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src/share/vm/gc/g1/g1BiasedArray.hpp

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  39 protected:
  40   address _base;          // the real base address
  41   size_t _length;         // the length of the array
  42   address _biased_base;   // base address biased by "bias" elements
  43   size_t _bias;           // the bias, i.e. the offset biased_base is located to the right in elements
  44   uint _shift_by;         // the amount of bits to shift right when mapping to an index of the array.
  45 
  46 protected:
  47 
  48   G1BiasedMappedArrayBase() : _base(NULL), _length(0), _biased_base(NULL),
  49     _bias(0), _shift_by(0) { }
  50 
  51   // Allocate a new array, generic version.
  52   static address create_new_base_array(size_t length, size_t elem_size);
  53 
  54   // Initialize the members of this class. The biased start address of this array
  55   // is the bias (in elements) multiplied by the element size.
  56   void initialize_base(address base, size_t length, size_t bias, size_t elem_size, uint shift_by) {
  57     assert(base != NULL, "just checking");
  58     assert(length > 0, "just checking");
  59     assert(shift_by < sizeof(uintptr_t) * 8, err_msg("Shifting by %u, larger than word size?", shift_by));
  60     _base = base;
  61     _length = length;
  62     _biased_base = base - (bias * elem_size);
  63     _bias = bias;
  64     _shift_by = shift_by;
  65   }
  66 
  67   // Allocate and initialize this array to cover the heap addresses in the range
  68   // of [bottom, end).
  69   void initialize(HeapWord* bottom, HeapWord* end, size_t target_elem_size_in_bytes, size_t mapping_granularity_in_bytes) {
  70     assert(mapping_granularity_in_bytes > 0, "just checking");
  71     assert(is_power_of_2(mapping_granularity_in_bytes),
  72       err_msg("mapping granularity must be power of 2, is %zd", mapping_granularity_in_bytes));
  73     assert((uintptr_t)bottom % mapping_granularity_in_bytes == 0,
  74       err_msg("bottom mapping area address must be a multiple of mapping granularity %zd, is  " PTR_FORMAT,
  75         mapping_granularity_in_bytes, p2i(bottom)));
  76     assert((uintptr_t)end % mapping_granularity_in_bytes == 0,
  77       err_msg("end mapping area address must be a multiple of mapping granularity %zd, is " PTR_FORMAT,
  78         mapping_granularity_in_bytes, p2i(end)));
  79     size_t num_target_elems = pointer_delta(end, bottom, mapping_granularity_in_bytes);
  80     idx_t bias = (uintptr_t)bottom / mapping_granularity_in_bytes;
  81     address base = create_new_base_array(num_target_elems, target_elem_size_in_bytes);
  82     initialize_base(base, num_target_elems, bias, target_elem_size_in_bytes, log2_intptr(mapping_granularity_in_bytes));
  83   }
  84 
  85   size_t bias() const { return _bias; }
  86   uint shift_by() const { return _shift_by; }
  87 
  88   void verify_index(idx_t index) const PRODUCT_RETURN;
  89   void verify_biased_index(idx_t biased_index) const PRODUCT_RETURN;
  90   void verify_biased_index_inclusive_end(idx_t biased_index) const PRODUCT_RETURN;
  91 
  92 public:
  93    // Return the length of the array in elements.
  94    size_t length() const { return _length; }
  95 };
  96 
  97 // Array that provides biased access and mapping from (valid) addresses in the
  98 // heap into this array.




  39 protected:
  40   address _base;          // the real base address
  41   size_t _length;         // the length of the array
  42   address _biased_base;   // base address biased by "bias" elements
  43   size_t _bias;           // the bias, i.e. the offset biased_base is located to the right in elements
  44   uint _shift_by;         // the amount of bits to shift right when mapping to an index of the array.
  45 
  46 protected:
  47 
  48   G1BiasedMappedArrayBase() : _base(NULL), _length(0), _biased_base(NULL),
  49     _bias(0), _shift_by(0) { }
  50 
  51   // Allocate a new array, generic version.
  52   static address create_new_base_array(size_t length, size_t elem_size);
  53 
  54   // Initialize the members of this class. The biased start address of this array
  55   // is the bias (in elements) multiplied by the element size.
  56   void initialize_base(address base, size_t length, size_t bias, size_t elem_size, uint shift_by) {
  57     assert(base != NULL, "just checking");
  58     assert(length > 0, "just checking");
  59     assert(shift_by < sizeof(uintptr_t) * 8, "Shifting by %u, larger than word size?", shift_by);
  60     _base = base;
  61     _length = length;
  62     _biased_base = base - (bias * elem_size);
  63     _bias = bias;
  64     _shift_by = shift_by;
  65   }
  66 
  67   // Allocate and initialize this array to cover the heap addresses in the range
  68   // of [bottom, end).
  69   void initialize(HeapWord* bottom, HeapWord* end, size_t target_elem_size_in_bytes, size_t mapping_granularity_in_bytes) {
  70     assert(mapping_granularity_in_bytes > 0, "just checking");
  71     assert(is_power_of_2(mapping_granularity_in_bytes),
  72            "mapping granularity must be power of 2, is %zd", mapping_granularity_in_bytes);
  73     assert((uintptr_t)bottom % mapping_granularity_in_bytes == 0,
  74            "bottom mapping area address must be a multiple of mapping granularity %zd, is  " PTR_FORMAT,
  75            mapping_granularity_in_bytes, p2i(bottom));
  76     assert((uintptr_t)end % mapping_granularity_in_bytes == 0,
  77            "end mapping area address must be a multiple of mapping granularity %zd, is " PTR_FORMAT,
  78            mapping_granularity_in_bytes, p2i(end));
  79     size_t num_target_elems = pointer_delta(end, bottom, mapping_granularity_in_bytes);
  80     idx_t bias = (uintptr_t)bottom / mapping_granularity_in_bytes;
  81     address base = create_new_base_array(num_target_elems, target_elem_size_in_bytes);
  82     initialize_base(base, num_target_elems, bias, target_elem_size_in_bytes, log2_intptr(mapping_granularity_in_bytes));
  83   }
  84 
  85   size_t bias() const { return _bias; }
  86   uint shift_by() const { return _shift_by; }
  87 
  88   void verify_index(idx_t index) const PRODUCT_RETURN;
  89   void verify_biased_index(idx_t biased_index) const PRODUCT_RETURN;
  90   void verify_biased_index_inclusive_end(idx_t biased_index) const PRODUCT_RETURN;
  91 
  92 public:
  93    // Return the length of the array in elements.
  94    size_t length() const { return _length; }
  95 };
  96 
  97 // Array that provides biased access and mapping from (valid) addresses in the
  98 // heap into this array.


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