gdb/arm-linux-tdep.c

/* GNU/Linux on ARM target support.
   Copyright 1999, 2000 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 "target.h"
#include "value.h"
#include "gdbtypes.h"
#include "floatformat.h"

#ifdef GET_LONGJMP_TARGET

/* Figure out where the longjmp will land.  We expect that we have
   just entered longjmp and haven't yet altered r0, r1, so the
   arguments are still in the registers.  (A1_REGNUM) points at the
   jmp_buf structure from which we extract the pc (JB_PC) that we will
   land at.  The pc is copied into ADDR.  This routine returns true on
   success. */

#define LONGJMP_TARGET_SIZE 	sizeof(int)
#define JB_ELEMENT_SIZE		sizeof(int)
#define JB_SL			18
#define JB_FP			19
#define JB_SP			20
#define JB_PC			21

int
arm_get_longjmp_target (CORE_ADDR * pc)
{
  CORE_ADDR jb_addr;
  char buf[LONGJMP_TARGET_SIZE];

  jb_addr = read_register (A1_REGNUM);

  if (target_read_memory (jb_addr + JB_PC * JB_ELEMENT_SIZE, buf,
			  LONGJMP_TARGET_SIZE))
    return 0;

  *pc = extract_address (buf, LONGJMP_TARGET_SIZE);
  return 1;
}

#endif /* GET_LONGJMP_TARGET */

/* Extract from an array REGBUF containing the (raw) register state
   a function return value of type TYPE, and copy that, in virtual format,
   into VALBUF.  */

void
arm_linux_extract_return_value (struct type *type,
				char regbuf[REGISTER_BYTES],
				char *valbuf)
{
  /* ScottB: This needs to be looked at to handle the different
     floating point emulators on ARM Linux.  Right now the code
     assumes that fetch inferior registers does the right thing for
     GDB.  I suspect this won't handle NWFPE registers correctly, nor
     will the default ARM version (arm_extract_return_value()).  */

  int regnum = (TYPE_CODE_FLT == TYPE_CODE (type)) ? F0_REGNUM : A1_REGNUM;
  memcpy (valbuf, &regbuf[REGISTER_BYTE (regnum)], TYPE_LENGTH (type));
}

/* Note: ScottB

   This function does not support passing parameters using the FPA
   variant of the APCS.  It passes any floating point arguments in the
   general registers and/or on the stack.
   
   FIXME:  This and arm_push_arguments should be merged.  However this 
   	   function breaks on a little endian host, big endian target
   	   using the COFF file format.  ELF is ok.  
   	   
   	   ScottB.  */
   	   
/* Addresses for calling Thumb functions have the bit 0 set.
   Here are some macros to test, set, or clear bit 0 of addresses.  */
#define IS_THUMB_ADDR(addr)	((addr) & 1)
#define MAKE_THUMB_ADDR(addr)	((addr) | 1)
#define UNMAKE_THUMB_ADDR(addr) ((addr) & ~1)
   	  
CORE_ADDR
arm_linux_push_arguments (int nargs, value_ptr * args, CORE_ADDR sp,
		          int struct_return, CORE_ADDR struct_addr)
{
  char *fp;
  int argnum, argreg, nstack_size;

  /* Walk through the list of args and determine how large a temporary
     stack is required.  Need to take care here as structs may be
     passed on the stack, and we have to to push them.  */
  nstack_size = -4 * REGISTER_SIZE;	/* Some arguments go into A1-A4.  */

  if (struct_return)			/* The struct address goes in A1.  */
    nstack_size += REGISTER_SIZE;

  /* Walk through the arguments and add their size to nstack_size.  */
  for (argnum = 0; argnum < nargs; argnum++)
    {
      int len;
      struct type *arg_type;

      arg_type = check_typedef (VALUE_TYPE (args[argnum]));
      len = TYPE_LENGTH (arg_type);

      /* ANSI C code passes float arguments as integers, K&R code
         passes float arguments as doubles.  Correct for this here.  */
      if (TYPE_CODE_FLT == TYPE_CODE (arg_type) && REGISTER_SIZE == len)
	nstack_size += FP_REGISTER_VIRTUAL_SIZE;
      else
	nstack_size += len;
    }

  /* Allocate room on the stack, and initialize our stack frame
     pointer.  */
  fp = NULL;
  if (nstack_size > 0)
    {
      sp -= nstack_size;
      fp = (char *) sp;
    }

  /* Initialize the integer argument register pointer.  */
  argreg = A1_REGNUM;

  /* The struct_return pointer occupies the first parameter passing
     register.  */
  if (struct_return)
    write_register (argreg++, struct_addr);

  /* Process arguments from left to right.  Store as many as allowed
     in the parameter passing registers (A1-A4), and save the rest on
     the temporary stack.  */
  for (argnum = 0; argnum < nargs; argnum++)
    {
      int len;
      char *val;
      double dbl_arg;
      CORE_ADDR regval;
      enum type_code typecode;
      struct type *arg_type, *target_type;

      arg_type = check_typedef (VALUE_TYPE (args[argnum]));
      target_type = TYPE_TARGET_TYPE (arg_type);
      len = TYPE_LENGTH (arg_type);
      typecode = TYPE_CODE (arg_type);
      val = (char *) VALUE_CONTENTS (args[argnum]);

      /* ANSI C code passes float arguments as integers, K&R code
         passes float arguments as doubles.  The .stabs record for 
         for ANSI prototype floating point arguments records the
         type as FP_INTEGER, while a K&R style (no prototype)
         .stabs records the type as FP_FLOAT.  In this latter case
         the compiler converts the float arguments to double before
         calling the function.  */
      if (TYPE_CODE_FLT == typecode && REGISTER_SIZE == len)
	{
	  /* Float argument in buffer is in host format.  Read it and 
	     convert to DOUBLEST, and store it in target double.  */
	  DOUBLEST dblval;
	  
	  len = TARGET_DOUBLE_BIT / TARGET_CHAR_BIT;
	  floatformat_to_doublest (HOST_FLOAT_FORMAT, val, &dblval);
	  store_floating (&dbl_arg, len, dblval);
	  val = (char *) &dbl_arg;
	}

      /* If the argument is a pointer to a function, and it is a Thumb
         function, set the low bit of the pointer.  */
      if (TYPE_CODE_PTR == typecode
	  && NULL != target_type
	  && TYPE_CODE_FUNC == TYPE_CODE (target_type))
	{
	  CORE_ADDR regval = extract_address (val, len);
	  if (arm_pc_is_thumb (regval))
	    store_address (val, len, MAKE_THUMB_ADDR (regval));
	}

      /* Copy the argument to general registers or the stack in
         register-sized pieces.  Large arguments are split between
         registers and stack.  */
      while (len > 0)
	{
	  int partial_len = len < REGISTER_SIZE ? len : REGISTER_SIZE;

	  if (argreg <= ARM_LAST_ARG_REGNUM)
	    {
	      /* It's an argument being passed in a general register.  */
	      regval = extract_address (val, partial_len);
	      write_register (argreg++, regval);
	    }
	  else
	    {
	      /* Push the arguments onto the stack.  */
	      write_memory ((CORE_ADDR) fp, val, REGISTER_SIZE);
	      fp += REGISTER_SIZE;
	    }

	  len -= partial_len;
	  val += partial_len;
	}
    }

  /* Return adjusted stack pointer.  */
  return sp;
}

void
_initialize_arm_linux_tdep (void)
{
}