/* bufLib.c - allocate/free a collection of fixed size memory buffers *//* Copyright 1984-1995 Wind River Systems, Inc. *//*modification history--------------------01a,04may95,ms  written.*//*DESCPRIPTIONThis library contains routines to allocate and free a collectionof fixed size memory buffers.It provides an alternative memory allocation scheme to the one providedin memPartLib.bufLib has several advantages over memPartLib:   1) It is an order of magnitude faster than memPartLib.   2) It can be used at interrupt time.   3) There is no per-buffer bookkeeping overhead.   4) There is no memory fragmentation.bufLib has several disadvantages compared with memPartLib:   1) It only handles fixed size blocks of memory.   2) The blocks it handles must be at least eight bytes (2*sizeof(void *)).A memory buffer object is initialized with    BUF_POOL bufPool;    bufPoolInit (&bufPool, pBufs, bufSize, numBufs);Memory is then allocated/freed with    pBuf = bufAlloc (pBufPool);    bufFree  (pBufPool, pData);*/#define FREE_MAGIC	0x753a012b#define ALLOC_MAGIC	0x2e63d498typedef struct    {    char *	next;		/* next free buffer */    int		type;		/* FREE_MAGIC or ALLOC_MAGIC */    } BUFFER;/* includes */#include "vxWorks.h"#include "intLib.h"#include "bufLib.h"#if DEBUGextern logMsg();/******************************************************************************** bufPoolShow - only used for debugging. XXX - remove.*/ void bufPoolShow (BUF_POOL * pBufPool)    {    char * pBuf;    int ix;    logMsg ("pBufs = 0x%x, numBufs = %d, bufSize = %d\n",		pBufPool->pBufs, pBufPool->numBufs, pBufPool->bufSize);    for (ix = 0; ix < pBufPool->numBufs; ix++)	{	pBuf = pBufPool->pBufs + ix * pBufPool->bufSize;	logMsg ("0x%x	%s\n", (int)pBuf,		((BUFFER *)pBuf)->type == FREE_MAGIC ? "Free" : "Allocated");	}    logMsg ("\n");    }#endif/******************************************************************************** bufPoolInit - initialize a buffer pool** bufLib manages I/O buffers for the WDB agent. Since the agent* can't use malloc(), the buffers are installed at library init time.* Currently, the agent uses mbufs.*/ void bufPoolInit    (    BUF_POOL *	pBufPool,		/* buffer pool to initialize */    char *	pBufs,			/* array of buffers to use */    int		numBufs,		/* number of bufs in the array */    int		bufSize			/* size of each buffer */    )    {    int ix;    pBufPool->pBufs	= pBufs;    pBufPool->numBufs	= numBufs;    pBufPool->bufSize	= bufSize;    pBufPool->pFreeBufs	= pBufs;    for (ix = 0; ix < numBufs - 1; ix++)	{        ((BUFFER *)(pBufs + bufSize*ix))->next = pBufs + bufSize * (ix + 1);	((BUFFER *)(pBufs + bufSize*ix))->type = FREE_MAGIC;	}    ((BUFFER *)(pBufs + bufSize*ix))->next = NULL;    ((BUFFER *)(pBufs + bufSize*ix))->type = FREE_MAGIC;    }/******************************************************************************** bufAlloc - allocate a buffer.** RETURNS: a char *, or NULL if none are available.*/ char * bufAlloc    (    BUF_POOL * pBufPool			/* buffer pool from which to alloc */    )    {    int 	lockKey;    char *	pThisBuf;    lockKey = intLock ();    if (pBufPool->pFreeBufs == NULL)	{	intUnlock (lockKey);	return (NULL);	}    pThisBuf = pBufPool->pFreeBufs;    pBufPool->pFreeBufs = ((BUFFER *)pBufPool->pFreeBufs)->next;    ((BUFFER *)pThisBuf)->type = ALLOC_MAGIC;    ((BUFFER *)pThisBuf)->next = NULL;    intUnlock (lockKey);    return (pThisBuf);    }/******************************************************************************** bufFree - return a buffer to the buffer pool.*/ void bufFree    (    BUF_POOL *	pBufPool,	/* buffer pool to which we free */    char *	pBuf		/* buffer to free */    )    {    int lockKey;    lockKey = intLock();    /* valid buffer? */    if ((((BUFFER *)pBuf)->type == FREE_MAGIC) ||	((unsigned int)pBuf < (unsigned int)pBufPool->pBufs) ||	((unsigned int)pBuf >= (unsigned int)pBufPool->pBufs +				pBufPool->bufSize * pBufPool->numBufs) ||	(((unsigned int)pBuf - (unsigned int)pBufPool->pBufs)			% pBufPool->bufSize != 0))	{	intUnlock (lockKey);	return;	}    ((BUFFER *)pBuf)->next	= pBufPool->pFreeBufs;    pBufPool->pFreeBufs		= pBuf;    ((BUFFER *)pBuf)->type	= FREE_MAGIC;    intUnlock (lockKey);    }