⟦6aa780e26⟧

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/* ps2pe.c - presentation stream to presentation element */

# ifndef lint
static char Rcsid[] = "@(#)$Header: /cs/research/pp/hubris/pp-beta/Chans/x40084/RCS/ps2pe.c,v 5.0 90/09/20 15:55:52 pp Exp Locker: pp $";
# endif

/*
 * $Header: /cs/research/pp/hubris/pp-beta/Chans/x40084/RCS/ps2pe.c,v 5.0 90/09/20 15:55:52 pp Exp Locker: pp $
 *
 * $Log:	ps2pe.c,v $
 * Revision 5.0  90/09/20  15:55:52  pp
 * rcsforce : 5.0 public release
 * 
 */



/*
 *				  NOTICE
 *
 *    Acquisition, use, and distribution of this module and related
 *    materials are subject to the restrictions of a license agreement.
 *    Consult the Preface in the User's Manual for the full terms of
 *    this agreement.
 *
 */


/* LINTLIBRARY */

#include <stdio.h>
#include <isode/psap.h>
#include <isode/tailor.h>

/* \f

 */
extern PE ps2pe_aux2 ();

PE	ps2pe_aux (ps, top)
PS	ps;
int	top;
{
	return ps2pe_aux2 (ps, top, 1);
}

PE	ps2pe_aux2 (ps, top, all)
register PS	ps;
int	top, all;
{
    register PElementLen len;
    PElementClass   class;
    PElementForm    form;
    PElementID	    id;
    register PE	    pe;

    if (top && ps_prime (ps) == NOTOK)
	return NULLPE;
    
    if (ps_read_id (ps, top, &class, &form, &id) == NOTOK)
	return NULLPE;
    if ((pe = pe_alloc (class, form, id)) == NULLPE)
	return ps_seterr (ps, PS_ERR_NMEM, NULLPE);
    if (ps_read_len (ps, &pe -> pe_len) == NOTOK)
	goto you_lose;

    if (all == 0)
	    return pe;
    len = pe -> pe_len;
    switch (pe -> pe_form) {
	case PE_FORM_PRIM: 
	    if (len == PE_LEN_INDF) {
		(void) ps_seterr (ps, PS_ERR_INDF, NULLPE);
	        goto you_lose;
	    }
	    if (len > 0) {
		if (ps -> ps_inline) {	/* "ultra-efficiency"... */
		    if (ps -> ps_base == NULLCP || ps -> ps_cnt < len) {
			(void) ps_seterr (ps, PS_ERR_EOF, NULLPE);
			goto you_lose;
		    }
		    pe -> pe_inline = 1;
		    pe -> pe_prim = (PElementData) ps -> ps_ptr;
		    ps -> ps_ptr += len, ps -> ps_cnt -= len;
		    ps -> ps_byteno += len;
		}
		else {
		    if ((pe -> pe_prim = PEDalloc (len)) == NULLPED) {
			(void) ps_seterr (ps, PS_ERR_NMEM, NULLPE);
			goto you_lose;
		    }
		    if (ps_read (ps, pe -> pe_prim, len) == NOTOK) {
#ifdef	DEBUG
			SLOG (psap_log, LLOG_DEBUG, NULLCP,
			      ("error reading primitive, %d bytes: %s",
			       len, ps_error (ps -> ps_errno)));
#endif
			goto you_lose;
		    }
		}
	    }
	    break;

	case PE_FORM_CONS: 
	    if (len != 0 && ps_read_cons (ps, &pe -> pe_cons, len) == NOTOK)
		goto you_lose;
	    break;
    }

    return pe;

you_lose: ;
#ifdef	DEBUG
    if (psap_log -> ll_events & LLOG_DEBUG) {
	LLOG (psap_log, LLOG_PDUS, ("PE read thus far"));
	pe2text (psap_log, pe, 1, NOTOK);
    }
#endif

    pe_free (pe);
    return NULLPE;
}

/* \f

 */

static int pe_id_overshift = PE_ID_MASK << (PE_ID_BITS - (PE_ID_SHIFT + 1));


int  ps_read_id (ps, top, class, form, id)
register PS	ps;
int	top;
register PElementClass *class;
register PElementForm *form;
register PElementID *id;
{
    byte    c,
	    d;
    register PElementID j;

