darling-gdb/opcodes/arm-dis.c

/* Instruction printing code for the ARM
   Copyright (C) 1994, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc. 
   Contributed by Richard Earnshaw (rwe@pegasus.esprit.ec.org)
   Modification by James G. Smith (jsmith@cygnus.co.uk)

This file is part of libopcodes. 

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 "sysdep.h"
#include "dis-asm.h"
#define DEFINE_TABLE
#include "arm-opc.h"
#include "coff/internal.h"
#include "libcoff.h"
#include "opintl.h"

/* FIXME: This shouldn't be done here */
#include "elf-bfd.h"
#include "elf/internal.h"
#include "elf/arm.h"

#ifndef streq
#define streq(a,b)	(strcmp ((a), (b)) == 0)
#endif

#ifndef strneq
#define strneq(a,b,n)	(strncmp ((a), (b), (n)) == 0)
#endif

#ifndef NUM_ELEM
#define NUM_ELEM(a)     (sizeof (a) / sizeof (a)[0])
#endif

static char * arm_conditional[] =
{"eq", "ne", "cs", "cc", "mi", "pl", "vs", "vc",
 "hi", "ls", "ge", "lt", "gt", "le", "", "nv"};

typedef struct
{
  const char * name;
  const char * description;
  const char * reg_names[16];
}
arm_regname;

static arm_regname regnames[] =
{
  { "raw" , "Select raw register names",
    { "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"}},
  { "std",  "Select register names used in ARM's ISA documentation",
    { "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "sp",  "lr",  "pc" }},
  { "apcs", "Select register names used in the APCS",
    { "a1", "a2", "a3", "a4", "v1", "v2", "v3", "v4", "v5", "v6", "sl",  "fp",  "ip",  "sp",  "lr",  "pc" }},
  { "atpcs", "Select register names used in the ATPCS",
    { "a1", "a2", "a3", "a4", "v1", "v2", "v3", "v4", "v5", "v6", "v7",  "v8",  "IP",  "SP",  "LR",  "PC" }},
  { "special-atpcs", "Select special register names used in the ATPCS",
    { "a1", "a2", "a3", "a4", "v1", "v2", "v3", "WR", "v5", "SB", "SL",  "FP",  "IP",  "SP",  "LR",  "PC" }}
};

/* Default to standard register name set.  */
static unsigned int regname_selected = 1;

#define NUM_ARM_REGNAMES  NUM_ELEM (regnames)
#define arm_regnames      regnames[regname_selected].reg_names

static boolean force_thumb = false;

static char * arm_fp_const[] =
{"0.0", "1.0", "2.0", "3.0", "4.0", "5.0", "0.5", "10.0"};

static char * arm_shift[] = 
{"lsl", "lsr", "asr", "ror"};

/* Forward declarations.  */
static void arm_decode_shift PARAMS ((long, fprintf_ftype, void *));
static int  print_insn_arm   PARAMS ((bfd_vma, struct disassemble_info *, long));
static int  print_insn_thumb PARAMS ((bfd_vma, struct disassemble_info *, long));
static void parse_disassembler_options PARAMS ((char *));
static int  print_insn       PARAMS ((bfd_vma, struct disassemble_info *, boolean));
int get_arm_regname_num_options (void);
int set_arm_regname_option (int option);
int get_arm_regnames (int option, const char **setname,
		      const char **setdescription,
		      const char ***register_names);

