/* xgate-dis.c -- Freescale XGATE disassembly

   Copyright (C) 2009-2023 Free Software Foundation, Inc.

   Written by Sean Keys (skeys@ipdatasys.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 program; if not, write to the Free Software

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

   MA 02110-1301, USA.  */

#include "sysdep.h"

#include <assert.h>

#include "disassemble.h"

#include "opintl.h"

#include "libiberty.h"

#include "ansidecl.h"

#include "opcode/xgate.h"

#define XGATE_TWO_BYTES      0x02

#define XGATE_NINE_BITS      0x1FF

#define XGATE_TEN_BITS       0x3FF

#define XGATE_NINE_SIGNBIT   0x100

#define XGATE_TEN_SIGNBIT    0x200

/* Structures.  */

struct decodeInfo

{

  unsigned int operMask;

  unsigned int operMasksRegisterBits;

  struct xgate_opcode *opcodePTR;

};

/* Prototypes for local functions.  */

static int print_insn (bfd_vma, struct disassemble_info *);

static int read_memory (bfd_vma, bfd_byte*, int, struct disassemble_info *);

static int ripBits (unsigned int *, int,

        struct xgate_opcode *, unsigned int);

static int macro_search (char *, char *);

static struct decodeInfo * find_match (unsigned int);

/* Statics.  */

static struct decodeInfo *decodeTable;

static int initialized;

static char previousOpName[10];

static unsigned int perviousBin;

/* Disassemble one instruction at address 'memaddr'.  Returns the number

   of bytes used by that instruction.  */

static int

print_insn (bfd_vma memaddr, struct disassemble_info* info)

{

  int status;

  unsigned int raw_code;

  char *s = 0;

  long bytesRead = 0;

  int i = 0;

  struct xgate_opcode *opcodePTR = (struct xgate_opcode*) xgate_opcodes;

  struct decodeInfo *decodeTablePTR = 0;

  struct decodeInfo *decodePTR = 0;

  unsigned int operandRegisterBits = 0;

  signed int relAddr = 0;

  signed int operandOne = 0;

  signed int operandTwo = 0;

  bfd_byte buffer[4];

  bfd_vma absAddress;

  unsigned int operMaskReg = 0;

  /* Initialize our array of opcode masks and check them against our constant

     table.  */

  if (!initialized)

    {

      decodeTable = xmalloc (sizeof (struct decodeInfo) * xgate_num_opcodes);

      for (i = 0, decodeTablePTR = decodeTable; i < xgate_num_opcodes;

          i++, decodeTablePTR++, opcodePTR++)

        {

          unsigned int bin = 0;

          unsigned int mask = 0;

          for (s = opcodePTR->format; *s; s++)

            {

              bin <<= 1;

              mask <<= 1;

              operandRegisterBits <<= 1;

              bin |= (*s == '1');

              mask |= (*s == '0' || *s == '1');

              operandRegisterBits |= (*s == 'r');

            }

          /* Asserting will uncover inconsistencies in our table.  */

          assert ((s - opcodePTR->format) == 16 || (s - opcodePTR->format) == 32);

          assert (opcodePTR->bin_opcode == bin);

          decodeTablePTR->operMask = mask;

          decodeTablePTR->operMasksRegisterBits = operandRegisterBits;

          decodeTablePTR->opcodePTR = opcodePTR;

        }

      initialized = 1;

    }

  /* Read 16 bits.  */

  bytesRead += XGATE_TWO_BYTES;

  status = read_memory (memaddr, buffer, XGATE_TWO_BYTES, info);

  if (status == 0)

    {

      raw_code = buffer[0];

      raw_code <<= 8;

      raw_code += buffer[1];

      decodePTR = find_match (raw_code);

      if (decodePTR)

        {

          operMaskReg = decodePTR->operMasksRegisterBits;

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

          /* First we compare the shorthand format of the constraints. If we

        still are unable to pinpoint the operands

        we analyze the opcodes constraint string.  */

          if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_MON_R_C))

          {

            (*info->fprintf_func)(info->stream, " R%x, CCR",

              (raw_code >> 8) & 0x7);

          }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_MON_C_R))

            {

            (*info->fprintf_func)(info->stream, " CCR, R%x",

                (raw_code >> 8) & 0x7);

            }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_MON_R_P))

            {

            (*info->fprintf_func)(info->stream, " R%x, PC",

                (raw_code >> 8) & 0x7);

            }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_TRI))

            {

                  (*info->fprintf_func)(info->stream, " R%x, R%x, R%x",

                      (raw_code >> 8) & 0x7, (raw_code >> 5) & 0x7,

                      (raw_code >> 2) & 0x7);

            }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_IDR))

            {

                  if (raw_code & 0x01)

                    {

                      (*info->fprintf_func)(info->stream, " R%x, (R%x, R%x+)",

                          (raw_code >> 8) & 0x7, (raw_code >> 5) & 0x7,

                          (raw_code >> 2) & 0x7);

                    }

                   else if (raw_code & 0x02)

                          {

                            (*info->fprintf_func)(info->stream, " R%x, (R%x, -R%x)",

                                (raw_code >> 8) & 0x7, (raw_code >> 5) & 0x7,

                                (raw_code >> 2) & 0x7);

                          }

                   else

                     {

                       (*info->fprintf_func)(info->stream, " R%x, (R%x, R%x)",

                           (raw_code >> 8) & 0x7, (raw_code >> 5) & 0x7,

                           (raw_code >> 2) & 0x7);

                     }

            }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_DYA))

            {

            operandOne = ripBits (&operMaskReg, 3, decodePTR->opcodePTR, raw_code);

            operandTwo = ripBits (&operMaskReg, 3, decodePTR->opcodePTR, raw_code);

