/*------------------------------------------------------------------------------
//	Copyright (c) 2001-2002, OpenBeOS
//
//	Permission is hereby granted, free of charge, to any person obtaining a
//	copy of this software and associated documentation files (the "Software"),
//	to deal in the Software without restriction, including without limitation
//	the rights to use, copy, modify, merge, publish, distribute, sublicense,
//	and/or sell copies of the Software, and to permit persons to whom the
//	Software is furnished to do so, subject to the following conditions:
//
//	The above copyright notice and this permission notice shall be included in
//	all copies or substantial portions of the Software.
//
//	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
//	FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
//	DEALINGS IN THE SOFTWARE.
//
//	File Name:		bget.c
//	Author:			John Walker <kelvin@fourmilab.ch>
//	Description:	BGET pool allocator. Originally released into public domain.
//					Distributed with OpenBeOS under MIT license
//  
//------------------------------------------------------------------------------*/
/*#define DoTestProg 1*/	/* defined if not used as a library */
#define NDEBUG
#define TestProg    20000	      /* Generate built-in test program
					 if defined.  The value specifies
					 how many buffer allocation attempts
					 the test program should make. */

#define SizeQuant   4		      /* Buffer allocation size quantum:
					 all buffers allocated are a
					 multiple of this size.  This
					 MUST be a power of two. */

#define BufDump     1		      /* Define this symbol to enable the
					 bpoold() function which dumps the
					 buffers in a buffer pool. */

#define BufValid    1		      /* Define this symbol to enable the
					 bpoolv() function for validating
					 a buffer pool. */ 

#define DumpData    1		      /* Define this symbol to enable the
					 bufdump() function which allows
					 dumping the contents of an allocated
					 or free buffer. */

#define BufStats    1		      /* Define this symbol to enable the
					 bstats() function which calculates
					 the total free space in the buffer
					 pool, the largest available
					 buffer, and the total space
					 currently allocated. */

#define FreeWipe    1		      /* Wipe free buffers to a guaranteed
					 pattern of garbage to trip up
					 miscreants who attempt to use
					 pointers into released buffers. */

#define BestFit     1		      /* Use a best fit algorithm when
					 searching for space for an
					 allocation request.  This uses
					 memory more efficiently, but
					 allocation will be much slower. */

#define BECtl	    1		      /* Define this symbol to enable the
					 bectl() function for automatic
					 pool space control.  */

#include <stdio.h>

#ifdef lint
#define NDEBUG			      /* Exits in asserts confuse lint */
/* LINTLIBRARY */                     /* Don't complain about def, no ref */
extern char *sprintf();               /* Sun includes don't define sprintf */
#endif

#include <assert.h>
#include <memory.h>

#ifdef BufDump			      /* BufDump implies DumpData */
#ifndef DumpData
#define DumpData    1
#endif
#endif

#ifdef DumpData
#include <ctype.h>
#endif

/*  Declare the interface, including the requested buffer size type,
    bufsize.  */

#include "bget.h"

#define MemSize     int 	      /* Type for size arguments to memxxx()
					 functions such as memcmp(). */

/* Queue links */

struct qlinks {
    struct bfhead *flink;	      /* Forward link */
    struct bfhead *blink;	      /* Backward link */
};

/* Header in allocated and free buffers */

struct bhead {
    bufsize prevfree;		      /* Relative link back to previous
					 free buffer in memory or 0 if
					 previous buffer is allocated.	*/
    bufsize bsize;		      /* Buffer size: positive if free,
					 negative if allocated. */
};
#define BH(p)	((struct bhead *) (p))

/*  Header in directly allocated buffers (by acqfcn) */

struct bdhead {
    bufsize tsize;		      /* Total size, including overhead */
    struct bhead bh;		      /* Common header */
};
#define BDH(p)	((struct bdhead *) (p))

/* Header in free buffers */

struct bfhead {
    struct bhead bh;		      /* Common allocated/free header */
    struct qlinks ql;		      /* Links on free list */
};
#define BFH(p)	((struct bfhead *) (p))

static struct bfhead freelist = {     /* List of free buffers */
    {0, 0},
    {&freelist, &freelist}
};


#ifdef BufStats
static bufsize totalloc = 0;	      /* Total space currently allocated */
static long numget = 0, numrel = 0;   /* Number of bget() and brel() calls */
#ifdef BECtl
static long numpblk = 0;	      /* Number of pool blocks */
static long numpget = 0, numprel = 0; /* Number of block gets and rels */
static long numdget = 0, numdrel = 0; /* Number of direct gets and rels */
#endif /* BECtl */
#endif /* BufStats */

