/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

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

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

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

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

#include "precompiled.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/resourceArea.hpp"

#include "runtime/atomic.inline.hpp"

#include "utilities/bitMap.inline.hpp"

#include "utilities/copy.hpp"

STATIC_ASSERT(sizeof(BitMap::bm_word_t) == BytesPerWord); // "Implementation assumption."

BitMap::BitMap(idx_t size_in_bits, bool in_resource_area) :

  _map(NULL), _size(0)

{

  resize(size_in_bits, in_resource_area);

}

#ifdef ASSERT

void BitMap::verify_index(idx_t index) const {

  assert(index < _size, "BitMap index out of bounds");

}

void BitMap::verify_range(idx_t beg_index, idx_t end_index) const {

  assert(beg_index <= end_index, "BitMap range error");

  // Note that [0,0) and [size,size) are both valid ranges.

  if (end_index != _size) verify_index(end_index);

}

#endif // #ifdef ASSERT

void BitMap::resize(idx_t size_in_bits, bool in_resource_area) {

  idx_t old_size_in_words = size_in_words();

  bm_word_t* old_map = map();

  _size = size_in_bits;

  idx_t new_size_in_words = size_in_words();

  if (in_resource_area) {

    _map = NEW_RESOURCE_ARRAY(bm_word_t, new_size_in_words);

    Copy::disjoint_words((HeapWord*)old_map, (HeapWord*) _map,

                         MIN2(old_size_in_words, new_size_in_words));

  } else {

    _map = ArrayAllocator<bm_word_t, mtInternal>::reallocate(old_map, old_size_in_words, new_size_in_words);

  }

  if (new_size_in_words > old_size_in_words) {

    clear_range_of_words(old_size_in_words, new_size_in_words);

  }

}

void BitMap::set_range_within_word(idx_t beg, idx_t end) {

  // With a valid range (beg <= end), this test ensures that end != 0, as

  // required by inverted_bit_mask_for_range.  Also avoids an unnecessary write.

  if (beg != end) {

    bm_word_t mask = inverted_bit_mask_for_range(beg, end);

    *word_addr(beg) |= ~mask;

  }

}

void BitMap::clear_range_within_word(idx_t beg, idx_t end) {

  // With a valid range (beg <= end), this test ensures that end != 0, as

  // required by inverted_bit_mask_for_range.  Also avoids an unnecessary write.

  if (beg != end) {

    bm_word_t mask = inverted_bit_mask_for_range(beg, end);

    *word_addr(beg) &= mask;

  }

}

void BitMap::par_put_range_within_word(idx_t beg, idx_t end, bool value) {

  assert(value == 0 || value == 1, "0 for clear, 1 for set");

  // With a valid range (beg <= end), this test ensures that end != 0, as

  // required by inverted_bit_mask_for_range.  Also avoids an unnecessary write.

  if (beg != end) {

    intptr_t* pw  = (intptr_t*)word_addr(beg);

    intptr_t  w   = *pw;

    intptr_t  mr  = (intptr_t)inverted_bit_mask_for_range(beg, end);

    intptr_t  nw  = value ? (w | ~mr) : (w & mr);

    while (true) {

      intptr_t res = Atomic::cmpxchg_ptr(nw, pw, w);

      if (res == w) break;

      w  = res;

      nw = value ? (w | ~mr) : (w & mr);

    }

  }

}

void BitMap::set_range(idx_t beg, idx_t end) {

  verify_range(beg, end);

  idx_t beg_full_word = word_index_round_up(beg);

  idx_t end_full_word = word_index(end);

  if (beg_full_word < end_full_word) {

    // The range includes at least one full word.

    set_range_within_word(beg, bit_index(beg_full_word));

    set_range_of_words(beg_full_word, end_full_word);

    set_range_within_word(bit_index(end_full_word), end);

  } else {

    // The range spans at most 2 partial words.

    idx_t boundary = MIN2(bit_index(beg_full_word), end);

    set_range_within_word(beg, boundary);

    set_range_within_word(boundary, end);

  }

}

void BitMap::clear_range(idx_t beg, idx_t end) {

  verify_range(beg, end);

  idx_t beg_full_word = word_index_round_up(beg);

  idx_t end_full_word = word_index(end);

  if (beg_full_word < end_full_word) {

    // The range includes at least one full word.

