2004-11-29 Tomer Levi <Tomer.Levi@nsc.com>

[external/binutils.git] / gas / config / tc-crx.c

/* tc-crx.c -- Assembler code for the CRX CPU core.
   Copyright 2004 Free Software Foundation, Inc.

   Contributed by Tomer Levi, NSC, Israel.
   Originally written for GAS 2.12 by Tomer Levi, NSC, Israel.
   Updates, BFDizing, GNUifying and ELF support by Tomer Levi.

   This file is part of GAS, the GNU Assembler.

   GAS 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, or (at your option)
   any later version.

   GAS 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 GAS; see the file COPYING.  If not, write to the
   Free Software Foundation, 59 Temple Place - Suite 330, Boston,
   MA 02111-1307, USA.  */

#include "as.h"
#include "safe-ctype.h"
#include "dwarf2dbg.h"
#include "opcode/crx.h"
#include "elf/crx.h"

/* Word is considered here as a 16-bit unsigned short int.  */
#define WORD_SHIFT  16

/* Register is 4-bit size.  */
#define REG_SIZE   4

/* Maximum size of a single instruction (in words).  */
#define INSN_MAX_SIZE   3

/* Maximum bits which may be set in a `mask16' operand.  */
#define MAX_REGS_IN_MASK16  8

/* Utility macros for string comparison.  */
#define streq(a, b)           (strcmp (a, b) == 0)
#define strneq(a, b, c)       (strncmp (a, b, c) == 0)

/* Assign a number NUM, shifted by SHIFT bytes, into a location
   pointed by index BYTE of array 'output_opcode'.  */
#define CRX_PRINT(BYTE, NUM, SHIFT)   output_opcode[BYTE] |= (NUM << SHIFT)

/* Operand errors.  */
typedef enum
  {
    OP_LEGAL = 0,       /* Legal operand.  */
    OP_OUT_OF_RANGE,    /* Operand not within permitted range.  */
    OP_NOT_EVEN,        /* Operand is Odd number, should be even.  */
    OP_ILLEGAL_DISPU4,  /* Operand is not within DISPU4 range.  */
    OP_ILLEGAL_CST4,    /* Operand is not within CST4 range.  */
    OP_NOT_UPPER_64KB   /* Operand is not within the upper 64KB 
                           (0xFFFF0000-0xFFFFFFFF).  */
  }
op_err;

/* Opcode mnemonics hash table.  */
static struct hash_control *crx_inst_hash;
/* CRX registers hash table.  */
static struct hash_control *reg_hash;
/* CRX coprocessor registers hash table.  */
static struct hash_control *copreg_hash;
/* Current instruction we're assembling.  */
const inst *instruction;

/* Global variables.  */

/* Array to hold an instruction encoding.  */
long output_opcode[2];

/* Nonzero means a relocatable symbol.  */
int relocatable;

/* A copy of the original instruction (used in error messages).  */
char ins_parse[MAX_INST_LEN];

/* The current processed argument number.  */
int cur_arg_num;

/* Generic assembler global variables which must be defined by all targets.  */

/* Characters which always start a comment.  */
const char comment_chars[] = "#";

/* Characters which start a comment at the beginning of a line.  */
const char line_comment_chars[] = "#";

/* This array holds machine specific line separator characters.  */
const char line_separator_chars[] = ";";

/* Chars that can be used to separate mant from exp in floating point nums.  */
const char EXP_CHARS[] = "eE";

/* Chars that mean this number is a floating point constant as in 0f12.456  */
const char FLT_CHARS[] = "f'";

/* Target-specific multicharacter options, not const-declared at usage.  */
const char *md_shortopts = "";
struct option md_longopts[] =
{
  {NULL, no_argument, NULL, 0}
};
size_t md_longopts_size = sizeof (md_longopts);

/* This table describes all the machine specific pseudo-ops
   the assembler has to support.  The fields are:
   *** Pseudo-op name without dot.
   *** Function to call to execute this pseudo-op.
   *** Integer arg to pass to the function.  */

const pseudo_typeS md_pseudo_table[] =
{
  /* In CRX machine, align is in bytes (not a ptwo boundary).  */
  {"align", s_align_bytes, 0},
  {0, 0, 0}
};

/* CRX relaxation table.  */
const relax_typeS md_relax_table[] =
{
  /* bCC  */
  {0xfa, -0x100, 2, 1},                 /*  8 */
  {0xfffe, -0x10000, 4, 2},             /* 16 */
  {0xfffffffe, -0xfffffffe, 6, 0},      /* 32 */

  /* bal  */
  {0xfffe, -0x10000, 4, 4},             /* 16 */
  {0xfffffffe, -0xfffffffe, 6, 0},      /* 32 */

  /* cmpbr  */
  {0xfe, -0x100, 4, 6},                 /*  8 */
  {0xfffffe, -0x1000000, 6, 0}          /* 24 */
};

static void    reset_vars               (char *);
static reg     get_register             (char *);
static copreg  get_copregister          (char *);
static argtype get_optype               (operand_type);
static int     get_opbits               (operand_type);
static int     get_opflags              (operand_type);
static int     get_number_of_operands   (void);
static void    parse_operand            (char *, ins *);
static int     gettrap                  (char *);
static void    handle_LoadStor          (char *);
static int     get_cinv_parameters      (char *);
static long    getconstant              (long, int);
static op_err  check_range              (long *, int, unsigned int, int);
static int     getreg_image             (reg);
static void    parse_operands           (ins *, char *);
static void    parse_insn               (ins *, char *);
static void    print_operand            (int, int, argument *);
static void    print_constant           (int, int, argument *);
static int     exponent2scale           (int);
static void    mask_reg                 (int, unsigned short *);
static void    process_label_constant   (char *, ins *);
static void    set_operand              (char *, ins *);
static char *  preprocess_reglist       (char *, int *);
static int     assemble_insn            (char *, ins *);
static void    print_insn               (ins *);
static void    warn_if_needed           (ins *);
static int     adjust_if_needed         (ins *);

/* Return the bit size for a given operand.  */

static int
get_opbits (operand_type op)
{
  if (op < MAX_OPRD)
    return crx_optab[op].bit_size;
  else
    return 0;
}

/* Return the argument type of a given operand.  */

static argtype
get_optype (operand_type op)
{
  if (op < MAX_OPRD)
    return crx_optab[op].arg_type;
  else
    return nullargs;
}

/* Return the flags of a given operand.  */

static int
get_opflags (operand_type op)
{
  if (op < MAX_OPRD)
    return crx_optab[op].flags;
  else
    return 0;
}

/* Get the core processor register 'reg_name'.  */

static reg
get_register (char *reg_name)
{
  const reg_entry *reg;

  reg = (const reg_entry *) hash_find (reg_hash, reg_name);

  if (reg != NULL)
    return reg->value.reg_val;
  else
    return nullregister;
}

/* Get the coprocessor register 'copreg_name'.  */

static copreg
get_copregister (char *copreg_name)
{
  const reg_entry *copreg;

  copreg = (const reg_entry *) hash_find (copreg_hash, copreg_name);

  if (copreg != NULL)
    return copreg->value.copreg_val;
  else
    return nullcopregister;
}

/* Round up a section size to the appropriate boundary.  */

valueT
md_section_align (segT seg, valueT val)
{
  /* Round .text section to a multiple of 2.  */
  if (seg == text_section)
    return (val + 1) & ~1;
  return val;
}

/* Parse an operand that is machine-specific (remove '*').  */

void
md_operand (expressionS * exp)
{
  char c = *input_line_pointer;

  switch (c)
    {
    case '*':
      input_line_pointer++;
      expression (exp);
      break;
    default:
      break;
    }
}

/* Reset global variables before parsing a new instruction.  */

static void
reset_vars (char *op)
{
  cur_arg_num = relocatable = 0;
  memset (& output_opcode, '\0', sizeof (output_opcode));