/* Functions. */
int
get_arm_regname_num_options (void)
{
  return NUM_ARM_REGNAMES;
}

int
set_arm_regname_option (int option)
{
  int old = regname_selected;
  regname_selected = option;
  return old;
}

int
get_arm_regnames (int option, const char **setname,
		  const char **setdescription,
                  const char ***register_names)
{
  *setname = regnames[option].name;
  *setdescription = regnames[option].description;
  *register_names = regnames[option].reg_names;
  return 16;
}

static void
arm_decode_shift (given, func, stream)
     long given;
     fprintf_ftype func;
     void * stream;
{
  func (stream, "%s", arm_regnames[given & 0xf]);
  
  if ((given & 0xff0) != 0)
    {
      if ((given & 0x10) == 0)
	{
	  int amount = (given & 0xf80) >> 7;
	  int shift = (given & 0x60) >> 5;
	  
	  if (amount == 0)
	    {
	      if (shift == 3)
		{
		  func (stream, ", rrx");
		  return;
		}
	      
	      amount = 32;
	    }
	  
	  func (stream, ", %s #%d", arm_shift[shift], amount);
	}
      else
	func (stream, ", %s %s", arm_shift[(given & 0x60) >> 5],
	      arm_regnames[(given & 0xf00) >> 8]);
    }
}

/* Print one instruction from PC on INFO->STREAM.
   Return the size of the instruction (always 4 on ARM). */
static int
print_insn_arm (pc, info, given)
     bfd_vma                   pc;
     struct disassemble_info * info;
     long                      given;
{
  struct arm_opcode *  insn;
  void *               stream = info->stream;
  fprintf_ftype        func   = info->fprintf_func;

  for (insn = arm_opcodes; insn->assembler; insn++)
    {
      if ((given & insn->mask) == insn->value)
	{
	  char * c;
	  
	  for (c = insn->assembler; *c; c++)
	    {
	      if (*c == '%')
		{
		  switch (*++c)
		    {
		    case '%':
		      func (stream, "%%");
		      break;

		    case 'a':
		      if (((given & 0x000f0000) == 0x000f0000)
			  && ((given & 0x02000000) == 0))
			{
			  int offset = given & 0xfff;
			  
			  func (stream, "[pc");
 
			  if (given & 0x01000000)
			    {
			      if ((given & 0x00800000) == 0)
				offset = - offset;
			  
			      /* pre-indexed */
			      func (stream, ", #%x]", offset);

			      offset += pc + 8;

			      /* Cope with the possibility of write-back
				 being used.  Probably a very dangerous thing
				 for the programmer to do, but who are we to
				 argue ?  */
			      if (given & 0x00200000)
				func (stream, "!");
			    }
			  else
			    {
			      /* Post indexed.  */
			      func (stream, "], #%x", offset);

			      offset = pc + 8;  /* ie ignore the offset.  */
			    }
			  
			  func (stream, "\t; ");
			  info->print_address_func (offset, info);
			}
		      else
			{
			  func (stream, "[%s", 
				arm_regnames[(given >> 16) & 0xf]);
			  if ((given & 0x01000000) != 0)
			    {
			      if ((given & 0x02000000) == 0)
				{
				  int offset = given & 0xfff;
				  if (offset)
				    func (stream, ", %s#%d",
					  (((given & 0x00800000) == 0)
					   ? "-" : ""), offset);
				}
			      else
				{
				  func (stream, ", %s",
					(((given & 0x00800000) == 0)
					 ? "-" : ""));
				  arm_decode_shift (given, func, stream);
				}

			      func (stream, "]%s", 
				    ((given & 0x00200000) != 0) ? "!" : "");
			    }
			  else
			    {
			      if ((given & 0x02000000) == 0)
				{
				  int offset = given & 0xfff;
				  if (offset)
				    func (stream, "], %s#%d",
					  (((given & 0x00800000) == 0)
					   ? "-" : ""), offset);
				  else 
				    func (stream, "]");
				}
			      else
				{
				  func (stream, "], %s",
					(((given & 0x00800000) == 0) 
					 ? "-" : ""));
				  arm_decode_shift (given, func, stream);
				}
			    }
			}
		      break;

		    case 's':
                      if ((given & 0x004f0000) == 0x004f0000)
			{
                          /* PC relative with immediate offset.  */
			  int offset = ((given & 0xf00) >> 4) | (given & 0xf);
			  
			  if ((given & 0x00800000) == 0)
			    offset = -offset;
			  
			  func (stream, "[pc, #%x]\t; ", offset);
			  
