/* CGEN generic disassembler support code.

   Copyright (C) 1996-2023 Free Software Foundation, Inc.

   This file is part of libopcodes.

   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 <stdio.h>

#include "ansidecl.h"

#include "libiberty.h"

#include "bfd.h"

#include "symcat.h"

#include "opcode/cgen.h"

#include "disassemble.h"

static CGEN_INSN_LIST *  hash_insn_array        (CGEN_CPU_DESC, const CGEN_INSN *, int, int, CGEN_INSN_LIST **, CGEN_INSN_LIST *);

static CGEN_INSN_LIST *  hash_insn_list         (CGEN_CPU_DESC, const CGEN_INSN_LIST *, CGEN_INSN_LIST **, CGEN_INSN_LIST *);

static void              build_dis_hash_table   (CGEN_CPU_DESC);

static int     count_decodable_bits   (const CGEN_INSN *);

static void    add_insn_to_hash_chain (CGEN_INSN_LIST *,

             const CGEN_INSN *,

             CGEN_INSN_LIST **,

             unsigned int);

/* Return the number of decodable bits in this insn.  */

static int

count_decodable_bits (const CGEN_INSN *insn)

{

  CGEN_INSN_LGUINT mask = CGEN_INSN_BASE_MASK (insn);

#if GCC_VERSION >= 3004

  return __builtin_popcount (mask);

#else

  int bits = 0;

  unsigned m;

  for (m = 1; m != 0; m <<= 1)

    {

      if (mask & m)

  ++bits;

    }

  return bits;

#endif

}

/* Add an instruction to the hash chain.  */

static void

add_insn_to_hash_chain (CGEN_INSN_LIST *hentbuf,

      const CGEN_INSN *insn,

      CGEN_INSN_LIST **htable,

      unsigned int hash)

{

  CGEN_INSN_LIST *current_buf;

  CGEN_INSN_LIST *previous_buf;

  int insn_decodable_bits;

  /* Add insns sorted by the number of decodable bits, in decreasing order.

     This ensures that any insn which is a special case of another will be

     checked first.  */

  insn_decodable_bits = count_decodable_bits (insn);

  previous_buf = NULL;

  for (current_buf = htable[hash]; current_buf != NULL;

       current_buf = current_buf->next)

    {

      int current_decodable_bits = count_decodable_bits (current_buf->insn);

      if (insn_decodable_bits >= current_decodable_bits)

  break;

      previous_buf = current_buf;

    }

  /* Now insert the new insn.  */

  hentbuf->insn = insn;

  hentbuf->next = current_buf;

  if (previous_buf == NULL)

    htable[hash] = hentbuf;

  else

    previous_buf->next = hentbuf;

}

/* Subroutine of build_dis_hash_table to add INSNS to the hash table.

   COUNT is the number of elements in INSNS.

   ENTSIZE is sizeof (CGEN_IBASE) for the target.

   ??? No longer used but leave in for now.

   HTABLE points to the hash table.

   HENTBUF is a pointer to sufficiently large buffer of hash entries.

   The result is a pointer to the next entry to use.

   The table is scanned backwards as additions are made to the front of the

   list and we want earlier ones to be preferred.  */

static CGEN_INSN_LIST *

hash_insn_array (CGEN_CPU_DESC cd,

     const CGEN_INSN * insns,

     int count,

     int entsize ATTRIBUTE_UNUSED,

     CGEN_INSN_LIST ** htable,

     CGEN_INSN_LIST * hentbuf)

{

  int big_p = CGEN_CPU_INSN_ENDIAN (cd) == CGEN_ENDIAN_BIG;

  int i;

  for (i = count - 1; i >= 0; --i, ++hentbuf)

    {

      unsigned int hash;

      char buf [8];

      unsigned long value;

      const CGEN_INSN *insn = &insns[i];

      size_t size;

      if (! (* cd->dis_hash_p) (insn))

  continue;

      /* We don't know whether the target uses the buffer or the base insn

   to hash on, so set both up.  */

      value = CGEN_INSN_BASE_VALUE (insn);

      size = CGEN_INSN_MASK_BITSIZE (insn);

      OPCODES_ASSERT (size <= sizeof (buf) * 8);

      bfd_put_bits ((bfd_vma) value, buf, size, big_p);

      hash = (* cd->dis_hash) (buf, value);

      add_insn_to_hash_chain (hentbuf, insn, htable, hash);

    }

  return hentbuf;

}

/* Subroutine of build_dis_hash_table to add INSNS to the hash table.

