set.c   [plain text]

/* $Xorg: set.c,v 1.4 2001/02/09 02:05:27 xorgcvs Exp $ */

/*

Copyright 1995, 1998  The Open Group

Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
the above copyright notice appear in all copies and that both that
copyright notice and this permission notice appear in supporting
documentation.

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 OPEN GROUP 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.

Except as contained in this notice, the name of The Open Group shall
not be used in advertising or otherwise to promote the sale, use or
other dealings in this Software without prior written authorization
from The Open Group.

*/
/* $XFree86: xc/programs/Xserver/record/set.c,v 1.8 2003/11/17 22:20:44 dawes Exp $ */

/*

    See the header set.h for a description of the set ADT.

    Implementation Strategy

    A bit vector is an obvious choice to represent the set, but may take
    too much memory, depending on the numerically largest member in the
    set.  One expected common case is for the client to ask for *all*
    protocol.  This means it would ask for minor opcodes 0 through 65535.
    Representing this as a bit vector takes 8K -- and there may be
    multiple minor opcode intervals, as many as one per major (extension)
    opcode).  In such cases, a list-of-intervals representation would be
    preferable to reduce memory consumption.  Both representations will be
    implemented, and RecordCreateSet will decide heuristically which one
    to use based on the set members.

    Note: When compiling for use in the server, do not use -DTESTING.
    When compiling for stand-alone testing of the set ADT, use -DTESTING.

*/

#ifndef TESTING
#include "misc.h"
#else
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* stuff that you normally get from the X Server's environment */

typedef int Bool;
#ifndef TRUE
#define TRUE 1
#define FALSE 0
#endif

typedef unsigned short CARD16;

#define xalloc malloc
#define xfree free
#define ALLOCATE_LOCAL malloc
#define DEALLOCATE_LOCAL free

void *Xcalloc(size)
    int size;
{
    void *p = malloc(size);
    if (p) memset(p, 0, size);
    return p;
}

#ifndef max
#define max(_a, _b) ( ((_a) > (_b)) ? (_a) : (_b) )
#endif

#endif /* TESTING */

#include "set.h"

#ifdef XFree86LOADER
#include "xf86_libc.h"
#include "xf86_ansic.h"
#endif

static int
maxMemberInInterval(pIntervals, nIntervals)
    RecordSetInterval *pIntervals;
    int nIntervals;
{
    int i;
    int maxMember = -1;
    for (i = 0; i < nIntervals; i++)
    {
	if (maxMember < (int)pIntervals[i].last)
	    maxMember = pIntervals[i].last;
    }
    return maxMember;
}

static void
NoopDestroySet(pSet)
    RecordSetPtr pSet;
{
}

/***************************************************************************/

/* set operations for bit vector representation */

typedef struct {
    RecordSetRec baseSet;
    int maxMember;
    /* followed by the bit vector itself */
} BitVectorSet, *BitVectorSetPtr;

#define BITS_PER_LONG (sizeof(unsigned long) * 8)

static void
BitVectorDestroySet(pSet)
    RecordSetPtr pSet;
{
    xfree(pSet);
}

static unsigned long
BitVectorIsMemberOfSet(pSet, pm)
    RecordSetPtr pSet;
    int pm;
{
    BitVectorSetPtr pbvs = (BitVectorSetPtr)pSet;
    unsigned long *pbitvec;

    if ((int)pm > pbvs->maxMember) return FALSE;
    pbitvec = (unsigned long *)(&pbvs[1]);
    return (pbitvec[pm / BITS_PER_LONG] & ((unsigned long)1 << (pm % BITS_PER_LONG)));
}


static int
BitVectorFindBit(pSet, iterbit, bitval)
    RecordSetPtr pSet;
    int iterbit;
    Bool bitval;
{
    BitVectorSetPtr pbvs = (BitVectorSetPtr)pSet;
    unsigned long *pbitvec = (unsigned long *)(&pbvs[1]);
    int startlong;
    int startbit;
    int walkbit;
    int maxMember;
    unsigned long skipval;
    unsigned long bits;
    unsigned long usefulbits;