			  (*info->print_address_func)
			    (offset + pc + 8, info);
			}
		      else
			{
			  func (stream, "[%s", 
				arm_regnames[(given >> 16) & 0xf]);
			  if ((given & 0x01000000) != 0)
			    {
                              /* Pre-indexed.  */
			      if ((given & 0x00400000) == 0x00400000)
				{
                                  /* Immediate.  */
                                  int offset = ((given & 0xf00) >> 4) | (given & 0xf);
				  if (offset)
				    func (stream, ", %s#%d",
					  (((given & 0x00800000) == 0)
					   ? "-" : ""), offset);
				}
			      else
				{
                                  /* Register.  */
				  func (stream, ", %s%s",
					(((given & 0x00800000) == 0)
					 ? "-" : ""),
                                        arm_regnames[given & 0xf]);
				}

			      func (stream, "]%s", 
				    ((given & 0x00200000) != 0) ? "!" : "");
			    }
			  else
			    {
                              /* Post-indexed.  */
			      if ((given & 0x00400000) == 0x00400000)
				{
                                  /* Immediate.  */
                                  int offset = ((given & 0xf00) >> 4) | (given & 0xf);
				  if (offset)
				    func (stream, "], %s#%d",
					  (((given & 0x00800000) == 0)
					   ? "-" : ""), offset);
				  else 
				    func (stream, "]");
				}
			      else
				{
                                  /* Register.  */
				  func (stream, "], %s%s",
					(((given & 0x00800000) == 0)
					 ? "-" : ""),
                                        arm_regnames[given & 0xf]);
				}
			    }
			}
		      break;
			  
		    case 'b':
		      (*info->print_address_func)
			(BDISP (given) * 4 + pc + 8, info);
		      break;

		    case 'c':
		      func (stream, "%s",
			    arm_conditional [(given >> 28) & 0xf]);
		      break;

		    case 'm':
		      {
			int started = 0;
			int reg;

			func (stream, "{");
			for (reg = 0; reg < 16; reg++)
			  if ((given & (1 << reg)) != 0)
			    {
			      if (started)
				func (stream, ", ");
			      started = 1;
			      func (stream, "%s", arm_regnames[reg]);
			    }
			func (stream, "}");
		      }
		      break;

		    case 'o':
		      if ((given & 0x02000000) != 0)
			{
			  int rotate = (given & 0xf00) >> 7;
			  int immed = (given & 0xff);
			  immed = (((immed << (32 - rotate))
				    | (immed >> rotate)) & 0xffffffff);
			  func (stream, "#%d\t; 0x%x", immed, immed);
			}
		      else
			arm_decode_shift (given, func, stream);
		      break;

		    case 'p':
		      if ((given & 0x0000f000) == 0x0000f000)
			func (stream, "p");
		      break;

		    case 't':
		      if ((given & 0x01200000) == 0x00200000)
			func (stream, "t");
		      break;

		    case 'h':
		      if ((given & 0x00000020) == 0x00000020)
			func (stream, "h");
                      else
                        func (stream, "b");
		      break;

		    case 'A':
		      func (stream, "[%s", arm_regnames [(given >> 16) & 0xf]);
		      if ((given & 0x01000000) != 0)
			{
			  int offset = given & 0xff;
			  if (offset)
			    func (stream, ", %s#%d]%s",
				  ((given & 0x00800000) == 0 ? "-" : ""),
				  offset * 4,
				  ((given & 0x00200000) != 0 ? "!" : ""));
			  else
			    func (stream, "]");
			}
		      else
			{
			  int offset = given & 0xff;
			  if (offset)
			    func (stream, "], %s#%d",
				  ((given & 0x00800000) == 0 ? "-" : ""),
				  offset * 4);
			  else
			    func (stream, "]");
			}
		      break;