  /* Save a copy of the original OP (used in error messages).  */
  strcpy (ins_parse, op);
}

/* This macro decides whether a particular reloc is an entry in a
   switch table.  It is used when relaxing, because the linker needs
   to know about all such entries so that it can adjust them if
   necessary.  */

#define SWITCH_TABLE(fix)                                 \
  (   (fix)->fx_addsy != NULL                             \
   && (fix)->fx_subsy != NULL                             \
   && S_GET_SEGMENT ((fix)->fx_addsy) ==                  \
      S_GET_SEGMENT ((fix)->fx_subsy)                     \
   && S_GET_SEGMENT (fix->fx_addsy) != undefined_section  \
   && (   (fix)->fx_r_type == BFD_RELOC_CRX_NUM8          \
       || (fix)->fx_r_type == BFD_RELOC_CRX_NUM16         \
       || (fix)->fx_r_type == BFD_RELOC_CRX_NUM32))

/* See whether we need to force a relocation into the output file.
   This is used to force out switch and PC relative relocations when
   relaxing.  */

int
crx_force_relocation (fixS *fix)
{
  if (generic_force_reloc (fix) || SWITCH_TABLE (fix))
    return 1;

  return 0;
}

/* Generate a relocation entry for a fixup.  */

arelent *
tc_gen_reloc (asection *section ATTRIBUTE_UNUSED, fixS * fixP)
{
  arelent * reloc;

  reloc = xmalloc (sizeof (arelent));
  reloc->sym_ptr_ptr  = xmalloc (sizeof (asymbol *));
  *reloc->sym_ptr_ptr = symbol_get_bfdsym (fixP->fx_addsy);
  reloc->address = fixP->fx_frag->fr_address + fixP->fx_where;
  reloc->addend = fixP->fx_offset;

  if (fixP->fx_subsy != NULL)
    {
      if (SWITCH_TABLE (fixP))
        {
          /* Keep the current difference in the addend.  */
          reloc->addend = (S_GET_VALUE (fixP->fx_addsy)
                           - S_GET_VALUE (fixP->fx_subsy) + fixP->fx_offset);

          switch (fixP->fx_r_type)
            {
            case BFD_RELOC_CRX_NUM8:
              fixP->fx_r_type = BFD_RELOC_CRX_SWITCH8;
              break;
            case BFD_RELOC_CRX_NUM16:
              fixP->fx_r_type = BFD_RELOC_CRX_SWITCH16;
              break;
            case BFD_RELOC_CRX_NUM32:
              fixP->fx_r_type = BFD_RELOC_CRX_SWITCH32;
              break;
            default:
              abort ();
              break;
            }
        }
      else
        {
          /* We only resolve difference expressions in the same section.  */
          as_bad_where (fixP->fx_file, fixP->fx_line,
                        _("can't resolve `%s' {%s section} - `%s' {%s section}"),
                        fixP->fx_addsy ? S_GET_NAME (fixP->fx_addsy) : "0",
                        segment_name (fixP->fx_addsy
                                      ? S_GET_SEGMENT (fixP->fx_addsy)
                                      : absolute_section),
                        S_GET_NAME (fixP->fx_subsy),
                        segment_name (S_GET_SEGMENT (fixP->fx_addsy)));
        }
    }

  assert ((int) fixP->fx_r_type > 0);
  reloc->howto = bfd_reloc_type_lookup (stdoutput, fixP->fx_r_type);

  if (reloc->howto == (reloc_howto_type *) NULL)
    {
      as_bad_where (fixP->fx_file, fixP->fx_line,
                    _("internal error: reloc %d (`%s') not supported by object file format"),
                    fixP->fx_r_type,
                    bfd_get_reloc_code_name (fixP->fx_r_type));
      return NULL;
    }
  assert (!fixP->fx_pcrel == !reloc->howto->pc_relative);

  return reloc;
}

/* Prepare machine-dependent frags for relaxation.  */

int
md_estimate_size_before_relax (fragS *fragp, asection *seg)
{
  /* If symbol is undefined or located in a different section,
     select the largest supported relocation.  */
  relax_substateT subtype;
  relax_substateT rlx_state[] = {0, 2,
                                 3, 4,
                                 5, 6};

  for (subtype = 0; subtype < ARRAY_SIZE (rlx_state); subtype += 2)
    {
      if (fragp->fr_subtype == rlx_state[subtype]
          && (!S_IS_DEFINED (fragp->fr_symbol)
              || seg != S_GET_SEGMENT (fragp->fr_symbol)))
        {
          fragp->fr_subtype = rlx_state[subtype + 1];
          break;
        }
    }

  if (fragp->fr_subtype >= ARRAY_SIZE (md_relax_table))
    abort ();

  return md_relax_table[fragp->fr_subtype].rlx_length;
}

void
md_convert_frag (bfd *abfd ATTRIBUTE_UNUSED, asection *sec, fragS *fragP)
{
  /* 'opcode' points to the start of the instruction, whether
     we need to change the instruction's fixed encoding.  */
  char *opcode = fragP->fr_literal + fragP->fr_fix;
  bfd_reloc_code_real_type reloc;

  subseg_change (sec, 0);

  switch (fragP->fr_subtype)
    {
    case 0:
      reloc = BFD_RELOC_CRX_REL8;
      break;
    case 1:
      *opcode = 0x7e;
      reloc = BFD_RELOC_CRX_REL16;
      break;
    case 2:
      *opcode = 0x7f;
      reloc = BFD_RELOC_CRX_REL32;
      break;
    case 3:
      reloc = BFD_RELOC_CRX_REL16;
      break;
    case 4:
      *++opcode = 0x31;
      reloc = BFD_RELOC_CRX_REL32;
      break;
    case 5:
      reloc = BFD_RELOC_CRX_REL8_CMP;
      break;
    case 6:
      *++opcode = 0x31;
      reloc = BFD_RELOC_CRX_REL24;
      break;
    default:
      abort ();
      break;
    }

    fix_new (fragP, fragP->fr_fix,
             bfd_get_reloc_size (bfd_reloc_type_lookup (stdoutput, reloc)),
             fragP->fr_symbol, fragP->fr_offset, 1, reloc);
    fragP->fr_var = 0;
    fragP->fr_fix += md_relax_table[fragP->fr_subtype].rlx_length;
}

/* Process machine-dependent command line options.  Called once for
   each option on the command line that the machine-independent part of
   GAS does not understand.  */

int
md_parse_option (int c ATTRIBUTE_UNUSED, char *arg ATTRIBUTE_UNUSED)
{
  return 0;
}

/* Machine-dependent usage-output.  */

void
md_show_usage (FILE *stream ATTRIBUTE_UNUSED)
{
  return;
}

/* Turn a string in input_line_pointer into a floating point constant
   of type TYPE, and store the appropriate bytes in *LITP.  The number
   of LITTLENUMS emitted is stored in *SIZEP.  An error message is
   returned, or NULL on OK.  */

char *
md_atof (int type, char *litP, int *sizeP)
{
  int prec;
  LITTLENUM_TYPE words[4];
  char *t;
  int i;

  switch (type)
    {
    case 'f':
      prec = 2;
      break;

    case 'd':
      prec = 4;
      break;

    default:
      *sizeP = 0;
      return _("bad call to md_atof");
    }

  t = atof_ieee (input_line_pointer, type, words);
  if (t)
    input_line_pointer = t;

