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Annotation of researchv8dc/cmd/sh/stak.c, revision 1.1

1.1     ! root        1: /*     @(#)stak.c      1.4     */
        !             2: /*
        !             3:  * UNIX shell
        !             4:  *
        !             5:  * Bell Telephone Laboratories
        !             6:  *
        !             7:  */
        !             8: 
        !             9: #include       "defs.h"
        !            10: 
        !            11: 
        !            12: /* ========    storage allocation      ======== */
        !            13: 
        !            14: char *
        !            15: getstak(asize)                 /* allocate requested stack */
        !            16: int    asize;
        !            17: {
        !            18:        register char   *oldstak;
        !            19:        register int    size;
        !            20: 
        !            21:        size = round(asize, BYTESPERWORD);
        !            22:        oldstak = stakbot;
        !            23:        staktop = stakbot += size;
        !            24:        return(oldstak);
        !            25: }
        !            26: 
        !            27: /*
        !            28:  * set up stack for local use
        !            29:  * should be followed by `endstak'
        !            30:  */
        !            31: char *
        !            32: locstak()
        !            33: {
        !            34:        if (brkend - stakbot < BRKINCR)
        !            35:        {
        !            36:                if (setbrk(brkincr) == -1)
        !            37:                        error(nostack);
        !            38:                if (brkincr < BRKMAX)
        !            39:                        brkincr += 256;
        !            40:        }
        !            41:        return(stakbot);
        !            42: }
        !            43: 
        !            44: char *
        !            45: savstak()
        !            46: {
        !            47:        assert(staktop == stakbot);
        !            48:        return(stakbot);
        !            49: }
        !            50: 
        !            51: char *
        !            52: endstak(argp)          /* tidy up after `locstak' */
        !            53: register char  *argp;
        !            54: {
        !            55:        register char   *oldstak;
        !            56: 
        !            57:        *argp++ = 0;
        !            58:        oldstak = stakbot;
        !            59:        stakbot = staktop = (char *)round(argp, BYTESPERWORD);
        !            60:        return(oldstak);
        !            61: }
        !            62: 
        !            63: tdystak(x)             /* try to bring stack back to x */
        !            64: register char  *x;
        !            65: {
        !            66:        while ((char *)(stakbsy) > (char *)(x))
        !            67:        {
        !            68:                free(stakbsy);
        !            69:                stakbsy = stakbsy->word;
        !            70:        }
        !            71:        staktop = stakbot = max((char *)(x), (char *)(stakbas));
        !            72:        rmtemp(x);
        !            73: }
        !            74: 
        !            75: stakchk()
        !            76: {
        !            77:        if ((brkend - stakbas) > BRKINCR + BRKINCR)
        !            78:                setbrk(-BRKINCR);
        !            79: }
        !            80: 
        !            81: char *
        !            82: cpystak(x)
        !            83: char   *x;
        !            84: {
        !            85:        return(endstak(movstr(x, locstak())));
        !            86: }

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