		    case 'C':
		      switch (given & 0x000f0000)
			{
			default:
			  func (stream, "_???");
			  break;
			case 0x90000:
			  func (stream, "_all");
			  break;
			case 0x10000:
			  func (stream, "_c");
			  break;
			case 0x20000:
			  func (stream, "_x");
			  break;
			case 0x40000:
			  func (stream, "_s");
			  break;
			case 0x80000:
			  func (stream, "_f");
			  break;
			}
		      break;

		    case 'F':
		      switch (given & 0x00408000)
			{
			case 0:
			  func (stream, "4");
			  break;
			case 0x8000:
			  func (stream, "1");
			  break;
			case 0x00400000:
			  func (stream, "2");
			  break;
			default:
			  func (stream, "3");
			}
		      break;
			
		    case 'P':
		      switch (given & 0x00080080)
			{
			case 0:
			  func (stream, "s");
			  break;
			case 0x80:
			  func (stream, "d");
			  break;
			case 0x00080000:
			  func (stream, "e");
			  break;
			default:
			  func (stream, _("<illegal precision>"));
			  break;
			}
		      break;
		    case 'Q':
		      switch (given & 0x00408000)
			{
			case 0:
			  func (stream, "s");
			  break;
			case 0x8000:
			  func (stream, "d");
			  break;
			case 0x00400000:
			  func (stream, "e");
			  break;
			default:
			  func (stream, "p");
			  break;
			}
		      break;
		    case 'R':
		      switch (given & 0x60)
			{
			case 0:
			  break;
			case 0x20:
			  func (stream, "p");
			  break;
			case 0x40:
			  func (stream, "m");
			  break;
			default:
			  func (stream, "z");
			  break;
			}
		      break;

		    case '0': case '1': case '2': case '3': case '4': 
		    case '5': case '6': case '7': case '8': case '9':
		      {
			int bitstart = *c++ - '0';
			int bitend = 0;
			while (*c >= '0' && *c <= '9')
			  bitstart = (bitstart * 10) + *c++ - '0';

			switch (*c)
			  {
			  case '-':
			    c++;
			    
			    while (*c >= '0' && *c <= '9')
			      bitend = (bitend * 10) + *c++ - '0';
			    
			    if (!bitend)
			      abort ();
			    
			    switch (*c)
			      {
			      case 'r':
				{
				  long reg;
				  
				  reg = given >> bitstart;
				  reg &= (2 << (bitend - bitstart)) - 1;
				  
				  func (stream, "%s", arm_regnames[reg]);
				}
				break;
			      case 'd':
				{
				  long reg;
				  
				  reg = given >> bitstart;
				  reg &= (2 << (bitend - bitstart)) - 1;
				  
				  func (stream, "%d", reg);
				}
				break;
			      case 'x':
				{
				  long reg;
				  
				  reg = given >> bitstart;
				  reg &= (2 << (bitend - bitstart)) - 1;
				  
				  func (stream, "0x%08x", reg);
				  
				  /* Some SWI instructions have special
				     meanings.  */
				  if ((given & 0x0fffffff) == 0x0FF00000)
				    func (stream, "\t; IMB");
				  else if ((given & 0x0fffffff) == 0x0FF00001)
				    func (stream, "\t; IMBRange");
				}
				break;
			      case 'X':
				{
				  long reg;
				  
				  reg = given >> bitstart;
				  reg &= (2 << (bitend - bitstart)) - 1;
				  
				  func (stream, "%01x", reg & 0xf);
				}
				break;
			      case 'f':
				{
				  long reg;
				  
				  reg = given >> bitstart;
				  reg &= (2 << (bitend - bitstart)) - 1;
				  
				  if (reg > 7)
				    func (stream, "#%s",
					  arm_fp_const[reg & 7]);
				  else
				    func (stream, "f%d", reg);
				}
				break;
			      default:
				abort ();
			      }
			    break;
			    