#ifdef BECtl

/* Automatic expansion block management functions */

static int (*compfcn) _((bufsize sizereq, int sequence)) = NULL;
static void *(*acqfcn) _((bufsize size)) = NULL;
static void (*relfcn) _((void *buf)) = NULL;

static bufsize exp_incr = 0;	      /* Expansion block size */
static bufsize pool_len = 0;	      /* 0: no bpool calls have been made
					 -1: not all pool blocks are
					     the same size
					 >0: (common) block size for all
					     bpool calls made so far
				      */
#endif

/*  Minimum allocation quantum: */

#define QLSize	(sizeof(struct qlinks))
#define SizeQ	((SizeQuant > QLSize) ? SizeQuant : QLSize)

#define V   (void)		      /* To denote unwanted returned values */

/* End sentinel: value placed in bsize field of dummy block delimiting
   end of pool block.  The most negative number which will  fit  in  a
   bufsize, defined in a way that the compiler will accept. */

#define ESent	((bufsize) (-(((1L << (sizeof(bufsize) * 8 - 2)) - 1) * 2) - 2))

/*  BGET  --  Allocate a buffer.  */

void *bget(requested_size)
  bufsize requested_size;
{
    bufsize size = requested_size;
    struct bfhead *b;
#ifdef BestFit
    struct bfhead *best;
#endif
    void *buf;
#ifdef BECtl
    int compactseq = 0;
#endif

    assert(size > 0);

    if (size < SizeQ) { 	      /* Need at least room for the */
	size = SizeQ;		      /*    queue links.  */
    }
#ifdef SizeQuant
#if SizeQuant > 1
    size = (size + (SizeQuant - 1)) & (~(SizeQuant - 1));
#endif
#endif

    size += sizeof(struct bhead);     /* Add overhead in allocated buffer
					 to size required. */

#ifdef BECtl
    /* If a compact function was provided in the call to bectl(), wrap
       a loop around the allocation process  to  allow	compaction  to
       intervene in case we don't find a suitable buffer in the chain. */

    while (1) {
#endif
	b = freelist.ql.flink;
#ifdef BestFit
	best = &freelist;
#endif


	/* Scan the free list searching for the first buffer big enough
	   to hold the requested size buffer. */

#ifdef BestFit
	while (b != &freelist) {
	    if (b->bh.bsize >= size) {
		if ((best == &freelist) || (b->bh.bsize < best->bh.bsize)) {
		    best = b;
		}
	    }
	    b = b->ql.flink;		  /* Link to next buffer */
	}
	b = best;
#endif /* BestFit */

	while (b != &freelist) {
	    if ((bufsize) b->bh.bsize >= size) {

		/* Buffer  is big enough to satisfy  the request.  Allocate it
		   to the caller.  We must decide whether the buffer is  large
		   enough  to  split  into  the part given to the caller and a
		   free buffer that remains on the free list, or  whether  the
		   entire  buffer  should  be  removed	from the free list and
		   given to the caller in its entirety.   We  only  split  the
		   buffer if enough room remains for a header plus the minimum
		   quantum of allocation. */

		if ((b->bh.bsize - size) > (SizeQ + (sizeof(struct bhead)))) {
		    struct bhead *ba, *bn;

		    ba = BH(((char *) b) + (b->bh.bsize - size));
		    bn = BH(((char *) ba) + size);
		    assert(bn->prevfree == b->bh.bsize);
		    /* Subtract size from length of free block. */
		    b->bh.bsize -= size;
		    /* Link allocated buffer to the previous free buffer. */
		    ba->prevfree = b->bh.bsize;
		    /* Plug negative size into user buffer. */
		    ba->bsize = -(bufsize) size;
		    /* Mark buffer after this one not preceded by free block. */
		    bn->prevfree = 0;

#ifdef BufStats
		    totalloc += size;
		    numget++;		  /* Increment number of bget() calls */
#endif
		    buf = (void *) ((((char *) ba) + sizeof(struct bhead)));
		    return buf;
		} else {
		    struct bhead *ba;

		    ba = BH(((char *) b) + b->bh.bsize);
		    assert(ba->prevfree == b->bh.bsize);

                    /* The buffer isn't big enough to split.  Give  the  whole
		       shebang to the caller and remove it from the free list. */

		    assert(b->ql.blink->ql.flink == b);
		    assert(b->ql.flink->ql.blink == b);
		    b->ql.blink->ql.flink = b->ql.flink;
		    b->ql.flink->ql.blink = b->ql.blink;

#ifdef BufStats
		    totalloc += b->bh.bsize;
		    numget++;		  /* Increment number of bget() calls */
#endif
		    /* Negate size to mark buffer allocated. */
		    b->bh.bsize = -(b->bh.bsize);