   This function is identical to hash_insn_array except the insns are

   in a list.  */

static CGEN_INSN_LIST *

hash_insn_list (CGEN_CPU_DESC cd,

    const CGEN_INSN_LIST *insns,

    CGEN_INSN_LIST **htable,

    CGEN_INSN_LIST *hentbuf)

{

  int big_p = CGEN_CPU_INSN_ENDIAN (cd) == CGEN_ENDIAN_BIG;

  const CGEN_INSN_LIST *ilist;

  for (ilist = insns; ilist != NULL; ilist = ilist->next, ++ hentbuf)

    {

      unsigned int hash;

      char buf[8];

      unsigned long value;

      size_t size;

      if (! (* cd->dis_hash_p) (ilist->insn))

  continue;

      /* We don't know whether the target uses the buffer or the base insn

   to hash on, so set both up.  */

      value = CGEN_INSN_BASE_VALUE (ilist->insn);

      size = CGEN_INSN_MASK_BITSIZE (ilist->insn);

      OPCODES_ASSERT (size <= sizeof (buf) * 8);

      bfd_put_bits ((bfd_vma) value, buf, size, big_p);

      hash = (* cd->dis_hash) (buf, value);

      add_insn_to_hash_chain (hentbuf, ilist->insn, htable, hash);

    }

  return hentbuf;

}

/* Build the disassembler instruction hash table.  */

static void

build_dis_hash_table (CGEN_CPU_DESC cd)

{

  int count = cgen_insn_count (cd) + cgen_macro_insn_count (cd);

  CGEN_INSN_TABLE *insn_table = & cd->insn_table;

  CGEN_INSN_TABLE *macro_insn_table = & cd->macro_insn_table;

  unsigned int hash_size = cd->dis_hash_size;

  CGEN_INSN_LIST *hash_entry_buf;

  CGEN_INSN_LIST **dis_hash_table;

  CGEN_INSN_LIST *dis_hash_table_entries;

  /* The space allocated for the hash table consists of two parts:

     the hash table and the hash lists.  */

  dis_hash_table = (CGEN_INSN_LIST **)

    xmalloc (hash_size * sizeof (CGEN_INSN_LIST *));

  memset (dis_hash_table, 0, hash_size * sizeof (CGEN_INSN_LIST *));

  dis_hash_table_entries = hash_entry_buf = (CGEN_INSN_LIST *)

    xmalloc (count * sizeof (CGEN_INSN_LIST));

  /* Add compiled in insns.

     Don't include the first one as it is a reserved entry.  */

  /* ??? It was the end of all hash chains, and also the special

     "invalid insn" marker.  May be able to do it differently now.  */

  hash_entry_buf = hash_insn_array (cd,

            insn_table->init_entries + 1,

            insn_table->num_init_entries - 1,

            insn_table->entry_size,

            dis_hash_table, hash_entry_buf);

  /* Add compiled in macro-insns.  */

  hash_entry_buf = hash_insn_array (cd, macro_insn_table->init_entries,

            macro_insn_table->num_init_entries,

            macro_insn_table->entry_size,

            dis_hash_table, hash_entry_buf);

  /* Add runtime added insns.

     Later added insns will be preferred over earlier ones.  */

  hash_entry_buf = hash_insn_list (cd, insn_table->new_entries,

           dis_hash_table, hash_entry_buf);

  /* Add runtime added macro-insns.  */

  hash_insn_list (cd, macro_insn_table->new_entries,

      dis_hash_table, hash_entry_buf);

  cd->dis_hash_table = dis_hash_table;

  cd->dis_hash_table_entries = dis_hash_table_entries;

}

/* Return the first entry in the hash list for INSN.  */

CGEN_INSN_LIST *

cgen_dis_lookup_insn (CGEN_CPU_DESC cd, const char * buf, CGEN_INSN_INT value)

{

  unsigned int hash;

  if (cd->dis_hash_table == NULL)

    build_dis_hash_table (cd);

  hash = (* cd->dis_hash) (buf, value);

  return cd->dis_hash_table[hash];

}