  *sizeP = prec * 2;

  if (! target_big_endian)
    {
      for (i = prec - 1; i >= 0; i--)
        {
          md_number_to_chars (litP, (valueT) words[i], 2);
          litP += 2;
        }
    }
  else
    {
      for (i = 0; i < prec; i++)
        {
          md_number_to_chars (litP, (valueT) words[i], 2);
          litP += 2;
        }
    }

  return NULL;
}

/* Apply a fixS (fixup of an instruction or data that we didn't have
   enough info to complete immediately) to the data in a frag.
   Since linkrelax is nonzero and TC_LINKRELAX_FIXUP is defined to disable
   relaxation of debug sections, this function is called only when
   fixuping relocations of debug sections.  */

void
md_apply_fix3 (fixS *fixP, valueT *valP, segT seg)
{
  valueT val = * valP;
  char *buf = fixP->fx_frag->fr_literal + fixP->fx_where;
  fixP->fx_offset = 0;

  switch (fixP->fx_r_type)
    {
    case BFD_RELOC_CRX_NUM8:
      bfd_put_8 (stdoutput, (unsigned char) val, buf);
      break;
    case BFD_RELOC_CRX_NUM16:
      bfd_put_16 (stdoutput, val, buf);
      break;
    case BFD_RELOC_CRX_NUM32:
      bfd_put_32 (stdoutput, val, buf);
      break;
    default:
      /* We shouldn't ever get here because linkrelax is nonzero.  */
      abort ();
      break;
    }

  fixP->fx_done = 0;

  if (fixP->fx_addsy == NULL
      && fixP->fx_pcrel == 0)
    fixP->fx_done = 1;

  if (fixP->fx_pcrel == 1
      && fixP->fx_addsy != NULL
      && S_GET_SEGMENT (fixP->fx_addsy) == seg)
    fixP->fx_done = 1;
}

/* The location from which a PC relative jump should be calculated,
   given a PC relative reloc.  */

long
md_pcrel_from (fixS *fixp)
{
  return fixp->fx_frag->fr_address + fixp->fx_where;
}

/* This function is called once, at assembler startup time.  This should
   set up all the tables, etc that the MD part of the assembler needs.  */

void
md_begin (void)
{
  const char *hashret = NULL;
  int i = 0;

  /* Set up a hash table for the instructions.  */
  if ((crx_inst_hash = hash_new ()) == NULL)
    as_fatal (_("Virtual memory exhausted"));
  
  while (crx_instruction[i].mnemonic != NULL)
    {
      const char *mnemonic = crx_instruction[i].mnemonic;

      hashret = hash_insert (crx_inst_hash, mnemonic,
        (PTR) &crx_instruction[i]);

      if (hashret != NULL && *hashret != '\0')
        as_fatal (_("Can't hash `%s': %s\n"), crx_instruction[i].mnemonic,
                  *hashret == 0 ? _("(unknown reason)") : hashret);

      /* Insert unique names into hash table.  The CRX instruction set
         has many identical opcode names that have different opcodes based
         on the operands.  This hash table then provides a quick index to
         the first opcode with a particular name in the opcode table.  */
      do
        {
          ++i;
        }
      while (crx_instruction[i].mnemonic != NULL
             && streq (crx_instruction[i].mnemonic, mnemonic));
    }

  /* Initialize reg_hash hash table.  */
  if ((reg_hash = hash_new ()) == NULL)
    as_fatal (_("Virtual memory exhausted"));

  {
    const reg_entry *regtab;

    for (regtab = crx_regtab;
         regtab < (crx_regtab + NUMREGS); regtab++)
      {
        hashret = hash_insert (reg_hash, regtab->name, (PTR) regtab);
        if (hashret)
          as_fatal (_("Internal Error:  Can't hash %s: %s"),
                    regtab->name,
                    hashret);
      }
  }

  /* Initialize copreg_hash hash table.  */
  if ((copreg_hash = hash_new ()) == NULL)
    as_fatal (_("Virtual memory exhausted"));

  {
    const reg_entry *copregtab;

    for (copregtab = crx_copregtab; copregtab < (crx_copregtab + NUMCOPREGS);
         copregtab++)
      {
        hashret = hash_insert (copreg_hash, copregtab->name, (PTR) copregtab);
        if (hashret)
          as_fatal (_("Internal Error:  Can't hash %s: %s"),
                    copregtab->name,
                    hashret);
      }
  }
  /*  Set linkrelax here to avoid fixups in most sections.  */
  linkrelax = 1;
}

/* Process constants (immediate/absolute) 
   and labels (jump targets/Memory locations).  */

static void
process_label_constant (char *str, ins * crx_ins)
{
  char *saved_input_line_pointer;
  argument *cur_arg = &crx_ins->arg[cur_arg_num];  /* Current argument.  */

  saved_input_line_pointer = input_line_pointer;
  input_line_pointer = str;

  expression (&crx_ins->exp);
  
  switch (crx_ins->exp.X_op)
    {
    case O_big:
    case O_absent:
      /* Missing or bad expr becomes absolute 0.  */
      as_bad (_("missing or invalid displacement expression `%s' taken as 0"),
              str);
      crx_ins->exp.X_op = O_constant;
      crx_ins->exp.X_add_number = 0;
      crx_ins->exp.X_add_symbol = (symbolS *) 0;
      crx_ins->exp.X_op_symbol = (symbolS *) 0;
      /* Fall through.  */

    case O_constant:
      cur_arg->X_op = O_constant;
      cur_arg->constant = crx_ins->exp.X_add_number;
      break;

    case O_symbol:
    case O_subtract:
    case O_add:
      cur_arg->X_op = O_symbol;
      crx_ins->rtype = BFD_RELOC_NONE;
      relocatable = 1;

      switch (cur_arg->type)
        {
        case arg_cr:
          if (IS_INSN_TYPE (LD_STOR_INS_INC))
            crx_ins->rtype = BFD_RELOC_CRX_REGREL12;
          else if (IS_INSN_TYPE (CSTBIT_INS)
                   || IS_INSN_TYPE (STOR_IMM_INS))
            crx_ins->rtype = BFD_RELOC_CRX_REGREL28;
          else
            crx_ins->rtype = BFD_RELOC_CRX_REGREL32;
          break;

        case arg_idxr:
            crx_ins->rtype = BFD_RELOC_CRX_REGREL22;
          break;
        
        case arg_c:
          if (IS_INSN_MNEMONIC ("bal") || IS_INSN_TYPE (DCR_BRANCH_INS))
            crx_ins->rtype = BFD_RELOC_CRX_REL16;
          else if (IS_INSN_TYPE (BRANCH_INS))
            crx_ins->rtype = BFD_RELOC_CRX_REL8;
          else if (IS_INSN_TYPE (LD_STOR_INS) || IS_INSN_TYPE (STOR_IMM_INS)
                   || IS_INSN_TYPE (CSTBIT_INS))
            crx_ins->rtype = BFD_RELOC_CRX_ABS32;
          else if (IS_INSN_TYPE (BRANCH_NEQ_INS))
            crx_ins->rtype = BFD_RELOC_CRX_REL4;
          else if (IS_INSN_TYPE (CMPBR_INS))
            crx_ins->rtype = BFD_RELOC_CRX_REL8_CMP;
          else if (IS_INSN_TYPE (COP_BRANCH_INS))
            crx_ins->rtype = BFD_RELOC_CRX_REL24;
          break;
        
        case arg_ic:
          if (IS_INSN_TYPE (ARITH_INS))
            crx_ins->rtype = BFD_RELOC_CRX_IMM32;
          else if (IS_INSN_TYPE (ARITH_BYTE_INS))
            crx_ins->rtype = BFD_RELOC_CRX_IMM16;
          break;
        default:
          break;
      }
      break;

    default:
      cur_arg->X_op = crx_ins->exp.X_op;
      break;
    }

  input_line_pointer = saved_input_line_pointer;
  return;
}

/* Get the values of the scale to be encoded -
   used for the scaled index mode of addressing.  */

static int
exponent2scale (int val)
{
  int exponent;

