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

1.1     ! root        1: #include <setup.h>
        !             2: 
        !             3: #define        oops(x, s)      /*if(x)sstep(s)*/
        !             4: long NLONGS, NAVAIL;
        !             5: /*
        !             6:  * Garbage-collecting allocator
        !             7:  *
        !             8:  * called as:  gcalloc(nbytes, where)
        !             9:  *     nbytes is unsigned long
        !            10:  *     where is a pointer to the location which will point to the area
        !            11:  *     (e.g. base in a Bitmap), to be updated when necessary
        !            12:  */
        !            13: 
        !            14: /*
        !            15:  * The arena is allocated in longs, to speed up compaction
        !            16:  * Garbage is compacted towards the top (high address end) of the arena,
        !            17:  * i.e. away from the regular, non-compacting, allocator.
        !            18:  * A block has a struct header as its top HEADERSIZE longs, and
        !            19:  * a pointer to the struct header as its bottom long, for use by gcfree.
        !            20:  * header.caller points to the allocating process so things can be cleaned
        !            21:  * up when it exits.
        !            22:  * header.pval points to the USER location where the pointer to the block
        !            23:  * is stored; this cell must be updated after a compaction.
        !            24:  * Deallocated blocks have header.pval odd.
        !            25:  */
        !            26: extern char *allocendp;                /* real allocendp defined in alloc.c */
        !            27: #define        STARTAREA       (long *)(allocendp)
        !            28: long *ENDAREA;
        !            29: /*static*/ long *nextlong;
        !            30: struct header{
        !            31:        union uuu{
        !            32:                long    Uival;          /* integer value of where */
        !            33:                long    **Upval;        /* where */
        !            34:        }u;
        !            35:        long    *caller;                /* which process allocated */
        !            36:        unsigned long nlongs;           /* # of longs in the user's data */
        !            37: };
        !            38: #define        ival    u.Uival
        !            39: #define        pval    u.Upval
        !            40: #define        HEADERSIZE      sizeof(struct header)/sizeof(long)
        !            41: #define        hp      ((struct header *)p)
        !            42: 
        !            43: gcinit()
        !            44: {
        !            45:        ENDAREA= maxaddr[VALMAXADDR]-4;
        !            46:        nextlong = ENDAREA;     /* init; this runs in rom, so .data no good */
        !            47: }
        !            48: 
        !            49: char *
        !            50: realgcalloc(nbytes, where, caller)
        !            51:        register unsigned long nbytes;
        !            52:        long **where;
        !            53:        char *caller;   /* really a Proc * */
        !            54: {
        !            55:        register retry = 0;
        !            56:        register long *p;
        !            57:        
        !            58:        if((long)caller&1)      /* head off a possible disaster */
        !            59:                return 0;
        !            60:        nbytes+=sizeof(long)-1;
        !            61:        nbytes>>=2;     /* convert bytes to longs */
        !            62: #define        Nlongs  nbytes
        !            63:        Nlongs+=HEADERSIZE+1;
        !            64:        while(nextlong-STARTAREA < Nlongs){
        !            65: NLONGS=Nlongs;
        !            66: NAVAIL=nextlong-STARTAREA;
        !            67:                if(retry++)
        !            68:                        return 0;
        !            69:                compact();
        !            70:        }
        !            71:        p=nextlong-HEADERSIZE;
        !            72:        hp->caller=(long *)caller;
        !            73:        hp->pval=where;
        !            74:        hp->nlongs=Nlongs-HEADERSIZE-1;
        !            75:        nextlong-=Nlongs;
        !            76:        *nextlong=(long)p;      /* so we can find the header when we free */
        !            77:        return (char *)(*(hp->pval)=nextlong+1);
        !            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:        oops((p<=nextlong || p>=ENDAREA),"gcfree 1");
        !            92:        if(p>nextlong && p<ENDAREA){
        !            93:                cp=(char *)(p[-1]);     /* pointer to the header */
        !            94:                oops(p<=nextlong || p>=ENDAREA, "gcfree 2");
        !            95:                if(p>nextlong && p<ENDAREA)
        !            96:                        hp->ival|=1;
        !            97:        }
        !            98: #undef p
        !            99: }
        !           100: gcfreeall(whichproc)
        !           101:        char *whichproc;
        !           102: {
        !           103:        register long *p;
        !           104:        for(p=ENDAREA; p>nextlong; p-=hp->nlongs+1){
        !           105:                p-=HEADERSIZE;
        !           106:                oops(hp->caller > nextlong, "gcfreeall 1");
        !           107:                oops(hp->pval > nextlong, "gcfreeall 2");
        !           108:                if(hp->caller==(long *)whichproc)
        !           109:                        hp->ival|=1;
        !           110:        }
        !           111: }
        !           112: #include <jerq.h>
        !           113: static
        !           114: compact()
        !           115: {
        !           116:        register long *w, *p;
        !           117:        register struct header *header;
        !           118:        register unsigned long n;
        !           119:        static Rectangle r={0, 0, 50, 50};
        !           120: 
        !           121:        rectf(&display, r, F_XOR);
        !           122:        w=ENDAREA;
        !           123:        p=w;
        !           124:        while(p>nextlong){
        !           125:                header=(struct header *)(p-HEADERSIZE);
        !           126: /*
        !           127:                if(w==p || (header->ival&1)){
        !           128:                        p-= n = header->nlongs+HEADERSIZE+1;
        !           129:                        if((header->ival&1)==0)
        !           130:                                w-=n;
        !           131:                        continue;
        !           132:                }
        !           133: */
        !           134:                oops(header->caller > nextlong, "compact 1");
        !           135:                oops(header->pval > nextlong, "compact 2");
        !           136:                if(header->ival&1){
        !           137:                        p -= header->nlongs+HEADERSIZE+1;
        !           138:                        continue;
        !           139:                }
        !           140:                *--w = n = header->nlongs;
        !           141:                *--w = (long)header->caller;
        !           142:                *--w = header->ival;
        !           143:                p-=HEADERSIZE;
        !           144:                header = (struct header *)w;
        !           145:                *(((struct header *)w)->pval)=w-n; /* update *where */
        !           146:                if(n>0) do
        !           147:                        *--w = *--p;
        !           148:                while(--n);
        !           149:                --p;
        !           150:                *--w = (long)header;    /* back pointer to header */
        !           151:        }
        !           152:        nextlong=w;
        !           153:        rectf(&display, r, F_XOR);
        !           154: }

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