    startlong = iterbit / BITS_PER_LONG;
    pbitvec  += startlong;
    startbit  = startlong * BITS_PER_LONG;
    skipval = bitval ? 0L : ~0L;
    maxMember = pbvs->maxMember;


    if (startbit > maxMember) return -1;
    bits = *pbitvec;
    usefulbits = ~(((unsigned long)1 << (iterbit - startbit)) - 1);
    if ( (bits & usefulbits) == (skipval & usefulbits) )
    {
	pbitvec++;
	startbit += BITS_PER_LONG;

	while (startbit <= maxMember && *pbitvec == skipval)
	{
	    pbitvec++;
	    startbit += BITS_PER_LONG;
	}
	if (startbit > maxMember) return -1;
    }

    walkbit = (startbit < iterbit) ? iterbit - startbit : 0;

    bits = *pbitvec;
    while (walkbit < BITS_PER_LONG && ((!(bits & ((unsigned long)1 << walkbit))) == bitval))
	walkbit++;

    return startbit + walkbit;
}


static RecordSetIteratePtr
BitVectorIterateSet(pSet, pIter, pInterval)
    RecordSetPtr pSet;
    RecordSetIteratePtr pIter;
    RecordSetInterval *pInterval;
{
    int iterbit = (int)(long)pIter;
    int b;

    b = BitVectorFindBit(pSet, iterbit, TRUE);
    if (b == -1) return (RecordSetIteratePtr)0;
    pInterval->first = b;

    b = BitVectorFindBit(pSet, b, FALSE);
    pInterval->last = (b < 0) ? ((BitVectorSetPtr)pSet)->maxMember : b - 1;
    return (RecordSetIteratePtr)(long)(pInterval->last + 1);
}

RecordSetOperations BitVectorSetOperations = {
    BitVectorDestroySet, BitVectorIsMemberOfSet, BitVectorIterateSet };

RecordSetOperations BitVectorNoFreeOperations = {
    NoopDestroySet, BitVectorIsMemberOfSet, BitVectorIterateSet };

static int
BitVectorSetMemoryRequirements(pIntervals, nIntervals, maxMember, alignment)
    RecordSetInterval *pIntervals;
    int nIntervals;
    int maxMember;
    int *alignment;
{
    int nlongs;

    *alignment = sizeof(unsigned long);
    nlongs = (maxMember + BITS_PER_LONG) / BITS_PER_LONG;
    return (sizeof(BitVectorSet) + nlongs * sizeof(unsigned long));
}

static RecordSetPtr
BitVectorCreateSet(pIntervals, nIntervals, pMem, memsize)
    RecordSetInterval *pIntervals;
    int nIntervals;
    void *pMem;
    int memsize;
{
    BitVectorSetPtr pbvs;
    int i, j;
    unsigned long *pbitvec;

    /* allocate all storage needed by this set in one chunk */

    if (pMem)
    {
	memset(pMem, 0, memsize);
	pbvs = (BitVectorSetPtr)pMem;
	pbvs->baseSet.ops = &BitVectorNoFreeOperations;
    }
    else
    {
	pbvs = (BitVectorSetPtr)Xcalloc(memsize);
	if (!pbvs) return NULL;
	pbvs->baseSet.ops = &BitVectorSetOperations;
    }

    pbvs->maxMember = maxMemberInInterval(pIntervals, nIntervals);

    /* fill in the set */

    pbitvec = (unsigned long *)(&pbvs[1]);
    for (i = 0; i < nIntervals; i++)
    {
	for (j = pIntervals[i].first; j <= (int)pIntervals[i].last; j++)
	{
	    pbitvec[j/BITS_PER_LONG] |= ((unsigned long)1 << (j % BITS_PER_LONG));
	}
    }
    return (RecordSetPtr)pbvs;
}


