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Annotation of 42BSD/ingres/source/gutil/freebuf.c, revision 1.1

1.1     ! root        1: # include      <sccs.h>
        !             2: 
        !             3: SCCSID(@(#)freebuf.c   7.1     2/5/81)
        !             4: 
        !             5: /*
        !             6: **  FREEBUF.C -- more routines for LIFO dynamic buffer allocation [need.c]
        !             7: **
        !             8: **     These routines allow the deallocation of a need() type buffer,
        !             9: **     and also using the same buffer for various SERIALIZED purposes
        !            10: **     by marking the end of one, beginning of the next.
        !            11: **
        !            12: **     Defines:
        !            13: **             freebuf()
        !            14: **             markbuf()
        !            15: **             seterr()
        !            16: */
        !            17: 
        !            18: 
        !            19: 
        !            20: 
        !            21: 
        !            22: 
        !            23: /* structure that the routines use to allocate space */
        !            24: struct nodbuffer
        !            25: {
        !            26:        int             nleft;          /* bytes left */
        !            27:        int             err_num;        /* error code on overflow */
        !            28:        int             (*err_func)();  /* error function on overflow */
        !            29:        char            *xfree;         /* next free byte */
        !            30:        char            buffer [1];     /*beginning of buffer area */
        !            31: };
        !            32: 
        !            33: /*
        !            34: **  MARKBUF -- Mark a place in the buffer to deallocate to
        !            35: **
        !            36: **     Parameters:
        !            37: **             bf -- buffer
        !            38: **
        !            39: **     Returns:
        !            40: **             int >= 0 marking place in buffer (should be used in calling
        !            41: **                     freebuf())
        !            42: **
        !            43: **     Side Effects:
        !            44: **             none
        !            45: */
        !            46: 
        !            47: markbuf(bf)
        !            48: struct nodbuffer       *bf;
        !            49: {
        !            50:        register struct nodbuffer       *buf;
        !            51: 
        !            52:        buf = bf;
        !            53:        return (buf->nleft);
        !            54: }
        !            55: /*
        !            56: **  FREEBUF -- frees part of a buffer
        !            57: **
        !            58: **     Parameters:
        !            59: **             bf -- buffer
        !            60: **             bytes -- a previous return from markbuf().
        !            61: **
        !            62: **     Returns:
        !            63: **             none
        !            64: **
        !            65: **     Side Effects:
        !            66: **             none
        !            67: */
        !            68: 
        !            69: freebuf(bf, bytes)
        !            70: struct nodbuffer       *bf;
        !            71: int                    bytes;
        !            72: {
        !            73:        register struct nodbuffer       *buf;
        !            74:        register int                    i;
        !            75: 
        !            76:        buf = bf;
        !            77:        i = bytes - buf->nleft;
        !            78:        if (i < 0)
        !            79:                syserr("freebuf %d, %d", i, bytes);
        !            80:        buf->xfree -= i;
        !            81:        buf->nleft += i;
        !            82: }
        !            83: /*
        !            84: **  SETERR -- change the error info for a buffer
        !            85: **
        !            86: **     Parameters:
        !            87: **             bf -- buffer
        !            88: **             errnum -- new overflow error code
        !            89: **             err_func -- new error handler
        !            90: **
        !            91: **     Returns:
        !            92: **             none
        !            93: **
        !            94: **     Side Effects:
        !            95: **             adjusts buffer structure
        !            96: */
        !            97: 
        !            98: seterr(bf, errnum, err_func)
        !            99: struct nodbuffer       *bf;
        !           100: int                    errnum;
        !           101: int                    (*err_func)();
        !           102: {
        !           103:        register struct nodbuffer       *buf;
        !           104:        register int                    (*erf)();
        !           105: 
        !           106:        buf = bf;
        !           107:        erf = err_func;
        !           108:        buf->err_num = errnum;
        !           109:        bf->err_func = erf;
        !           110: }

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