/*
 * The basic `switch' instruction dispatcher.
 * Copyright (c) 1998 New Generation Software (NGS) Oy
 *
 * Author: Markku Rossi <mtr@ngs.fi>
 */

/*
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA
 */

/*
 * $Source: /usr/local/cvsroot/ngs/js/src/vmswt0.c,v $
 * $Id: vmswt0.c,v 1.8 1998/10/26 14:13:41 mtr Exp $
 */

#include "jsint.h"

/*
 * Types and definitions.
 */

struct function_st
{
  JSHeapDestroyableCB destroy;

  char *name;
  unsigned char *code;
  unsigned int length;
};

typedef struct function_st Function;


/*
 * Prototypes for static functions.
 */

static void function_destroy (void *ptr);

static void link_code (JSVirtualMachine *vm, unsigned char *code,
		       unsigned int code_len, unsigned int consts_offset);

static void execute_code (JSVirtualMachine *vm, JSNode *object, Function *f,
			  unsigned int argc, JSNode *argv);


/*
 * Global functions.
 */

int
js_vm_switch0_exec (JSVirtualMachine *vm, JSByteCode *bc,
		    JSSymtabEntry *symtab,
		    unsigned int num_symtab_entries,
		    unsigned int consts_offset,
		    unsigned int anonymous_function_offset,
		    unsigned char *debug_info, unsigned int debug_info_len,
		    JSNode *object, JSNode *func,
		    unsigned int argc, JSNode *argv)
{
  int i;
  unsigned int ui;
  Function *global_f = NULL;
  Function *f;
  unsigned char *code = NULL;
  char buf[512];

  if (bc)
    {
      /* Executing byte-code. */

      /* Find the code section. */
      for (i = 0; i < bc->num_sects; i++)
	if (bc->sects[i].type == JS_BCST_CODE)
	  code = bc->sects[i].data;
      assert (code != NULL);

      /* Enter all functions to the known functions of the VM. */
      for (i = 0; i < num_symtab_entries; i++)
	{
	  /* Need one function. */
	  f = js_vm_alloc_destroyable (vm, sizeof (*f));
	  f->destroy = function_destroy;
	  f->name = js_strdup (vm, symtab[i].name);

	  f->length = symtab[i + 1].offset - symtab[i].offset + 1;
	  f->code = js_malloc (vm, f->length);
	  memcpy (f->code, code + symtab[i].offset, f->length - 1);
	  f->code[f->length - 1] = 1; /* op `done' */

	  /* Link the code to our environment. */
	  link_code (vm, f->code, f->length, consts_offset);

	  if (strcmp (symtab[i].name, JS_GLOBAL_NAME) == 0)
	    global_f = f;
	  else
	    {
	      int is_anonymous = 0;

	      /* Check for the anonymous function. */
	      if (symtab[i].name[0] == '.' && symtab[i].name[1] == 'F'
		  && symtab[i].name[2] == ':')
		is_anonymous = 1;

	      if (vm->verbose > 3)
		{
		  sprintf (buf, "VM: link: %s(): start=%d, length=%d",
			   symtab[i].name, symtab[i].offset,
			   symtab[i + 1].offset - symtab[i].offset);
		  if (is_anonymous)
		    sprintf (buf + strlen (buf),
			     ", relocating with offset %u",
			     anonymous_function_offset);
		  strcat (buf, JS_HOST_LINE_BREAK);
		  js_iostream_write (vm->s_stderr, buf, strlen (buf));
		}

	      if (is_anonymous)
		{
		  sprintf (buf, ".F:%u",
			   (unsigned int) atoi (symtab[i].name + 3)
			   + anonymous_function_offset);
		  ui = js_vm_intern (vm, buf);
		}
	      else
		ui = js_vm_intern (vm, symtab[i].name);

	      vm->globals[ui].type = JS_FUNC;
	      vm->globals[ui].u.vfunction = js_vm_make_function (vm, f);
	    }
	}
    }
  else
    {
      /* Applying arguments to function. */
      if (func->type != JS_FUNC)
	{
	  sprintf (vm->error, "illegal function in apply");
	  return 0;
	}

      if (vm->verbose > 1)
	{
	  sprintf (buf, "VM: calling function%s",
		   JS_HOST_LINE_BREAK);
	  js_iostream_write (vm->s_stderr, buf, strlen (buf));
	}
      f = func->u.vfunction->implementation;

      execute_code (vm, object, f, argc, argv);
    }

  if (global_f)
    {
      if (vm->verbose > 1)
	{
	  sprintf (buf, "VM: exec: %s%s", global_f->name,
		   JS_HOST_LINE_BREAK);
	  js_iostream_write (vm->s_stderr, buf, strlen (buf));
	}