/***************************************************************************/

/* set operations for interval list representation */

typedef struct {
    RecordSetRec baseSet;
    int nIntervals;
    /* followed by the intervals (RecordSetInterval) */
} IntervalListSet, *IntervalListSetPtr;

static void
IntervalListDestroySet(pSet)
    RecordSetPtr pSet;
{
    xfree(pSet);
}

static unsigned long
IntervalListIsMemberOfSet(pSet, pm)
    RecordSetPtr pSet;
    int pm;
{
    IntervalListSetPtr prls = (IntervalListSetPtr)pSet;
    RecordSetInterval *pInterval = (RecordSetInterval *)(&prls[1]);
    int hi, lo, probe;

    /* binary search */
    lo = 0; hi = prls->nIntervals - 1;
    while (lo <= hi)
    {
	probe = (hi + lo) / 2;
	if (pm >= pInterval[probe].first && pm <= pInterval[probe].last) return 1;
	else if (pm < pInterval[probe].first) hi = probe - 1;
	else				   lo = probe + 1;
    }
    return 0;
}


static RecordSetIteratePtr
IntervalListIterateSet(pSet, pIter, pIntervalReturn)
    RecordSetPtr pSet;
    RecordSetIteratePtr pIter;
    RecordSetInterval *pIntervalReturn;
{
    RecordSetInterval *pInterval = (RecordSetInterval *)pIter;
    IntervalListSetPtr prls = (IntervalListSetPtr)pSet;

    if (pInterval == NULL)
    {
	pInterval = (RecordSetInterval *)(&prls[1]);
    }

    if ( (pInterval - (RecordSetInterval *)(&prls[1])) < prls->nIntervals )
    {
	*pIntervalReturn = *pInterval;
	return (RecordSetIteratePtr)(++pInterval);
    }
    else
	return (RecordSetIteratePtr)NULL;
}

RecordSetOperations IntervalListSetOperations = {
    IntervalListDestroySet, IntervalListIsMemberOfSet, IntervalListIterateSet };

RecordSetOperations IntervalListNoFreeOperations = {
    NoopDestroySet, IntervalListIsMemberOfSet, IntervalListIterateSet };

static int
IntervalListMemoryRequirements(pIntervals, nIntervals, maxMember, alignment)
    RecordSetInterval *pIntervals;
    int nIntervals;
    int maxMember;
    int *alignment;
{
    *alignment = sizeof(unsigned long);
    return sizeof(IntervalListSet) + nIntervals * sizeof(RecordSetInterval);
}

static RecordSetPtr
IntervalListCreateSet(pIntervals, nIntervals, pMem, memsize)
    RecordSetInterval *pIntervals;
    int nIntervals;
    void *pMem;
    int memsize;
{
    IntervalListSetPtr prls;
    int i, j, k;
    RecordSetInterval *stackIntervals = NULL;
    CARD16 first;

    if (nIntervals > 0)
    {
	stackIntervals = (RecordSetInterval *)ALLOCATE_LOCAL(
				sizeof(RecordSetInterval) * nIntervals);
	if (!stackIntervals) return NULL;

	/* sort intervals, store in stackIntervals (insertion sort) */

	for (i = 0; i < nIntervals; i++)
	{
	    first = pIntervals[i].first;
	    for (j = 0; j < i; j++)
	    {
		if (first < stackIntervals[j].first)
		    break;
	    }
	    for (k = i; k > j; k--)
	    {
		stackIntervals[k] = stackIntervals[k-1];
	    }
	    stackIntervals[j] = pIntervals[i];
	}

	/* merge abutting/overlapping intervals */

	for (i = 0; i < nIntervals - 1; )
	{
	    if ( (stackIntervals[i].last + (unsigned int)1) <
		  stackIntervals[i + 1].first)
	    {
		i++; /* disjoint intervals */
	    }
	    else
	    {
		stackIntervals[i].last = max(stackIntervals[i].last,
					  stackIntervals[i + 1].last);
		nIntervals--;
		for (j = i + 1; j < nIntervals; j++)
		    stackIntervals[j] = stackIntervals[j + 1];
	    }
	}
    }

