/* xgate-dis.c -- Freescale XGATE disassembly
  Copyright (C) 2009-2024 Free Software Foundation, Inc.
  Written by Sean Keys ([email protected])

  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;
}

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