interpreter.c

专业汽车级嵌入式操作系统OSEK的源代码

#include "trace.h"
#include "types.h"
#include "constants.h"
#include "classes.h"
#include "interpreter.h"
#include "platform_hooks.h"
#include "threads.h"
#include "opcodes.h"
#include "configure.h"
#include "memory.h"
#include "language.h"
#include "exceptions.h"
#include "specialclasses.h"
#include "fields.h"
#include "stack.h"
#include "poll.h"


#define F_OFFSET_MASK  0x0F

#if DEBUG_BYTECODE
extern char *OPCODE_NAME[];
#endif

// Interpreter globals:

volatile boolean gMakeRequest;
byte    gRequestCode;

byte *pc;
STACKWORD *localsBase;
STACKWORD *stackTop;

// Temporary globals:

byte tempByte;
byte *tempBytePtr;
JFLOAT tempFloat;
ConstantRecord *tempConstRec;
STACKWORD tempStackWord;
STACKWORD *tempWordPtr;
JSHORT tempInt;
  
/**
 * Assumes pc points to 2-byte offset, and jumps.
 */
void do_goto (boolean aCond)
{
  if (aCond)
  {
    pc += (JSHORT) (((TWOBYTES) *pc << 8) | *(pc+1));
    pc--;
  }
  else
  {
    pc += 2;
  }
}

void do_isub (void)
{
  STACKWORD poppedWord;

  poppedWord = pop_word();
  set_top_word (word2jint(get_top_word()) - word2jint(poppedWord));
}

#if FP_ARITHMETIC

void do_fcmp (JFLOAT f1, JFLOAT f2, STACKWORD def)
{
  if (f1 > f2)
    push_word (1);
  else if (f1 == f2)
    push_word (0);
  else if (f1 < f2)
    push_word (-1);
  else 
    push_word (def);
}

#endif

/**
 * @return A String instance, or JNULL if an exception was thrown
 *         or the static initializer of String had to be executed.
 */
static inline Object *create_string (ConstantRecord *constantRecord, 
                                     byte *btAddr)
{
  Object *ref;
  Object *arr;
  TWOBYTES i;

  ref = new_object_checked (JAVA_LANG_STRING, btAddr);
  if (ref == JNULL)
    return JNULL;
  arr = new_primitive_array (T_CHAR, constantRecord->constantSize);
  if (arr == JNULL)
  {
    deallocate (obj2ptr(ref), class_size (JAVA_LANG_STRING));    
    return JNULL;
  }
  
//  printf ("char array at %d\n", (int) arr);
  
  store_word ((byte *) &(((String *) ref)->characters), 4, obj2word(arr));
  
  for (i = 0; i < constantRecord->constantSize; i++)
  {
    jchar_array(arr)[i] = (JCHAR) get_constant_ptr(constantRecord)[i];

    //printf ("char %d: %c\n", i, (char) (jchar_array(arr)[i])); 
  }
  return ref;
}

/**
 * Pops the array index off the stack, assigns
 * both tempInt and tempBytePtr, and checks
 * bounds and null reference. The array reference
 * is the top word on the stack after this operation.
 * @return True if successful, false if an exception has been scheduled.
 */
boolean array_load_helper()
{
  tempInt = word2jshort(pop_word());
  tempBytePtr = word2ptr(get_top_ref());
  if (tempBytePtr == JNULL)
    throw_exception (nullPointerException);
  else if (tempInt < 0 || tempInt >= get_array_length ((Object *) tempBytePtr))
    throw_exception (arrayIndexOutOfBoundsException);
  else
    return true;
  return false;
}

/**
 * Same as array_load_helper, except that it pops
 * the reference from the stack.
 */
boolean array_store_helper()
{
  if (array_load_helper())
  {
    pop_ref();
    return true;
  }
  return false;
}

/**
 * Everything runs inside here, essentially.
 *
 * To be able use only a single fast test on each instruction
 * several assumptions are made:
 * - currentThread is initialized and non-null and
 *   it is not set to null by any bytecode instruction.
 * - Thus it is not allowed to call schedule_thread() in instructions,
 *   use schedule_request( REQUEST_SWITCH_THREAD) instead.
 * - Whenever gMakeRequest is false, gRequestCode is REQUEST_TICK.
 * - Thus anybody who sets gRequestCode must also set gMakeRequest to true
 *   (using schedule_request assures this).
 * - Only the request handler may set gMakeRequest to false.
 * - The millisecond timer interrupt must set gMakeRequest to true
 *   for time slices to work.
 * 
 */
void engine()
{
  byte ticks_until_switch = TICKS_PER_TIME_SLICE;

  int lgginst = 0;

  assert( currentThread != null, INTERPRETER0);

  schedule_request( REQUEST_SWITCH_THREAD);

 LABEL_ENGINELOOP: 
  instruction_hook();

  assert( currentThread != null, INTERPRETER1);

  while( gMakeRequest)
  {
    byte requestCode = gRequestCode;

    gMakeRequest = false;
    gRequestCode = REQUEST_TICK;
    
    tick_hook();

    if( requestCode == REQUEST_EXIT)
    {
      return;
    }

    if( requestCode == REQUEST_TICK)
      ticks_until_switch--;

    if( requestCode == REQUEST_SWITCH_THREAD
        || ticks_until_switch == 0){
      ticks_until_switch = TICKS_PER_TIME_SLICE;
#if DEBUG_THREADS
      printf ("switching thread: %d\n", (int)ticks_until_switch);
#endif
      switch_thread();
#if DEBUG_THREADS
      printf ("done switching thread\n");
#endif
      switch_thread_hook();
    }
    if( currentThread == null   /* no runnable thread */
        && gRequestCode == REQUEST_TICK){ /* no important request */
      idle_hook();
      schedule_request( REQUEST_SWITCH_THREAD);
    }
  }

  assert( gRequestCode == REQUEST_TICK, INTERPRETER2);
  assert( currentThread != null, INTERPRETER3);

  //-----------------------------------------------
  // SWITCH BEGINS HERE
  //-----------------------------------------------

  #if DEBUG_BYTECODE
  printf ("0x%X: \n", (int) pc);
  printf ("OPCODE (0x%X) %s\n", (int) *pc, OPCODE_NAME[*pc]);
  #endif

  switch (*pc++)
  {
    case OP_NOP:
        goto LABEL_ENGINELOOP;

    #include "op_stack.hc"
    #include "op_locals.hc"
    #include "op_arrays.hc"
    #include "op_objects.hc"
    #include "op_control.hc"
    #include "op_other.hc"
    #include "op_conversions.hc"
    #include "op_logical.hc"
    #include "op_arithmetic.hc"
    #include "op_methods.hc"

/*
#ifdef VERIFY
	default:
		assert(false, (TWOBYTES)(pc-1) % 10000);
		break;
#endif
*/
  }

  //-----------------------------------------------
  // SWITCH ENDS HERE
  //-----------------------------------------------

   #if !FP_ARITHMETIC

   throw_exception (noSuchMethodError);

   #else
  
   // This point should never be reached

   #ifdef VERIFY
   assert (false, 1000 + *pc);
   #endif // VERIFY

   #endif // FP_ARITHMETIC
}