		    /* Zero the back pointer in the next buffer in memory
		       to indicate that this buffer is allocated. */
		    ba->prevfree = 0;

		    /* Give user buffer starting at queue links. */
		    buf =  (void *) &(b->ql);
		    return buf;
		}
	    }
	    b = b->ql.flink;		  /* Link to next buffer */
	}
#ifdef BECtl

        /* We failed to find a buffer.  If there's a compact  function
	   defined,  notify  it  of the size requested.  If it returns
	   TRUE, try the allocation again. */

	if ((compfcn == NULL) || (!(*compfcn)(size, ++compactseq))) {
	    break;
	}
    }

    /* No buffer available with requested size free. */

    /* Don't give up yet -- look in the reserve supply. */

    if (acqfcn != NULL) {
	if (size > exp_incr - sizeof(struct bhead)) {

	    /* Request	is  too  large	to  fit in a single expansion
	       block.  Try to satisy it by a direct buffer acquisition. */

	    struct bdhead *bdh;

	    size += sizeof(struct bdhead) - sizeof(struct bhead);
	    if ((bdh = BDH((*acqfcn)((bufsize) size))) != NULL) {

		/*  Mark the buffer special by setting the size field
		    of its header to zero.  */
		bdh->bh.bsize = 0;
		bdh->bh.prevfree = 0;
		bdh->tsize = size;
#ifdef BufStats
		totalloc += size;
		numget++;	      /* Increment number of bget() calls */
		numdget++;	      /* Direct bget() call count */
#endif
		buf =  (void *) (bdh + 1);
		return buf;
	    }

	} else {

	    /*	Try to obtain a new expansion block */

	    void *newpool;

	    if ((newpool = (*acqfcn)((bufsize) exp_incr)) != NULL) {
		bpool(newpool, exp_incr);
                buf =  bget(requested_size);  /* This can't, I say, can't
						 get into a loop. */
		return buf;
	    }
	}
    }

    /*	Still no buffer available */

#endif /* BECtl */

    return NULL;
}

/*  BGETZ  --  Allocate a buffer and clear its contents to zero.  We clear
	       the  entire  contents  of  the buffer to zero, not just the
	       region requested by the caller. */

void *bgetz(size)
  bufsize size;
{
    char *buf = (char *) bget(size);

    if (buf != NULL) {
	struct bhead *b;
	bufsize rsize;

	b = BH(buf - sizeof(struct bhead));
	rsize = -(b->bsize);
	if (rsize == 0) {
	    struct bdhead *bd;

	    bd = BDH(buf - sizeof(struct bdhead));
	    rsize = bd->tsize - sizeof(struct bdhead);
	} else {
	    rsize -= sizeof(struct bhead);
	}
	assert(rsize >= size);
	V memset(buf, 0, (MemSize) rsize);
    }
    return ((void *) buf);
}

/*  BGETR  --  Reallocate a buffer.  This is a minimal implementation,
	       simply in terms of brel()  and  bget().	 It  could  be
	       enhanced to allow the buffer to grow into adjacent free
	       blocks and to avoid moving data unnecessarily.  */

void *bgetr(buf, size)
  void *buf;
  bufsize size;
{
    void *nbuf;
    bufsize osize;		      /* Old size of buffer */
    struct bhead *b;

    if ((nbuf = bget(size)) == NULL) { /* Acquire new buffer */
	return NULL;
    }
    if (buf == NULL) {
	return nbuf;
    }
    b = BH(((char *) buf) - sizeof(struct bhead));
    osize = -b->bsize;
#ifdef BECtl
    if (osize == 0) {
	/*  Buffer acquired directly through acqfcn. */
	struct bdhead *bd;

	bd = BDH(((char *) buf) - sizeof(struct bdhead));
	osize = bd->tsize - sizeof(struct bdhead);
    } else
#endif
	osize -= sizeof(struct bhead);
    assert(osize > 0);
    V memcpy((char *) nbuf, (char *) buf, /* Copy the data */
	     (MemSize) ((size < osize) ? size : osize));
    brel(buf);
    return nbuf;
}

/*  BREL  --  Release a buffer.  */

void brel(buf)
  void *buf;
{
    struct bfhead *b, *bn;

    b = BFH(((char *) buf) - sizeof(struct bhead));
#ifdef BufStats
    numrel++;			      /* Increment number of brel() calls */
#endif
    assert(buf != NULL);

