/* Traditional frame unwind support, for GDB the GNU Debugger.

   Copyright (C) 2003, 2004, 2007, 2008, 2009, 2010
   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 3 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, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "frame.h"
#include "trad-frame.h"
#include "regcache.h"
#include "frame-unwind.h"
#include "value.h"

struct trad_frame_cache
{
  struct frame_info *this_frame;
  CORE_ADDR this_base;
  struct trad_frame_saved_reg *prev_regs;
  struct frame_id this_id;
};

struct trad_frame_cache *
trad_frame_cache_zalloc (struct frame_info *this_frame)
{
  struct trad_frame_cache *this_trad_cache;

  this_trad_cache = FRAME_OBSTACK_ZALLOC (struct trad_frame_cache);
  this_trad_cache->prev_regs = trad_frame_alloc_saved_regs (this_frame);
  this_trad_cache->this_frame = this_frame;
  return this_trad_cache;
}

/* A traditional frame is unwound by analysing the function prologue
   and using the information gathered to track registers.  For
   non-optimized frames, the technique is reliable (just need to check
   for all potential instruction sequences).  */

struct trad_frame_saved_reg *
trad_frame_alloc_saved_regs (struct frame_info *this_frame)
{
  int regnum;
  struct gdbarch *gdbarch = get_frame_arch (this_frame);
  int numregs = gdbarch_num_regs (gdbarch) + gdbarch_num_pseudo_regs (gdbarch);
  struct trad_frame_saved_reg *this_saved_regs
    = FRAME_OBSTACK_CALLOC (numregs, struct trad_frame_saved_reg);

  for (regnum = 0; regnum < numregs; regnum++)
    {
      this_saved_regs[regnum].realreg = regnum;
      this_saved_regs[regnum].addr = -1;
    }      
  return this_saved_regs;
}

enum { REG_VALUE = -1, REG_UNKNOWN = -2 };

int
trad_frame_value_p (struct trad_frame_saved_reg this_saved_regs[], int regnum)
{
  return (this_saved_regs[regnum].realreg == REG_VALUE);
}

int
trad_frame_addr_p (struct trad_frame_saved_reg this_saved_regs[], int regnum)
{
  return (this_saved_regs[regnum].realreg >= 0
	  && this_saved_regs[regnum].addr != -1);
}

int
trad_frame_realreg_p (struct trad_frame_saved_reg this_saved_regs[],
		      int regnum)
{
  return (this_saved_regs[regnum].realreg >= 0
	  && this_saved_regs[regnum].addr == -1);
}

void
trad_frame_set_value (struct trad_frame_saved_reg this_saved_regs[],
		      int regnum, LONGEST val)
{
  /* Make the REALREG invalid, indicating that the ADDR contains the
     register's value.  */
  this_saved_regs[regnum].realreg = REG_VALUE;
  this_saved_regs[regnum].addr = val;
}

void
trad_frame_set_reg_value (struct trad_frame_cache *this_trad_cache,
			  int regnum, LONGEST val)
{
  /* External interface for users of trad_frame_cache
     (who cannot access the prev_regs object directly).  */
  trad_frame_set_value (this_trad_cache->prev_regs, regnum, val);
}

void
trad_frame_set_reg_realreg (struct trad_frame_cache *this_trad_cache,
			    int regnum, int realreg)
{
  this_trad_cache->prev_regs[regnum].realreg = realreg;
  this_trad_cache->prev_regs[regnum].addr = -1;
}

void
trad_frame_set_reg_addr (struct trad_frame_cache *this_trad_cache,
			 int regnum, CORE_ADDR addr)
{
  this_trad_cache->prev_regs[regnum].addr = addr;
}

void
trad_frame_set_unknown (struct trad_frame_saved_reg this_saved_regs[],
			int regnum)
{
  /* Make the REALREG invalid, indicating that the value is not known.  */
  this_saved_regs[regnum].realreg = REG_UNKNOWN;
  this_saved_regs[regnum].addr = -1;
}

struct value *
trad_frame_get_prev_register (struct frame_info *this_frame,
			      struct trad_frame_saved_reg this_saved_regs[],
			      int regnum)
{
  if (trad_frame_addr_p (this_saved_regs, regnum))
    /* The register was saved in memory.  */
    return frame_unwind_got_memory (this_frame, regnum,
				    this_saved_regs[regnum].addr);
  else if (trad_frame_realreg_p (this_saved_regs, regnum))
    return frame_unwind_got_register (this_frame, regnum,
				      this_saved_regs[regnum].realreg);
  else if (trad_frame_value_p (this_saved_regs, regnum))
    /* The register's value is available.  */
    return frame_unwind_got_constant (this_frame, regnum,
				      this_saved_regs[regnum].addr);
  else
    return frame_unwind_got_optimized (this_frame, regnum);
}

struct value *
trad_frame_get_register (struct trad_frame_cache *this_trad_cache,
			 struct frame_info *this_frame,
			 int regnum)
{
  return trad_frame_get_prev_register (this_frame, this_trad_cache->prev_regs,
				       regnum);
}

void
trad_frame_set_id (struct trad_frame_cache *this_trad_cache,
		   struct frame_id this_id)
{
  this_trad_cache->this_id = this_id;
}

void
trad_frame_get_id (struct trad_frame_cache *this_trad_cache,
		   struct frame_id *this_id)
{
  (*this_id) = this_trad_cache->this_id;
}

void
trad_frame_set_this_base (struct trad_frame_cache *this_trad_cache,
			  CORE_ADDR this_base)
{
  this_trad_cache->this_base = this_base;
}

CORE_ADDR
trad_frame_get_this_base (struct trad_frame_cache *this_trad_cache)
{
  return this_trad_cache->this_base;
}