  /* If 'val' is 0, the following 'for' will be an endless loop.  */
  if (val == 0)
    return 0;

  for (exponent = 0; (val != 1); val >>= 1, exponent++)
    ;

  return exponent;
}

/* Parsing different types of operands
   -> constants             Immediate/Absolute/Relative numbers
   -> Labels                Relocatable symbols
   -> (rbase)               Register base
   -> disp(rbase)           Register relative
   -> disp(rbase)+          Post-increment mode
   -> disp(rbase,ridx,scl)  Register index mode  */

static void
set_operand (char *operand, ins * crx_ins)
{
  char *operandS; /* Pointer to start of sub-opearand.  */
  char *operandE; /* Pointer to end of sub-opearand.  */
  expressionS scale;
  int scale_val;
  char *input_save, c;
  argument *cur_arg = &crx_ins->arg[cur_arg_num]; /* Current argument.  */

  /* Initialize pointers.  */
  operandS = operandE = operand;

  switch (cur_arg->type)
    {
    case arg_sc:    /* Case *+0x18.  */
    case arg_ic:    /* Case $0x18.  */
      operandS++;
    case arg_c:     /* Case 0x18.  */
      /* Set constant.  */
      process_label_constant (operandS, crx_ins);
      
      if (cur_arg->type != arg_ic)
        cur_arg->type = arg_c;
      break;

    case arg_icr:   /* Case $0x18(r1).  */
      operandS++;
    case arg_cr:    /* Case 0x18(r1).   */
      /* Set displacement constant.  */
      while (*operandE != '(')
        operandE++;
      *operandE = '\0';
      process_label_constant (operandS, crx_ins);
      operandS = operandE;    
    case arg_rbase: /* Case (r1).  */
      operandS++;
      /* Set register base.  */
      while (*operandE != ')')
        operandE++;
      *operandE = '\0';
      if ((cur_arg->r = get_register (operandS)) == nullregister)
        as_bad (_("Illegal register `%s' in Instruction `%s'"),
                operandS, ins_parse);

      if (cur_arg->type != arg_rbase)
        cur_arg->type = arg_cr;
      break;

    case arg_idxr:
      /* Set displacement constant.  */
      while (*operandE != '(')
        operandE++;
      *operandE = '\0';
      process_label_constant (operandS, crx_ins);
      operandS = ++operandE;
      
      /* Set register base.  */
      while ((*operandE != ',') && (! ISSPACE (*operandE)))
        operandE++;
      *operandE++ = '\0';
      if ((cur_arg->r = get_register (operandS)) == nullregister)
        as_bad (_("Illegal register `%s' in Instruction `%s'"),
                operandS, ins_parse);

      /* Skip leading white space.  */
      while (ISSPACE (*operandE))
        operandE++;
      operandS = operandE;

      /* Set register index.  */
      while ((*operandE != ')') && (*operandE != ','))
        operandE++;
      c = *operandE;
      *operandE++ = '\0';

      if ((cur_arg->i_r = get_register (operandS)) == nullregister)
        as_bad (_("Illegal register `%s' in Instruction `%s'"),
                operandS, ins_parse);

      /* Skip leading white space.  */
      while (ISSPACE (*operandE))
        operandE++;
      operandS = operandE;

      /* Set the scale.  */
      if (c == ')')
        cur_arg->scale = 0;
      else
        {
          while (*operandE != ')')
            operandE++;
          *operandE = '\0';

          /* Preprocess the scale string.  */
          input_save = input_line_pointer;
          input_line_pointer = operandS;
          expression (&scale);
          input_line_pointer = input_save;

          scale_val = scale.X_add_number;

          /* Check if the scale value is legal.  */
          if (scale_val != 1 && scale_val != 2
              && scale_val != 4 && scale_val != 8)
            as_bad (_("Illegal Scale - `%d'"), scale_val);

          cur_arg->scale = exponent2scale (scale_val);
        }
      break;

    default:
      break;
    }
}

/* Parse a single operand.
   operand - Current operand to parse.
   crx_ins - Current assembled instruction.  */

static void
parse_operand (char *operand, ins * crx_ins)
{
  int ret_val;
  argument *cur_arg = &crx_ins->arg[cur_arg_num]; /* Current argument.  */

  /* Initialize the type to NULL before parsing.  */
  cur_arg->type = nullargs;

  /* Check whether this is a general processor register.  */
  if ((ret_val = get_register (operand)) != nullregister)
    {
      cur_arg->type = arg_r;
      cur_arg->r = ret_val;
      cur_arg->X_op = O_register;
      return;
    }

  /* Check whether this is a core [special] coprocessor register.  */
  if ((ret_val = get_copregister (operand)) != nullcopregister)
    {
      cur_arg->type = arg_copr;
      if (ret_val >= cs0)
        cur_arg->type = arg_copsr;
      cur_arg->cr = ret_val;
      cur_arg->X_op = O_register;
      return;
    }

  /* Deal with special characters.  */
  switch (operand[0])
    {
    case '$':
      if (strchr (operand, '(') != NULL)
        cur_arg->type = arg_icr;
      else
        cur_arg->type = arg_ic;
      goto set_params;
      break;

    case '*':
      cur_arg->type = arg_sc;
      goto set_params;
      break;

    case '(':
      cur_arg->type = arg_rbase;
      goto set_params;
      break;

    default:
        break;
    }
      
  if (strchr (operand, '(') != NULL)
    {
      if (strchr (operand, ',') != NULL
          && (strchr (operand, ',') > strchr (operand, '(')))
            cur_arg->type = arg_idxr;
      else
        cur_arg->type = arg_cr;
    }
  else
    cur_arg->type = arg_c;
  goto set_params;

/* Parse an operand according to its type.  */
set_params:
  cur_arg->constant = 0;
  set_operand (operand, crx_ins);
}

/* Parse the various operands. Each operand is then analyzed to fillup 
   the fields in the crx_ins data structure.  */

static void
parse_operands (ins * crx_ins, char *operands)
{
  char *operandS;              /* Operands string.  */
  char *operandH, *operandT;   /* Single operand head/tail pointers.  */
  int allocated = 0;           /* Indicates a new operands string was allocated.  */
  char *operand[MAX_OPERANDS]; /* Separating the operands.  */
  int op_num = 0;              /* Current operand number we are parsing.  */
  int bracket_flag = 0;        /* Indicates a bracket '(' was found.  */
  int sq_bracket_flag = 0;     /* Indicates a square bracket '[' was found.  */

  /* Preprocess the list of registers, if necessary.  */
  operandS = operandH = operandT = (INST_HAS_REG_LIST) ?
    preprocess_reglist (operands, &allocated) : operands;

  while (*operandT != '\0')
    {
      if (*operandT == ',' && bracket_flag != 1 && sq_bracket_flag != 1)
        {
          *operandT++ = '\0';
          operand[op_num++] = strdup (operandH);
          operandH = operandT;
          continue;
        }

      if (*operandT == ' ')
        as_bad (_("Illegal operands (whitespace): `%s'"), ins_parse);

      if (*operandT == '(')
        bracket_flag = 1;
      else if (*operandT == '[')
        sq_bracket_flag = 1;

      if (*operandT == ')')
        {
          if (bracket_flag)
            bracket_flag = 0;
          else
            as_fatal (_("Missing matching brackets : `%s'"), ins_parse);
        }
      else if (*operandT == ']')
        {
          if (sq_bracket_flag)
            sq_bracket_flag = 0;
          else
            as_fatal (_("Missing matching brackets : `%s'"), ins_parse);
        }

      if (bracket_flag == 1 && *operandT == ')')
        bracket_flag = 0;
      else if (sq_bracket_flag == 1 && *operandT == ']')
        sq_bracket_flag = 0;

      operandT++;
    }

  /* Adding the last operand.  */
  operand[op_num++] = strdup (operandH);
  crx_ins->nargs = op_num;

  /* Verifying correct syntax of operands (all brackets should be closed).  */
  if (bracket_flag || sq_bracket_flag)
    as_fatal (_("Missing matching brackets : `%s'"), ins_parse);

