/* Altera Nios II disassemble routines

   Copyright (C) 2012-2024 Free Software Foundation, Inc.

   Contributed by Nigel Gray (ngray@altera.com).

   Contributed by Mentor Graphics, Inc.

   This file is part of the GNU opcodes library.

   This library 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 3, or (at your option)

   any later version.

   It 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 file; see the file COPYING.  If not, write to the

   Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston,

   MA 02110-1301, USA.  */

#include "sysdep.h"

#include "disassemble.h"

#include "opintl.h"

#include "opcode/nios2.h"

#include "libiberty.h"

#include <string.h>

#include <assert.h>

/* No symbol table is available when this code runs out in an embedded

   system as when it is used for disassembler support in a monitor.  */

#if !defined(EMBEDDED_ENV)

#define SYMTAB_AVAILABLE 1

#include "elf-bfd.h"

#include "elf/nios2.h"

#endif

/* Default length of Nios II instruction in bytes.  */

#define INSNLEN 4

/* Data structures used by the opcode hash table.  */

typedef struct _nios2_opcode_hash

{

  const struct nios2_opcode *opcode;

  struct _nios2_opcode_hash *next;

} nios2_opcode_hash;

/* Hash table size.  */

#define OPCODE_HASH_SIZE (IW_R1_OP_UNSHIFTED_MASK + 1)

/* Extract the opcode from an instruction word.  */

static unsigned int

nios2_r1_extract_opcode (unsigned int x)

{

  return GET_IW_R1_OP (x);

}

static unsigned int

nios2_r2_extract_opcode (unsigned int x)

{

  return GET_IW_R2_OP (x);

}

/* We maintain separate hash tables for R1 and R2 opcodes, and pseudo-ops

   are stored in a different table than regular instructions.  */

typedef struct _nios2_disassembler_state

{

  const struct nios2_opcode *opcodes;

  const int *num_opcodes;

  unsigned int (*extract_opcode) (unsigned int);

  nios2_opcode_hash *hash[OPCODE_HASH_SIZE];

  nios2_opcode_hash *ps_hash[OPCODE_HASH_SIZE];

  const struct nios2_opcode *nop;

  bool init;

} nios2_disassembler_state;

static nios2_disassembler_state

nios2_r1_disassembler_state = {

  nios2_r1_opcodes,

  &nios2_num_r1_opcodes,

  nios2_r1_extract_opcode,

  {},

  {},

  NULL,

  0

};

static nios2_disassembler_state

nios2_r2_disassembler_state = {

  nios2_r2_opcodes,

  &nios2_num_r2_opcodes,

  nios2_r2_extract_opcode,

  {},

  {},

  NULL,

  0

};

/* Function to initialize the opcode hash table.  */

static void

nios2_init_opcode_hash (nios2_disassembler_state *state)

{

  unsigned int i;

  register const struct nios2_opcode *op;

  for (i = 0; i < OPCODE_HASH_SIZE; i++)

    for (op = state->opcodes; op < &state->opcodes[*(state->num_opcodes)]; op++)

      {

  nios2_opcode_hash *new_hash;

  nios2_opcode_hash **bucket = NULL;

  if ((op->pinfo & NIOS2_INSN_MACRO) == NIOS2_INSN_MACRO)

    {

      if (i == state->extract_opcode (op->match)

    && (op->pinfo & (NIOS2_INSN_MACRO_MOV | NIOS2_INSN_MACRO_MOVI)

        & 0x7fffffff))

        {

    bucket = &(state->ps_hash[i]);

    if (strcmp (op->name, "nop") == 0)

      state->nop = op;

        }

    }

  else if (i == state->extract_opcode (op->match))

    bucket = &(state->hash[i]);

  if (bucket)

    {

      new_hash =

        (nios2_opcode_hash *) malloc (sizeof (nios2_opcode_hash));

      if (new_hash == NULL)

        {

    /* xgettext:c-format */

    opcodes_error_handler (_("out of memory"));

    exit (1);

        }

      new_hash->opcode = op;

      new_hash->next = NULL;

      while (*bucket)

        bucket = &((*bucket)->next);

