/* Print VAX instructions for GDB, the GNU debugger.
   Copyright 1986, 1989, 1991, 1992, 1996 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include "symtab.h"
#include "opcode/vax.h"

/* Vax instructions are never longer than this.  */
#define MAXLEN 62

/* Number of elements in the opcode table.  */
#define NOPCODES (sizeof votstrs / sizeof votstrs[0])

static unsigned char *print_insn_arg ();

/* Advance PC across any function entry prologue instructions
   to reach some "real" code.  */

CORE_ADDR
vax_skip_prologue (pc)
     CORE_ADDR pc;
{
  register int op = (unsigned char) read_memory_integer (pc, 1);
  if (op == 0x11)
    pc += 2;			/* skip brb */
  if (op == 0x31)
    pc += 3;			/* skip brw */
  if (op == 0xC2
      && ((unsigned char) read_memory_integer (pc + 2, 1)) == 0x5E)
    pc += 3;			/* skip subl2 */
  if (op == 0x9E
      && ((unsigned char) read_memory_integer (pc + 1, 1)) == 0xAE
      && ((unsigned char) read_memory_integer (pc + 3, 1)) == 0x5E)
    pc += 4;			/* skip movab */
  if (op == 0x9E
      && ((unsigned char) read_memory_integer (pc + 1, 1)) == 0xCE
      && ((unsigned char) read_memory_integer (pc + 4, 1)) == 0x5E)
    pc += 5;			/* skip movab */
  if (op == 0x9E
      && ((unsigned char) read_memory_integer (pc + 1, 1)) == 0xEE
      && ((unsigned char) read_memory_integer (pc + 6, 1)) == 0x5E)
    pc += 7;			/* skip movab */
  return pc;
}

/* Return number of args passed to a frame.
   Can return -1, meaning no way to tell.  */

int
vax_frame_num_args (fi)
     struct frame_info *fi;
{
  return (0xff & read_memory_integer (FRAME_ARGS_ADDRESS (fi), 1));
}


/* Print the vax instruction at address MEMADDR in debugged memory,
   from disassembler info INFO.
   Returns length of the instruction, in bytes.  */

static int
vax_print_insn (memaddr, info)
     CORE_ADDR memaddr;
     disassemble_info *info;
{
  unsigned char buffer[MAXLEN];
  register int i;
  register unsigned char *p;
  register char *d;

  int status = (*info->read_memory_func) (memaddr, buffer, MAXLEN, info);
  if (status != 0)
    {
      (*info->memory_error_func) (status, memaddr, info);
      return -1;
    }

  for (i = 0; i < NOPCODES; i++)
    if (votstrs[i].detail.code == buffer[0]
	|| votstrs[i].detail.code == *(unsigned short *) buffer)
      break;

  /* Handle undefined instructions.  */
  if (i == NOPCODES)
    {
      (*info->fprintf_func) (info->stream, "0%o", buffer[0]);
      return 1;
    }

  (*info->fprintf_func) (info->stream, "%s", votstrs[i].name);

  /* Point at first byte of argument data,
     and at descriptor for first argument.  */
  p = buffer + 1 + (votstrs[i].detail.code >= 0x100);
  d = votstrs[i].detail.args;

  if (*d)
    (*info->fprintf_func) (info->stream, " ");

  while (*d)
    {
      p = print_insn_arg (d, p, memaddr + (p - buffer), info);
      d += 2;
      if (*d)
	(*info->fprintf_func) (info->stream, ",");
    }
  return p - buffer;
}

static unsigned char *
print_insn_arg (d, p, addr, info)
     char *d;
     register char *p;
     CORE_ADDR addr;
     disassemble_info *info;
{
  register int regnum = *p & 0xf;
  float floatlitbuf;

  if (*d == 'b')
    {
      if (d[1] == 'b')
	(*info->fprintf_func) (info->stream, "0x%x", addr + *p++ + 1);
      else
	{
	  (*info->fprintf_func) (info->stream, "0x%x", addr + *(short *) p + 2);
	  p += 2;
	}
    }
  else
    switch ((*p++ >> 4) & 0xf)
      {
      case 0:
      case 1:
      case 2:
      case 3:			/* Literal mode */
	if (d[1] == 'd' || d[1] == 'f' || d[1] == 'g' || d[1] == 'h')
	  {
	    *(int *) &floatlitbuf = 0x4000 + ((p[-1] & 0x3f) << 4);
	    (*info->fprintf_func) (info->stream, "$%f", floatlitbuf);
	  }
	else
	  (*info->fprintf_func) (info->stream, "$%d", p[-1] & 0x3f);
	break;