  /* Now we parse each operand separately.  */
  for (op_num = 0; op_num < crx_ins->nargs; op_num++)
    {
      cur_arg_num = op_num;
      parse_operand (operand[op_num], crx_ins);
      free (operand[op_num]);
    }

  if (allocated)
    free (operandS);
}

/* Get the trap index in dispatch table, given its name.
   This routine is used by assembling the 'excp' instruction.  */

static int
gettrap (char *s)
{
  const trap_entry *trap;

  for (trap = crx_traps; trap < (crx_traps + NUMTRAPS); trap++)
    if (strcasecmp (trap->name, s) == 0)
      return trap->entry;

  as_bad (_("Unknown exception: `%s'"), s);
  return 0;
}

/* Post-Increment instructions, as well as Store-Immediate instructions, are a 
   sub-group within load/stor instruction groups. 
   Therefore, when parsing a Post-Increment/Store-Immediate insn, we have to 
   advance the instruction pointer to the start of that sub-group (that is, up 
   to the first instruction of that type).
   Otherwise, the insn will be mistakenly identified as of type LD_STOR_INS.  */

static void
handle_LoadStor (char *operands)
{
  /* Post-Increment instructions precede Store-Immediate instructions in 
     CRX instruction table, hence they are handled before. 
     This synchronization should be kept.  */

  /* Assuming Post-Increment insn has the following format :
     'MNEMONIC DISP(REG)+, REG' (e.g. 'loadw 12(r5)+, r6').
     LD_STOR_INS_INC are the only store insns containing a plus sign (+).  */
  if (strstr (operands, ")+") != NULL)
    {
      while (! IS_INSN_TYPE (LD_STOR_INS_INC))
        instruction++;
      return;
    }

  /* Assuming Store-Immediate insn has the following format :
     'MNEMONIC $DISP, ...' (e.g. 'storb $1, 12(r5)').
     STOR_IMM_INS are the only store insns containing a dollar sign ($).  */
  if (strstr (operands, "$") != NULL)
    while (! IS_INSN_TYPE (STOR_IMM_INS))
      instruction++;
}

/* Top level module where instruction parsing starts.
   crx_ins - data structure holds some information.
   operands - holds the operands part of the whole instruction.  */

static void
parse_insn (ins *insn, char *operands)
{
  int i;

  /* Handle instructions with no operands.  */
  for (i = 0; no_op_insn[i] != NULL; i++)
  {
    if (streq (no_op_insn[i], instruction->mnemonic))
    {
      insn->nargs = 0;
      return;
    }
  }

  /* Handle 'excp'/'cinv' instructions.  */
  if (IS_INSN_MNEMONIC ("excp") || IS_INSN_MNEMONIC ("cinv"))
    {
      insn->nargs = 1;
      insn->arg[0].type = arg_ic;
      insn->arg[0].constant = IS_INSN_MNEMONIC ("excp") ?
        gettrap (operands) : get_cinv_parameters (operands);
      insn->arg[0].X_op = O_constant;
      return;
    }

  /* Handle load/stor unique instructions before parsing.  */
  if (IS_INSN_TYPE (LD_STOR_INS))
    handle_LoadStor (operands);

  if (operands != NULL)
    parse_operands (insn, operands);
}

/* Cinv instruction requires special handling.  */

static int
get_cinv_parameters (char * operand)
{
  char *p = operand;
  int d_used = 0, i_used = 0, u_used = 0, b_used = 0;

  while (*++p != ']')
    {
      if (*p == ',' || *p == ' ')
        continue;

      if (*p == 'd')
        d_used = 1;
      else if (*p == 'i')
        i_used = 1;
      else if (*p == 'u')
        u_used = 1;
      else if (*p == 'b')
        b_used = 1;
      else
        as_bad (_("Illegal `cinv' parameter: `%c'"), *p);
    }

  return ((b_used ? 8 : 0)
        + (d_used ? 4 : 0)
        + (i_used ? 2 : 0)
        + (u_used ? 1 : 0));
}

/* Retrieve the opcode image of a given register.
   If the register is illegal for the current instruction,
   issue an error.  */

static int
getreg_image (reg r)
{
  const reg_entry *reg;
  char *reg_name;
  int is_procreg = 0; /* Nonzero means argument should be processor reg.  */

  if (((IS_INSN_MNEMONIC ("mtpr")) && (cur_arg_num == 1))
      || ((IS_INSN_MNEMONIC ("mfpr")) && (cur_arg_num == 0)) )
    is_procreg = 1;

  /* Check whether the register is in registers table.  */
  if (r < MAX_REG)
    reg = &crx_regtab[r];
  /* Check whether the register is in coprocessor registers table.  */
  else if (r < MAX_COPREG)
    reg = &crx_copregtab[r-MAX_REG];
  /* Register not found.  */
  else
    {
      as_bad (_("Unknown register: `%d'"), r);
      return 0;
    }

  reg_name = reg->name;

/* Issue a error message when register is illegal.  */
#define IMAGE_ERR \
  as_bad (_("Illegal register (`%s') in Instruction: `%s'"), \
            reg_name, ins_parse);                            \
  break;

  switch (reg->type)
  {
    case CRX_U_REGTYPE:
      if (is_procreg || (instruction->flags & USER_REG))
        return reg->image;
      else
        IMAGE_ERR;

    case CRX_CFG_REGTYPE:
      if (is_procreg)
        return reg->image;
      else
        IMAGE_ERR;

    case CRX_R_REGTYPE:
      if (! is_procreg)
        return reg->image;
      else
        IMAGE_ERR;

    case CRX_C_REGTYPE:
    case CRX_CS_REGTYPE:
      return reg->image;
      break;

    default:
      IMAGE_ERR;
  }

  return 0;
}

/* Routine used to represent integer X using NBITS bits.  */

static long
getconstant (long x, int nbits)
{
  /* The following expression avoids overflow if
     'nbits' is the number of bits in 'bfd_vma'.  */
  return (x & ((((1 << (nbits - 1)) - 1) << 1) | 1));
}

/* Print a constant value to 'output_opcode':
   ARG holds the operand's type and value.
   SHIFT represents the location of the operand to be print into.
   NBITS determines the size (in bits) of the constant.  */

static void
print_constant (int nbits, int shift, argument *arg)
{
  unsigned long mask = 0;

  long constant = getconstant (arg->constant, nbits);

  switch (nbits)
  {
    case 32:
    case 28:
    case 24:
    case 22:
      /* mask the upper part of the constant, that is, the bits
         going to the lowest byte of output_opcode[0].
         The upper part of output_opcode[1] is always filled,
         therefore it is always masked with 0xFFFF.  */
      mask = (1 << (nbits - 16)) - 1;
      /* Divide the constant between two consecutive words :
                 0         1         2         3
            +---------+---------+---------+---------+
            |         | X X X X | X X X X |         |
            +---------+---------+---------+---------+
              output_opcode[0]    output_opcode[1]     */

      CRX_PRINT (0, (constant >> WORD_SHIFT) & mask, 0);
      CRX_PRINT (1, (constant & 0xFFFF), WORD_SHIFT);
      break;

    case 16:
    case 12:
      /* Special case - in arg_cr, the SHIFT represents the location
         of the REGISTER, not the constant, which is itself not shifted.  */
      if (arg->type == arg_cr)
        {
          CRX_PRINT (0, constant,  0);
          break;
        }

