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      1 /*
      2  * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
      3  * Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
      4  *
      5  * Permission is hereby granted, free of charge, to any person obtaining a
      6  * copy of this software and associated documentation files (the "Software"),
      7  * to deal in the Software without restriction, including without limitation
      8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
      9  * and/or sell copies of the Software, and to permit persons to whom the
     10  * Software is furnished to do so, subject to the following conditions:
     11  *
     12  * The above copyright notice including the dates of first publication and
     13  * either this permission notice or a reference to
     14  * http://oss.sgi.com/projects/FreeB/
     15  * shall be included in all copies or substantial portions of the Software.
     16  *
     17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
     18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
     20  * SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
     21  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
     22  * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     23  * SOFTWARE.
     24  *
     25  * Except as contained in this notice, the name of Silicon Graphics, Inc.
     26  * shall not be used in advertising or otherwise to promote the sale, use or
     27  * other dealings in this Software without prior written authorization from
     28  * Silicon Graphics, Inc.
     29  */
     30 
     31 /*
     32  * bufpool.h
     33  *
     34  */
     35 
     36 #ifndef __glubufpool_h_
     37 #define __glubufpool_h_
     38 
     39 #include "gluos.h"
     40 #include "myassert.h"
     41 #include "mystdlib.h"
     42 
     43 #define NBLOCKS	32
     44 
     45 class Buffer {
     46 	friend class 	Pool;
     47 	Buffer	*	next;		/* next buffer on free list	*/
     48 };
     49 
     50 class Pool {
     51 public:
     52 			Pool( int, int, const char * );
     53 			~Pool( void );
     54     inline void*	new_buffer( void );
     55     inline void		free_buffer( void * );
     56     void		clear( void );
     57 
     58 private:
     59     void		grow( void );
     60 
     61 protected:
     62     Buffer		*freelist;		/* linked list of free buffers */
     63     char		*blocklist[NBLOCKS];	/* blocks of malloced memory */
     64     int			nextblock;		/* next free block index */
     65     char		*curblock;		/* last malloced block */
     66     int			buffersize;		/* bytes per buffer */
     67     int			nextsize;		/* size of next block of memory	*/
     68     int			nextfree;		/* byte offset past next free buffer */
     69     int			initsize;
     70     enum Magic { is_allocated = 0xf3a1, is_free = 0xf1a2 };
     71     const char		*name;			/* name of the pool */
     72     Magic		magic;			/* marker for valid pool */
     73 };
     74 
     75 /*-----------------------------------------------------------------------------
     76  * Pool::free_buffer - return a buffer to a pool
     77  *-----------------------------------------------------------------------------
     78  */
     79 
     80 inline void
     81 Pool::free_buffer( void *b )
     82 {
     83     assert( (this != 0) && (magic == is_allocated) );
     84 
     85     /* add buffer to singly connected free list */
     86 
     87     ((Buffer *) b)->next = freelist;
     88     freelist = (Buffer *) b;
     89 }
     90 
     91 
     92 /*-----------------------------------------------------------------------------
     93  * Pool::new_buffer - allocate a buffer from a pool
     94  *-----------------------------------------------------------------------------
     95  */
     96 
     97 inline void *
     98 Pool::new_buffer( void )
     99 {
    100     void *buffer;
    101 
    102     assert( (this != 0) && (magic == is_allocated) );
    103 
    104     /* find free buffer */
    105 
    106     if( freelist ) {
    107     	buffer = (void *) freelist;
    108     	freelist = freelist->next;
    109     } else {
    110     	if( ! nextfree )
    111     	    grow( );
    112     	nextfree -= buffersize;;
    113     	buffer = (void *) (curblock + nextfree);
    114     }
    115     return buffer;
    116 }
    117 
    118 class PooledObj {
    119 public:
    120     inline void *	operator new( size_t, Pool & );
    121     inline void * 	operator new( size_t, void *);
    122     inline void * 	operator new( size_t s)
    123 				{ return ::new char[s]; }
    124     inline void 	operator delete( void * ) { assert( 0 ); }
    125     inline void         operator delete( void *, Pool & ) { assert( 0 ); }
    126     inline void		deleteMe( Pool & );
    127 };
    128 
    129 inline void *
    130 PooledObj::operator new( size_t, Pool& pool )
    131 {
    132     return pool.new_buffer();
    133 }
    134 
    135 inline void
    136 PooledObj::deleteMe( Pool& pool )
    137 {
    138     pool.free_buffer( (void *) this );
    139 }
    140 
    141 #endif /* __glubufpool_h_ */
    142