#ifdef BECtl
    if (b->bh.bsize == 0) {	      /* Directly-acquired buffer? */
	struct bdhead *bdh;

	bdh = BDH(((char *) buf) - sizeof(struct bdhead));
	assert(b->bh.prevfree == 0);
#ifdef BufStats
	totalloc -= bdh->tsize;
	assert(totalloc >= 0);
	numdrel++;		      /* Number of direct releases */
#endif /* BufStats */
#ifdef FreeWipe
	V memset((char *) buf, 0x55,
		 (MemSize) (bdh->tsize - sizeof(struct bdhead)));
#endif /* FreeWipe */
	assert(relfcn != NULL);
	(*relfcn)((void *) bdh);      /* Release it directly. */
	return;
    }
#endif /* BECtl */

    /* Buffer size must be negative, indicating that the buffer is
       allocated. */

    if (b->bh.bsize >= 0) {
	bn = NULL;
    }
    assert(b->bh.bsize < 0);

    /*	Back pointer in next buffer must be zero, indicating the
	same thing: */

    assert(BH((char *) b - b->bh.bsize)->prevfree == 0);

#ifdef BufStats
    totalloc += b->bh.bsize;
    assert(totalloc >= 0);
#endif

    /* If the back link is nonzero, the previous buffer is free.  */

    if (b->bh.prevfree != 0) {

	/* The previous buffer is free.  Consolidate this buffer  with	it
	   by  adding  the  length  of	this  buffer  to the previous free
	   buffer.  Note that we subtract the size  in	the  buffer  being
           released,  since  it's  negative to indicate that the buffer is
	   allocated. */

	register bufsize size = b->bh.bsize;

        /* Make the previous buffer the one we're working on. */
	assert(BH((char *) b - b->bh.prevfree)->bsize == b->bh.prevfree);
	b = BFH(((char *) b) - b->bh.prevfree);
	b->bh.bsize -= size;
    } else {

        /* The previous buffer isn't allocated.  Insert this buffer
	   on the free list as an isolated free block. */

	assert(freelist.ql.blink->ql.flink == &freelist);
	assert(freelist.ql.flink->ql.blink == &freelist);
	b->ql.flink = &freelist;
	b->ql.blink = freelist.ql.blink;
	freelist.ql.blink = b;
	b->ql.blink->ql.flink = b;
	b->bh.bsize = -b->bh.bsize;
    }

    /* Now we look at the next buffer in memory, located by advancing from
       the  start  of  this  buffer  by its size, to see if that buffer is
       free.  If it is, we combine  this  buffer  with	the  next  one	in
       memory, dechaining the second buffer from the free list. */

    bn =  BFH(((char *) b) + b->bh.bsize);
    if (bn->bh.bsize > 0) {

	/* The buffer is free.	Remove it from the free list and add
	   its size to that of our buffer. */

	assert(BH((char *) bn + bn->bh.bsize)->prevfree == bn->bh.bsize);
	assert(bn->ql.blink->ql.flink == bn);
	assert(bn->ql.flink->ql.blink == bn);
	bn->ql.blink->ql.flink = bn->ql.flink;
	bn->ql.flink->ql.blink = bn->ql.blink;
	b->bh.bsize += bn->bh.bsize;

	/* Finally,  advance  to   the	buffer	that   follows	the  newly
	   consolidated free block.  We must set its  backpointer  to  the
	   head  of  the  consolidated free block.  We know the next block
	   must be an allocated block because the process of recombination
	   guarantees  that  two  free	blocks will never be contiguous in
	   memory.  */

	bn = BFH(((char *) b) + b->bh.bsize);
    }
#ifdef FreeWipe
    V memset(((char *) b) + sizeof(struct bfhead), 0x55,
	    (MemSize) (b->bh.bsize - sizeof(struct bfhead)));
#endif
    assert(bn->bh.bsize < 0);

    /* The next buffer is allocated.  Set the backpointer in it  to  point
       to this buffer; the previous free buffer in memory. */

    bn->bh.prevfree = b->bh.bsize;

#ifdef BECtl

    /*	If  a  block-release function is defined, and this free buffer
	constitutes the entire block, release it.  Note that  pool_len
	is  defined  in  such a way that the test will fail unless all
	pool blocks are the same size.	*/

    if (relfcn != NULL &&
	((bufsize) b->bh.bsize) == (pool_len - sizeof(struct bhead))) {

	assert(b->bh.prevfree == 0);
	assert(BH((char *) b + b->bh.bsize)->bsize == ESent);
	assert(BH((char *) b + b->bh.bsize)->prevfree == b->bh.bsize);
	/*  Unlink the buffer from the free list  */
	b->ql.blink->ql.flink = b->ql.flink;
	b->ql.flink->ql.blink = b->ql.blink;

	(*relfcn)(b);
#ifdef BufStats
	numprel++;		      /* Nr of expansion block releases */
	numpblk--;		      /* Total number of blocks */
	assert(numpblk == numpget - numprel);
#endif /* BufStats */
    }
#endif /* BECtl */
}