      /* Execute. */
      execute_code (vm, NULL, global_f, 0, NULL);
    }

  return 1;
}


const char *
js_vm_switch0_func_name (JSVirtualMachine *vm, void *program_counter)
{
  int i;
  Function *f;
  unsigned char *pc = program_counter;
  JSNode *sp = vm->sp;

  /* Check the globals. */
  for (i = 0; i < vm->num_globals; i++)
    if (vm->globals[i].type == JS_FUNC)
      {
	f = (Function *) vm->globals[i].u.vfunction->implementation;
	if (f->code < pc && pc < f->code + f->length)
	  return f->name;
      }

  /* No luck.  Let's try the stack. */
  for (sp++; sp < vm->stack + vm->stack_size; sp++)
    if (sp->type == JS_FUNC)
      {
	f = (Function *) sp->u.vfunction->implementation;
	if (f->code < pc && pc < f->code + f->length)
	  return f->name;
      }

  /* Still no matches.  This shouldn't be reached... ok, who cares? */
  return JS_GLOBAL_NAME;
}


const char *
js_vm_switch0_debug_position (JSVirtualMachine *vm,
			      unsigned int *linenum_return)
{
  /* XXX */
  return NULL;
}


/*
 * Static functions.
 */

static void
function_destroy (void *ptr)
{
  Function *f = ptr;

  js_free (f->name);
  js_free (f->code);
}


static void
link_code (JSVirtualMachine *vm, unsigned char *code, unsigned int code_len,
	   unsigned int consts_offset)
{
  unsigned char *cp, *end;
  JSInt32 i;

  cp = code;
  end = code + code_len;

  while (cp < end)
    {
      switch (*cp++)
	{
	  /* include c1swt0.h */
#include "c1swt0.h"
	  /* end include c1swt0.h */
	}
    }
}


/*
 * Execute byte code by using the `switch' dispatch technique.
 */

#define READ_INT8(i)	JS_BC_READ_INT8(pc, (i)); (i) = (JSInt8) (i); pc++
#define READ_INT16(i)	JS_BC_READ_INT16(pc, (i)); (i) = (JSInt16) (i); pc += 2
#define READ_INT32(i)	JS_BC_READ_INT32(pc, (i)); (i) = (JSInt32) (i); pc += 4

#define SETPC(ofs)		pc = (ofs)
#define SETPC_RELATIVE(ofs)	pc += (ofs)

#define CALL_USER_FUNC(f)	pc = ((Function *) (f))->code

#define DONE() goto done

#define ERROR(msg)		\
  do {				\
    JS_SAVE_REGS ();		\
    strcpy (vm->error, (msg));	\
    js_vm_error (vm);		\
    /* NOTREACHED */		\
  } while (0)

static void
execute_code (JSVirtualMachine *vm, JSNode *object, Function *f,
	      unsigned int argc, JSNode *argv)
{
  JSNode *sp;
  JSNode *fp;
  JSNode *function;
  JSNode builtin_result;
  unsigned char *pc;
  JSInt32 i, j;
  JSInt8 i8;
  char buf[512];

  /* Create the initial stack frame by hand. */
  sp = vm->sp;

  /* Protect the function from gc. */
  JS_SP0->type = JS_FUNC;
  JS_SP0->u.vfunction = js_vm_make_function (vm, f);
  JS_PUSH ();

  /* Push arguments to the stack. */
  i = argc;
  for (i--; i >= 0; i--)
    {
      JS_COPY (JS_SP0, &argv[i]);
      JS_PUSH ();
    }

  /* This pointer. */
  if (object)
    JS_COPY (JS_SP0, object);
  else
    JS_SP0->type = JS_NULL;
  JS_PUSH ();

  /* Init fp and pc so our SUBROUTINE_CALL will work. */
  fp = NULL;
  pc = NULL;

  JS_SUBROUTINE_CALL (f);

  /* Ok, now we are ready to run. */

  while (1)
    {
      switch (*pc++)
	{
	  /* include eswt0.h */
#include "eswt0.h"
	  /* end include eswt0.h */

	default:
	  sprintf (buf, "execute_code: unknown opcode %d%s", *(pc - 1),
		   JS_HOST_LINE_BREAK);
	  js_iostream_write (vm->s_stderr, buf, strlen (buf));
	  js_iostream_flush (vm->s_stderr);

	  abort ();
	  break;
	}
    }

 done:

  /* All done. */

  JS_COPY (&vm->exec_result, JS_SP1);
}