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

   Copyright 2000, 2001 Free Software Foundation, Inc.

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

   This file is part of GDB, GAS and the GNU binutils.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 2 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA

   02111-1307, USA.  */

#include <stdio.h>

#include "ansidecl.h"

#include "sysdep.h"

#include "dis-asm.h"

#include "opcode/s390.h"

static int init_flag = 0;

static int opc_index[256];

static int current_arch_mask = 0;

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

static void

init_disasm(info)

    struct disassemble_info *info ATTRIBUTE_UNUSED;

{

  const struct s390_opcode *opcode;

  const struct s390_opcode *opcode_end;

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

  opcode_end = s390_opcodes + s390_num_opcodes;

  for (opcode = s390_opcodes; opcode < opcode_end; opcode++) {

    opc_index[(int) opcode->opcode[0]] = opcode - s390_opcodes;

    while ((opcode < opcode_end) &&

           (opcode[1].opcode[0] == opcode->opcode[0]))

      opcode++;

  }

  switch (info->mach) {

  case bfd_mach_s390_esa:

    current_arch_mask = 1 << S390_OPCODE_ESA;

    break;

  case bfd_mach_s390_esame:

    current_arch_mask = 1 << S390_OPCODE_ESAME;

    break;

  default:

    abort();

  }

  init_flag = 1;

}

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

static inline unsigned int

s390_extract_operand (insn, operand)

     unsigned char *insn;

     const struct s390_operand *operand;

{

  unsigned int val;

  int bits;

  /* 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;

  /* sign extend value if the operand is signed or pc relative */

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

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

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

  /* double value if the operand is pc relative */

  if (operand->flags & S390_OPERAND_PCREL)

    val <<= 1;

  /* length x in an instructions has real length x+1 */

  if (operand->flags & S390_OPERAND_LENGTH)

    val++;

  return val;

}

/* Print a S390 instruction.  */

int

print_insn_s390 (memaddr, info)

     bfd_vma memaddr;

     struct disassemble_info *info;

{

  bfd_byte buffer[6];

  const struct s390_opcode *opcode;

  const struct s390_opcode *opcode_end;

  unsigned int value;

  int status, opsize, bufsize;

  char separator;

  if (init_flag == 0)

    init_disasm(info);

  /* 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 calculation looks strange but it works

       00xxxxxx -> 2 bytes, 01xxxxxx/10xxxxxx -> 4 bytes,

       11xxxxxx -> 6 bytes.  */

    opsize = ((((buffer[0]>>6)+1)>>1)+1)<<1;

    status = opsize > bufsize;

  } else {

    bufsize = 6;

    opsize = ((((buffer[0]>>6)+1)>>1)+1)<<1;

  }

  if (status == 0) {

    /* Find the first match in the opcode table.  */

    opcode_end = s390_opcodes + s390_num_opcodes;

    for (opcode = s390_opcodes + opc_index[(int) buffer[0]];

         (opcode < opcode_end) && (buffer[0] == opcode->opcode[0]);

         opcode++) {

      const struct s390_operand *operand;

      const unsigned char *opindex;

      /* check architecture */

      if (!(opcode->architecture & current_arch_mask))

        continue;

      /* check signature of the opcode */

      if ((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])

        continue;

      /* the instruction is valid */

      if (opcode->operands[0] != 0)

        (*info->fprintf_func) (info->stream, "%s\t", opcode->name);

      else

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

      /* Extract the operands.  */

      separator = 0;

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

        unsigned int value;

        operand = s390_operands + *opindex;

        value = s390_extract_operand(buffer, operand);

        if ((operand->flags & S390_OPERAND_INDEX) && value == 0)

          continue;

        if ((operand->flags & S390_OPERAND_BASE) &&

            value == 0 && separator == '(') {

          separator = ',';

          continue;

        }

        if (separator)

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

        if (operand->flags & S390_OPERAND_GPR)

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

        else if (operand->flags & S390_OPERAND_FPR)

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

        else if (operand->flags & S390_OPERAND_AR)

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

        else if (operand->flags & S390_OPERAND_CR)

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

        else if (operand->flags & S390_OPERAND_PCREL)

          (*info->print_address_func) (memaddr + (int) value, info);

        else if (operand->flags & S390_OPERAND_SIGNED)

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

        else

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

        if (operand->flags & S390_OPERAND_DISP) {

          separator = '(';

        } else if (operand->flags & S390_OPERAND_BASE) {

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

          separator = ',';

        } else

          separator = ',';

      }

      /* found instruction, printed it, return its size */

      return opsize;

    }

    /* no matching instruction found, fall through to hex print  */

  }

  if (bufsize >= 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_func) (info->stream,".long\t0x%08x", value);

    return 4;

  } else if (bufsize >= 2) {

    value = (unsigned int) buffer[0];

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

    (*info->fprintf_func) (info->stream,".short\t0x%04x", value);

    return 2;

  } else {

    value = (unsigned int) buffer[0];

    (*info->fprintf_func) (info->stream,".byte\t0x%02x", value);

    return 1;

  }

}