      *bucket = new_hash;

    }

      }

  state->init = 1;

#ifdef DEBUG_HASHTABLE

  for (i = 0; i < OPCODE_HASH_SIZE; ++i)

    {

      nios2_opcode_hash *tmp_hash = state->hash[i];

      printf ("index: 0x%02X  ops: ", i);

      while (tmp_hash != NULL)

  {

    printf ("%s ", tmp_hash->opcode->name);

    tmp_hash = tmp_hash->next;

  }

      printf ("\n");

    }

  for (i = 0; i < OPCODE_HASH_SIZE; ++i)

    {

      nios2_opcode_hash *tmp_hash = state->ps_hash[i];

      printf ("index: 0x%02X  ops: ", i);

      while (tmp_hash != NULL)

  {

    printf ("%s ", tmp_hash->opcode->name);

    tmp_hash = tmp_hash->next;

  }

      printf ("\n");

    }

#endif /* DEBUG_HASHTABLE */

}

/* Return a pointer to an nios2_opcode struct for a given instruction

   word OPCODE for bfd machine MACH, or NULL if there is an error.  */

const struct nios2_opcode *

nios2_find_opcode_hash (unsigned long opcode, unsigned long mach)

{

  nios2_opcode_hash *entry;

  nios2_disassembler_state *state;

  /* Select the right instruction set, hash tables, and opcode accessor

     for the mach variant.  */

  if (mach == bfd_mach_nios2r2)

    state = &nios2_r2_disassembler_state;

  else

    state = &nios2_r1_disassembler_state;

  /* Build a hash table to shorten the search time.  */

  if (!state->init)

    nios2_init_opcode_hash (state);

  /* Check for NOP first.  Both NOP and MOV are macros that expand into

     an ADD instruction, and we always want to give priority to NOP.  */

  if (state->nop->match == (opcode & state->nop->mask))

    return state->nop;

  /* First look in the pseudo-op hashtable.  */

  for (entry = state->ps_hash[state->extract_opcode (opcode)];

       entry; entry = entry->next)

    if (entry->opcode->match == (opcode & entry->opcode->mask))

      return entry->opcode;

  /* Otherwise look in the main hashtable.  */

  for (entry = state->hash[state->extract_opcode (opcode)];

       entry; entry = entry->next)

    if (entry->opcode->match == (opcode & entry->opcode->mask))

      return entry->opcode;

  return NULL;

}

/* There are 32 regular registers, 32 coprocessor registers,

   and 32 control registers.  */

#define NUMREGNAMES 32

/* Return a pointer to the base of the coprocessor register name array.  */

static struct nios2_reg *

nios2_coprocessor_regs (void)

{

  static struct nios2_reg *cached = NULL;

  if (!cached)

    {

      int i;

      for (i = NUMREGNAMES; i < nios2_num_regs; i++)

  if (!strcmp (nios2_regs[i].name, "c0"))

    {

      cached = nios2_regs + i;

      break;

    }

      assert (cached);

    }

  return cached;

}

/* Return a pointer to the base of the control register name array.  */

static struct nios2_reg *

nios2_control_regs (void)

{

  static struct nios2_reg *cached = NULL;

  if (!cached)

    {

      int i;

      for (i = NUMREGNAMES; i < nios2_num_regs; i++)

  if (!strcmp (nios2_regs[i].name, "status"))

    {

      cached = nios2_regs + i;

      break;

    }

      assert (cached);

    }

  return cached;

}

/* Helper routine to report internal errors.  */

static void

bad_opcode (const struct nios2_opcode *op)

{

  opcodes_error_handler

    /* xgettext:c-format */

    (_("internal error: broken opcode descriptor for `%s %s'"),

     op->name, op->args);

  abort ();

}

/* The function nios2_print_insn_arg uses the character pointed

   to by ARGPTR to determine how it print the next token or separator

   character in the arguments to an instruction.  */

static int

nios2_print_insn_arg (const char *argptr,

          unsigned long opcode, bfd_vma address,

          disassemble_info *info,

          const struct nios2_opcode *op)

