/* s390-dis.c -- Disassemble S390 instructions

   Copyright (C) 2000-2023 Free Software Foundation, Inc.

   Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).

   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 <stdio.h>

#include "ansidecl.h"

#include "disassemble.h"

#include "opintl.h"

#include "opcode/s390.h"

#include "libiberty.h"

static int opc_index[256];

static int current_arch_mask = 0;

static int option_use_insn_len_bits_p = 0;

typedef struct

{

  const char *name;

  const char *description;

} s390_options_t;

static const s390_options_t options[] =

{

  { "esa" ,       N_("Disassemble in ESA architecture mode") },

  { "zarch",      N_("Disassemble in z/Architecture mode") },

  { "insnlength", N_("Print unknown instructions according to "

         "length from first two bits") }

};

/* Set up index table for first opcode byte.  */

void

disassemble_init_s390 (struct disassemble_info *info)

{

  int i;

  const char *p;

  memset (opc_index, 0, sizeof (opc_index));

  /* Reverse order, such that each opc_index ends up pointing to the

     first matching entry instead of the last.  */

  for (i = s390_num_opcodes; i--; )

    opc_index[s390_opcodes[i].opcode[0]] = i;

  current_arch_mask = 1 << S390_OPCODE_ZARCH;

  option_use_insn_len_bits_p = 0;

  for (p = info->disassembler_options; p != NULL; )

    {

      if (startswith (p, "esa"))

  current_arch_mask = 1 << S390_OPCODE_ESA;

      else if (startswith (p, "zarch"))

  current_arch_mask = 1 << S390_OPCODE_ZARCH;

      else if (startswith (p, "insnlength"))

  option_use_insn_len_bits_p = 1;

      else

  /* xgettext:c-format */

  opcodes_error_handler (_("unknown S/390 disassembler option: %s"), p);

      p = strchr (p, ',');

      if (p != NULL)

  p++;

    }

}

/* Derive the length of an instruction from its first byte.  */

static inline int

s390_insn_length (const bfd_byte *buffer)

{

  /* 00xxxxxx -> 2, 01xxxxxx/10xxxxxx -> 4, 11xxxxxx -> 6.  */

  return ((buffer[0] >> 6) + 3) & ~1U;

}

/* Match the instruction in BUFFER against the given OPCODE, excluding

   the first byte.  */

static inline int

s390_insn_matches_opcode (const bfd_byte *buffer,

        const struct s390_opcode *opcode)

{

  return (buffer[1] & opcode->mask[1]) == opcode->opcode[1]

    && (buffer[2] & opcode->mask[2]) == opcode->opcode[2]

    && (buffer[3] & opcode->mask[3]) == opcode->opcode[3]

    && (buffer[4] & opcode->mask[4]) == opcode->opcode[4]

    && (buffer[5] & opcode->mask[5]) == opcode->opcode[5];

}

union operand_value

{

  int i;

  unsigned int u;

};

/* Extracts an operand value from an instruction.  */

/* We do not perform the shift operation for larl-type address

   operands here since that would lead to an overflow of the 32 bit

   integer value.  Instead the shift operation is done when printing

   the operand.  */

static inline union operand_value

s390_extract_operand (const bfd_byte *insn,

          const struct s390_operand *operand)

{

  union operand_value ret;

  unsigned int val;

  int bits;

  const bfd_byte *orig_insn = insn;

  /* Extract fragments of the operand byte for byte.  */

  insn += operand->shift / 8;

  bits = (operand->shift & 7) + operand->bits;

  val = 0;

  do

    {

      val <<= 8;

      val |= (unsigned int) *insn++;

      bits -= 8;

    }

  while (bits > 0);

  val >>= -bits;

  val &= ((1U << (operand->bits - 1)) << 1) - 1;

  /* Check for special long displacement case.  */

  if (operand->bits == 20 && operand->shift == 20)

    val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;

  /* Sign extend value if the operand is signed or pc relative.  Avoid

     integer overflows.  */

  if (operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))

    {

      unsigned int m = 1U << (operand->bits - 1);

      if (val >= m)

  ret.i = (int) (val - m) - 1 - (int) (m - 1U);

      else

  ret.i = (int) val;

    }

  else if (operand->flags & S390_OPERAND_LENGTH)

    /* Length x in an instruction has real length x + 1.  */

    ret.u = val + 1;

  else if (operand->flags & S390_OPERAND_VR)

    {

      /* Extract the extra bits for a vector register operand stored

   in the RXB field.  */

      unsigned vr = operand->shift == 32 ? 3

  : (unsigned) operand->shift / 4 - 2;

      ret.u = val | ((orig_insn[4] & (1 << (3 - vr))) << (vr + 1));

    }

  else

    ret.u = val;

  return ret;

}

/* Print the S390 instruction in BUFFER, assuming that it matches the

   given OPCODE.  */

static void

s390_print_insn_with_opcode (bfd_vma memaddr,

           struct disassemble_info *info,

           const bfd_byte *buffer,

           const struct s390_opcode *opcode)

