/* Print DEC PDP-11 instructions.

   Copyright (C) 2001-2026 Free Software Foundation, 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 program; if not, write to the Free Software

   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,

   MA 02110-1301, USA.  */

#include "sysdep.h"

#include "disassemble.h"

#include "opcode/pdp11.h"

#define AFTER_INSTRUCTION "\t"

#define OPERAND_SEPARATOR ", "

#define JUMP  0x1000  /* Flag that this operand is used in a jump.  */

#define FPRINTF (*info->fprintf_func)

#define F info->stream

/* Sign-extend a 16-bit number in an int.  */

#define sign_extend(x) ((((x) & 0xffff) ^ 0x8000) - 0x8000)

static int

read_word (bfd_vma memaddr, int *word, disassemble_info *info)

{

  int status;

  bfd_byte x[2];

  status = (*info->read_memory_func) (memaddr, x, 2, info);

  if (status != 0)

    return -1;

  *word = x[1] << 8 | x[0];

  return 0;

}

static void

print_signed_octal (int n, disassemble_info *info)

{

  if (n < 0)

    FPRINTF (F, "-%o", -n);

  else

    FPRINTF (F, "%o", n);

}

static void

print_reg (int reg, disassemble_info *info)

{

  /* Mask off the addressing mode, if any.  */

  reg &= 7;

  switch (reg)

    {

    case 0: case 1: case 2: case 3: case 4: case 5:

    FPRINTF (F, "r%d", reg); break;

    case 6: FPRINTF (F, "sp"); break;

    case 7: FPRINTF (F, "pc"); break;

    default: ;  /* error */

    }

}

static void

print_freg (int freg, disassemble_info *info)

{

  FPRINTF (F, "fr%d", freg);

}

static int

print_operand (bfd_vma *memaddr, int code, disassemble_info *info)

{

  int mode = (code >> 3) & 7;

  int reg = code & 7;

  int disp;

  switch (mode)

    {

    case 0:

      print_reg (reg, info);

      break;

    case 1:

      FPRINTF (F, "(");

      print_reg (reg, info);

      FPRINTF (F, ")");

      break;

    case 2:

      if (reg == 7)

  {

    int data;

    if (read_word (*memaddr, &data, info) < 0)

      return -1;

    FPRINTF (F, "$");

    print_signed_octal (sign_extend (data), info);

    *memaddr += 2;

  }

      else

  {

    FPRINTF (F, "(");

    print_reg (reg, info);

    FPRINTF (F, ")+");

  }

  break;

    case 3:

      if (reg == 7)

  {

    int address;

    if (read_word (*memaddr, &address, info) < 0)

      return -1;

    FPRINTF (F, "*$%o", address);

    *memaddr += 2;

  }

      else

  {

    FPRINTF (F, "*(");

    print_reg (reg, info);

    FPRINTF (F, ")+");

  }

  break;

    case 4:

      FPRINTF (F, "-(");

      print_reg (reg, info);

      FPRINTF (F, ")");

      break;

    case 5:

      FPRINTF (F, "*-(");

      print_reg (reg, info);

      FPRINTF (F, ")");

      break;

    case 6:

    case 7:

      if (read_word (*memaddr, &disp, info) < 0)

  return -1;

      *memaddr += 2;

      if (reg == 7)

  {

    bfd_vma address = *memaddr + sign_extend (disp);

    if (mode == 7)

      FPRINTF (F, "*");

    if (!(code & JUMP))

      FPRINTF (F, "$");

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

  }

      else

  {

    if (mode == 7)

      FPRINTF (F, "*");

    print_signed_octal (sign_extend (disp), info);

    FPRINTF (F, "(");

    print_reg (reg, info);

    FPRINTF (F, ")");

  }

      break;

    }

  return 0;

}

static int

print_foperand (bfd_vma *memaddr, int code, disassemble_info *info)

{

  int mode = (code >> 3) & 7;

  int reg = code & 7;

  if (mode == 0)

    print_freg (reg, info);

  else

    return print_operand (memaddr, code, info);

  return 0;

}

/* Print the PDP-11 instruction at address MEMADDR in debugged memory,

   on INFO->STREAM.  Returns length of the instruction, in bytes.  */

int

print_insn_pdp11 (bfd_vma memaddr, disassemble_info *info)

{

  bfd_vma start_memaddr = memaddr;

  int opcode;

  int src, dst;

  int i;

  info->bytes_per_line = 6;

  info->bytes_per_chunk = 2;

  info->display_endian = BFD_ENDIAN_LITTLE;

  if (read_word (memaddr, &opcode, info) != 0)

    return -1;

  memaddr += 2;

  src = (opcode >> 6) & 0x3f;

  dst = opcode & 0x3f;

  for (i = 0; i < pdp11_num_opcodes; i++)

    {

#define OP pdp11_opcodes[i]

      if ((opcode & OP.mask) == OP.opcode)

  switch (OP.type)

    {

    case PDP11_OPCODE_NO_OPS:

      FPRINTF (F, "%s", OP.name);

      goto done;

    case PDP11_OPCODE_REG:

      FPRINTF (F, "%s", OP.name);

      FPRINTF (F, AFTER_INSTRUCTION);

      print_reg (dst, info);

      goto done;

    case PDP11_OPCODE_OP:

      FPRINTF (F, "%s", OP.name);

