z8k-tdep.c   [plain text]

/* Target-machine dependent code for Zilog Z8000, for GDB.
   Copyright (C) 1992, 1993, 1994 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.  */

/*
   Contributed by Steve Chamberlain
   sac@cygnus.com
 */

#include "defs.h"
#include "frame.h"
#include "obstack.h"
#include "symtab.h"
#include "gdbcmd.h"
#include "gdbtypes.h"
#include "dis-asm.h"
#include "gdbcore.h"

#include "value.h" /* For read_register() */


static int read_memory_pointer (CORE_ADDR x);

/* Return the saved PC from this frame.

   If the frame has a memory copy of SRP_REGNUM, use that.  If not,
   just use the register SRP_REGNUM itself.  */

CORE_ADDR
z8k_frame_saved_pc (struct frame_info *frame)
{
  return read_memory_pointer (frame->frame + (BIG ? 4 : 2));
}

#define IS_PUSHL(x) (BIG ? ((x & 0xfff0) == 0x91e0):((x & 0xfff0) == 0x91F0))
#define IS_PUSHW(x) (BIG ? ((x & 0xfff0) == 0x93e0):((x & 0xfff0)==0x93f0))
#define IS_MOVE_FP(x) (BIG ? x == 0xa1ea : x == 0xa1fa)
#define IS_MOV_SP_FP(x) (BIG ? x == 0x94ea : x == 0x0d76)
#define IS_SUB2_SP(x) (x==0x1b87)
#define IS_MOVK_R5(x) (x==0x7905)
#define IS_SUB_SP(x) ((x & 0xffff) == 0x020f)
#define IS_PUSH_FP(x) (BIG ? (x == 0x93ea) : (x == 0x93fa))

/* work out how much local space is on the stack and
   return the pc pointing to the first push */

static CORE_ADDR
skip_adjust (CORE_ADDR pc, int *size)
{
  *size = 0;

  if (IS_PUSH_FP (read_memory_short (pc))
      && IS_MOV_SP_FP (read_memory_short (pc + 2)))
    {
      /* This is a function with an explict frame pointer */
      pc += 4;
      *size += 2;		/* remember the frame pointer */
    }

  /* remember any stack adjustment */
  if (IS_SUB_SP (read_memory_short (pc)))
    {
      *size += read_memory_short (pc + 2);
      pc += 4;
    }
  return pc;
}

static CORE_ADDR examine_frame (CORE_ADDR, CORE_ADDR * regs, CORE_ADDR);
static CORE_ADDR
examine_frame (CORE_ADDR pc, CORE_ADDR *regs, CORE_ADDR sp)
{
  int w = read_memory_short (pc);
  int offset = 0;
  int regno;

  for (regno = 0; regno < NUM_REGS; regno++)
    regs[regno] = 0;

  while (IS_PUSHW (w) || IS_PUSHL (w))
    {
      /* work out which register is being pushed to where */
      if (IS_PUSHL (w))
	{
	  regs[w & 0xf] = offset;
	  regs[(w & 0xf) + 1] = offset + 2;
	  offset += 4;
	}
      else
	{
	  regs[w & 0xf] = offset;
	  offset += 2;
	}
      pc += 2;
      w = read_memory_short (pc);
    }

  if (IS_MOVE_FP (w))
    {
      /* We know the fp */

    }
  else if (IS_SUB_SP (w))
    {
      /* Subtracting a value from the sp, so were in a function
         which needs stack space for locals, but has no fp.  We fake up
         the values as if we had an fp */
      regs[FP_REGNUM] = sp;
    }
  else
    {
      /* This one didn't have an fp, we'll fake it up */
      regs[SP_REGNUM] = sp;
    }
  /* stack pointer contains address of next frame */
  /*  regs[fp_regnum()] = fp; */
  regs[SP_REGNUM] = sp;
  return pc;
}

