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Annotation of xinu/sys/getstk.c, revision 1.1.1.2

1.1       root        1: /* getstk.c - getstk */
                      2: 
                      3: #include <conf.h>
                      4: #include <kernel.h>
                      5: #include <mem.h>
                      6: 
                      7: /*------------------------------------------------------------------------
1.1.1.2 ! root        8:  * getstk  --  allocate stack memory, returning address of topmost WORD
1.1       root        9:  *------------------------------------------------------------------------
                     10:  */
1.1.1.2 ! root       11: WORD   *getstk(nbytes)
1.1       root       12:        unsigned  int nbytes;
                     13: {
                     14:        struct  mblock  *p, *q; /* q follows p along memlist            */
                     15:        struct  mblock  *fits, *fitsq;
1.1.1.2 ! root       16:        WORD    address;
1.1       root       17: 
1.1.1.2 ! root       18:        disable();
1.1       root       19:        if (nbytes == 0) {
1.1.1.2 ! root       20:                restore();
        !            21:                return( (WORD *)SYSERR );
1.1       root       22:        }
1.1.1.2 ! root       23:        nbytes = (unsigned int) roundew(nbytes);
        !            24:        fits = (struct mblock *) NULL;
1.1       root       25:        q = &memlist;
1.1.1.2 ! root       26:        for (p = q->mnext ; p !=(struct mblock *) NULL ; q = p,p = p->mnext)
1.1       root       27:                if ( p->mlen >= nbytes) {
                     28:                        fitsq = q;
                     29:                        fits = p;
                     30:                }
1.1.1.2 ! root       31:        if (fits == (struct mblock *) NULL) {
        !            32:                restore();
        !            33:                return( (WORD *)SYSERR );
1.1       root       34:        }
1.1.1.2 ! root       35:        /* eoneil 2/29/88--moved address calc up above if */
        !            36:        /* so pointing to last word in area returned */
        !            37:        address = (WORD) fits + fits->mlen - sizeof(WORD);
        !            38:        if (nbytes == fits->mlen) {
1.1       root       39:                fitsq->mnext = fits->mnext;
                     40:        } else {
                     41:                fits->mlen -= nbytes;
                     42:        }
1.1.1.2 ! root       43: /*     address = (WORD) fits;
        !            44:        address += fits->mlen - sizeof(WORD); */
        !            45:        restore();
        !            46:        return( (WORD *) address);
1.1       root       47: }

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