Return to gcalloc.c CVS log

Up to [Research Unix] / researchv9 / jtools / src / sam

Annotation of researchv9/jtools/src/sam/gcalloc.c, revision 1.1

1.1     ! root        1: #include "sam.h"
        !             2: /*
        !             3:  * Garbage-compacting allocator
        !             4:  *
        !             5:  * called as:  gcalloc(nbytes, where)
        !             6:  *             gcrealloc(p, nbytes)
        !             7:  *             gcfree(p)
        !             8:  *     nbytes is unsigned long
        !             9:  *     where is a pointer to the location which will point to the area
        !            10:  *     (e.g. base in a Bitmap), to be updated when necessary.
        !            11:  *     The return values  for the allocators are the new address,
        !            12:  *     but since they update *where, the value isn't too useful.
        !            13:  *     They panic if they fail.
        !            14:  */
        !            15: 
        !            16: /*
        !            17:  * The arena is allocated in longs, to speed up compaction
        !            18:  * Garbage is compacted towards the bottom (low address end) of the arena.
        !            19:  * A block has a struct header as its bottom HEADERSIZE longs for use by gcfree.
        !            20:  * header.pval points to the USER location where the pointer to the block
        !            21:  * is stored; this cell must be updated after a compaction.
        !            22:  * Deallocated blocks have header.pval odd.
        !            23:  */
        !            24: 
        !            25: #define        BRKINCR         (16*1024)       /* bytes to add to arena each time */
        !            26: #define LBRKINCR       (BRKINCR/sizeof(long))
        !            27: #define        FREE            1
        !            28: #define        HEADERSIZE      sizeof(struct header)/sizeof(long)
        !            29: 
        !            30: static long    *nextlong;
        !            31: static long    *startarena;
        !            32: static long    *endarena;
        !            33: static         compact();
        !            34: int            dontcompact;
        !            35: 
        !            36: extern char    *brk();
        !            37: extern char    *sbrk();
        !            38: 
        !            39: struct header{
        !            40:        union uuu{
        !            41:                long    Uival;          /* integer value of where */
        !            42:                long    **Upval;        /* where */
        !            43:        }u;
        !            44:        ulong nlongs;                   /* # of longs in the user's data */
        !            45: };
        !            46: #define        ival    u.Uival
        !            47: #define        pval    u.Upval
        !            48: #define        hp      ((struct header *)p)
        !            49: 
        !            50: uchar *
        !            51: gcalloc(nbytes, where)
        !            52:        register ulong nbytes;
        !            53:        long **where;
        !            54: {
        !            55:        register long *p;
        !            56:        register ulong nl;
        !            57:        if(nextlong>endarena)
        !            58:                panic("nextlong>endarena");
        !            59:        if((long)where&FREE)    /* head off a possible disaster */
        !            60:                panic("where&FREE");
        !            61:        if(startarena==0){
        !            62:                if((int)(startarena=(long *)sbrk(BRKINCR))==-1)
        !            63:                        error(Ealloc);
        !            64:                endarena=startarena+(BRKINCR/sizeof(long));
        !            65:                nextlong=startarena;
        !            66:        }
        !            67:        nbytes+=sizeof(long)-1;
        !            68:        nbytes/=sizeof(long);   /* convert bytes to longs */
        !            69: #define        Nlongs  nbytes
        !            70:        Nlongs+=HEADERSIZE;
        !            71:        if(endarena-nextlong < Nlongs){
        !            72:                if(!dontcompact)
        !            73:                        compact();
        !            74:                if(endarena-nextlong < Nlongs){
        !            75:                        nl=(nextlong+Nlongs)-startarena;
        !            76:                        /* if !compacting, avoid greed */
        !            77:                        if(!dontcompact)
        !            78:                                nl=((nl+LBRKINCR-1)/LBRKINCR)*LBRKINCR;
        !            79:                        if(brk((char *)(startarena+nl))!=0)
        !            80:                                error(Ealloc);
        !            81:                        endarena=startarena+nl;
        !            82:                }
        !            83:        }                       
        !            84:        p=nextlong;
        !            85:        hp->pval=where;
        !            86:        hp->nlongs=Nlongs;
        !            87:        nextlong+=Nlongs;