      /* When instruction size is 3 and 'shift' is 16, a 16-bit constant is 
         always filling the upper part of output_opcode[1]. If we mistakenly 
         write it to output_opcode[0], the constant prefix (that is, 'match')
         will be overriden.
                 0         1         2         3
            +---------+---------+---------+---------+
            | 'match' |         | X X X X |         |
            +---------+---------+---------+---------+
              output_opcode[0]    output_opcode[1]     */

      if ((instruction->size > 2) && (shift == WORD_SHIFT))
        CRX_PRINT (1, constant, WORD_SHIFT);
      else
        CRX_PRINT (0, constant, shift);
      break;

    default:
      CRX_PRINT (0, constant,  shift);
      break;
  }
}

/* Print an operand to 'output_opcode', which later on will be
   printed to the object file:
   ARG holds the operand's type, size and value.
   SHIFT represents the printing location of operand.
   NBITS determines the size (in bits) of a constant operand.  */

static void
print_operand (int nbits, int shift, argument *arg)
{
  switch (arg->type)
    {
    case arg_r:
      CRX_PRINT (0, getreg_image (arg->r), shift);
      break;

    case arg_copr:
      if (arg->cr < c0 || arg->cr > c15)
        as_bad (_("Illegal Co-processor register in Instruction `%s' "),
                ins_parse);
      CRX_PRINT (0, getreg_image (arg->cr), shift);
      break;

    case arg_copsr:
      if (arg->cr < cs0 || arg->cr > cs15)
        as_bad (_("Illegal Co-processor special register in Instruction `%s' "),
                ins_parse);
      CRX_PRINT (0, getreg_image (arg->cr), shift);
      break;

    case arg_idxr:
      /*    16      12        8    6         0
            +--------------------------------+
            | r_base | r_idx  | scl|  disp   |
            +--------------------------------+    */
      CRX_PRINT (0, getreg_image (arg->r), 12);
      CRX_PRINT (0, getreg_image (arg->i_r), 8);
      CRX_PRINT (0, arg->scale, 6);
    case arg_ic:
    case arg_c:
      print_constant (nbits, shift, arg);
      break;

    case arg_rbase:
      CRX_PRINT (0, getreg_image (arg->r), shift);
      break;

    case arg_cr:
      /* case base_cst4.  */
      if (instruction->flags & DISPU4MAP)
        print_constant (nbits, shift + REG_SIZE, arg);
      else
        /* rbase_disps<NN> and other such cases.  */
        print_constant (nbits, shift, arg);
      /* Add the register argument to the output_opcode.  */
      CRX_PRINT (0, getreg_image (arg->r), shift);
      break;

    default:
      break;
    }
}

/* Retrieve the number of operands for the current assembled instruction.  */

static int
get_number_of_operands (void)
{
  int i;

  for (i = 0; instruction->operands[i].op_type && i < MAX_OPERANDS; i++)
    ;
  return i;
}

/* Verify that the number NUM can be represented in BITS bits (that is, 
   within its permitted range), based on the instruction's FLAGS.  
   If UPDATE is nonzero, update the value of NUM if necessary.
   Return OP_LEGAL upon success, actual error type upon failure.  */

static op_err
check_range (long *num, int bits, int unsigned flags, int update)
{
  long min, max;
  int retval = OP_LEGAL;
  int bin;
  long upper_64kb = 0xFFFF0000;
  long value = *num;

  /* Verify operand value is even.  */
  if (flags & OP_EVEN)
    {
      if (value % 2)
        return OP_NOT_EVEN;
    }

  if (flags & OP_UPPER_64KB)
    {
      /* Check if value is to be mapped to upper 64 KB memory area.  */
      if ((value & upper_64kb) == upper_64kb)
        {
          value -= upper_64kb;
          if (update)
            *num = value;
        }
      else
        return OP_NOT_UPPER_64KB;
    }

  if (flags & OP_SHIFT)
    {
      value >>= 1;
      if (update)
        *num = value;
    }
  else if (flags & OP_SHIFT_DEC)
    {
      value = (value >> 1) - 1;
      if (update)
        *num = value;
    }

  if (flags & OP_ESC)
    {
      /* 0x7e and 0x7f are reserved escape sequences of dispe9.  */
      if (value == 0x7e || value == 0x7f)
        return OP_OUT_OF_RANGE;
    }

  if (flags & OP_DISPU4)
    {
      int is_dispu4 = 0;

      int mul = (instruction->flags & DISPUB4) ? 1 
                : (instruction->flags & DISPUW4) ? 2
                : (instruction->flags & DISPUD4) ? 4 : 0;
      
      for (bin = 0; bin < cst4_maps; bin++)
        {
          if (value == (mul * bin))
            {
              is_dispu4 = 1;
              if (update)
                *num = bin;
              break;
            }
        }
      if (!is_dispu4)
        retval = OP_ILLEGAL_DISPU4;
    }
  else if (flags & OP_CST4)
    {
      int is_cst4 = 0;

      for (bin = 0; bin < cst4_maps; bin++)
        {
          if (value == cst4_map[bin])
            {
              is_cst4 = 1;
              if (update)
                *num = bin;
              break;
            }
        }
      if (!is_cst4)
        retval = OP_ILLEGAL_CST4;
    }
  else if (flags & OP_SIGNED)
    {
      max = (1 << (bits - 1)) - 1;
      min = - (1 << (bits - 1));
      if ((value > max) || (value < min))
        retval = OP_OUT_OF_RANGE;
    }
  else if (flags & OP_UNSIGNED)
    {
      max = ((((1 << (bits - 1)) - 1) << 1) | 1);
      min = 0;
      if (((unsigned long) value > (unsigned long) max) 
            || ((unsigned long) value < (unsigned long) min))
        retval = OP_OUT_OF_RANGE;
    }
  return retval;
}

/* Assemble a single instruction:
   INSN is already parsed (that is, all operand values and types are set).
   For instruction to be assembled, we need to find an appropriate template in 
   the instruction table, meeting the following conditions:
    1: Has the same number of operands.
    2: Has the same operand types.
    3: Each operand size is sufficient to represent the instruction's values.
   Returns 1 upon success, 0 upon failure.  */

static int
assemble_insn (char *mnemonic, ins *insn)
{
  /* Type of each operand in the current template.  */
  argtype cur_type[MAX_OPERANDS];
  /* Size (in bits) of each operand in the current template.  */
  unsigned int cur_size[MAX_OPERANDS];
  /* Flags of each operand in the current template.  */
  unsigned int cur_flags[MAX_OPERANDS];
  /* Instruction type to match.  */
  unsigned int ins_type;
  /* Boolean flag to mark whether a match was found.  */
  int match = 0;
  int i;
  /* Nonzero if an instruction with same number of operands was found.  */
  int found_same_number_of_operands = 0;
  /* Nonzero if an instruction with same argument types was found.  */
  int found_same_argument_types = 0;
  /* Nonzero if a constant was found within the required range.  */
  int found_const_within_range  = 0;
  /* Argument number of an operand with invalid type.  */
  int invalid_optype = -1;
  /* Argument number of an operand with invalid constant value.  */
  int invalid_const  = -1;
  /* Operand error (used for issuing various constant error messages).  */
  op_err op_error, const_err = OP_LEGAL;

/* Retrieve data (based on FUNC) for each operand of a given instruction.  */
#define GET_CURRENT_DATA(FUNC, ARRAY)                             \
  for (i = 0; i < insn->nargs; i++)                               \
    ARRAY[i] = FUNC (instruction->operands[i].op_type)

#define GET_CURRENT_TYPE    GET_CURRENT_DATA(get_optype, cur_type)
#define GET_CURRENT_SIZE    GET_CURRENT_DATA(get_opbits, cur_size)
#define GET_CURRENT_FLAGS   GET_CURRENT_DATA(get_opflags, cur_flags)

  /* Instruction has no operands -> only copy the constant opcode.   */
  if (insn->nargs == 0)
    {
      output_opcode[0] = BIN (instruction->match, instruction->match_bits);
      return 1;
    }

  /* In some case, same mnemonic can appear with different instruction types.
     For example, 'storb' is supported with 3 different types :
     LD_STOR_INS, LD_STOR_INS_INC, STOR_IMM_INS.
     We assume that when reaching this point, the instruction type was 
     pre-determined. We need to make sure that the type stays the same
     during a search for matching instruction.  */
  ins_type = CRX_INS_TYPE(instruction->flags);

  while (/* Check that match is still not found.  */
         match != 1
         /* Check we didn't get to end of table.  */
         && instruction->mnemonic != NULL
         /* Check that the actual mnemonic is still available.  */
         && IS_INSN_MNEMONIC (mnemonic)
         /* Check that the instruction type wasn't changed.  */
         && IS_INSN_TYPE(ins_type))
    {
      /* Check whether number of arguments is legal.  */
      if (get_number_of_operands () != insn->nargs)
        goto next_insn;
      found_same_number_of_operands = 1;