    clear_range_within_word(beg, bit_index(beg_full_word));

    clear_range_of_words(beg_full_word, end_full_word);

    clear_range_within_word(bit_index(end_full_word), end);

  } else {

    // The range spans at most 2 partial words.

    idx_t boundary = MIN2(bit_index(beg_full_word), end);

    clear_range_within_word(beg, boundary);

    clear_range_within_word(boundary, end);

  }

}

void BitMap::set_large_range(idx_t beg, idx_t end) {

  verify_range(beg, end);

  idx_t beg_full_word = word_index_round_up(beg);

  idx_t end_full_word = word_index(end);

  assert(end_full_word - beg_full_word >= 32,

         "the range must include at least 32 bytes");

  // The range includes at least one full word.

  set_range_within_word(beg, bit_index(beg_full_word));

  set_large_range_of_words(beg_full_word, end_full_word);

  set_range_within_word(bit_index(end_full_word), end);

}

void BitMap::clear_large_range(idx_t beg, idx_t end) {

  verify_range(beg, end);

  idx_t beg_full_word = word_index_round_up(beg);

  idx_t end_full_word = word_index(end);

  // The range includes at least one full word.

  clear_range_within_word(beg, bit_index(beg_full_word));

  clear_large_range_of_words(beg_full_word, end_full_word);

  clear_range_within_word(bit_index(end_full_word), end);

}

void BitMap::at_put(idx_t offset, bool value) {

  if (value) {

    set_bit(offset);

  } else {

    clear_bit(offset);

  }

}

// Return true to indicate that this thread changed

// the bit, false to indicate that someone else did.

// In either case, the requested bit is in the

// requested state some time during the period that

// this thread is executing this call. More importantly,

// if no other thread is executing an action to

// change the requested bit to a state other than

// the one that this thread is trying to set it to,

// then the the bit is in the expected state

// at exit from this method. However, rather than

// make such a strong assertion here, based on

// assuming such constrained use (which though true

// today, could change in the future to service some

// funky parallel algorithm), we encourage callers

// to do such verification, as and when appropriate.

bool BitMap::par_at_put(idx_t bit, bool value) {

  return value ? par_set_bit(bit) : par_clear_bit(bit);

}

void BitMap::at_put_grow(idx_t offset, bool value) {

  if (offset >= size()) {

    resize(2 * MAX2(size(), offset));

  }

  at_put(offset, value);

}

void BitMap::at_put_range(idx_t start_offset, idx_t end_offset, bool value) {

  if (value) {

    set_range(start_offset, end_offset);

  } else {

    clear_range(start_offset, end_offset);

  }

}

void BitMap::par_at_put_range(idx_t beg, idx_t end, bool value) {

  verify_range(beg, end);

  idx_t beg_full_word = word_index_round_up(beg);

  idx_t end_full_word = word_index(end);

  if (beg_full_word < end_full_word) {

    // The range includes at least one full word.

    par_put_range_within_word(beg, bit_index(beg_full_word), value);

    if (value) {

      set_range_of_words(beg_full_word, end_full_word);

    } else {

      clear_range_of_words(beg_full_word, end_full_word);

    }

    par_put_range_within_word(bit_index(end_full_word), end, value);

  } else {

    // The range spans at most 2 partial words.

    idx_t boundary = MIN2(bit_index(beg_full_word), end);

    par_put_range_within_word(beg, boundary, value);

    par_put_range_within_word(boundary, end, value);

  }

}

void BitMap::at_put_large_range(idx_t beg, idx_t end, bool value) {

  if (value) {

    set_large_range(beg, end);

  } else {

    clear_large_range(beg, end);

  }

}

void BitMap::par_at_put_large_range(idx_t beg, idx_t end, bool value) {

  verify_range(beg, end);

  idx_t beg_full_word = word_index_round_up(beg);

  idx_t end_full_word = word_index(end);

  assert(end_full_word - beg_full_word >= 32,

         "the range must include at least 32 bytes");

  // The range includes at least one full word.

  par_put_range_within_word(beg, bit_index(beg_full_word), value);

  if (value) {

    set_large_range_of_words(beg_full_word, end_full_word);

