src/hotspot/share/gc/shenandoah/shenandoahSimpleBitMap.inline.hpp

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#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHSIMPLEBITMAP_INLINE_HPP
#define SHARE_GC_SHENANDOAH_SHENANDOAHSIMPLEBITMAP_INLINE_HPP

#include "gc/shenandoah/shenandoahSimpleBitMap.hpp"

inline uintx ShenandoahSimpleBitMap::tail_mask(uintx bit_number) {
  if (bit_number >= BitsPerWord) {
    return -1;
  }
  return (uintx(1) << bit_number) - 1;
}

inline idx_t ShenandoahSimpleBitMap::find_first_set_bit(idx_t beg, idx_t end) const {
  assert((beg >= 0) && (beg < _num_bits), "precondition");
  assert((end > beg) && (end <= _num_bits), "precondition");
  do {
    size_t array_idx = beg >> LogBitsPerWord;
    uintx bit_number = beg & (BitsPerWord - 1);
    uintx element_bits = _bitmap[array_idx];
    if (bit_number > 0) {
      uintx mask_out = tail_mask(bit_number);
      element_bits &= ~mask_out;
    }
    if (element_bits) {
      // The next set bit is here.  Find first set bit >= bit_number;
      uintx aligned = element_bits >> bit_number;
      uintx first_set_bit = count_trailing_zeros<uintx>(aligned);
      idx_t candidate_result = (array_idx * BitsPerWord) + bit_number + first_set_bit;
      return (candidate_result < end)? candidate_result: end;
    } else {
      // Next bit is not here.  Try the next array element
      beg += BitsPerWord - bit_number;
    }
  } while (beg < end);
  return end;
}

inline idx_t ShenandoahSimpleBitMap::find_first_set_bit(idx_t beg) const {
  assert((beg >= 0) && (beg < size()), "precondition");
  return find_first_set_bit(beg, size());
}

inline idx_t ShenandoahSimpleBitMap::find_last_set_bit(idx_t beg, idx_t end) const {
  assert((end >= 0) && (end < _num_bits), "precondition");
  assert((beg >= -1) && (beg < end), "precondition");
  do {
    idx_t array_idx = end >> LogBitsPerWord;
    uint8_t bit_number = end & (BitsPerWord - 1);
    uintx element_bits = _bitmap[array_idx];
    if (bit_number < BitsPerWord - 1){
      uintx mask_in = tail_mask(bit_number + 1);
      element_bits &= mask_in;
    }
    if (element_bits) {
      // The prev set bit is here.  Find the first set bit <= bit_number
      uintx aligned = element_bits << (BitsPerWord - (bit_number + 1));
      uintx first_set_bit = count_leading_zeros<uintx>(aligned);
      idx_t candidate_result = array_idx * BitsPerWord + (bit_number - first_set_bit);
      return (candidate_result > beg)? candidate_result: beg;
    } else {
      // Next bit is not here.  Try the previous array element
      end -= (bit_number + 1);
    }
  } while (end > beg);
  return beg;
}

inline idx_t ShenandoahSimpleBitMap::find_last_set_bit(idx_t end) const {
  assert((end >= 0) && (end < _num_bits), "precondition");
  return find_last_set_bit(-1, end);
}

inline idx_t ShenandoahSimpleBitMap::find_first_consecutive_set_bits(idx_t beg, size_t num_bits) const {
  assert((beg >= 0) && (beg < _num_bits), "precondition");
  return find_first_consecutive_set_bits(beg, size(), num_bits);
}

inline idx_t ShenandoahSimpleBitMap::find_last_consecutive_set_bits(idx_t end, size_t num_bits) const {
  assert((end >= 0) && (end < _num_bits), "precondition");
  return find_last_consecutive_set_bits((idx_t) -1, end, num_bits);
}

#endif // SHARE_GC_SHENANDOAH_SHENANDOAHSIMPLEBITMAP_INLINE_HPP