{

  unsigned long i = 0;

  long s = 0;

  int32_t o = 0;

  struct nios2_reg *reg_base;

  switch (*argptr)

    {

    case ',':

    case '(':

    case ')':

      (*info->fprintf_func) (info->stream, "%c", *argptr);

      break;

    case 'c':

      /* Control register index.  */

      switch (op->format)

  {

  case iw_r_type:

    i = GET_IW_R_IMM5 (opcode);

    break;

  case iw_F3X6L5_type:

    i = GET_IW_F3X6L5_IMM5 (opcode);

    break;

  default:

    bad_opcode (op);

  }

      reg_base = nios2_control_regs ();

      (*info->fprintf_func) (info->stream, "%s", reg_base[i].name);

      break;

    case 'd':

      reg_base = nios2_regs;

      switch (op->format)

  {

  case iw_r_type:

    i = GET_IW_R_C (opcode);

    break;

  case iw_custom_type:

    i = GET_IW_CUSTOM_C (opcode);

    if (GET_IW_CUSTOM_READC (opcode) == 0)

      reg_base = nios2_coprocessor_regs ();

    break;

  case iw_F3X6L5_type:

  case iw_F3X6_type:

    i = GET_IW_F3X6L5_C (opcode);

    break;

  case iw_F3X8_type:

    i = GET_IW_F3X8_C (opcode);

    if (GET_IW_F3X8_READC (opcode) == 0)

      reg_base = nios2_coprocessor_regs ();

    break;

  case iw_F2_type:

    i = GET_IW_F2_B (opcode);

    break;

  default:

    bad_opcode (op);

  }

      if (i < NUMREGNAMES)

  (*info->fprintf_func) (info->stream, "%s", reg_base[i].name);

      else

  (*info->fprintf_func) (info->stream, "unknown");

      break;

    case 's':

      reg_base = nios2_regs;

      switch (op->format)

  {

  case iw_r_type:

    i = GET_IW_R_A (opcode);

    break;

  case iw_i_type:

    i = GET_IW_I_A (opcode);

    break;

  case iw_custom_type:

    i = GET_IW_CUSTOM_A (opcode);

    if (GET_IW_CUSTOM_READA (opcode) == 0)

      reg_base = nios2_coprocessor_regs ();

    break;

  case iw_F2I16_type:

    i = GET_IW_F2I16_A (opcode);

    break;

  case iw_F2X4I12_type:

    i = GET_IW_F2X4I12_A (opcode);

    break;

  case iw_F1X4I12_type:

    i = GET_IW_F1X4I12_A (opcode);

    break;

  case iw_F1X4L17_type:

    i = GET_IW_F1X4L17_A (opcode);

    break;

  case iw_F3X6L5_type:

  case iw_F3X6_type:

    i = GET_IW_F3X6L5_A (opcode);

    break;

  case iw_F2X6L10_type:

    i = GET_IW_F2X6L10_A (opcode);

    break;

  case iw_F3X8_type:

    i = GET_IW_F3X8_A (opcode);

    if (GET_IW_F3X8_READA (opcode) == 0)

      reg_base = nios2_coprocessor_regs ();

    break;

  case iw_F1X1_type:

    i = GET_IW_F1X1_A (opcode);

    break;

  case iw_F1I5_type:

    i = 27;   /* Implicit stack pointer reference.  */

    break;

  case iw_F2_type:

    i = GET_IW_F2_A (opcode);

    break;

  default:

    bad_opcode (op);

  }

      if (i < NUMREGNAMES)

  (*info->fprintf_func) (info->stream, "%s", reg_base[i].name);

      else

  (*info->fprintf_func) (info->stream, "unknown");

      break;

    case 't':

      reg_base = nios2_regs;

      switch (op->format)