  } else {

    clear_large_range_of_words(beg_full_word, end_full_word);

  }

  par_put_range_within_word(bit_index(end_full_word), end, value);

}

bool BitMap::contains(const BitMap other) const {

  assert(size() == other.size(), "must have same size");

  bm_word_t* dest_map = map();

  bm_word_t* other_map = other.map();

  idx_t size = size_in_words();

  for (idx_t index = 0; index < size_in_words(); index++) {

    bm_word_t word_union = dest_map[index] | other_map[index];

    // If this has more bits set than dest_map[index], then other is not a

    // subset.

    if (word_union != dest_map[index]) return false;

  }

  return true;

}

bool BitMap::intersects(const BitMap other) const {

  assert(size() == other.size(), "must have same size");

  bm_word_t* dest_map = map();

  bm_word_t* other_map = other.map();

  idx_t size = size_in_words();

  for (idx_t index = 0; index < size_in_words(); index++) {

    if ((dest_map[index] & other_map[index]) != 0) return true;

  }

  // Otherwise, no intersection.

  return false;

}

void BitMap::set_union(BitMap other) {

  assert(size() == other.size(), "must have same size");

  bm_word_t* dest_map = map();

  bm_word_t* other_map = other.map();

  idx_t size = size_in_words();

  for (idx_t index = 0; index < size_in_words(); index++) {

    dest_map[index] = dest_map[index] | other_map[index];

  }

}

void BitMap::set_difference(BitMap other) {

  assert(size() == other.size(), "must have same size");

  bm_word_t* dest_map = map();

  bm_word_t* other_map = other.map();

  idx_t size = size_in_words();

  for (idx_t index = 0; index < size_in_words(); index++) {

    dest_map[index] = dest_map[index] & ~(other_map[index]);

  }

}

void BitMap::set_intersection(BitMap other) {

  assert(size() == other.size(), "must have same size");

  bm_word_t* dest_map = map();

  bm_word_t* other_map = other.map();

  idx_t size = size_in_words();

  for (idx_t index = 0; index < size; index++) {

    dest_map[index]  = dest_map[index] & other_map[index];

  }

}

void BitMap::set_intersection_at_offset(BitMap other, idx_t offset) {

  assert(other.size() >= offset, "offset not in range");

  assert(other.size() - offset >= size(), "other not large enough");

  // XXX Ideally, we would remove this restriction.

  guarantee((offset % (sizeof(bm_word_t) * BitsPerByte)) == 0,

            "Only handle aligned cases so far.");

  bm_word_t* dest_map = map();

  bm_word_t* other_map = other.map();

  idx_t offset_word_ind = word_index(offset);

  idx_t size = size_in_words();

  for (idx_t index = 0; index < size; index++) {

    dest_map[index] = dest_map[index] & other_map[offset_word_ind + index];

  }

}

bool BitMap::set_union_with_result(BitMap other) {

  assert(size() == other.size(), "must have same size");

  bool changed = false;

  bm_word_t* dest_map = map();

  bm_word_t* other_map = other.map();

  idx_t size = size_in_words();

  for (idx_t index = 0; index < size; index++) {

    idx_t temp = dest_map[index] | other_map[index];

    changed = changed || (temp != dest_map[index]);

    dest_map[index] = temp;

  }

  return changed;

}

bool BitMap::set_difference_with_result(BitMap other) {

  assert(size() == other.size(), "must have same size");

  bool changed = false;

  bm_word_t* dest_map = map();

  bm_word_t* other_map = other.map();

  idx_t size = size_in_words();

  for (idx_t index = 0; index < size; index++) {

    bm_word_t temp = dest_map[index] & ~(other_map[index]);

    changed = changed || (temp != dest_map[index]);

    dest_map[index] = temp;

  }

  return changed;

}

bool BitMap::set_intersection_with_result(BitMap other) {

  assert(size() == other.size(), "must have same size");

  bool changed = false;

  bm_word_t* dest_map = map();

  bm_word_t* other_map = other.map();

  idx_t size = size_in_words();

  for (idx_t index = 0; index < size; index++) {

    bm_word_t orig = dest_map[index];

    bm_word_t temp = orig & other_map[index];

    changed = changed || (temp != orig);

    dest_map[index]  = temp;

