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Annotation of researchv9/jerq/sgs/inc/sdpsrc/hi/allocate.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * static char ID_allocc[] = "@(#) allocate.c: 1.1 1/7/82";
        !             3:  */
        !             4: 
        !             5: ITEMID allocate(request, spacenbr, partnbr)
        !             6: int request, spacenbr, partnbr;
        !             7: {
        !             8: 
        !             9:        register HEADER *gframe;
        !            10:        int framenbr;
        !            11:        long pagenbr;
        !            12:        long itemid;
        !            13:        long getnxtpage();
        !            14: 
        !            15: /*
        !            16:  * The request must be for an even number of bytes, and must hold an
        !            17:  * itemid. No request can exceed one page
        !            18:  */
        !            19: 
        !            20:        request = (request < ITEMIDSIZE) ? (ITEMIDSIZE) : ((request+1) & (~1));
        !            21: 
        !            22:        if( (request == 0)  ||  (request > PAGESIZE) )
        !            23:                return( (ITEMID) fatal("allocate request out of range") );
        !            24: 
        !            25:        if( open_spacenumbers[spacenbr] != YES )
        !            26:                return( (ITEMID) fatal("address space not yet opened") );
        !            27: 
        !            28:        if( (partnbr < 0)  ||  (partnbr > num_partitions) )
        !            29:                return( (ITEMID) fatal("allocate partition out of range") );
        !            30: 
        !            31: 
        !            32: /*
        !            33:  * Satisfy the request. There are two cases:
        !            34:  *
        !            35:  *     1. Allocate a piece of the current page
        !            36:  *     2. Allocate an entirely new page
        !            37:  */
        !            38: 
        !            39:        gframe = &global_frames[spacenbr];
        !            40: 
        !            41: #if DEBUG
        !            42:        if( dflag > 15 )
        !            43:                fprintf( stderr, " alloc %04x %d %d ",
        !            44:                        request, spacenbr, partnbr);
        !            45: #endif
        !            46:                
        !            47:        if( gframe->curoffset + request <= PAGESIZE ) {
        !            48: 
        !            49:                itemid = BUILDPN(gframe->curpage, spacenbr) + gframe->curoffset;
        !            50:                gframe->curoffset += request;
        !            51: 
        !            52:                return( (ITEMID) itemid );
        !            53: 
        !            54:                }
        !            55:        
        !            56:        if( (pagenbr = getnxtpage(spacenbr)) < 0 )
        !            57:                return( (ITEMID) fatal("unable to allocate new page") );
        !            58: 
        !            59:        itemid = BUILDPN(pagenbr, spacenbr);
        !            60: 
        !            61:        if( (framenbr = sojourn(itemid, partnbr, NO)) < 0 )
        !            62:                return( (ITEMID) fatal("unable to find frame for new page") );
        !            63: 
        !            64:        if( delist(framenbr) < 0 )
        !            65:                return( (ITEMID) fatal("unable to delist frame of new page") );
        !            66:        if( enlist(framenbr, MRU) < 0 )
        !            67:                return( (ITEMID) fatal("unable to enlist frame of new page") );
        !            68: 
        !            69:        gframe->curpage = pagenbr;
        !            70:        gframe->curoffset = request;
        !            71: 
        !            72:        return( (ITEMID) itemid );
        !            73: }

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