  {

  case iw_r_type:

    i = GET_IW_R_B (opcode);

    break;

  case iw_i_type:

    i = GET_IW_I_B (opcode);

    break;

  case iw_custom_type:

    i = GET_IW_CUSTOM_B (opcode);

    if (GET_IW_CUSTOM_READB (opcode) == 0)

      reg_base = nios2_coprocessor_regs ();

    break;

  case iw_F2I16_type:

    i = GET_IW_F2I16_B (opcode);

    break;

  case iw_F2X4I12_type:

    i = GET_IW_F2X4I12_B (opcode);

    break;

  case iw_F3X6L5_type:

  case iw_F3X6_type:

    i = GET_IW_F3X6L5_B (opcode);

    break;

  case iw_F2X6L10_type:

    i = GET_IW_F2X6L10_B (opcode);

    break;

  case iw_F3X8_type:

    i = GET_IW_F3X8_B (opcode);

    if (GET_IW_F3X8_READB (opcode) == 0)

      reg_base = nios2_coprocessor_regs ();

    break;

  case iw_F1I5_type:

    i = GET_IW_F1I5_B (opcode);

    break;

  case iw_F2_type:

    i = GET_IW_F2_B (opcode);

    break;

  case iw_T1X1I6_type:

    i = 0;

    break;

  default:

    bad_opcode (op);

  }

      if (i < NUMREGNAMES)

  (*info->fprintf_func) (info->stream, "%s", reg_base[i].name);

      else

  (*info->fprintf_func) (info->stream, "unknown");

      break;

    case 'D':

      switch (op->format)

  {

  case iw_T1I7_type:

    i = GET_IW_T1I7_A3 (opcode);

    break;

  case iw_T2X1L3_type:

    i = GET_IW_T2X1L3_B3 (opcode);

    break;

  case iw_T2X1I3_type:

    i = GET_IW_T2X1I3_B3 (opcode);

    break;

  case iw_T3X1_type:

    i = GET_IW_T3X1_C3 (opcode);

    break;

  case iw_T2X3_type:

    if (op->num_args == 3)

      i = GET_IW_T2X3_A3 (opcode);

    else

      i = GET_IW_T2X3_B3 (opcode);

    break;

  default:

    bad_opcode (op);

  }

      i = nios2_r2_reg3_mappings[i];

      (*info->fprintf_func) (info->stream, "%s", nios2_regs[i].name);

      break;

    case 'M':

      /* 6-bit unsigned immediate with no shift.  */

      switch (op->format)

  {

  case iw_T1X1I6_type:

    i = GET_IW_T1X1I6_IMM6 (opcode);

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", i);

      break;

    case 'N':

      /* 6-bit unsigned immediate with 2-bit shift.  */

      switch (op->format)

  {

  case iw_T1X1I6_type:

    i = GET_IW_T1X1I6_IMM6 (opcode) << 2;

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", i);

      break;

    case 'S':

      switch (op->format)

  {

  case iw_T1I7_type:

    i = GET_IW_T1I7_A3 (opcode);

    break;

  case iw_T2I4_type:

    i = GET_IW_T2I4_A3 (opcode);

    break;

  case iw_T2X1L3_type:

    i = GET_IW_T2X1L3_A3 (opcode);

    break;

  case iw_T2X1I3_type:

    i = GET_IW_T2X1I3_A3 (opcode);

    break;

  case iw_T3X1_type:

    i = GET_IW_T3X1_A3 (opcode);

    break;

  case iw_T2X3_type:

    i = GET_IW_T2X3_A3 (opcode);

    break;

  case iw_T1X1I6_type:

    i = GET_IW_T1X1I6_A3 (opcode);

    break;

  default:

    bad_opcode (op);

  }

      i = nios2_r2_reg3_mappings[i];

      (*info->fprintf_func) (info->stream, "%s", nios2_regs[i].name);

      break;

    case 'T':

      switch (op->format)

  {

  case iw_T2I4_type:

    i = GET_IW_T2I4_B3 (opcode);

    break;

  case iw_T3X1_type:

    i = GET_IW_T3X1_B3 (opcode);

    break;

  case iw_T2X3_type:

    i = GET_IW_T2X3_B3 (opcode);

    break;

  default:

    bad_opcode (op);

  }

      i = nios2_r2_reg3_mappings[i];

      (*info->fprintf_func) (info->stream, "%s", nios2_regs[i].name);

      break;

    case 'i':

      /* 16-bit signed immediate.  */

      switch (op->format)