CORE_ADDR
z8k_skip_prologue (CORE_ADDR start_pc)
{
  CORE_ADDR dummy[NUM_REGS];

  return examine_frame (start_pc, dummy, 0);
}

CORE_ADDR
z8k_addr_bits_remove (CORE_ADDR addr)
{
  return (addr & PTR_MASK);
}

static int
read_memory_pointer (CORE_ADDR x)
{
  return read_memory_integer (ADDR_BITS_REMOVE (x), BIG ? 4 : 2);
}

CORE_ADDR
z8k_frame_chain (struct frame_info *thisframe)
{
  if (thisframe->prev == 0)
    {
      /* This is the top of the stack, let's get the sp for real */
    }
  if (!inside_entry_file (thisframe->pc))
    {
      return read_memory_pointer (thisframe->frame);
    }
  return 0;
}

void
init_frame_pc (void)
{
  abort ();
}

/* Put here the code to store, into a struct frame_saved_regs,
   the addresses of the saved registers of frame described by FRAME_INFO.
   This includes special registers such as pc and fp saved in special
   ways in the stack frame.  sp is even more special:
   the address we return for it IS the sp for the next frame.  */

void
z8k_frame_init_saved_regs (struct frame_info *frame_info)
{
  CORE_ADDR pc;
  int w;

  frame_saved_regs_zalloc (frame_info);
  pc = get_pc_function_start (frame_info->pc);

  /* wander down the instruction stream */
  examine_frame (pc, frame_info->saved_regs, frame_info->frame);

}

void
z8k_push_dummy_frame (void)
{
  abort ();
}

int
gdb_print_insn_z8k (bfd_vma memaddr, disassemble_info *info)
{
  if (BIG)
    return print_insn_z8001 (memaddr, info);
  else
    return print_insn_z8002 (memaddr, info);
}

/* Fetch the instruction at ADDR, returning 0 if ADDR is beyond LIM or
   is not the address of a valid instruction, the address of the next
   instruction beyond ADDR otherwise.  *PWORD1 receives the first word
   of the instruction. */

CORE_ADDR
NEXT_PROLOGUE_INSN (CORE_ADDR addr, CORE_ADDR lim, short *pword1)
{
  char buf[2];
  if (addr < lim + 8)
    {
      read_memory (addr, buf, 2);
      *pword1 = extract_signed_integer (buf, 2);

      return addr + 2;
    }
  return 0;
}

#if 0
/* Put here the code to store, into a struct frame_saved_regs,
   the addresses of the saved registers of frame described by FRAME_INFO.
   This includes special registers such as pc and fp saved in special
   ways in the stack frame.  sp is even more special:
   the address we return for it IS the sp for the next frame.

   We cache the result of doing this in the frame_cache_obstack, since
   it is fairly expensive.  */

void
frame_find_saved_regs (struct frame_info *fip, struct frame_saved_regs *fsrp)
{
  int locals;
  CORE_ADDR pc;
  CORE_ADDR adr;
  int i;

  memset (fsrp, 0, sizeof *fsrp);

  pc = skip_adjust (get_pc_function_start (fip->pc), &locals);

  {
    adr = FRAME_FP (fip) - locals;
    for (i = 0; i < 8; i++)
      {
	int word = read_memory_short (pc);

	pc += 2;
	if (IS_PUSHL (word))
	  {
	    fsrp->regs[word & 0xf] = adr;
	    fsrp->regs[(word & 0xf) + 1] = adr - 2;
	    adr -= 4;
	  }
	else if (IS_PUSHW (word))
	  {
	    fsrp->regs[word & 0xf] = adr;
	    adr -= 2;
	  }
	else
	  break;
      }

  }

  fsrp->regs[PC_REGNUM] = fip->frame + 4;
  fsrp->regs[FP_REGNUM] = fip->frame;