      case 4:			/* Indexed */
	p = (char *) print_insn_arg (d, p, addr + 1, info);
	(*info->fprintf_func) (info->stream, "[%s]", REGISTER_NAME (regnum));
	break;

      case 5:			/* Register */
	(*info->fprintf_func) (info->stream, REGISTER_NAME (regnum));
	break;

      case 7:			/* Autodecrement */
	(*info->fprintf_func) (info->stream, "-");
      case 6:			/* Register deferred */
	(*info->fprintf_func) (info->stream, "(%s)", REGISTER_NAME (regnum));
	break;

      case 9:			/* Autoincrement deferred */
	(*info->fprintf_func) (info->stream, "@");
	if (regnum == PC_REGNUM)
	  {
	    (*info->fprintf_func) (info->stream, "#");
	    info->target = *(long *) p;
	    (*info->print_address_func) (info->target, info);
	    p += 4;
	    break;
	  }
      case 8:			/* Autoincrement */
	if (regnum == PC_REGNUM)
	  {
	    (*info->fprintf_func) (info->stream, "#");
	    switch (d[1])
	      {
	      case 'b':
		(*info->fprintf_func) (info->stream, "%d", *p++);
		break;

	      case 'w':
		(*info->fprintf_func) (info->stream, "%d", *(short *) p);
		p += 2;
		break;

	      case 'l':
		(*info->fprintf_func) (info->stream, "%d", *(long *) p);
		p += 4;
		break;

	      case 'q':
		(*info->fprintf_func) (info->stream, "0x%x%08x",
				       ((long *) p)[1], ((long *) p)[0]);
		p += 8;
		break;

	      case 'o':
		(*info->fprintf_func) (info->stream, "0x%x%08x%08x%08x",
				       ((long *) p)[3], ((long *) p)[2],
				       ((long *) p)[1], ((long *) p)[0]);
		p += 16;
		break;

	      case 'f':
		if (INVALID_FLOAT (p, 4))
		  (*info->fprintf_func) (info->stream,
					 "<<invalid float 0x%x>>",
					 *(int *) p);
		else
		  (*info->fprintf_func) (info->stream, "%f", *(float *) p);
		p += 4;
		break;

	      case 'd':
		if (INVALID_FLOAT (p, 8))
		  (*info->fprintf_func) (info->stream,
					 "<<invalid float 0x%x%08x>>",
					 ((long *) p)[1], ((long *) p)[0]);
		else
		  (*info->fprintf_func) (info->stream, "%f", *(double *) p);
		p += 8;
		break;

	      case 'g':
		(*info->fprintf_func) (info->stream, "g-float");
		p += 8;
		break;

	      case 'h':
		(*info->fprintf_func) (info->stream, "h-float");
		p += 16;
		break;

	      }
	  }
	else
	  (*info->fprintf_func) (info->stream, "(%s)+", REGISTER_NAME (regnum));
	break;

      case 11:			/* Byte displacement deferred */
	(*info->fprintf_func) (info->stream, "@");
      case 10:			/* Byte displacement */
	if (regnum == PC_REGNUM)
	  {
	    info->target = addr + *p + 2;
	    (*info->print_address_func) (info->target, info);
	  }
	else
	  (*info->fprintf_func) (info->stream, "%d(%s)", *p, REGISTER_NAME (regnum));
	p += 1;
	break;

      case 13:			/* Word displacement deferred */
	(*info->fprintf_func) (info->stream, "@");
      case 12:			/* Word displacement */
	if (regnum == PC_REGNUM)
	  {
	    info->target = addr + *(short *) p + 3;
	    (*info->print_address_func) (info->target, info);
	  }
	else
	  (*info->fprintf_func) (info->stream, "%d(%s)",
				 *(short *) p, REGISTER_NAME (regnum));
	p += 2;
	break;

      case 15:			/* Long displacement deferred */
	(*info->fprintf_func) (info->stream, "@");
      case 14:			/* Long displacement */
	if (regnum == PC_REGNUM)
	  {
	    info->target = addr + *(short *) p + 5;
	    (*info->print_address_func) (info->target, info);
	  }
	else
	  (*info->fprintf_func) (info->stream, "%d(%s)",
				 *(long *) p, REGISTER_NAME (regnum));
	p += 4;
      }

  return (unsigned char *) p;
}

void
_initialize_vax_tdep ()
{
  tm_print_insn = vax_print_insn;
}