  {

  case iw_i_type:

    s = ((int32_t) ((GET_IW_I_IMM16 (opcode) & 0xffff) ^ 0x8000)

         - 0x8000);

    break;

  case iw_F2I16_type:

    s = ((int32_t) ((GET_IW_F2I16_IMM16 (opcode) & 0xffff) ^ 0x8000)

         - 0x8000);

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", s);

      break;

    case 'I':

      /* 12-bit signed immediate.  */

      switch (op->format)

  {

  case iw_F2X4I12_type:

    s = ((int32_t) ((GET_IW_F2X4I12_IMM12 (opcode) & 0xfff) ^ 0x800)

         - 0x800);

    break;

  case iw_F1X4I12_type:

    s = ((int32_t) ((GET_IW_F1X4I12_IMM12 (opcode) & 0xfff) ^ 0x800)

         - 0x800);

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", s);

      break;

    case 'u':

      /* 16-bit unsigned immediate.  */

      switch (op->format)

  {

  case iw_i_type:

    i = GET_IW_I_IMM16 (opcode);

    break;

  case iw_F2I16_type:

    i = GET_IW_F2I16_IMM16 (opcode);

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", i);

      break;

    case 'U':

      /* 7-bit unsigned immediate with 2-bit shift.  */

      switch (op->format)

  {

  case iw_T1I7_type:

    i = GET_IW_T1I7_IMM7 (opcode) << 2;

    break;

  case iw_X1I7_type:

    i = GET_IW_X1I7_IMM7 (opcode) << 2;

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", i);

      break;

    case 'V':

      /* 5-bit unsigned immediate with 2-bit shift.  */

      switch (op->format)

  {

  case iw_F1I5_type:

    i = GET_IW_F1I5_IMM5 (opcode) << 2;

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", i);

      break;

    case 'W':

      /* 4-bit unsigned immediate with 2-bit shift.  */

      switch (op->format)

  {

  case iw_T2I4_type:

    i = GET_IW_T2I4_IMM4 (opcode) << 2;

    break;

  case iw_L5I4X1_type:

    i = GET_IW_L5I4X1_IMM4 (opcode) << 2;

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", i);

      break;

    case 'X':

      /* 4-bit unsigned immediate with 1-bit shift.  */

      switch (op->format)

  {

  case iw_T2I4_type:

    i = GET_IW_T2I4_IMM4 (opcode) << 1;

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", i);

      break;

    case 'Y':

      /* 4-bit unsigned immediate without shift.  */

      switch (op->format)

  {

  case iw_T2I4_type:

    i = GET_IW_T2I4_IMM4 (opcode);

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", i);

      break;

    case 'o':

      /* 16-bit signed immediate address offset.  */

      switch (op->format)

  {

  case iw_i_type:

    o = ((GET_IW_I_IMM16 (opcode) & 0xffff) ^ 0x8000) - 0x8000;

    break;

  case iw_F2I16_type:

    o = ((GET_IW_F2I16_IMM16 (opcode) & 0xffff) ^ 0x8000) - 0x8000;

    break;

  default:

    bad_opcode (op);

  }

      address = address + 4 + o;

      (*info->print_address_func) (address, info);

      break;

    case 'O':

      /* 10-bit signed address offset with 1-bit shift.  */

      switch (op->format)

  {

  case iw_I10_type:

    o = (((GET_IW_I10_IMM10 (opcode) & 0x3ff) ^ 0x200) - 0x200) * 2;

    break;

  default:

    bad_opcode (op);

  }

      address = address + 2 + o;

      (*info->print_address_func) (address, info);

      break;

    case 'P':

      /* 7-bit signed address offset with 1-bit shift.  */

      switch (op->format)

  {

  case iw_T1I7_type:

    o = (((GET_IW_T1I7_IMM7 (opcode) & 0x7f) ^ 0x40) - 0x40) * 2;

    break;

  default:

    bad_opcode (op);

  }

      address = address + 2 + o;

      (*info->print_address_func) (address, info);

      break;

    case 'j':

      /* 5-bit unsigned immediate.  */

      switch (op->format)

