#ifndef SHARE_VM_MEMORY_HEAP_HPP

#define SHARE_VM_MEMORY_HEAP_HPP

#include "memory/allocation.hpp"

#include "runtime/virtualspace.hpp"

class HeapBlock VALUE_OBJ_CLASS_SPEC {

friend class VMStructs;

public:

struct Header {

size_t _length; // the length in segments

bool _used; // Used bit

};

protected:

union {

Header _header;

int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ];

// pad to 0 mod 8

};

public:

// Initialization

void initialize(size_t length) { _header._length = length; set_used(); }

// Accessors

void* allocated_space() const { return (void*)(this + 1); }

size_t length() const { return _header._length; }

// Used/free

void set_used() { _header._used = true; }

void set_free() { _header._used = false; }

bool free() { return !_header._used; }

};

class FreeBlock: public HeapBlock {

friend class VMStructs;

protected:

FreeBlock* _link;

public:

// Initialization

void initialize(size_t length) { HeapBlock::initialize(length); _link= NULL; }

// Merging

void set_length(size_t l) { _header._length = l; }

// Accessors

FreeBlock* link() const { return _link; }

void set_link(FreeBlock* link) { _link = link; }

};

class CodeHeap : public CHeapObj<mtCode> {

friend class VMStructs;

private:

VirtualSpace _memory; // the memory holding the blocks

VirtualSpace _segmap; // the memory holding the segment map

size_t _number_of_committed_segments;

size_t _number_of_reserved_segments;

size_t _segment_size;

int _log2_segment_size;

size_t _next_segment;

FreeBlock* _freelist;

size_t _free_segments; // No. of segments in freelist

// Helper functions

size_t number_of_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; }

size_t size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; }

size_t segment_for(void* p) const { return ((char*)p - _memory.low()) >> _log2_segment_size; }

HeapBlock* block_at(size_t i) const { return (HeapBlock*)(_memory.low() + (i << _log2_segment_size)); }

void mark_segmap_as_free(size_t beg, size_t end);

void mark_segmap_as_used(size_t beg, size_t end);

// Freelist management helpers

FreeBlock* following_block(FreeBlock *b);

void insert_after(FreeBlock* a, FreeBlock* b);

void merge_right (FreeBlock* a);

// Toplevel freelist management

void add_to_freelist(HeapBlock *b);

FreeBlock* search_freelist(size_t length);

// Iteration helpers

void* next_free(HeapBlock* b) const;

HeapBlock* first_block() const;

HeapBlock* next_block(HeapBlock* b) const;

HeapBlock* block_start(void* p) const;

// to perform additional actions on creation of executable code

void on_code_mapping(char* base, size_t size);

public:

CodeHeap();

// Heap extents

bool reserve(size_t reserved_size, size_t committed_size, size_t segment_size);

void release(); // releases all allocated memory

bool expand_by(size_t size); // expands commited memory by size

void shrink_by(size_t size); // shrinks commited memory by size

void clear(); // clears all heap contents

// Memory allocation

void* allocate (size_t size); // allocates a block of size or returns NULL

void deallocate(void* p); // deallocates a block

// Attributes

void* begin() const { return _memory.low (); }

void* end() const { return _memory.high(); }

bool contains(void* p) const { return begin() <= p && p < end(); }

void* find_start(void* p) const; // returns the block containing p or NULL

size_t alignment_unit() const; // alignment of any block

size_t alignment_offset() const; // offset of first byte of any block, within the enclosing alignment unit

static size_t header_size(); // returns the header size for each heap block

// Returns reserved area high and low addresses

char *low_boundary() const { return _memory.low_boundary (); }

char *high() const { return _memory.high(); }

char *high_boundary() const { return _memory.high_boundary(); }

// Iteration

// returns the first block or NULL

void* first() const { return next_free(first_block()); }

// returns the next block given a block p or NULL

void* next(void* p) const { return next_free(next_block(block_start(p))); }

// Statistics

size_t capacity() const;

size_t max_capacity() const;

size_t allocated_capacity() const;

size_t unallocated_capacity() const { return max_capacity() - allocated_capacity(); }

size_t largest_free_block() const;

// Debugging

void verify();

void print() PRODUCT_RETURN;

};

#endif // SHARE_VM_MEMORY_HEAP_HPP