint64_t value)
+{
+  frame->operand_stack[frame->operand_stack_ix] = (uint32_t)(value >> 0);
+  frame->operand_stack_ix++;
+  frame->operand_stack[frame->operand_stack_ix] = (uint32_t)(value >> 32);
+  frame->operand_stack_ix++;
+}
+
+static inline uint64_t operand_stack_pop_u64(struct frame * frame)
+{
+  frame->operand_stack_ix--;
+  uint64_t high = frame->operand_stack[frame->operand_stack_ix];
+  frame->operand_stack_ix--;
+  uint64_t low = frame->operand_stack[frame->operand_stack_ix];
+  uint64_t value = (high << 32) | (low << 0);
+  return value;
+}
+
 bool vm_initialize_class(struct vm * vm, struct class_entry * class_entry);
 void vm_static_method_call(struct vm * vm, struct class_file * class_file, struct method_info * method_info);
 void vm_method_return(struct vm * vm);
diff --git a/c/main.c b/c/main.c
index 4447875..2891208 100644
--- a/c/main.c
+++ b/c/main.c
@@ -18,6 +18,7 @@ int main(int argc, const char * argv[])
                                                                  class_hash_table,
                                                                  (const uint8_t *)main_class,
                                                                  string_length(main_class));
+  assert(class_entry != nullptr);
 
   const char * method_name = "main";
   int method_name_length = string_length(method_name);
@@ -28,6 +29,7 @@ int main(int argc, const char * argv[])
                                                                   method_name_length,
                                                                   (const uint8_t *)method_descriptor,
                                                                   method_descriptor_length);
+  assert(method_info != nullptr);
 
   struct vm vm;
   vm.class_hash_table.entry = class_hash_table;
diff --git a/class_file.py b/class_file.py
index fbe8452..5d3ff2c 100644
--- a/class_file.py
+++ b/class_file.py
@@ -1,17 +1,11 @@
 import struct
 import sys
 from binascii import hexlify
+import csv
 
-def parse_row(s):
-    a, b, c, d = s.strip().split(',')
-    return int(a), c, int(d)
+from gen_decoder import parse_opcode_table
 
-def parse_opcode_table(buf):
-    rows = [parse_row(i) for i in buf.strip().split('\n')]
-    return {opcode: (name, args) for opcode, name, args in rows}
-
-with open('opcodes.csv', 'r') as f:
-    opcode_table = parse_opcode_table(f.read())
+opcode_table = parse_opcode_table()
 
 def size_to_format(size):
     if size == 4:
@@ -60,7 +54,11 @@ def parse_cp_info(buf):
             buf, value = field(buf, field_size)
             last_value = value
         d[field_name] = value
-    return buf, (name, d)
+    if tag in {5, 6}:
+        entries = 2
+    else:
+        entries = 1
+    return buf, (name, d), entries
 
 def parse_attribute_info(buf):
     buf, attribute_name_index = field(buf, 2)
@@ -96,12 +94,12 @@ def dump_opcodes(buf, indent):
     ix = 0
     while len(buf) > 0:
         op = buf[0]
-        name, arg_length = opcode_table[op]
+        instruction = opcode_table[op]
         buf = buf[1:]
-        args = list(buf[0:arg_length])
-        print(indent, f"{ix:> 3}", name, args)
-        ix += 1 + arg_length
-        buf = buf[arg_length:]
+        args = list(buf[0:instruction.arguments_size])
+        print(indent, f"{ix:> 3}", instruction.mnemonic, args)
+        ix += 1 + instruction.arguments_size
+        buf = buf[instruction.arguments_size:]
 
 def print_code_info(buf, indent, constant_pool):
     code_attribute = [
@@ -158,10 +156,14 @@ def parse_class(buf):
 
     print("constant_pool:")
     constant_pool = []
-    for i in range(constant_pool_count - 1):
-        buf, cp_info = parse_cp_info(buf)
+    i = 1
+    while i < constant_pool_count:
+        buf, cp_info, entries = parse_cp_info(buf)
         constant_pool.append(cp_info)
-        print(i + 1, cp_info)
+        if entries == 2:
+            constant_pool.append(None)
+        print(i, cp_info)
+        i += entries
 
     buf, access_flags = field(buf, 2)
     buf, this_class = field(buf, 2)
diff --git a/gen_decoder.py b/gen_decoder.py
index 7264f06..0d08bb9 100644
--- a/gen_decoder.py
+++ b/gen_decoder.py
@@ -240,7 +240,8 @@ def renderer():
         return _render(out, lines)
     return render, out
 
-render, out = renderer()
-render(generate_print_decoder())
-render(generate_execute_decoder())
-sys.stdout.write(out.getvalue())
+if __name__ == "__main__":
+    render, out = renderer()
+    render(generate_print_decoder())
+    render(generate_execute_decoder())
+    sys.stdout.write(out.getvalue())
diff --git a/p/Long.java b/p/Long.java
new file mode 100644
index 0000000..ea63248
--- /dev/null
+++ b/p/Long.java
@@ -0,0 +1,57 @@
+package p;
+
+class Long {
+    static long test(long n, long m) {
+        long y = n + m; // 21
+        long z = y % 9999; // 21
+        long a = z * 5; // 105
+        long b = a + 1; // 106
+        long c = b / 3;
+        long d = c & 0x0ffffffff0L; // 32
+        long e = d | 0x1000000000L; // 68719476768 (16, 32)
+        long f = e - 2; // 68719476766 (16, 30)
+        long g = -f; // -68719476766 (-17, -30)
+        long h = g >> 1;
+        long i = h << 2;
+        long j = i >>> 1;
+        long k = j ^ 0xffffffffffffffffL; // -9223371968135299043
+        return k;
+    }
+
+    static void test2(long a) {
+        int b = (int)a;
+        float c = (float)a;
+        long d = (long)b;
+        long e = (long)c;
+    }
+
+    static boolean test3(long a, long b) {
+        boolean c = a > b;
+        if (c) {
+            return -a == b;
+        } else {
+            return -b <= a;
+        }
+    }
+
+    static long test4() {
+        long[] arr = {1, 2, 3, 4};
+        long sum = 0;
+        for (int i = 0; i < arr.length; i++) {
+            sum += arr[i];
+        }
+        boolean b = sum > 1;
+        return sum * 4; // 40
+    }
+
+    // -9223371968135299059
+    // -2147483632
+    // 13
+    public static void main() {
+        long a = test(10, 11);
+        int b = (int)a;
+        test2(10);
+        test3(88, 123);
+        test4();
+    }
+}