  {

  case iw_r_type:

    i = GET_IW_R_IMM5 (opcode);

    break;

  case iw_F3X6L5_type:

    i = GET_IW_F3X6L5_IMM5 (opcode);

    break;

  case iw_F2X6L10_type:

    i = GET_IW_F2X6L10_MSB (opcode);

    break;

  case iw_X2L5_type:

    i = GET_IW_X2L5_IMM5 (opcode);

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", i);

      break;

    case 'k':

      /* Second 5-bit unsigned immediate field.  */

      switch (op->format)

  {

  case iw_F2X6L10_type:

    i = GET_IW_F2X6L10_LSB (opcode);

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", i);

      break;

    case 'l':

      /* 8-bit unsigned immediate.  */

      switch (op->format)

  {

  case iw_custom_type:

    i = GET_IW_CUSTOM_N (opcode);

    break;

  case iw_F3X8_type:

    i = GET_IW_F3X8_N (opcode);

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%lu", i);

      break;

    case 'm':

      /* 26-bit unsigned immediate.  */

      switch (op->format)

  {

  case iw_j_type:

    i = GET_IW_J_IMM26 (opcode);

    break;

  case iw_L26_type:

    i = GET_IW_L26_IMM26 (opcode);

    break;

  default:

    bad_opcode (op);

  }

      /* This translates to an address because it's only used in call

   instructions.  */

      address = (address & 0xf0000000) | (i << 2);

      (*info->print_address_func) (address, info);

      break;

    case 'e':

      /* Encoded enumeration for addi.n/subi.n.  */

      switch (op->format)

  {

  case iw_T2X1I3_type:

    i = nios2_r2_asi_n_mappings[GET_IW_T2X1I3_IMM3 (opcode)];

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%lu", i);

      break;

    case 'f':

      /* Encoded enumeration for slli.n/srli.n.  */

      switch (op->format)

  {

  case iw_T2X1L3_type:

    i = nios2_r2_shi_n_mappings[GET_IW_T2X1I3_IMM3 (opcode)];

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%lu", i);

      break;

    case 'g':

      /* Encoded enumeration for andi.n.  */

      switch (op->format)

  {

  case iw_T2I4_type:

    i = nios2_r2_andi_n_mappings[GET_IW_T2I4_IMM4 (opcode)];

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%lu", i);

      break;

    case 'h':

      /* Encoded enumeration for movi.n.  */

      switch (op->format)

  {

  case iw_T1I7_type:

    i = GET_IW_T1I7_IMM7 (opcode);

    if (i == 125)

      i = 0xff;

    else if (i == 126)

      i = -2;

    else if (i == 127)

      i = -1;

    break;

  default:

    bad_opcode (op);

  }

      (*info->fprintf_func) (info->stream, "%ld", i);

      break;

    case 'R':

      {

  unsigned long reglist = 0;

  int dir = 1;

  int k, t;

  switch (op->format)

    {

    case iw_F1X4L17_type:

      /* Encoding for ldwm/stwm.  */

      i = GET_IW_F1X4L17_REGMASK (opcode);

      if (GET_IW_F1X4L17_RS (opcode))

        {

    reglist = ((i << 14) & 0x00ffc000);

    if (i & (1 << 10))

      reglist |= (1 << 28);

    if (i & (1 << 11))

      reglist |= (1u << 31);

        }

      else

        reglist = i << 2;

      dir = GET_IW_F1X4L17_REGMASK (opcode) ? 1 : -1;

      break;

    case iw_L5I4X1_type:

      /* Encoding for push.n/pop.n.  */

      reglist |= (1u << 31);

      if (GET_IW_L5I4X1_FP (opcode))

        reglist |= (1 << 28);

      if (GET_IW_L5I4X1_CS (opcode))

        {

    int val = GET_IW_L5I4X1_REGRANGE (opcode);

    reglist |= nios2_r2_reg_range_mappings[val];

        }

      dir = (op->match == MATCH_R2_POP_N ? 1 : -1);

      break;

    default:

      bad_opcode (op);

    }

  t = 0;