#ifdef BECtl

/*  BECTL  --  Establish automatic pool expansion control  */

void bectl(compact, acquire, release, pool_incr)
  int (*compact) _((bufsize sizereq, int sequence));
  void *(*acquire) _((bufsize size));
  void (*release) _((void *buf));
  bufsize pool_incr;
{
    compfcn = compact;
    acqfcn = acquire;
    relfcn = release;
    exp_incr = pool_incr;
}
#endif

/*  BPOOL  --  Add a region of memory to the buffer pool.  */

void bpool(buf, len)
  void *buf;
  bufsize len;
{
    struct bfhead *b = BFH(buf);
    struct bhead *bn;

#ifdef SizeQuant
    len &= ~(SizeQuant - 1);
#endif
#ifdef BECtl
    if (pool_len == 0) {
	pool_len = len;
    } else if (len != pool_len) {
	pool_len = -1;
    }
#ifdef BufStats
    numpget++;			      /* Number of block acquisitions */
    numpblk++;			      /* Number of blocks total */
    assert(numpblk == numpget - numprel);
#endif /* BufStats */
#endif /* BECtl */

    /* Since the block is initially occupied by a single free  buffer,
       it  had	better	not  be  (much) larger than the largest buffer
       whose size we can store in bhead.bsize. */

    assert(len - sizeof(struct bhead) <= -((bufsize) ESent + 1));

    /* Clear  the  backpointer at  the start of the block to indicate that
       there  is  no  free  block  prior  to  this   one.    That   blocks
       recombination when the first block in memory is released. */

    b->bh.prevfree = 0;

    /* Chain the new block to the free list. */

    assert(freelist.ql.blink->ql.flink == &freelist);
    assert(freelist.ql.flink->ql.blink == &freelist);
    b->ql.flink = &freelist;
    b->ql.blink = freelist.ql.blink;
    freelist.ql.blink = b;
    b->ql.blink->ql.flink = b;

    /* Create a dummy allocated buffer at the end of the pool.	This dummy
       buffer is seen when a buffer at the end of the pool is released and
       blocks  recombination  of  the last buffer with the dummy buffer at
       the end.  The length in the dummy buffer  is  set  to  the  largest
       negative  number  to  denote  the  end  of  the pool for diagnostic
       routines (this specific value is  not  counted  on  by  the  actual
       allocation and release functions). */

    len -= sizeof(struct bhead);
    b->bh.bsize = (bufsize) len;
#ifdef FreeWipe
    V memset(((char *) b) + sizeof(struct bfhead), 0x55,
	     (MemSize) (len - sizeof(struct bfhead)));
#endif
    bn = BH(((char *) b) + len);
    bn->prevfree = (bufsize) len;
    /* Definition of ESent assumes two's complement! */
    assert((~0) == -1);
    bn->bsize = ESent;
}

#ifdef BufStats

/*  BSTATS  --	Return buffer allocation free space statistics.  */

void bstats(curalloc, totfree, maxfree, nget, nrel)
  bufsize *curalloc, *totfree, *maxfree;
  long *nget, *nrel;
{
    struct bfhead *b = freelist.ql.flink;

    *nget = numget;
    *nrel = numrel;
    *curalloc = totalloc;
    *totfree = 0;
    *maxfree = -1;
    while (b != &freelist) {
	assert(b->bh.bsize > 0);
	*totfree += b->bh.bsize;
	if (b->bh.bsize > *maxfree) {
	    *maxfree = b->bh.bsize;
	}
	b = b->ql.flink;	      /* Link to next buffer */
    }
}

#ifdef BECtl

/*  BSTATSE  --  Return extended statistics  */

void bstatse(pool_incr, npool, npget, nprel, ndget, ndrel)
  bufsize *pool_incr;
  long *npool, *npget, *nprel, *ndget, *ndrel;
{
    *pool_incr = (pool_len < 0) ? -exp_incr : exp_incr;
    *npool = numpblk;
    *npget = numpget;
    *nprel = numprel;
    *ndget = numdget;
    *ndrel = numdrel;
}
#endif /* BECtl */
#endif /* BufStats */