    if (ps_read (ps, &c, 1) == NOTOK) {
	if (top && ps -> ps_errno == PS_ERR_EOF)
	    ps -> ps_errno = PS_ERR_NONE;
	else {
#ifdef	DEBUG
	SLOG (psap_log, LLOG_DEBUG, NULLCP,
	      ("error reading initial octet: %s", ps_error (ps -> ps_errno)));
#endif
	}
	    
	return NOTOK;
    }

    *class = (c & PE_CLASS_MASK) >> PE_CLASS_SHIFT;
    *form = (c & PE_FORM_MASK) >> PE_FORM_SHIFT;
    j = (c & PE_CODE_MASK);

    if (j == PE_ID_XTND)
	for (j = 0;; j <<= PE_ID_SHIFT) {
	    if (ps_read (ps, &d, 1) == NOTOK) {
		if (ps -> ps_errno == PS_ERR_EOF)
		    ps -> ps_errno = PS_ERR_EOFID;
		return NOTOK;
	    }

	    j |= d & PE_ID_MASK;
	    if (!(d & PE_ID_MORE))
		break;
	    if (j & pe_id_overshift)
		return ps_seterr (ps, PS_ERR_OVERID, NOTOK);
	}
    *id = j;
    DLOG (psap_log, LLOG_DEBUG, ("class=%d form=%d id=%d",*class, *form, *id));

    return OK;
}

/* \f

 */

int  ps_read_len (ps, len)
register PS	ps;
register PElementLen   *len;
{
    register int    i;
    register PElementLen j;
    byte    c;

    if (ps_read (ps, &c, 1) == NOTOK) {
#ifdef	DEBUG
	SLOG (psap_log, LLOG_DEBUG, NULLCP,
	      ("error reading initial length octet: %s",
	       ps_error (ps -> ps_errno)));
#endif

	return NOTOK;
    }

    if ((i = c) & PE_LEN_XTND) {
	if ((i &= PE_LEN_MASK) > sizeof (PElementLen))
	    return ps_seterr (ps, PS_ERR_OVERLEN, NOTOK);

	if (i) {
	    for (j = 0; i-- > 0;) {
		if (ps_read (ps, &c, 1) == NOTOK) {
		    if (ps -> ps_errno == PS_ERR_EOF)
			ps -> ps_errno = PS_ERR_EOFLEN;
		    return NOTOK;
		}

		j = (j << 8) | (c & 0xff);
	    }
	    *len = j;
	}
	else
	    *len = PE_LEN_INDF;
    }
    else
	*len = i;
#ifdef	DEBUG
    SLOG (psap_log, LLOG_DEBUG, NULLCP, ("len=%d", *len));
#endif

    return OK;
}

/* \f

 */

int  ps_read_cons (ps, pe, len)
register PS	ps;
register PE    *pe;
register PElementLen len;
{
    register int    cc;
    register PE	    p,
		    q;

    cc = ps -> ps_byteno + len;

    if ((p = ps2pe_aux2 (ps, 0, 1)) == NULLPE) {
no_cons: ;
#ifdef	DEBUG
	if (len == PE_LEN_INDF)
	    LLOG (psap_log, LLOG_DEBUG,
		  ("error building indefinite constructor, %s",
		   ps_error (ps -> ps_errno)));
	else
	    LLOG (psap_log, LLOG_DEBUG,
		  ("error building constructor, stream at %d, wanted %d: %s",
		   ps -> ps_byteno, cc, ps_error (ps -> ps_errno)));
#endif

	return NOTOK;
    }
    *pe = p;

    if (len == PE_LEN_INDF) {
	if (p -> pe_class == PE_CLASS_UNIV && p -> pe_id == PE_UNIV_EOC) {
	    pe_free (p);
	    *pe = NULLPE;
	    return OK;
	}
	for (q = p; p = ps2pe_aux2 (ps, 0, 1); q = q -> pe_next = p) {
	    if (p -> pe_class == PE_CLASS_UNIV && p -> pe_id == PE_UNIV_EOC) {
		pe_free (p);
		return OK;
	    }
	}

	goto no_cons;
    }

    for (q = p;; q = q -> pe_next = p) {
	if (cc < ps -> ps_byteno)
	    return ps_seterr (ps, PS_ERR_LEN, NOTOK);
	if (cc == ps -> ps_byteno)
	    return OK;
	if ((p = ps2pe_aux2 (ps, 0, 1)) == NULLPE)
	    goto no_cons;
    }
}
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