bufpool.h

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

/*
 * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
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 * shall be included in all copies or substantial portions of the Software.
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/*
 * bufpool.h
 *
 * $Date: 2006/03/29 18:46:46 $ $Revision: 1.3 $
 * $Header: /home/krh/git/sync/mesa-cvs-repo/Mesa/src/glu/sgi/libnurbs/internals/bufpool.h,v 1.3 2006/03/29 18:46:46 brianp Exp $
 */

#ifndef __glubufpool_h_
#define __glubufpool_h_

#include "gluos.h"
#include "myassert.h"
#include "mystdlib.h"

#define NBLOCKS	32

class Buffer {
	friend class 	Pool;
	Buffer	*	next;		/* next buffer on free list	*/
};

class Pool {
public:
			Pool( int, int, const char * );
			~Pool( void );
    inline void*	new_buffer( void );
    inline void		free_buffer( void * );
    void		clear( void );
    
private:
    void		grow( void );

protected:
    Buffer		*freelist;		/* linked list of free buffers */
    char		*blocklist[NBLOCKS];	/* blocks of malloced memory */
    int			nextblock;		/* next free block index */
    char		*curblock;		/* last malloced block */
    int			buffersize;		/* bytes per buffer */
    int			nextsize;		/* size of next block of memory	*/
    int			nextfree;		/* byte offset past next free buffer */
    int			initsize;
    enum Magic { is_allocated = 0xf3a1, is_free = 0xf1a2 };
    const char		*name;			/* name of the pool */
    Magic		magic;			/* marker for valid pool */
};

/*-----------------------------------------------------------------------------
 * Pool::free_buffer - return a buffer to a pool
 *-----------------------------------------------------------------------------
 */

inline void
Pool::free_buffer( void *b )
{
    assert( (this != 0) && (magic == is_allocated) );

    /* add buffer to singly connected free list */

    ((Buffer *) b)->next = freelist;
    freelist = (Buffer *) b;
}


/*-----------------------------------------------------------------------------
 * Pool::new_buffer - allocate a buffer from a pool
 *-----------------------------------------------------------------------------
 */

inline void * 
Pool::new_buffer( void )
{
    void *buffer;

    assert( (this != 0) && (magic == is_allocated) );

    /* find free buffer */

    if( freelist ) {
    	buffer = (void *) freelist; 
    	freelist = freelist->next;
    } else {
    	if( ! nextfree )
    	    grow( );
    	nextfree -= buffersize;;
    	buffer = (void *) (curblock + nextfree);
    }
    return buffer;
}
	
class PooledObj {
public:
    inline void *	operator new( size_t, Pool & );
    inline void * 	operator new( size_t, void *);
    inline void * 	operator new( size_t s)
				{ return ::new char[s]; }
    inline void 	operator delete( void * ) { assert( 0 ); }
    inline void         operator delete( void *, Pool & ) { assert( 0 ); }
    inline void		deleteMe( Pool & );
};

inline void *
PooledObj::operator new( size_t, Pool& pool )
{
    return pool.new_buffer();
}

inline void
PooledObj::deleteMe( Pool& pool )
{
    pool.free_buffer( (void *) this );
}

#endif /* __glubufpool_h_ */