#ifdef DumpData

/*  BUFDUMP  --  Dump the data in a buffer.  This is called with the  user
		 data pointer, and backs up to the buffer header.  It will
		 dump either a free block or an allocated one.	*/

void bufdump(buf)
  void *buf;
{
    struct bfhead *b;
    unsigned char *bdump;
    bufsize bdlen;

    b = BFH(((char *) buf) - sizeof(struct bhead));
    assert(b->bh.bsize != 0);
    if (b->bh.bsize < 0) {
	bdump = (unsigned char *) buf;
	bdlen = (-b->bh.bsize) - sizeof(struct bhead);
    } else {
	bdump = (unsigned char *) (((char *) b) + sizeof(struct bfhead));
	bdlen = b->bh.bsize - sizeof(struct bfhead);
    }

    while (bdlen > 0) {
	int i, dupes = 0;
	bufsize l = bdlen;
	char bhex[50], bascii[20];

	if (l > 16) {
	    l = 16;
	}

	for (i = 0; i < l; i++) {
            V sprintf(bhex + i * 3, "%02X ", bdump[i]);
            bascii[i] = isprint(bdump[i]) ? bdump[i] : ' ';
	}
	bascii[i] = 0;
        V printf("%-48s   %s\n", bhex, bascii);
	bdump += l;
	bdlen -= l;
	while ((bdlen > 16) && (memcmp((char *) (bdump - 16),
				       (char *) bdump, 16) == 0)) {
	    dupes++;
	    bdump += 16;
	    bdlen -= 16;
	}
	if (dupes > 1) {
	    V printf(
                "     (%d lines [%d bytes] identical to above line skipped)\n",
		dupes, dupes * 16);
	} else if (dupes == 1) {
	    bdump -= 16;
	    bdlen += 16;
	}
    }
}
#endif

#ifdef BufDump

/*  BPOOLD  --	Dump a buffer pool.  The buffer headers are always listed.
		If DUMPALLOC is nonzero, the contents of allocated buffers
		are  dumped.   If  DUMPFREE  is  nonzero,  free blocks are
		dumped as well.  If FreeWipe  checking	is  enabled,  free
		blocks	which  have  been clobbered will always be dumped. */

void bpoold(buf, dumpalloc, dumpfree)
  void *buf;
  int dumpalloc, dumpfree;
{
    struct bfhead *b = BFH(buf);

    while (b->bh.bsize != ESent) {
	bufsize bs = b->bh.bsize;

	if (bs < 0) {
	    bs = -bs;
            V printf("Allocated buffer: size %6ld bytes.\n", (long) bs);
	    if (dumpalloc) {
		bufdump((void *) (((char *) b) + sizeof(struct bhead)));
	    }
	} else {
            char *lerr = "";

	    assert(bs > 0);
	    if ((b->ql.blink->ql.flink != b) ||
		(b->ql.flink->ql.blink != b)) {
                lerr = "  (Bad free list links)";
	    }
            V printf("Free block:       size %6ld bytes.%s\n",
		(long) bs, lerr);
#ifdef FreeWipe
	    lerr = ((char *) b) + sizeof(struct bfhead);
	    if ((bs > sizeof(struct bfhead)) && ((*lerr != 0x55) ||
		(memcmp(lerr, lerr + 1,
		  (MemSize) (bs - (sizeof(struct bfhead) + 1))) != 0))) {
		V printf(
                    "(Contents of above free block have been overstored.)\n");
		bufdump((void *) (((char *) b) + sizeof(struct bhead)));
	    } else
#endif
	    if (dumpfree) {
		bufdump((void *) (((char *) b) + sizeof(struct bhead)));
	    }
	}
	b = BFH(((char *) b) + bs);
    }
}
#endif /* BufDump */

#ifdef BufValid

/*  BPOOLV  --  Validate a buffer pool.  If NDEBUG isn't defined,
		any error generates an assertion failure.  */

int bpoolv(buf)
  void *buf;
{
    struct bfhead *b = BFH(buf);

    while (b->bh.bsize != ESent) {
	bufsize bs = b->bh.bsize;

	if (bs < 0) {
	    bs = -bs;
	} else {
            char *lerr = "";

	    assert(bs > 0);
	    if (bs <= 0) {
		return 0;
	    }
	    if ((b->ql.blink->ql.flink != b) ||
		(b->ql.flink->ql.blink != b)) {
                V printf("Free block: size %6ld bytes.  (Bad free list links)\n",
		     (long) bs);
		assert(0);
		return 0;
	    }
#ifdef FreeWipe
	    lerr = ((char *) b) + sizeof(struct bfhead);
	    if ((bs > sizeof(struct bfhead)) && ((*lerr != 0x55) ||
		(memcmp(lerr, lerr + 1,
		  (MemSize) (bs - (sizeof(struct bfhead) + 1))) != 0))) {
		V printf(
                    "(Contents of above free block have been overstored.)\n");
		bufdump((void *) (((char *) b) + sizeof(struct bhead)));
		assert(0);
		return 0;
	    }
#endif
	}
	b = BFH(((char *) b) + bs);
    }
    return 1;
}
#endif /* BufValid */