  }

  return changed;

}

void BitMap::set_from(BitMap other) {

  assert(size() == other.size(), "must have same size");

  bm_word_t* dest_map = map();

  bm_word_t* other_map = other.map();

  idx_t size = size_in_words();

  for (idx_t index = 0; index < size; index++) {

    dest_map[index] = other_map[index];

  }

}

bool BitMap::is_same(BitMap other) {

  assert(size() == other.size(), "must have same size");

  bm_word_t* dest_map = map();

  bm_word_t* other_map = other.map();

  idx_t size = size_in_words();

  for (idx_t index = 0; index < size; index++) {

    if (dest_map[index] != other_map[index]) return false;

  }

  return true;

}

bool BitMap::is_full() const {

  bm_word_t* word = map();

  idx_t rest = size();

  for (; rest >= (idx_t) BitsPerWord; rest -= BitsPerWord) {

    if (*word != ~(bm_word_t)0) return false;

    word++;

  }

  return rest == 0 || (*word | ~right_n_bits((int)rest)) == ~(bm_word_t)0;

}

bool BitMap::is_empty() const {

  bm_word_t* word = map();

  idx_t rest = size();

  for (; rest >= (idx_t) BitsPerWord; rest -= BitsPerWord) {

    if (*word != 0) return false;

    word++;

  }

  return rest == 0 || (*word & right_n_bits((int)rest)) == 0;

}

void BitMap::clear_large() {

  clear_large_range_of_words(0, size_in_words());

}

// Note that if the closure itself modifies the bitmap

// then modifications in and to the left of the _bit_ being

// currently sampled will not be seen. Note also that the

// interval [leftOffset, rightOffset) is right open.

bool BitMap::iterate(BitMapClosure* blk, idx_t leftOffset, idx_t rightOffset) {

  verify_range(leftOffset, rightOffset);

  idx_t startIndex = word_index(leftOffset);

  idx_t endIndex   = MIN2(word_index(rightOffset) + 1, size_in_words());

  for (idx_t index = startIndex, offset = leftOffset;

       offset < rightOffset && index < endIndex;

       offset = (++index) << LogBitsPerWord) {

    idx_t rest = map(index) >> (offset & (BitsPerWord - 1));

    for (; offset < rightOffset && rest != 0; offset++) {

      if (rest & 1) {

        if (!blk->do_bit(offset)) return false;

        //  resample at each closure application

        // (see, for instance, CMS bug 4525989)

        rest = map(index) >> (offset & (BitsPerWord -1));

      }

      rest = rest >> 1;

    }

  }

  return true;

}

BitMap::idx_t* BitMap::_pop_count_table = NULL;

void BitMap::init_pop_count_table() {

  if (_pop_count_table == NULL) {

    BitMap::idx_t *table = NEW_C_HEAP_ARRAY(idx_t, 256, mtInternal);

    for (uint i = 0; i < 256; i++) {

      table[i] = num_set_bits(i);

    }

    intptr_t res = Atomic::cmpxchg_ptr((intptr_t)  table,

                                       (intptr_t*) &_pop_count_table,

                                       (intptr_t)  NULL_WORD);

    if (res != NULL_WORD) {

      guarantee( _pop_count_table == (void*) res, "invariant" );

      FREE_C_HEAP_ARRAY(idx_t, table);

    }

  }

}

BitMap::idx_t BitMap::num_set_bits(bm_word_t w) {

  idx_t bits = 0;

  while (w != 0) {

    while ((w & 1) == 0) {

      w >>= 1;

    }

    bits++;

    w >>= 1;

  }

  return bits;

}

BitMap::idx_t BitMap::num_set_bits_from_table(unsigned char c) {

  assert(_pop_count_table != NULL, "precondition");

  return _pop_count_table[c];

}

BitMap::idx_t BitMap::count_one_bits() const {

  init_pop_count_table(); // If necessary.

  idx_t sum = 0;

  typedef unsigned char uchar;

  for (idx_t i = 0; i < size_in_words(); i++) {

    bm_word_t w = map()[i];

    for (size_t j = 0; j < sizeof(bm_word_t); j++) {

      sum += num_set_bits_from_table(uchar(w & 255));

      w >>= 8;

    }

  }

  return sum;

}