      FPRINTF (F, AFTER_INSTRUCTION);

      if (strcmp (OP.name, "jmp") == 0)

        dst |= JUMP;

      if (print_operand (&memaddr, dst, info) < 0)

        return -1;

      goto done;

    case PDP11_OPCODE_FOP:

      FPRINTF (F, "%s", OP.name);

      FPRINTF (F, AFTER_INSTRUCTION);

      if (strcmp (OP.name, "jmp") == 0)

        dst |= JUMP;

      if (print_foperand (&memaddr, dst, info) < 0)

        return -1;

      goto done;

    case PDP11_OPCODE_REG_OP:

      FPRINTF (F, "%s", OP.name);

      FPRINTF (F, AFTER_INSTRUCTION);

      print_reg (src, info);

      FPRINTF (F, OPERAND_SEPARATOR);

      if (strcmp (OP.name, "jsr") == 0)

        dst |= JUMP;

      if (print_operand (&memaddr, dst, info) < 0)

        return -1;

      goto done;

    case PDP11_OPCODE_REG_OP_REV:

      FPRINTF (F, "%s", OP.name);

      FPRINTF (F, AFTER_INSTRUCTION);

      if (print_operand (&memaddr, dst, info) < 0)

        return -1;

      FPRINTF (F, OPERAND_SEPARATOR);

      print_reg (src, info);

      goto done;

    case PDP11_OPCODE_AC_FOP:

      {

        int ac = (opcode & 0xe0) >> 6;

        FPRINTF (F, "%s", OP.name);

        FPRINTF (F, AFTER_INSTRUCTION);

        print_freg (ac, info);

        FPRINTF (F, OPERAND_SEPARATOR);

        if (print_foperand (&memaddr, dst, info) < 0)

    return -1;

        goto done;

      }

    case PDP11_OPCODE_FOP_AC:

      {

        int ac = (opcode & 0xe0) >> 6;

        FPRINTF (F, "%s", OP.name);

        FPRINTF (F, AFTER_INSTRUCTION);

        if (print_foperand (&memaddr, dst, info) < 0)

    return -1;

        FPRINTF (F, OPERAND_SEPARATOR);

        print_freg (ac, info);

        goto done;

      }

    case PDP11_OPCODE_AC_OP:

      {

        int ac = (opcode & 0xe0) >> 6;

        FPRINTF (F, "%s", OP.name);

        FPRINTF (F, AFTER_INSTRUCTION);

        print_freg (ac, info);

        FPRINTF (F, OPERAND_SEPARATOR);

        if (print_operand (&memaddr, dst, info) < 0)

    return -1;

        goto done;

      }

    case PDP11_OPCODE_OP_AC:

      {

        int ac = (opcode & 0xe0) >> 6;

        FPRINTF (F, "%s", OP.name);

        FPRINTF (F, AFTER_INSTRUCTION);

        if (print_operand (&memaddr, dst, info) < 0)

    return -1;

        FPRINTF (F, OPERAND_SEPARATOR);

        print_freg (ac, info);

        goto done;

      }

    case PDP11_OPCODE_OP_OP:

      FPRINTF (F, "%s", OP.name);

      FPRINTF (F, AFTER_INSTRUCTION);

      if (print_operand (&memaddr, src, info) < 0)

        return -1;

      FPRINTF (F, OPERAND_SEPARATOR);

      if (print_operand (&memaddr, dst, info) < 0)

        return -1;

      goto done;

    case PDP11_OPCODE_DISPL:

      {

        int displ = (opcode & 0xff) << 8;

        bfd_vma address = memaddr + (sign_extend (displ) >> 7);

        FPRINTF (F, "%s", OP.name);

        FPRINTF (F, AFTER_INSTRUCTION);

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

        goto done;

      }

    case PDP11_OPCODE_REG_DISPL:

      {

        int displ = (opcode & 0x3f) << 10;

        bfd_vma address = memaddr - (displ >> 9);

        FPRINTF (F, "%s", OP.name);

        FPRINTF (F, AFTER_INSTRUCTION);

        print_reg (src, info);

        FPRINTF (F, OPERAND_SEPARATOR);

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

        goto done;

      }

    case PDP11_OPCODE_IMM8:

      {

        int code = opcode & 0xff;

        FPRINTF (F, "%s", OP.name);

        FPRINTF (F, AFTER_INSTRUCTION);

        FPRINTF (F, "%o", code);

        goto done;

      }

    case PDP11_OPCODE_IMM6:

      {

        int code = opcode & 0x3f;

        FPRINTF (F, "%s", OP.name);

        FPRINTF (F, AFTER_INSTRUCTION);

        FPRINTF (F, "%o", code);

        goto done;

      }

    case PDP11_OPCODE_IMM3:

      {

        int code = opcode & 7;

        FPRINTF (F, "%s", OP.name);

        FPRINTF (F, AFTER_INSTRUCTION);

        FPRINTF (F, "%o", code);

        goto done;

      }

    case PDP11_OPCODE_ILLEGAL:

      {

        FPRINTF (F, ".word");

        FPRINTF (F, AFTER_INSTRUCTION);

        FPRINTF (F, "%o", opcode);

        goto done;

      }

    default:

      /* TODO: is this a proper way of signalling an error? */

      FPRINTF (F, "<internal error: unrecognized instruction type>");

      return -1;

    }

#undef OP

    }

 done:

  return memaddr - start_memaddr;

}