        !            88:        return (uchar *)(*(hp->pval)=p+HEADERSIZE);
        !            89: }
        !            90: uchar *
        !            91: gcrealloc(cp, nbytes)
        !            92:        uchar *cp;
        !            93:        register ulong nbytes;
        !            94: {
        !            95:        register long *p=(long *)cp, *q;
        !            96:        register long *newp;
        !            97:        register long **ptrold;
        !            98:        register n;
        !            99:        long *x;
        !           100:        p-=HEADERSIZE;  /* the header */
        !           101:        n=hp->nlongs;
        !           102:        nbytes+=sizeof(long)-1;
        !           103:        nbytes/=sizeof(long);   /* convert bytes to longs; nbytes is now Nlongs */
        !           104:        ptrold=hp->pval; /* location that will be updated if compaction occurs */
        !           105:        /* we give where==x to gcalloc to avoid collision with old header */
        !           106:        newp=(long *)gcalloc((ulong)(Nlongs*sizeof(long)), &x);
        !           107:        /* now it's safe to have both headers point to the same place */
        !           108:        ((struct header *)(newp-HEADERSIZE))->pval=ptrold;
        !           109:        p= *ptrold;
        !           110:        q=newp;
        !           111:        if(n>Nlongs)
        !           112:                n=Nlongs;
        !           113:        if(n>0) do
        !           114:                *q++= *p++;
        !           115:        while(--n);
        !           116:        (void)gcfree((uchar *)*ptrold);
        !           117:        return (uchar *)(*ptrold=newp);
        !           118: }
        !           119: shiftgcarena(nl)
        !           120:        ulong nl;
        !           121: {
        !           122:        register long *p;
        !           123:        if(startarena==0 || dontcompact)
        !           124:                return;
        !           125:        if(nl<0)
        !           126:                panic("shiftgcarena");
        !           127:        bcopy((uchar *)startarena, (uchar *)nextlong, (uchar *)(startarena+nl), -1);
        !           128:        nextlong+=nl;
        !           129:        startarena+=nl;
        !           130:        endarena+=nl;
        !           131:        for(p=startarena; p<nextlong; p+=hp->nlongs){
        !           132:                if((hp->ival&FREE)==0)
        !           133:                        *(hp->pval)+=nl;
        !           134:        }
        !           135: }
        !           136: gcfree(cp)
        !           137:        uchar *cp;
        !           138: {
        !           139:        register long *p=(long *)cp;
        !           140:        if(p==0)
        !           141:                return;
        !           142:        p-=HEADERSIZE;
        !           143:        if(p<startarena || nextlong<=p)
        !           144:                panic("gcfree");
        !           145:        hp->ival|=FREE;
        !           146: }
        !           147: static
        !           148: compact()
        !           149: {
        !           150:        register long *w, *p;
        !           151:        register ulong n;
        !           152: 
        !           153:        w=p=startarena;
        !           154:        while(p<nextlong){
        !           155:                if(hp->ival&FREE){
        !           156:                        p+=hp->nlongs;
        !           157:                        continue;
        !           158:                }
        !           159:                if(w==p){
        !           160:                        w+=hp->nlongs;
        !           161:                        p+=hp->nlongs;
        !           162:                        continue;
        !           163:                }
        !           164:                *(hp->pval)=w+HEADERSIZE; /* update *where */
        !           165:                *w++=hp->ival;
        !           166:                *w++=n=hp->nlongs;
        !           167:                p+=HEADERSIZE;
        !           168:                if((n-=HEADERSIZE)>0) do
        !           169:                        *w++ = *p++;
        !           170:                while(--n);
        !           171:        }
        !           172:        nextlong=w;
        !           173: }
        !           174: gcchk()
        !           175: {
        !           176:        register long *p;
        !           177:        if(startarena==0)
        !           178:                return;
        !           179:        for(p=startarena; p<nextlong; p+=hp->nlongs)
        !           180:                if((hp->ival&FREE)==0){
        !           181:                        if(hp->pval==0 || ((long *)hp->pval>=startarena && ((int)(hp->pval)&0x70000000L)==0))
        !           182:                                panic("gcchk 1");
        !           183:                        if(p+hp->nlongs>nextlong)
        !           184:                                panic("gcchk 2");
        !           185:                }
        !           186: }

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.