  (*info->fprintf_func) (info->stream, "{");

  for (k = (dir == 1 ? 0 : 31);

       (dir == 1 && k < 32) || (dir == -1 && k >= 0);

       k += dir)

    if (reglist & (1u << k))

      {

        if (t)

    (*info->fprintf_func) (info->stream, ",");

        else

    t++;

        (*info->fprintf_func) (info->stream, "%s", nios2_regs[k].name);

      }

  (*info->fprintf_func) (info->stream, "}");

  break;

      }

    case 'B':

      /* Base register and options for ldwm/stwm.  */

      switch (op->format)

  {

  case iw_F1X4L17_type:

    if (GET_IW_F1X4L17_ID (opcode) == 0)

      (*info->fprintf_func) (info->stream, "--");

    i = GET_IW_F1X4I12_A (opcode);

    (*info->fprintf_func) (info->stream, "(%s)",

         nios2_builtin_regs[i].name);

    if (GET_IW_F1X4L17_ID (opcode))

      (*info->fprintf_func) (info->stream, "++");

    if (GET_IW_F1X4L17_WB (opcode))

      (*info->fprintf_func) (info->stream, ",writeback");

    if (GET_IW_F1X4L17_PC (opcode))

      (*info->fprintf_func) (info->stream, ",ret");

    break;

  default:

    bad_opcode (op);

  }

      break;

    default:

      (*info->fprintf_func) (info->stream, "unknown");

      break;

    }

  return 0;

}

/* nios2_disassemble does all the work of disassembling a Nios II

   instruction opcode.  */

static int

nios2_disassemble (bfd_vma address, unsigned long opcode,

       disassemble_info *info)

{

  const struct nios2_opcode *op;

  info->bytes_per_line = INSNLEN;

  info->bytes_per_chunk = INSNLEN;

  info->display_endian = info->endian;

  info->insn_info_valid = 1;

  info->branch_delay_insns = 0;

  info->data_size = 0;

  info->insn_type = dis_nonbranch;

  info->target = 0;

  info->target2 = 0;

  /* Find the major opcode and use this to disassemble

     the instruction and its arguments.  */

  op = nios2_find_opcode_hash (opcode, info->mach);

  if (op != NULL)

    {

      const char *argstr = op->args;

      (*info->fprintf_func) (info->stream, "%s", op->name);

      if (argstr != NULL && *argstr != '\0')

  {

    (*info->fprintf_func) (info->stream, "\t");

    while (*argstr != '\0')

      {

        nios2_print_insn_arg (argstr, opcode, address, info, op);

        ++argstr;

      }

  }

      /* Tell the caller how far to advance the program counter.  */

      info->bytes_per_chunk = op->size;

      return op->size;

    }

  else

    {

      /* Handle undefined instructions.  */

      info->insn_type = dis_noninsn;

      (*info->fprintf_func) (info->stream, "0x%lx", opcode);

      return INSNLEN;

    }

}

/* print_insn_nios2 is the main disassemble function for Nios II.

   The function diassembler(abfd) (source in disassemble.c) returns a

   pointer to this either print_insn_big_nios2 or

   print_insn_little_nios2, which in turn call this function when the

   bfd machine type is Nios II. print_insn_nios2 reads the

   instruction word at the address given, and prints the disassembled

   instruction on the stream info->stream using info->fprintf_func. */

static int

print_insn_nios2 (bfd_vma address, disassemble_info *info,

      enum bfd_endian endianness)

{

  bfd_byte buffer[INSNLEN];

  int status;

  status = (*info->read_memory_func) (address, buffer, INSNLEN, info);

  if (status == 0)

    {

      unsigned long insn;

      if (endianness == BFD_ENDIAN_BIG)

  insn = (unsigned long) bfd_getb32 (buffer);

      else

  insn = (unsigned long) bfd_getl32 (buffer);

      return nios2_disassemble (address, insn, info);

    }

  /* We might have a 16-bit R2 instruction at the end of memory.  Try that.  */

  if (info->mach == bfd_mach_nios2r2)

    {

      status = (*info->read_memory_func) (address, buffer, 2, info);