/* CGEN generic disassembler support code.
  Copyright (C) 1996-2024 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];
}