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Annotation of researchv9/jerq/src/lib/j/gcalloc.c, revision 1.1

1.1     ! root        1: #include <jerq.h>
        !             2: #include <setup.h>
        !             3: /*
        !             4:  * Garbage-collecting allocator
        !             5:  *
        !             6:  * called as:  gcalloc(nbytes, where)
        !             7:  *     nbytes is unsigned long
        !             8:  *     where is a pointer to the location which will point to the area
        !             9:  *     (e.g. base in a Bitmap), to be updated when necessary
        !            10:  */
        !            11: 
        !            12: /*
        !            13:  * The arena is allocated in longs, to speed up compaction
        !            14:  * Garbage is compacted towards the top (high address end) of the arena,
        !            15:  * i.e. away from the regular, non-compacting, allocator.
        !            16:  * A block has a struct header as its top HEADERSIZE longs, and
        !            17:  * a pointer to the struct header as its bottom long, for use by gcfree.
        !            18:  * header.caller points to the allocating process so things can be cleaned
        !            19:  * up when it exits.
        !            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: extern char *allocendp;        /* defined in alloc.c */
        !            25: #define        STARTAREA       (long *)(allocendp)
        !            26: long   *ENDAREA;
        !            27: static long *nextlong;
        !            28: struct header{
        !            29:        union uuu{
        !            30:                long    Uival;          /* integer value of where */
        !            31:                long    **Upval;        /* where */
        !            32:        }u;
        !            33:        long    *caller;                /* which process allocated */
        !            34:        unsigned long nlongs;           /* # of longs in the user's data */
        !            35: };
        !            36: #define        ival    u.Uival
        !            37: #define        pval    u.Upval
        !            38: #define        HEADERSIZE      sizeof(struct header)/sizeof(long)
        !            39: #define        hp      ((struct header *)p)
        !            40: 
        !            41: gcinit()
        !            42: {
        !            43:        ENDAREA=(long *)(maxaddr[VALMAXADDR]-4);
        !            44:        nextlong=ENDAREA;       /* init; this runs in rom, so .data no good */
        !            45: }
        !            46: 
        !            47: char *
        !            48: realgcalloc(nbytes, where, caller)
        !            49:        register unsigned long nbytes;
        !            50:        long **where;
        !            51:        char *caller;   /* really a Proc * */
        !            52: {
        !            53:        register retry = 0, i;
        !            54:        register long *p, *q;
        !            55:        if(nextlong==0)
        !            56:                nextlong=ENDAREA;       /* initialization; this runs in rom */
        !            57:        if((long)caller&1)      /* head off a possible disaster */
        !            58:                return 0;
        !            59:        nbytes+=sizeof(long)-1;
        !            60:        nbytes>>=2;     /* convert bytes to longs */
        !            61: #define        Nlongs  nbytes
        !            62:        Nlongs+=HEADERSIZE+1;
        !            63:        while(nextlong-STARTAREA < Nlongs){
        !            64:                if(retry++)
        !            65:                        return 0;
        !            66:                compact();
        !            67:        }
        !            68:        p=nextlong-HEADERSIZE;
        !            69:        hp->caller=(long *)caller;
        !            70:        hp->pval=where;
        !            71:        hp->nlongs=Nlongs-HEADERSIZE-1;
        !            72:        nextlong-=Nlongs;
        !            73:        *nextlong=(long)p;      /* so we can find the header when we free */
        !            74:        *hp->pval=nextlong+1;
        !            75:        for(q=*hp->pval, i=0; i<hp->nlongs; i++)
        !            76:                *q++=0;
        !            77:        return (char *)(*hp->pval);
        !            78: }
        !            79: char *
        !            80: gcalloc(n, w)
        !            81:        unsigned long n;
        !            82:        long **w;
        !            83: {
        !            84:        return realgcalloc(n, w, (char *)0);
        !            85: }
        !            86: gcfree(cp)
        !            87:        register char *cp;
        !            88: {
        !            89: #define        p       ((long *)cp)
        !            90:        /* nice and safe */
        !            91:        if(p>nextlong && p<ENDAREA){
        !            92:                cp=(char *)(p[-1]);     /* pointer to the header */
        !            93:                if(p>nextlong && p<ENDAREA)
        !            94:                        hp->ival|=1;
        !            95:        }
        !            96: #undef p
        !            97: }
        !            98: gcfreeall(whichproc)
        !            99:        char *whichproc;
        !           100: {
        !           101:        register long *p;
        !           102:        for(p=ENDAREA; p>nextlong; p-=hp->nlongs+1){
        !           103:                p-=HEADERSIZE;
        !           104:                if(hp->caller==(long *)whichproc)
        !           105:                        hp->ival|=1;
        !           106:        }
        !           107: }
        !           108: static
        !           109: compact()
        !           110: {
        !           111:        register long *w, *p;
        !           112:        register struct header *header;
        !           113:        register unsigned long n;
        !           114:        static Rectangle r={750, 0, 800, 50};
        !           115: 
        !           116:        rectf(&display, r, F_XOR);
        !           117:        w=ENDAREA;
        !           118:        p=w;
        !           119:        while(p>nextlong){
        !           120:                header=(struct header *)(p-HEADERSIZE);
        !           121:                n = header->nlongs;
        !           122:                if(header->ival&1){
        !           123:                        p -= n+HEADERSIZE+1;
        !           124:                        continue;
        !           125:                }
        !           126:                if(w==p){
        !           127:                        p -= n+HEADERSIZE+1;
        !           128:                        w -= n+HEADERSIZE+1;
        !           129:                        continue;
        !           130:                }
        !           131:                *--w = n;
        !           132:                *--w = (long)header->caller;
        !           133:                *--w = header->ival;
        !           134:                p-=HEADERSIZE;
        !           135:                header = (struct header *)w;
        !           136:                *(((struct header *)w)->pval)=w-n; /* update *where */
        !           137:                if(n>0) do
        !           138:                        *--w = *--p;
        !           139:                while(--n);
        !           140:                --p;
        !           141:                *--w = (long)header;    /* back pointer to header */
        !           142:        }
        !           143:        nextlong=w;
        !           144:        rectf(&display, r, F_XOR);
        !           145: }

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