			  case '`':
			    c++;
			    if ((given & (1 << bitstart)) == 0)
			      func (stream, "%c", *c);
			    break;
			  case '\'':
			    c++;
			    if ((given & (1 << bitstart)) != 0)
			      func (stream, "%c", *c);
			    break;
			  case '?':
			    ++c;
			    if ((given & (1 << bitstart)) != 0)
			      func (stream, "%c", *c++);
			    else
			      func (stream, "%c", *++c);
			    break;
			  default:
			    abort ();
			  }
			break;

		      default:
			abort ();
		      }
		    }
		}
	      else
		func (stream, "%c", *c);
	    }
	  return 4;
	}
    }
  abort ();
}

/* Print one instruction from PC on INFO->STREAM.
   Return the size of the instruction. */
static int
print_insn_thumb (pc, info, given)
     bfd_vma                   pc;
     struct disassemble_info * info;
     long                      given;
{
  struct thumb_opcode * insn;
  void *                stream = info->stream;
  fprintf_ftype         func = info->fprintf_func;

  for (insn = thumb_opcodes; insn->assembler; insn++)
    {
      if ((given & insn->mask) == insn->value)
        {
          char * c = insn->assembler;

          /* Special processing for Thumb 2 instruction BL sequence:  */
          if (!*c) /* Check for empty (not NULL) assembler string.  */
            {
	      info->bytes_per_chunk = 4;
	      info->bytes_per_line  = 4;
	      
                func (stream, "bl\t");
		
              info->print_address_func (BDISP23 (given) * 2 + pc + 4, info);
              return 4;
            }
          else
            {
	      info->bytes_per_chunk = 2;
	      info->bytes_per_line  = 4;
	  	      
              given &= 0xffff;
	      
              for (; *c; c++)
                {
                  if (*c == '%')
                    {
                      int domaskpc = 0;
                      int domasklr = 0;
		      
                      switch (*++c)
                        {
                        case '%':
                          func (stream, "%%");
                          break;

                        case 'S':
                          {
                            long reg;
			    
                            reg = (given >> 3) & 0x7;
                            if (given & (1 << 6))
                              reg += 8;
			    
                            func (stream, "%s", arm_regnames[reg]);
                          }
                          break;

                        case 'D':
                          {
                            long reg;
			    
                            reg = given & 0x7;
                            if (given & (1 << 7))
                             reg += 8;
			    
                            func (stream, "%s", arm_regnames[reg]);
                          }
                          break;

                        case 'T':
                          func (stream, "%s",
                                arm_conditional [(given >> 8) & 0xf]);
                          break;

                        case 'N':
                          if (given & (1 << 8))
                            domasklr = 1;
                          /* Fall through.  */
                        case 'O':
                          if (*c == 'O' && (given & (1 << 8)))
                            domaskpc = 1;
                          /* Fall through.  */
                        case 'M':
                          {
                            int started = 0;
                            int reg;
			    
                            func (stream, "{");
			    
                            /* It would be nice if we could spot
                               ranges, and generate the rS-rE format: */
                            for (reg = 0; (reg < 8); reg++)
                              if ((given & (1 << reg)) != 0)
                                {
                                  if (started)
                                    func (stream, ", ");
                                  started = 1;
                                  func (stream, "%s", arm_regnames[reg]);
                                }

                            if (domasklr)
                              {
                                if (started)
                                  func (stream, ", ");
                                started = 1;
                                func (stream, arm_regnames[14] /* "lr" */);
                              }

                            if (domaskpc)
                              {
                                if (started)
                                  func (stream, ", ");
                                func (stream, arm_regnames[15] /* "pc" */);
                              }

                            func (stream, "}");
                          }
                          break;


                        case '0': case '1': case '2': case '3': case '4': 
                        case '5': case '6': case '7': case '8': case '9':
                          {
                            int bitstart = *c++ - '0';
                            int bitend = 0;
			    