      /* Initialize arrays with data of each operand in current template.  */
      GET_CURRENT_TYPE;
      GET_CURRENT_SIZE;
      GET_CURRENT_FLAGS;

      /* Check for type compatibility.  */
      for (i = 0; i < insn->nargs; i++)
        {
          if (cur_type[i] != insn->arg[i].type)
            {
              if (invalid_optype == -1)
                invalid_optype = i + 1;
              goto next_insn;
            }
        }
      found_same_argument_types = 1;

      for (i = 0; i < insn->nargs; i++)
        {
          /* Reverse the operand indices for certain opcodes:
             Index 0      -->> 1
             Index 1      -->> 0        
             Other index  -->> stays the same.  */
          int j = instruction->flags & REVERSE_MATCH ? 
                  i == 0 ? 1 : 
                  i == 1 ? 0 : i : 
                  i;

          /* Only check range - don't update the constant's value, since the 
             current instruction may not be the last we try to match.  
             The constant's value will be updated later, right before printing 
             it to the object file.  */
          if ((insn->arg[j].X_op == O_constant) 
               && (op_error = check_range (&insn->arg[j].constant, cur_size[j], 
                                           cur_flags[j], 0)))
            {
              if (invalid_const == -1)
              {
                invalid_const = j + 1;
                const_err = op_error;
              }
              goto next_insn;
            }
          /* For symbols, we make sure the relocation size (which was already 
             determined) is sufficient.  */
          else if ((insn->arg[j].X_op == O_symbol)
                    && ((bfd_reloc_type_lookup (stdoutput, insn->rtype))->bitsize 
                         > cur_size[j]))
                  goto next_insn;
        }
      found_const_within_range = 1;

      /* If we got till here -> Full match is found.  */
      match = 1;
      break;

/* Try again with next instruction.  */
next_insn:
      instruction++;
    }

  if (!match)
    {
      /* We haven't found a match - instruction can't be assembled.  */
      if (!found_same_number_of_operands)
        as_bad (_("Incorrect number of operands"));
      else if (!found_same_argument_types)
        as_bad (_("Illegal type of operand (arg %d)"), invalid_optype);
      else if (!found_const_within_range)
      {
        switch (const_err)
        {
        case OP_OUT_OF_RANGE:
          as_bad (_("Operand out of range (arg %d)"), invalid_const);
          break;
        case OP_NOT_EVEN:
          as_bad (_("Operand has odd displacement (arg %d)"), invalid_const);
          break;
        case OP_ILLEGAL_DISPU4:
          as_bad (_("Invalid DISPU4 operand value (arg %d)"), invalid_const);
          break;
        case OP_ILLEGAL_CST4:
          as_bad (_("Invalid CST4 operand value (arg %d)"), invalid_const);
          break;
        case OP_NOT_UPPER_64KB:
          as_bad (_("Operand value is not within upper 64 KB (arg %d)"), 
                    invalid_const);
          break;
        default:
          as_bad (_("Illegal operand (arg %d)"), invalid_const);
          break;
        }
      }
      
      return 0;
    }
  else
    /* Full match - print the encoding to output file.  */
    {
      /* Make further checkings (such that couldn't be made earlier).
         Warn the user if necessary.  */
      warn_if_needed (insn);
      
      /* Check whether we need to adjust the instruction pointer.  */
      if (adjust_if_needed (insn))
        /* If instruction pointer was adjusted, we need to update 
           the size of the current template operands.  */
        GET_CURRENT_SIZE;

      for (i = 0; i < insn->nargs; i++)
        {
          int j = instruction->flags & REVERSE_MATCH ? 
                  i == 0 ? 1 : 
                  i == 1 ? 0 : i : 
                  i;

          /* This time, update constant value before printing it.  */
          if ((insn->arg[j].X_op == O_constant) 
               && (check_range (&insn->arg[j].constant, cur_size[j], 
                                cur_flags[j], 1) != OP_LEGAL))
              as_fatal (_("Illegal operand (arg %d)"), j+1);
        }

      /* First, copy the instruction's opcode.  */
      output_opcode[0] = BIN (instruction->match, instruction->match_bits);

      for (i = 0; i < insn->nargs; i++)
        {
          cur_arg_num = i;
          print_operand (cur_size[i], instruction->operands[i].shift, 
                         &insn->arg[i]);
        }
    }

  return 1;
}

/* Bunch of error checkings.
   The checks are made after a matching instruction was found.  */

void
warn_if_needed (ins *insn)
{
  /* If the post-increment address mode is used and the load/store 
     source register is the same as rbase, the result of the 
     instruction is undefined.  */
  if (IS_INSN_TYPE (LD_STOR_INS_INC))
    {
      /* Enough to verify that one of the arguments is a simple reg.  */
      if ((insn->arg[0].type == arg_r) || (insn->arg[1].type == arg_r))
        if (insn->arg[0].r == insn->arg[1].r)
          as_bad (_("Same src/dest register is used (`r%d'), result is undefined"), 
                   insn->arg[0].r);
    }

  /* Some instruction assume the stack pointer as rptr operand.
     Issue an error when the register to be loaded is also SP.  */
  if (instruction->flags & NO_SP)
    {
      if (getreg_image (insn->arg[0].r) == getreg_image (sp))
        as_bad (_("`%s' has undefined result"), ins_parse);
    }

  /* If the rptr register is specified as one of the registers to be loaded, 
     the final contents of rptr are undefined. Thus, we issue an error.  */
  if (instruction->flags & NO_RPTR)
    {
      if ((1 << getreg_image (insn->arg[0].r)) & insn->arg[1].constant)
        as_bad (_("Same src/dest register is used (`r%d'), result is undefined"), 
         getreg_image (insn->arg[0].r));
    }
}

/* In some cases, we need to adjust the instruction pointer although a 
   match was already found. Here, we gather all these cases.
   Returns 1 if instruction pointer was adjusted, otherwise 0.  */

int
adjust_if_needed (ins *insn)
{
  int ret_value = 0;

  /* Special check for 'addub $0, r0' instruction -
     The opcode '0000 0000 0000 0000' is not allowed.  */
  if (IS_INSN_MNEMONIC ("addub"))
    {
      if ((instruction->operands[0].op_type == cst4)
          && instruction->operands[1].op_type == regr)
        {
          if (insn->arg[0].constant == 0 && insn->arg[1].r == r0)
            {
              instruction++;
              ret_value = 1;
            }
        }
    }

  /* Optimization: Omit a zero displacement in bit operations, 
     saving 2-byte encoding space (e.g., 'cbitw $8, 0(r1)').  */
  if (IS_INSN_TYPE (CSTBIT_INS))
    {
      if ((instruction->operands[1].op_type == rbase_disps12)
           && (insn->arg[1].X_op == O_constant)
           && (insn->arg[1].constant == 0))
            {
              instruction--;
              ret_value = 1;
            }
    }

  return ret_value;
}

/* Set the appropriate bit for register 'r' in 'mask'.
   This indicates that this register is loaded or stored by
   the instruction.  */

static void
mask_reg (int r, unsigned short int *mask)
{
  if ((reg)r > (reg)sp)
    {
      as_bad (_("Invalid Register in Register List"));
      return;
    }

  *mask |= (1 << r);
}

/* Preprocess register list - create a 16-bit mask with one bit for each
   of the 16 general purpose registers. If a bit is set, it indicates
   that this register is loaded or stored by the instruction.  */

static char *
preprocess_reglist (char *param, int *allocated)
{
  char reg_name[MAX_REGNAME_LEN]; /* Current parsed register name.  */
  char *regP;                     /* Pointer to 'reg_name' string.  */
  int reg_counter = 0;            /* Count number of parsed registers.  */
  unsigned short int mask = 0;    /* Mask for 16 general purpose registers.  */
  char *new_param;                /* New created operands string.  */
  char *paramP = param;           /* Pointer to original opearands string.  */
  char maskstring[10];            /* Array to print the mask as a string.  */
  int hi_found = 0, lo_found = 0; /* Boolean flags for hi/lo registers.  */
  reg r;
  copreg cr;