        /***********************\
	*			*
	* Built-in test program *
	*			*
        \***********************/

#ifdef DoTestProg
#ifdef TestProg

#define Repeatable  1		      /* Repeatable pseudorandom sequence */
				      /* If Repeatable is not defined, a
					 time-seeded pseudorandom sequence
					 is generated, exercising BGET with
					 a different pattern of calls on each
					 run. */
#define OUR_RAND		      /* Use our own built-in version of
					 rand() to guarantee the test is
					 100% repeatable. */

#ifdef BECtl
#define PoolSize    300000	      /* Test buffer pool size */
#else
#define PoolSize    50000	      /* Test buffer pool size */
#endif
#define ExpIncr     32768	      /* Test expansion block size */
#define CompactTries 10 	      /* Maximum tries at compacting */

#define dumpAlloc   0		      /* Dump allocated buffers ? */
#define dumpFree    0		      /* Dump free buffers ? */

#ifndef Repeatable
extern long time();
#endif

extern char *malloc();
extern int free _((char *));

static char *bchain = NULL;	      /* Our private buffer chain */
static char *bp = NULL; 	      /* Our initial buffer pool */

#include <math.h>

#ifdef OUR_RAND

static unsigned long int next = 1;

/* Return next random integer */

int rand()
{
	next = next * 1103515245L + 12345;
	return (unsigned int) (next / 65536L) % 32768L;
}

/* Set seed for random generator */

void srand(seed)
  unsigned int seed;
{
	next = seed;
}

#endif /* TestProg */
#endif /* DoTestProg */

/*  STATS  --  Edit statistics returned by bstats() or bstatse().  */

static void stats(when)
  char *when;
{
    bufsize cural, totfree, maxfree;
    long nget, nfree;
#ifdef BECtl
    bufsize pincr;
    long totblocks, npget, nprel, ndget, ndrel;
#endif

    bstats(&cural, &totfree, &maxfree, &nget, &nfree);
    V printf(
        "%s: %ld gets, %ld releases.  %ld in use, %ld free, largest = %ld\n",
	when, nget, nfree, (long) cural, (long) totfree, (long) maxfree);
#ifdef BECtl
    bstatse(&pincr, &totblocks, &npget, &nprel, &ndget, &ndrel);
    V printf(
         "  Blocks: size = %ld, %ld (%ld bytes) in use, %ld gets, %ld frees\n",
	 (long)pincr, totblocks, pincr * totblocks, npget, nprel);
    V printf("  %ld direct gets, %ld direct frees\n", ndget, ndrel);
#endif /* BECtl */
}

#ifdef BECtl
static int protect = 0; 	      /* Disable compaction during bgetr() */

/*  BCOMPACT  --  Compaction call-back function.  */

static int bcompact(bsize, seq)
  bufsize bsize;
  int seq;
{
#ifdef CompactTries
    char *bc = bchain;
    int i = rand() & 0x3;

#ifdef COMPACTRACE
    V printf("Compaction requested.  %ld bytes needed, sequence %d.\n",
	(long) bsize, seq);
#endif

    if (protect || (seq > CompactTries)) {
#ifdef COMPACTRACE
        V printf("Compaction gave up.\n");
#endif
	return 0;
    }

    /* Based on a random cast, release a random buffer in the list
       of allocated buffers. */

    while (i > 0 && bc != NULL) {
	bc = *((char **) bc);
	i--;
    }
    if (bc != NULL) {
	char *fb;

	fb = *((char **) bc);
	if (fb != NULL) {
	    *((char **) bc) = *((char **) fb);
	    brel((void *) fb);
	    return 1;
	}
    }

#ifdef COMPACTRACE
    V printf("Compaction bailed out.\n");
#endif
#endif /* CompactTries */
    return 0;
}

/*  BEXPAND  --  Expand pool call-back function.  */

static void *bexpand(size)
  bufsize size;
{
    void *np = NULL;
    bufsize cural, totfree, maxfree;
    long nget, nfree;

    /* Don't expand beyond the total allocated size given by PoolSize. */

    bstats(&cural, &totfree, &maxfree, &nget, &nfree);

    if (cural < PoolSize) {
	np = (void *) malloc((unsigned) size);
    }
#ifdef EXPTRACE
    V printf("Expand pool by %ld -- %s.\n", (long) size,
        np == NULL ? "failed" : "succeeded");
#endif
    return np;
}

/*  BSHRINK  --  Shrink buffer pool call-back function.  */

static void bshrink(buf)
  void *buf;
{
    if (((char *) buf) == bp) {
#ifdef EXPTRACE
        V printf("Initial pool released.\n");
#endif
	bp = NULL;
    }
#ifdef EXPTRACE
    V printf("Shrink pool.\n");
#endif
    free((char *) buf);
}