{

  const unsigned char *opindex;

  char separator;

  /* Mnemonic.  */

  info->fprintf_styled_func (info->stream, dis_style_mnemonic,

           "%s", opcode->name);

  /* Operands.  */

  separator = '\t';

  for (opindex = opcode->operands; *opindex != 0; opindex++)

    {

      const struct s390_operand *operand = s390_operands + *opindex;

      union operand_value val = s390_extract_operand (buffer, operand);

      unsigned long flags = operand->flags;

      if ((flags & S390_OPERAND_INDEX) && val.u == 0)

  continue;

      if ((flags & S390_OPERAND_BASE) &&

    val.u == 0 && separator == '(')

  {

    separator = ',';

    continue;

  }

      /* For instructions with a last optional operand don't print it

   if zero.  */

      if ((opcode->flags & (S390_INSTR_FLAG_OPTPARM | S390_INSTR_FLAG_OPTPARM2))

    && val.u == 0

    && opindex[1] == 0)

  break;

      if ((opcode->flags & S390_INSTR_FLAG_OPTPARM2)

    && val.u == 0 && opindex[1] != 0 && opindex[2] == 0)

  {

    union operand_value next_op_val =

      s390_extract_operand (buffer, s390_operands + opindex[1]);

    if (next_op_val.u == 0)

      break;

  }

      if (flags & S390_OPERAND_GPR)

  {

    info->fprintf_styled_func (info->stream, dis_style_text,

             "%c", separator);

    info->fprintf_styled_func (info->stream, dis_style_register,

             "%%r%u", val.u);

  }

      else if (flags & S390_OPERAND_FPR)

  {

    info->fprintf_styled_func (info->stream, dis_style_text,

             "%c", separator);

    info->fprintf_styled_func (info->stream, dis_style_register,

             "%%f%u", val.u);

  }

      else if (flags & S390_OPERAND_VR)

  {

    info->fprintf_styled_func (info->stream, dis_style_text,

             "%c", separator);

    info->fprintf_styled_func (info->stream, dis_style_register,

             "%%v%i", val.u);

  }

      else if (flags & S390_OPERAND_AR)

  {

    info->fprintf_styled_func (info->stream, dis_style_text,

             "%c", separator);

    info->fprintf_styled_func (info->stream, dis_style_register,

             "%%a%u", val.u);

  }

      else if (flags & S390_OPERAND_CR)

  {

    info->fprintf_styled_func (info->stream, dis_style_text,

             "%c", separator);

    info->fprintf_styled_func (info->stream, dis_style_register,

             "%%c%u", val.u);

  }

      else if (flags & S390_OPERAND_PCREL)

  {

    info->fprintf_styled_func (info->stream, dis_style_text,

             "%c", separator);

    info->print_address_func (memaddr + val.i + val.i, info);

  }

      else if (flags & S390_OPERAND_SIGNED)

  {

    enum disassembler_style style;

    info->fprintf_styled_func (info->stream, dis_style_text,

             "%c", separator);

    style = ((flags & S390_OPERAND_DISP)

       ? dis_style_address_offset : dis_style_immediate);

    info->fprintf_styled_func (info->stream, style, "%i", val.i);

  }

      else

  {

    enum disassembler_style style;

    if (flags & S390_OPERAND_OR1)

      val.u &= ~1;

    if (flags & S390_OPERAND_OR2)

      val.u &= ~2;

    if (flags & S390_OPERAND_OR8)

      val.u &= ~8;

    if ((opcode->flags & S390_INSTR_FLAG_OPTPARM)

        && val.u == 0

        && opindex[1] == 0)

      break;

    info->fprintf_styled_func (info->stream, dis_style_text,

             "%c", separator);

    style = ((flags & S390_OPERAND_DISP)

       ? dis_style_address_offset : dis_style_immediate);

    info->fprintf_styled_func (info->stream, style, "%u", val.u);

  }

      if (flags & S390_OPERAND_DISP)

  separator = '(';

      else if (flags & S390_OPERAND_BASE)

  {

    info->fprintf_styled_func (info->stream, dis_style_text, ")");

    separator = ',';

  }

      else

  separator = ',';

    }

}

/* Check whether opcode A's mask is more specific than that of B.  */

static int

opcode_mask_more_specific (const struct s390_opcode *a,

         const struct s390_opcode *b)

{

  return (((int) a->mask[0] + a->mask[1] + a->mask[2]

     + a->mask[3] + a->mask[4] + a->mask[5])

    > ((int) b->mask[0] + b->mask[1] + b->mask[2]

       + b->mask[3] + b->mask[4] + b->mask[5]));

}

/* Print a S390 instruction.  */

int

print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)

{

  bfd_byte buffer[6];

  const struct s390_opcode *opcode = NULL;

  unsigned int value;

  int status, opsize, bufsize, bytes_to_dump, i;

  /* The output looks better if we put 6 bytes on a line.  */

  info->bytes_per_line = 6;