  /* If 'param' is already in form of a number, no need to preprocess.  */
  if (strchr (paramP, '{') == NULL)
    return param;

  /* Verifying correct syntax of operand.  */
  if (strchr (paramP, '}') == NULL)
    as_fatal (_("Missing matching brackets : `%s'"), ins_parse);

  while (*paramP++ != '{');

  new_param = (char *)xcalloc (MAX_INST_LEN, sizeof (char));
  *allocated = 1;
  strncpy (new_param, param, paramP - param - 1);

  while (*paramP != '}')
    {
      regP = paramP;
      memset (&reg_name, '\0', sizeof (reg_name));

      while (ISALNUM (*paramP))
        paramP++;

      strncpy (reg_name, regP, paramP - regP);

      /* Coprocessor register c<N>.  */
      if (IS_INSN_TYPE (COP_REG_INS))
        {
          if (((cr = get_copregister (reg_name)) == nullcopregister)
              || (crx_copregtab[cr-MAX_REG].type != CRX_C_REGTYPE))
            as_fatal (_("Illegal register `%s' in cop-register list"), reg_name);
          mask_reg (getreg_image (cr - c0), &mask);
        }
      /* Coprocessor Special register cs<N>.  */
      else if (IS_INSN_TYPE (COPS_REG_INS))
        {
          if (((cr = get_copregister (reg_name)) == nullcopregister)
              || (crx_copregtab[cr-MAX_REG].type != CRX_CS_REGTYPE))
            as_fatal (_("Illegal register `%s' in cop-special-register list"), 
                      reg_name);
          mask_reg (getreg_image (cr - cs0), &mask);
        }
      /* User register u<N>.  */
      else if (instruction->flags & USER_REG)
        {
          if (streq(reg_name, "uhi"))
            {
              hi_found = 1;
              goto next_inst;
            }
          else if (streq(reg_name, "ulo"))
            {
              lo_found = 1;
              goto next_inst;
            }
          else if (((r = get_register (reg_name)) == nullregister)
              || (crx_regtab[r].type != CRX_U_REGTYPE))
            as_fatal (_("Illegal register `%s' in user register list"), reg_name);
          
          mask_reg (getreg_image (r - u0), &mask);        
        }
      /* General purpose register r<N>.  */
      else
        {
          if (streq(reg_name, "hi"))
            {
              hi_found = 1;
              goto next_inst;
            }
          else if (streq(reg_name, "lo"))
            {
              lo_found = 1;
              goto next_inst;
            }
          else if (((r = get_register (reg_name)) == nullregister)
              || (crx_regtab[r].type != CRX_R_REGTYPE))
            as_fatal (_("Illegal register `%s' in register list"), reg_name);

          mask_reg (getreg_image (r - r0), &mask);
        }

      if (++reg_counter > MAX_REGS_IN_MASK16)
        as_bad (_("Maximum %d bits may be set in `mask16' operand"),
                MAX_REGS_IN_MASK16);

next_inst:
      while (!ISALNUM (*paramP) && *paramP != '}')
          paramP++;
    }

  if (*++paramP != '\0')
    as_warn (_("rest of line ignored; first ignored character is `%c'"),
             *paramP);

  switch (hi_found + lo_found)
    {
    case 0:
      /* At least one register should be specified.  */
      if (mask == 0)
        as_bad (_("Illegal `mask16' operand, operation is undefined - `%s'"),
                ins_parse);
      break;

    case 1:
      /* HI can't be specified without LO (and vise-versa).  */
      as_bad (_("HI/LO registers should be specified together"));
      break;

    case 2:
      /* HI/LO registers mustn't be masked with additional registers.  */
      if (mask != 0)
        as_bad (_("HI/LO registers should be specified without additional registers"));

    default:
      break;
    }

  sprintf (maskstring, "$0x%x", mask);
  strcat (new_param, maskstring);
  return new_param;
}

/* Print the instruction.
   Handle also cases where the instruction is relaxable/relocatable.  */

void
print_insn (ins *insn)
{
  unsigned int i, j, insn_size;
  char *this_frag;
  unsigned short words[4];
  int addr_mod;

  /* Arrange the insn encodings in a WORD size array.  */
  for (i = 0, j = 0; i < 2; i++)
    {
      words[j++] = (output_opcode[i] >> 16) & 0xFFFF;
      words[j++] = output_opcode[i] & 0xFFFF;
    }

  /* Handle relaxtion.  */
  if ((instruction->flags & RELAXABLE) && relocatable)
    {
      int relax_subtype;

      /* Write the maximal instruction size supported.  */
      insn_size = INSN_MAX_SIZE;

      /* bCC  */
      if (IS_INSN_TYPE (BRANCH_INS))
        relax_subtype = 0;
      /* bal  */
      else if (IS_INSN_TYPE (DCR_BRANCH_INS) || IS_INSN_MNEMONIC ("bal"))
        relax_subtype = 3;
      /* cmpbr  */
      else if (IS_INSN_TYPE (CMPBR_INS))
        relax_subtype = 5;
      else
        abort ();

      this_frag = frag_var (rs_machine_dependent, insn_size * 2,
                            4, relax_subtype,
                            insn->exp.X_add_symbol,
                            insn->exp.X_add_number,
                            0);
    }
  else
    {
      insn_size = instruction->size;
      this_frag = frag_more (insn_size * 2);

      /* Handle relocation.  */
      if ((relocatable) && (insn->rtype != BFD_RELOC_NONE))
        {
          reloc_howto_type *reloc_howto;
          int size;

          reloc_howto = bfd_reloc_type_lookup (stdoutput, insn->rtype);

          if (!reloc_howto)
            abort ();

          size = bfd_get_reloc_size (reloc_howto);

          if (size < 1 || size > 4)
            abort ();

          fix_new_exp (frag_now, this_frag - frag_now->fr_literal,
                       size, &insn->exp, reloc_howto->pc_relative,
                       insn->rtype);
        }
    }

  /* Verify a 2-byte code alignment.  */
  addr_mod = frag_now_fix () & 1;
  if (frag_now->has_code && frag_now->insn_addr != addr_mod)
    as_bad (_("instruction address is not a multiple of 2"));
  frag_now->insn_addr = addr_mod;
  frag_now->has_code = 1;

  /* Write the instruction encoding to frag.  */
  for (i = 0; i < insn_size; i++)
    {
      md_number_to_chars (this_frag, (valueT) words[i], 2);
      this_frag += 2;
    }
}

/* This is the guts of the machine-dependent assembler.  OP points to a
   machine dependent instruction.  This function is supposed to emit
   the frags/bytes it assembles to.  */

void
md_assemble (char *op)
{
  ins crx_ins;
  char *param;
  char c;

  /* Reset global variables for a new instruction.  */
  reset_vars (op);

  /* Strip the mnemonic.  */
  for (param = op; *param != 0 && !ISSPACE (*param); param++)
    ;
  c = *param;
  *param++ = '\0';

  /* Find the instruction.  */
  instruction = (const inst *) hash_find (crx_inst_hash, op);
  if (instruction == NULL)
    {
      as_bad (_("Unknown opcode: `%s'"), op);
      return;
    }

  /* Tie dwarf2 debug info to the address at the start of the insn.  */
  dwarf2_emit_insn (0);

  /* Parse the instruction's operands.  */
  parse_insn (&crx_ins, param);

  /* Assemble the instruction - return upon failure.  */
  if (assemble_insn (op, &crx_ins) == 0)
    return;

  /* Print the instruction.  */
  print_insn (&crx_ins);
}