                            while (*c >= '0' && *c <= '9')
                              bitstart = (bitstart * 10) + *c++ - '0';

                            switch (*c)
                              {
                              case '-':
                                {
                                  long reg;
				  
                                  c++;
                                  while (*c >= '0' && *c <= '9')
                                    bitend = (bitend * 10) + *c++ - '0';
                                  if (!bitend)
                                    abort ();
                                  reg = given >> bitstart;
                                  reg &= (2 << (bitend - bitstart)) - 1;
                                  switch (*c)
                                    {
                                    case 'r':
                                      func (stream, "%s", arm_regnames[reg]);
                                      break;

                                    case 'd':
                                      func (stream, "%d", reg);
                                      break;

                                    case 'H':
                                      func (stream, "%d", reg << 1);
                                      break;

                                    case 'W':
                                      func (stream, "%d", reg << 2);
                                      break;

                                    case 'a':
				      /* PC-relative address -- the bottom two
					 bits of the address are dropped
					 before the calculation.  */
                                      info->print_address_func
					(((pc + 4) & ~3) + (reg << 2), info);
                                      break;

                                    case 'x':
                                      func (stream, "0x%04x", reg);
                                      break;

                                    case 'I':
                                      reg = ((reg ^ (1 << bitend)) - (1 << bitend));
                                      func (stream, "%d", reg);
                                      break;

                                    case 'B':
                                      reg = ((reg ^ (1 << bitend)) - (1 << bitend));
                                      (*info->print_address_func)
                                        (reg * 2 + pc + 4, info);
                                      break;

                                    default:
                                      abort ();
                                    }
                                }
                                break;

                              case '\'':
                                c++;
                                if ((given & (1 << bitstart)) != 0)
                                  func (stream, "%c", *c);
                                break;

                              case '?':
                                ++c;
                                if ((given & (1 << bitstart)) != 0)
                                  func (stream, "%c", *c++);
                                else
                                  func (stream, "%c", *++c);
                                break;

                              default:
                                 abort ();
                              }
                          }
                          break;

                        default:
                          abort ();
                        }
                    }
                  else
                    func (stream, "%c", *c);
                }
             }
          return 2;
       }
    }

  /* No match.  */
  abort ();
}

/* Parse an individual disassembler option.  */
void
parse_arm_disassembler_option (option)
     char * option;
{
  if (option == NULL)
    return;
      
  if (strneq (option, "reg-names-", 10))
    {
      int i;
	
      option += 10;

      for (i = NUM_ARM_REGNAMES; i--;)
	if (streq (option, regnames[i].name))
	  {
	    regname_selected = i;
	    break;
	  }
      
      if (i < 0)
	fprintf (stderr, _("Unrecognised register name set: %s\n"), option);
    }
  else if (streq (option, "force-thumb"))
    force_thumb = 1;
  else if (streq (option, "no-force-thumb"))
    force_thumb = 0;
  else
    fprintf (stderr, _("Unrecognised disassembler option: %s\n"), option);
  
  return;
}

/* Parse the string of disassembler options, spliting it at whitespaces.  */
static void
parse_disassembler_options (options)
     char * options;
{
  char * space;
  
  if (options == NULL)
    return;

  do
    {
      space = strchr (options, ' ');

      if (space)
	{
	  * space = '\0';
	  parse_arm_disassembler_option (options);
	  * space = ' ';
	  options = space + 1;
	}
      else
	parse_arm_disassembler_option (options);
    }
  while (space);
}

/* NOTE: There are no checks in these routines that
   the relevant number of data bytes exist.  */
static int
print_insn (pc, info, little)
     bfd_vma pc;
     struct disassemble_info * info;
     boolean little;
{
  unsigned char      b[4];
  long               given;
  int                status;
  int                is_thumb;

  if (info->disassembler_options)
    {
      parse_disassembler_options (info->disassembler_options);
      