    /* allocate and fill in set structure */

    if (pMem)
    {
	prls = (IntervalListSetPtr)pMem;
	prls->baseSet.ops = &IntervalListNoFreeOperations;
    }
    else
    {
	prls = (IntervalListSetPtr)
	    xalloc(sizeof(IntervalListSet) + nIntervals * sizeof(RecordSetInterval));
	if (!prls) goto bailout;
	prls->baseSet.ops = &IntervalListSetOperations;
    }
    memcpy(&prls[1], stackIntervals, nIntervals * sizeof(RecordSetInterval));
    prls->nIntervals = nIntervals;
bailout:
    if (stackIntervals) DEALLOCATE_LOCAL(stackIntervals);
    return (RecordSetPtr)prls;
}

#ifdef TESTING
typedef enum {
  BitVectorImplementation, IntervalListImplementation} RecordSetImplementation;

RecordSetImplementation _RecordSetImpl;

static void
_RecordForceSetImplementation(setimpl)
    RecordSetImplementation setimpl;
{
    _RecordSetImpl = setimpl;
}
#endif

typedef RecordSetPtr (*RecordCreateSetProcPtr)(
    RecordSetInterval *pIntervals,
    int nIntervals,
    void *pMem,
    int memsize
);

static int
_RecordSetMemoryRequirements(pIntervals, nIntervals, alignment, ppCreateSet)
    RecordSetInterval *pIntervals;
    int nIntervals;
    int *alignment;
    RecordCreateSetProcPtr *ppCreateSet;
{
    int bmsize, rlsize, bma, rla;
    int maxMember;

    /* find maximum member of set so we know how big to make the bit vector */
    maxMember = maxMemberInInterval(pIntervals, nIntervals);

    bmsize = BitVectorSetMemoryRequirements(pIntervals, nIntervals, maxMember,
					    &bma);
    rlsize = IntervalListMemoryRequirements(pIntervals, nIntervals, maxMember,
					    &rla);
#ifdef TESTING
    if (_RecordSetImpl == BitVectorImplementation)
#else
    if ( ( (nIntervals > 1) && (maxMember <= 255) )
	|| (bmsize < rlsize) )
#endif
    {
	*alignment = bma;
	*ppCreateSet = BitVectorCreateSet;
	return bmsize;
    }
    else
    {
	*alignment = rla;
	*ppCreateSet = IntervalListCreateSet;
	return rlsize;
    }
}

/***************************************************************************/

/* user-visible functions */

int
RecordSetMemoryRequirements(pIntervals, nIntervals, alignment)
    RecordSetInterval *pIntervals;
    int nIntervals;
    int *alignment;
{
    RecordCreateSetProcPtr pCreateSet;
    return _RecordSetMemoryRequirements(pIntervals, nIntervals, alignment,
					&pCreateSet);
}

RecordSetPtr
RecordCreateSet(pIntervals, nIntervals, pMem, memsize)
    RecordSetInterval *pIntervals;
    int nIntervals;
    void *pMem;
    int memsize;
{
    RecordCreateSetProcPtr pCreateSet;
    int alignment;
    int size;

    size = _RecordSetMemoryRequirements(pIntervals, nIntervals, &alignment,
					&pCreateSet);
    if (pMem)
    {
	if ( ((long)pMem & (alignment-1) ) || memsize < size)
	    return NULL;
    }
    return (*pCreateSet)(pIntervals, nIntervals, pMem, size);
}

/***************************************************************************/

#ifdef TESTING

/*

Test Strategy

Having two set representations is convenient for testing because we
can play them against each other.  The test code will be able to
specify which implementation to use.  This breaks the encapsulation,
but that seems acceptable for testing.  The crux of the test loop
looks like this:

loop:
    generate random list of Intervals

    create set A using bit vector implementation
    create set B using Interval list implementation

    for each possible set member
        if set A and set B disagree on whether this is a member    error;

    iterate over both sets, comparing the intervals returned by each.
    if intervals or number of intervals are different    error;

    iterate over intervals of set A
	for i = interval.first to interval.last
	    if i is not a member of set B	error;

    iterate over intervals of set B
	for i = interval.first to interval.last
	    if i is not a member of set A	error;

    destroy sets A, B

*/

int GenerateRandomIntervals(pIntervals, maxintervals)
    RecordSetInterval *pIntervals;
    int maxintervals;
{
    int i, nIntervals;

    nIntervals = rand() % maxintervals;

    for (i = 0; i < nIntervals; i++)
    {
	pIntervals[i].first = rand();
	pIntervals[i].last  = pIntervals[i].first + rand();
    }
    return nIntervals;
}

