/* Definitions to target GDB on an ISI Optimum V (3.05) under 4.3bsd.
   Copyright (C) 1987, 1989, 1991, 1993 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., 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* This has not been tested on ISI's running BSD 4.2, but it will probably
   work.  */

/* Data segment starts at etext rounded up to DATAROUND in {N,Z}MAGIC files */

#define DATAROUND	0x20000
#define N_DATADDR(hdr)	(hdr.a_magic != OMAGIC ? \
	(hdr.a_text + DATAROUND) & ~(DATAROUND-1) : hdr.a_text)

/* Text segment starts at sizeof (struct exec) in {N,Z}MAGIC files */

#define N_TXTADDR(hdr)	(hdr.a_magic != OMAGIC ? sizeof (struct exec) : 0)

/* Amount PC must be decremented by after a breakpoint.
   This is often the number of bytes in BREAKPOINT
   but not always.
   On the ISI, the kernel resets the pc to the trap instr */

#define DECR_PC_AFTER_BREAK 0

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

#define FRAME_NUM_ARGS(val, fi)  \
{ register CORE_ADDR pc = FRAME_SAVED_PC (fi);			\
  register int insn = 0177777 & read_memory_integer (pc, 2);	\
  val = 0;							\
  if (insn == 0047757 || insn == 0157374)  /* lea W(sp),sp or addaw #W,sp */ \
    val = read_memory_integer (pc + 2, 2);			\
  else if ((insn & 0170777) == 0050217 /* addql #N, sp */	\
	   || (insn & 0170777) == 0050117)  /* addqw */		\
    { val = (insn >> 9) & 7; if (val == 0) val = 8; }		\
  else if (insn == 0157774) /* addal #WW, sp */			\
    val = read_memory_integer (pc + 2, 4);			\
  val >>= 2; }

/* 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.  */

#define FRAME_FIND_SAVED_REGS(frame_info, frame_saved_regs)		\
{ register int regnum;							\
  register int regmask;							\
  register CORE_ADDR next_addr;						\
  register CORE_ADDR pc;						\
  register int insn;							\
  register int offset;							\
  memset (&frame_saved_regs, '\0', sizeof frame_saved_regs);			\
  if ((frame_info)->pc >= (frame_info)->frame - CALL_DUMMY_LENGTH - FP_REGNUM*4 - 8*12 - 4 \
      && (frame_info)->pc <= (frame_info)->frame)				\
    { next_addr = (frame_info)->frame;					\
      pc = (frame_info)->frame - CALL_DUMMY_LENGTH - FP_REGNUM * 4 - 8*12 - 4; }\
  else   								\
    { pc = get_pc_function_start ((frame_info)->pc); 			\
      /* Verify we have a link a6 instruction next,			\
	 or a branch followed by a link a6 instruction;			\
	 if not we lose.  If we win, find the address above the saved   \
	 regs using the amount of storage from the link instruction.  */\
retry:									\
      insn = read_memory_integer (pc, 2);				\
      if (insn == 044016)						\
	next_addr = (frame_info)->frame - read_memory_integer (pc += 2, 4), pc+=4; \
      else if (insn == 047126)						\
	next_addr = (frame_info)->frame - read_memory_integer (pc += 2, 2), pc+=2; \
      else if ((insn & 0177400) == 060000)	/* bra insn */		\
	{ offset = insn & 0377;						\
          pc += 2;				/* advance past bra */	\
	  if (offset == 0)			/* bra #word */		\
	    offset = read_memory_integer (pc, 2), pc += 2;		\
	  else if (offset == 0377)		/* bra #long */		\
	    offset = read_memory_integer (pc, 4), pc += 4;		\
	  pc += offset;							\
	  goto retry;							\
      } else goto lose;							\
      /* If have an addal #-n, sp next, adjust next_addr.  */		\
      if ((0177777 & read_memory_integer (pc, 2)) == 0157774)		\
	next_addr += read_memory_integer (pc += 2, 4), pc += 4;		\
    }									\
  /* next should be a moveml to (sp) or -(sp) or a movl r,-(sp) */	\
  insn = read_memory_integer (pc, 2), pc += 2;				\
  regmask = read_memory_integer (pc, 2);				\
  if ((insn & 0177760) == 022700)	/* movl rn, (sp) */		\
    (frame_saved_regs).regs[(insn&7) + ((insn&010)?8:0)] = next_addr;	\
  else if ((insn & 0177760) == 024700)	/* movl rn, -(sp) */		\
    (frame_saved_regs).regs[(insn&7) + ((insn&010)?8:0)] = next_addr-=4; \
  else if (insn == 0044327)		/* moveml mask, (sp) */		\
    { pc += 2;								\
      /* Regmask's low bit is for register 0, the first written */	\
      next_addr -= 4;							\
      for (regnum = 0; regnum < 16; regnum++, regmask >>= 1)		\
	if (regmask & 1)						\
          (frame_saved_regs).regs[regnum] = (next_addr += 4);		\
  } else if (insn == 0044347)		/* moveml mask, -(sp) */	\
    { pc += 2;								\
      /* Regmask's low bit is for register 15, the first pushed */	\
      for (regnum = 15; regnum >= 0; regnum--, regmask >>= 1)		\
	if (regmask & 1)						\
          (frame_saved_regs).regs[regnum] = (next_addr -= 4); }		\
  /* clrw -(sp); movw ccr,-(sp) may follow.  */				\
  if (read_memory_integer (pc, 2) == 041147 				\
      && read_memory_integer (pc+2, 2) == 042347)			\
    (frame_saved_regs).regs[PS_REGNUM] = (next_addr -= 4);		\
  lose: ;								\
  (frame_saved_regs).regs[SP_REGNUM] = (frame_info)->frame + 8;		\
  (frame_saved_regs).regs[FP_REGNUM] = (frame_info)->frame;		\
  (frame_saved_regs).regs[PC_REGNUM] = (frame_info)->frame + 4;		\
}

/* The only reason this is here is the tm-isi.h reference below.  It
   was moved back here from tm-m68k.h.  FIXME? */

#define SKIP_PROLOGUE(pc)   \
{ register int op = read_memory_integer (pc, 2);	\
  if (op == 0047126)					\
    pc += 4;   /* Skip link #word */			\
  else if (op == 0044016)				\
    pc += 6;   /* Skip link #long */			\
  /* Not sure why branches are here.  */		\
  /* From tm-isi.h, tm-altos.h */			\
  else if (op == 0060000)				\
    pc += 4;   /* Skip bra #word */			\
  else if (op == 00600377)				\
    pc += 6;   /* skip bra #long */			\
  else if ((op & 0177400) == 0060000)			\
    pc += 2;   /* skip bra #char */			\
}

#include "m68k/tm-m68k.h"