  /* Every S390 instruction is max 6 bytes long.  */

  memset (buffer, 0, 6);

  status = info->read_memory_func (memaddr, buffer, 6, info);

  if (status != 0)

    {

      for (bufsize = 0; bufsize < 6; bufsize++)

  if (info->read_memory_func (memaddr, buffer, bufsize + 1, info) != 0)

    break;

      if (bufsize <= 0)

  {

    info->memory_error_func (status, memaddr, info);

    return -1;

  }

      opsize = s390_insn_length (buffer);

      status = opsize > bufsize;

    }

  else

    {

      bufsize = 6;

      opsize = s390_insn_length (buffer);

    }

  if (status == 0)

    {

      const struct s390_opcode *op;

      /* Find the "best match" in the opcode table.  */

      for (op = s390_opcodes + opc_index[buffer[0]];

     op != s390_opcodes + s390_num_opcodes

       && op->opcode[0] == buffer[0];

     op++)

  {

    if ((op->modes & current_arch_mask)

        && s390_insn_matches_opcode (buffer, op)

        && (opcode == NULL

      || opcode_mask_more_specific (op, opcode)))

      opcode = op;

  }

      if (opcode != NULL)

  {

    /* The instruction is valid.  Print it and return its size.  */

    s390_print_insn_with_opcode (memaddr, info, buffer, opcode);

    return opsize;

  }

    }

  /* For code sections it makes sense to skip unknown instructions

     according to their length bits.  */

  if (status == 0

      && option_use_insn_len_bits_p

      && info->section != NULL

      && (info->section->flags & SEC_CODE))

    bytes_to_dump = opsize;

  else

    /* By default unknown instructions are printed as .long's/.short'

       depending on how many bytes are available.  */

    bytes_to_dump = bufsize >= 4 ? 4 : bufsize;

  if (bytes_to_dump == 0)

    return 0;

  /* Fall back to hex print.  */

  switch (bytes_to_dump)

    {

    case 4:

      value = (unsigned int) buffer[0];

      value = (value << 8) + (unsigned int) buffer[1];

      value = (value << 8) + (unsigned int) buffer[2];

      value = (value << 8) + (unsigned int) buffer[3];

      info->fprintf_styled_func (info->stream, dis_style_assembler_directive,

         ".long");

      info->fprintf_styled_func (info->stream, dis_style_text,

         "\t");

      info->fprintf_styled_func (info->stream, dis_style_immediate,

         "0x%08x", value);

      return 4;

    case 2:

      value = (unsigned int) buffer[0];

      value = (value << 8) + (unsigned int) buffer[1];

      info->fprintf_styled_func (info->stream, dis_style_assembler_directive,

         ".short");

      info->fprintf_styled_func (info->stream, dis_style_text,

         "\t");

      info->fprintf_styled_func (info->stream, dis_style_immediate,

         "0x%04x", value);

      return 2;

    default:

      info->fprintf_styled_func (info->stream, dis_style_assembler_directive,

         ".byte");

      info->fprintf_styled_func (info->stream, dis_style_text,

         "\t");

      info->fprintf_styled_func (info->stream, dis_style_immediate,

         "0x%02x", (unsigned int) buffer[0]);

      for (i = 1; i < bytes_to_dump; i++)

  info->fprintf_styled_func (info->stream, dis_style_immediate,

           "0x%02x", (unsigned int) buffer[i]);

      return bytes_to_dump;

    }

  return 0;

}

const disasm_options_and_args_t *

disassembler_options_s390 (void)

{

  static disasm_options_and_args_t *opts_and_args;

  if (opts_and_args == NULL)

    {

      size_t i, num_options = ARRAY_SIZE (options);

      disasm_options_t *opts;

      opts_and_args = XNEW (disasm_options_and_args_t);

      opts_and_args->args = NULL;

      opts = &opts_and_args->options;

      opts->name = XNEWVEC (const char *, num_options + 1);

      opts->description = XNEWVEC (const char *, num_options + 1);

      opts->arg = NULL;

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

  {

    opts->name[i] = options[i].name;

    opts->description[i] = _(options[i].description);

  }

      /* The array we return must be NULL terminated.  */

      opts->name[i] = NULL;

      opts->description[i] = NULL;

    }

  return opts_and_args;

}

void

print_s390_disassembler_options (FILE *stream)

{

  unsigned int i, max_len = 0;

  fprintf (stream, _("\n\

The following S/390 specific disassembler options are supported for use\n\

with the -M switch (multiple options should be separated by commas):\n"));

  for (i = 0; i < ARRAY_SIZE (options); i++)

    {

      unsigned int len = strlen (options[i].name);

      if (max_len < len)

  max_len = len;

    }

  for (i = 0, max_len++; i < ARRAY_SIZE (options); i++)

    fprintf (stream, "  %s%*c %s\n",

       options[i].name,

       (int)(max_len - strlen (options[i].name)), ' ',

       _(options[i].description));

}