}
#endif

int
z8k_saved_pc_after_call (struct frame_info *frame)
{
  return ADDR_BITS_REMOVE
    (read_memory_integer (read_register (SP_REGNUM), PTR_SIZE));
}


void
extract_return_value (struct type *type, char *regbuf, char *valbuf)
{
  int b;
  int len = TYPE_LENGTH (type);

  for (b = 0; b < len; b += 2)
    {
      int todo = len - b;

      if (todo > 2)
	todo = 2;
      memcpy (valbuf + b, regbuf + b, todo);
    }
}

void
write_return_value (struct type *type, char *valbuf)
{
  int reg;
  int len;

  for (len = 0; len < TYPE_LENGTH (type); len += 2)
    write_register_bytes (REGISTER_BYTE (len / 2 + 2), valbuf + len, 2);
}

void
store_struct_return (CORE_ADDR addr, CORE_ADDR sp)
{
  write_register (2, addr);
}


void
z8k_print_register_hook (int regno)
{
  if ((regno & 1) == 0 && regno < 16)
    {
      unsigned short l[2];

      read_relative_register_raw_bytes (regno, (char *) (l + 0));
      read_relative_register_raw_bytes (regno + 1, (char *) (l + 1));
      printf_unfiltered ("\t");
      printf_unfiltered ("%04x%04x", l[0], l[1]);
    }

  if ((regno & 3) == 0 && regno < 16)
    {
      unsigned short l[4];

      read_relative_register_raw_bytes (regno, (char *) (l + 0));
      read_relative_register_raw_bytes (regno + 1, (char *) (l + 1));
      read_relative_register_raw_bytes (regno + 2, (char *) (l + 2));
      read_relative_register_raw_bytes (regno + 3, (char *) (l + 3));

      printf_unfiltered ("\t");
      printf_unfiltered ("%04x%04x%04x%04x", l[0], l[1], l[2], l[3]);
    }
  if (regno == 15)
    {
      unsigned short rval;
      int i;

      read_relative_register_raw_bytes (regno, (char *) (&rval));

      printf_unfiltered ("\n");
      for (i = 0; i < 10; i += 2)
	{
	  printf_unfiltered ("(sp+%d=%04x)", i,
			     (unsigned int)read_memory_short (rval + i));
	}
    }

}

void
z8k_pop_frame (void)
{
}

struct cmd_list_element *setmemorylist;

void
z8k_set_pointer_size (int newsize)
{
  static int oldsize = 0;

  if (oldsize != newsize)
    {
      printf_unfiltered ("pointer size set to %d bits\n", newsize);
      oldsize = newsize;
      if (newsize == 32)
	{
	  BIG = 1;
	}
      else
	{
	  BIG = 0;
	}
      /* FIXME: This code should be using the GDBARCH framework to
         handle changed type sizes.  If this problem is ever fixed
         (the direct reference to _initialize_gdbtypes() below
         eliminated) then Makefile.in should be updated so that
         z8k-tdep.c is again compiled with -Werror. */
      _initialize_gdbtypes ();
    }
}

static void
segmented_command (char *args, int from_tty)
{
  z8k_set_pointer_size (32);
}

static void
unsegmented_command (char *args, int from_tty)
{
  z8k_set_pointer_size (16);
}

static void
set_memory (char *args, int from_tty)
{
  printf_unfiltered ("\"set memory\" must be followed by the name of a memory subcommand.\n");
  help_list (setmemorylist, "set memory ", -1, gdb_stdout);
}

void
_initialize_z8ktdep (void)
{
  tm_print_insn = gdb_print_insn_z8k;

  add_prefix_cmd ("memory", no_class, set_memory,
		  "set the memory model", &setmemorylist, "set memory ", 0,
		  &setlist);
  add_cmd ("segmented", class_support, segmented_command,
	   "Set segmented memory model.", &setmemorylist);
  add_cmd ("unsegmented", class_support, unsegmented_command,
	   "Set unsegmented memory model.", &setmemorylist);

}