           ( *info->fprintf_func)(info->stream, " R%x, R%x", operandOne,

                operandTwo);

            }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_IDO5))

            {

            (*info->fprintf_func)(info->stream, " R%x, (R%x, #0x%x)",

                (raw_code >> 8) & 0x7, (raw_code >> 5) & 0x7, raw_code & 0x1f);

            }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_MON))

            {

            operandOne = ripBits (&operMaskReg, 3, decodePTR->opcodePTR,

               raw_code);

           (*info->fprintf_func)(info->stream, " R%x", operandOne);

            }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_REL9))

            {

              /* If address is negative handle it accordingly.  */

              if (raw_code & XGATE_NINE_SIGNBIT)

                {

                  relAddr = XGATE_NINE_BITS >> 1; /* Clip sign bit.  */

                  relAddr = ~relAddr; /* Make signed.  */

                  relAddr |= (raw_code & 0xFF) + 1; /* Apply our value.  */

                  relAddr *= 2; /* Multiply by two as per processor docs.  */

                }

              else

                {

                  relAddr = raw_code & 0xff;

                  relAddr = relAddr * 2 + 2;

                }

             (*info->fprintf_func)(info->stream, " *%d", relAddr);

             (*info->fprintf_func)(info->stream, "  Abs* 0x");

             (*info->print_address_func)(memaddr + relAddr, info);

           }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_REL10))

            {

              /* If address is negative handle it accordingly.  */

              if (raw_code & XGATE_TEN_SIGNBIT)

                {

                  relAddr = XGATE_TEN_BITS >> 1; /* Clip sign bit.  */

                  relAddr = ~relAddr; /* Make signed.  */

                  relAddr |= (raw_code & 0x1FF) + 1; /* Apply our value.  */

                  relAddr *= 2; /* Multiply by two as per processor docs.  */

                }

              else

                {

                  relAddr = raw_code & 0x1FF;

                  relAddr = relAddr * 2 + 2;

                }

              (*info->fprintf_func)(info->stream, " *%d", relAddr);

              (*info->fprintf_func)(info->stream, "  Abs* 0x");

              (*info->print_address_func)(memaddr + relAddr, info);

            }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_IMM4))

            {

              (*info->fprintf_func)(info->stream, " R%x, #0x%02x",

              (raw_code >> 8) & 0x7, (raw_code >> 4) & 0xF);

            }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_IMM8))

            {

              if (macro_search (decodePTR->opcodePTR->name, previousOpName) &&

                 previousOpName[0])

               {

                 absAddress = (0xFF & raw_code) << 8;

                 absAddress |= perviousBin & 0xFF;

                 (*info->fprintf_func)(info->stream, " R%x, #0x%02x Abs* 0x",

                     (raw_code >> 8) & 0x7, raw_code & 0xff);

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

                 previousOpName[0] = 0;

               }

              else

               {

                 strcpy (previousOpName, decodePTR->opcodePTR->name);

                 (*info->fprintf_func)(info->stream, " R%x, #0x%02x",

                     (raw_code >> 8) & 0x7, raw_code & 0xff);

               }

            }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_IMM3))

            {

            (*info->fprintf_func)(info->stream, " #0x%x",

               (raw_code >> 8) & 0x7);

            }

          else if (!strcmp (decodePTR->opcodePTR->constraints, XGATE_OP_INH))

            {

            }

          else

            {

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

            decodePTR->opcodePTR->constraints);

            }

          perviousBin = raw_code;

        }

      else

        {

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

        " unable to find opcode match #0%x", raw_code);

        }

    }

  return bytesRead;

}

int

print_insn_xgate (bfd_vma memaddr, struct disassemble_info* info)

{

  return print_insn (memaddr, info);

}

static int

read_memory (bfd_vma memaddr, bfd_byte* buffer, int size,

    struct disassemble_info* info)

{

  int status;

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

  if (status != 0)

    {

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

      return -1;

    }

  return 0;

}

static int

ripBits (unsigned int *operandBitsRemaining,

   int numBitsRequested,

   struct xgate_opcode *opcodePTR,

   unsigned int memory)

{

  unsigned int currentBit;

  unsigned int operand = 0;

  int numBitsFound;

  for (numBitsFound = 0, currentBit = 1u << ((opcodePTR->size * 8) - 1);

       numBitsFound < numBitsRequested && currentBit != 0;

       currentBit >>= 1)

    {

      if (currentBit & *operandBitsRemaining)

  {

    *operandBitsRemaining &= ~(currentBit); /* Consume the current bit.  */

    operand <<= 1; /* Make room for our next bit.  */

    numBitsFound++;

    operand |= (currentBit & memory) > 0;

  }

    }

  return operand;

}

static int

macro_search (char *currentName, char *lastName)

{

  int i;

  int length = 0;

  char *where;

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

    {

      where = strstr (xgate_opcodes[i].constraints, lastName);

      if (where)

        {

          length = strlen (where);

        }

      if (length)

        {

          where = strstr (xgate_opcodes[i].constraints, currentName);

          if (where)

            {

              length = strlen (where);

              return 1;

            }

        }

    }

  return 0;

}

static struct decodeInfo *

find_match (unsigned int raw_code)

{

  struct decodeInfo *decodeTablePTR = 0;

  int i;

  for (i = 0, decodeTablePTR = decodeTable; i < xgate_num_opcodes;

      i++, decodeTablePTR++)

    {

      if ((raw_code & decodeTablePTR->operMask)

          == decodeTablePTR->opcodePTR->bin_opcode)

        {

          /* Make sure we didn't run into a macro or alias.  */

          if (decodeTablePTR->opcodePTR->cycles_min != 0)

            {

              return decodeTablePTR;

              break;

            }

          else

      continue;

        }

    }

  return 0;

}