#endif /* BECtl */

/*  Restrict buffer requests to those large enough to contain our pointer and
    small enough for the CPU architecture.  */

static bufsize blimit(bs)
  bufsize bs;
{
    if (bs < sizeof(char *)) {
	bs = sizeof(char *);
    }

    /* This is written out in this ugly fashion because the
       cool expression in sizeof(int) that auto-configured
       to any length int befuddled some compilers. */

    if (sizeof(int) == 2) {
	if (bs > 32767) {
	    bs = 32767;
	}
    } else {
	if (bs > 200000) {
	    bs = 200000;
	}
    }
    return bs;
}

#ifdef DoTestProg

int main()
{
    int i;
    double x;

    /* Seed the random number generator.  If Repeatable is defined, we
       always use the same seed.  Otherwise, we seed from the clock to
       shake things up from run to run. */

#ifdef Repeatable
    V srand(1234);
#else
    V srand((int) time((long *) NULL));
#endif

    /*	Compute x such that pow(x, p) ranges between 1 and 4*ExpIncr as
	p ranges from 0 to ExpIncr-1, with a concentration in the lower
	numbers.  */

    x = 4.0 * ExpIncr;
    x = log(x);
    x = exp(log(4.0 * ExpIncr) / (ExpIncr - 1.0));

#ifdef BECtl
    bectl(bcompact, bexpand, bshrink, (bufsize) ExpIncr);
    bp = malloc(ExpIncr);
    assert(bp != NULL);
    bpool((void *) bp, (bufsize) ExpIncr);
#else
    bp = malloc(PoolSize);
    assert(bp != NULL);
    bpool((void *) bp, (bufsize) PoolSize);
#endif

    stats("Create pool");
    V bpoolv((void *) bp);
    bpoold((void *) bp, dumpAlloc, dumpFree);

    for (i = 0; i < TestProg; i++) {
	char *cb;
	bufsize bs = pow(x, (double) (rand() & (ExpIncr - 1)));

	assert(bs <= (((bufsize) 4) * ExpIncr));
	bs = blimit(bs);
	if (rand() & 0x400) {
	    cb = (char *) bgetz(bs);
	} else {
	    cb = (char *) bget(bs);
	}
	if (cb == NULL) {
#ifdef EasyOut
	    break;
#else
	    char *bc = bchain;

	    if (bc != NULL) {
		char *fb;

		fb = *((char **) bc);
		if (fb != NULL) {
		    *((char **) bc) = *((char **) fb);
		    brel((void *) fb);
		}
		continue;
	    }
#endif
	}
	*((char **) cb) = (char *) bchain;
	bchain = cb;

	/* Based on a random cast, release a random buffer in the list
	   of allocated buffers. */

	if ((rand() & 0x10) == 0) {
	    char *bc = bchain;
	    int i = rand() & 0x3;

	    while (i > 0 && bc != NULL) {
		bc = *((char **) bc);
		i--;
	    }
	    if (bc != NULL) {
		char *fb;

		fb = *((char **) bc);
		if (fb != NULL) {
		    *((char **) bc) = *((char **) fb);
		    brel((void *) fb);
		}
	    }
	}

	/* Based on a random cast, reallocate a random buffer in the list
	   to a random size */

	if ((rand() & 0x20) == 0) {
	    char *bc = bchain;
	    int i = rand() & 0x3;

	    while (i > 0 && bc != NULL) {
		bc = *((char **) bc);
		i--;
	    }
	    if (bc != NULL) {
		char *fb;

		fb = *((char **) bc);
		if (fb != NULL) {
		    char *newb;

		    bs = pow(x, (double) (rand() & (ExpIncr - 1)));
		    bs = blimit(bs);
#ifdef BECtl
		    protect = 1;      /* Protect against compaction */
#endif
		    newb = (char *) bgetr((void *) fb, bs);
#ifdef BECtl
		    protect = 0;
#endif
		    if (newb != NULL) {
			*((char **) bc) = newb;
		    }
		}
	    }
	}
    }
    stats("\nAfter allocation");
    if (bp != NULL) {
	V bpoolv((void *) bp);
	bpoold((void *) bp, dumpAlloc, dumpFree);
    }

    while (bchain != NULL) {
	char *buf = bchain;

	bchain = *((char **) buf);
	brel((void *) buf);
    }
    stats("\nAfter release");
#ifndef BECtl
    if (bp != NULL) {
	V bpoolv((void *) bp);
	bpoold((void *) bp, dumpAlloc, dumpFree);
    }
#endif

    return 0;
}
#endif

#endif /* DoTestProg */
