JLANG::JAllocatorBuffer Struct Reference

Low-level memory management. More...

#include <JAllocator.hh>

Public Types
typedef unsigned short	JBlock_t

Public Member Functions
	JAllocatorBuffer (const std::size_t block_size, const JBlock_t number_of_blocks)
	Constructor.
void *	allocate (const std::size_t block_size)
	Allocate memory.
void	free (void *p, const std::size_t block_size)
	Deallocate memory.

Public Attributes
unsigned char *	buffer
JBlock_t	firstAvailableBlock
JBlock_t	numberOfFreeBlocks

Detailed Description

Low-level memory management.

Source code is taken from reference: A. Alexandrescu, Modern C++ Design, Addison Wesley.

Definition at line 26 of file JAllocator.hh.

Member Typedef Documentation

JBlock_t

unsigned short JLANG::JAllocatorBuffer::JBlock_t

Definition at line 28 of file JAllocator.hh.

Constructor & Destructor Documentation

JAllocatorBuffer()

JLANG::JAllocatorBuffer::JAllocatorBuffer ( const std::size_t block_size, const JBlock_t number_of_blocks )

inline

Constructor.

Parameters

block_size	number of bytes
number_of_blocks	number of blocks

Definition at line 37 of file JAllocator.hh.

    {
      buffer = new unsigned char[block_size * number_of_blocks];
 
      if (buffer == NULL) {
        THROW(JException, "JAllocatorBuffer::init(): not enough space in memory.");
      }
 
      // initialise memory as linked list
 
      unsigned char* p = buffer;
 
      for (JBlock_t i = 0; i != number_of_blocks; p += block_size) {
        ((JBlock_t&) *p) = ++i;
      }
 
      firstAvailableBlock = 0;
      numberOfFreeBlocks  = number_of_blocks;
    }

Member Function Documentation

allocate()

void * JLANG::JAllocatorBuffer::allocate ( const std::size_t block_size )

inline

Allocate memory.

Parameters

block_size

number of bytes

Returns

pointer to available memory

Definition at line 65 of file JAllocator.hh.

    {
      unsigned char* p = buffer + firstAvailableBlock * block_size;
 
      firstAvailableBlock = ((JBlock_t&) *p);
 
      --numberOfFreeBlocks;
 
      return p;
    }

free()

void JLANG::JAllocatorBuffer::free ( void * p, const std::size_t block_size )

inline

Deallocate memory.

Parameters

p	pointer to memory to be freed
block_size	number of bytes

Definition at line 83 of file JAllocator.hh.

    {
      unsigned char* q = static_cast<unsigned char*>(p);
 
      if (p < buffer || (q - buffer) % block_size != 0) {
        THROW(JException, "JAllocatorBuffer::free(): inconsistent pointer.");
      }
 
      ((JBlock_t&) *q) = firstAvailableBlock;
 
      firstAvailableBlock = static_cast<JBlock_t>((q - buffer) / block_size);
 
      if (firstAvailableBlock != (q - buffer) / block_size) {
        THROW(JException, "JAllocatorBuffer::free(): failed truncation check.");
      }
 
      ++numberOfFreeBlocks;
    }

Member Data Documentation

buffer

unsigned char* JLANG::JAllocatorBuffer::buffer

Definition at line 103 of file JAllocator.hh.

firstAvailableBlock

JBlock_t JLANG::JAllocatorBuffer::firstAvailableBlock

Definition at line 104 of file JAllocator.hh.

numberOfFreeBlocks

JBlock_t JLANG::JAllocatorBuffer::numberOfFreeBlocks

Definition at line 105 of file JAllocator.hh.

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The documentation for this struct was generated from the following file:

• JAllocator.hh