source: trunk/minix/lib/ack/libp/new.c@ 10

/* $Header: /cvsup/minix/src/lib/ack/libp/new.c,v 1.1 2005/10/10 15:27:47 beng Exp $ */
/*
 * (c) copyright 1983 by the Vrije Universiteit, Amsterdam, The Netherlands.
 *
 *          This product is part of the Amsterdam Compiler Kit.
 *
 * Permission to use, sell, duplicate or disclose this software must be
 * obtained in writing. Requests for such permissions may be sent to
 *
 *      Dr. Andrew S. Tanenbaum
 *      Wiskundig Seminarium
 *      Vrije Universiteit
 *      Postbox 7161
 *      1007 MC Amsterdam
 *      The Netherlands
 *
 */

/* Author: J.W. Stevenson */

extern          _sav();
extern          _rst();

#define assert(x)       /* nothing */
#define UNDEF           0x8000

struct adm {
        struct adm      *next;
        int             size;
};

struct adm      *_lastp = 0;
struct adm      *_highp = 0;

_new(n,pp) int n; struct adm **pp; {
        struct adm *p,*q;
        int *ptmp;

        n = ((n+sizeof(*p)-1) / sizeof(*p)) * sizeof(*p);
        if ((p = _lastp) != 0)
                do {
                        q = p->next;
                        if (q->size >= n) {
                                assert(q->size%sizeof(adm) == 0);
                                if ((q->size -= n) == 0) {
                                        if (p == q)
                                                p = 0;
                                        else
                                                p->next = q->next;
                                        if (q == _highp)
                                                _highp = p;
                                }
                                _lastp = p;
                                p = (struct adm *)((char *)q + q->size);
                                q = (struct adm *)((char *)p + n);
                                goto initialize;
                        }
                        p = q;
                } while (p != _lastp);
        /*no free block big enough*/
        _sav(&p);
        q = (struct adm *)((char *)p + n);
        _rst(&q);
initialize:
        *pp = p;
        ptmp = (int *)p;
        while (ptmp < (int *)q)
                *ptmp++ = UNDEF;
}