#define MAXINTERVALS 100

int main(argc, argv)
    int argc;
    char **argv;
{
    RecordSetPtr bs, rs;
    RecordSetInterval br, rr;
    RecordSetIteratePtr bi, ri;
    CARD16 i;
    int testcount;
    RecordSetInterval intervals[MAXINTERVALS];
    int nIntervals;
    int bsize, rsize;
    int balign, ralign;
    int pad;

    for (testcount = 0; 1; testcount++)
    {
	nIntervals = GenerateRandomIntervals(intervals, MAXINTERVALS);
	printf("%d nIntervals %d\n", testcount, nIntervals);

	if (testcount & 1)
	{
	    _RecordForceSetImplementation(BitVectorImplementation);
	    bsize = RecordSetMemoryRequirements(intervals, nIntervals, &balign);
	    _RecordForceSetImplementation(IntervalListImplementation);
	    rsize = RecordSetMemoryRequirements(intervals, nIntervals, &ralign);
	    pad = (ralign - (bsize & (ralign - 1))) & (ralign - 1);
	    bs = (RecordSetPtr)xalloc(bsize + pad + rsize );
	    if (!bs)
	    {
		fprintf(stderr, "%d: failed to alloc memory for  sets\n",
			testcount);
		continue;
	    }
	    rs = (RecordSetPtr)(((char *)bs) + bsize + pad);
	}
	else
	{
	    bs = rs = NULL;
	    bsize = rsize = 0;
	}

	_RecordForceSetImplementation(BitVectorImplementation);
	bs = RecordCreateSet(intervals, nIntervals, bs, bsize);
	_RecordForceSetImplementation(IntervalListImplementation);
	rs = RecordCreateSet(intervals, nIntervals, rs, rsize);

	if (!bs || !rs)
	{
	    fprintf(stderr, "%d: failed to create sets\n", testcount);
	    continue;
	}

	for (i = 0; i < 65535; i++)
	{
	    unsigned long b, r;

	    b = RecordIsMemberOfSet(bs, i);
	    r = RecordIsMemberOfSet(rs, i);
	    if ( (b && !r) || (!b && r) )
	    {
		fprintf(stderr, "%d: isMemberOfSet %d\n",
			testcount, (int)i);
	    }
	}

	bi = RecordIterateSet(bs, NULL, &br);
	ri = RecordIterateSet(rs, NULL, &rr);

	while (bi && ri)
	{
	    if ( (rr.first != br.first) || (rr.last != br.last) )
	    {
		fprintf(stderr, "%d: iterateSet interval value mismatch\n",
			testcount);
	    }
	    bi = RecordIterateSet(bs, bi, &br);
	    ri = RecordIterateSet(rs, ri, &rr);
	}
	if (bi != ri)
	{
	    fprintf(stderr, "%d: iterateSet interval count mismatch\n",
		    testcount);
	}
	

	bi = NULL;
	while (bi = RecordIterateSet(bs, bi, &br))
	{
	    for (i = br.first; i <= br.last; i++)
	    {
		if (!RecordIsMemberOfSet(rs, i))
		{
		    fprintf(stderr, "%d: iterateSet b / isMemberOfSet r %d\n",
			    testcount, (int)i);
		}
	    }
	}

	ri = NULL;
	while (ri = RecordIterateSet(rs, ri, &rr))
	{
	    for (i = rr.first; i <= rr.last; i++)
	    {
		if (!RecordIsMemberOfSet(bs, i) )
		{
		    fprintf(stderr, "%d: iterateSet r / isMemberOfSet b %d\n",
			    testcount, (int)i);
		}
	    }
	}

	RecordDestroySet(bs);
	RecordDestroySet(rs);

	if (testcount & 1)
	{
	    xfree(bs);
	}
    }
}

#endif /* TESTING */