      /* To avoid repeated parsing of these options, we remove them here.  */
      info->disassembler_options = NULL;
    }
  
  is_thumb = force_thumb;
  
  if (!is_thumb && info->symbols != NULL)
    {
      if (bfd_asymbol_flavour (*info->symbols) == bfd_target_coff_flavour)
	{
	  coff_symbol_type * cs;
	  
	  cs = coffsymbol (*info->symbols);
	  is_thumb = (   cs->native->u.syment.n_sclass == C_THUMBEXT
		      || cs->native->u.syment.n_sclass == C_THUMBSTAT
		      || cs->native->u.syment.n_sclass == C_THUMBLABEL
		      || cs->native->u.syment.n_sclass == C_THUMBEXTFUNC
		      || cs->native->u.syment.n_sclass == C_THUMBSTATFUNC);
	}
      else if (bfd_asymbol_flavour (*info->symbols) == bfd_target_elf_flavour)
	{
	  elf_symbol_type *  es;
	  unsigned int       type;
	  
	  es = *(elf_symbol_type **)(info->symbols);
	  type = ELF_ST_TYPE (es->internal_elf_sym.st_info);
	  
	  is_thumb = (type == STT_ARM_TFUNC) || (type == STT_ARM_16BIT);
	}
    }
  
  info->bytes_per_chunk = 4;
  info->display_endian  = little ? BFD_ENDIAN_LITTLE : BFD_ENDIAN_BIG;

  if (little)
    {
      status = info->read_memory_func (pc, (bfd_byte *) &b[0], 4, info);
      if (status != 0 && is_thumb)
	{
	  info->bytes_per_chunk = 2;
	  
	  status = info->read_memory_func (pc, (bfd_byte *) b, 2, info);
	  b[3] = b[2] = 0;
	}
      
      if (status != 0)
	{
	  info->memory_error_func (status, pc, info);
	  return -1;
	}
      
      given = (b[0]) | (b[1] << 8) | (b[2] << 16) | (b[3] << 24);
    }
  else
    {
      status = info->read_memory_func
	(pc & ~ 0x3, (bfd_byte *) &b[0], 4, info);
      if (status != 0)
	{
	  info->memory_error_func (status, pc, info);
	  return -1;
	}
      
      if (is_thumb)
	{
	  if (pc & 0x2)
	    {
	      given = (b[2] << 8) | b[3];
	      
	      status = info->read_memory_func
		((pc + 4) & ~ 0x3, (bfd_byte *) b, 4, info);
	      if (status != 0)
		{
		  info->memory_error_func (status, pc + 4, info);
		  return -1;
		}
	      
	      given |= (b[0] << 24) | (b[1] << 16);
	    }
	  else
	    given = (b[0] << 8) | b[1] | (b[2] << 24) | (b[3] << 16);
	}
      else
	given = (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | (b[3]);
    }
  
  if (is_thumb)
    status = print_insn_thumb (pc, info, given);
  else
    status = print_insn_arm (pc, info, given);

  return status;
}

int
print_insn_big_arm (pc, info)
     bfd_vma pc;
     struct disassemble_info * info;
{
  return print_insn (pc, info, false);
}

int
print_insn_little_arm (pc, info)
     bfd_vma pc;
     struct disassemble_info * info;
{
  return print_insn (pc, info, true);
}

void
print_arm_disassembler_options (FILE * stream)
{
  int i;

  fprintf (stream, _("\n\
The following ARM specific disassembler options are supported for use with\n\
the -M switch:\n"));
  
  for (i = NUM_ARM_REGNAMES; i--;)
    fprintf (stream, "  reg-names-%s %*c%s\n",
	     regnames[i].name,
	     14 - strlen (regnames[i].name), ' ',
	     regnames[i].description);

  fprintf (stream, "  force-thumb              Assume all insns are Thumb insns\n");
  fprintf (stream, "  no-force-thumb           Examine preceeding label to determine an insn's type\n\n");
}