BSD 4_3_Net_2 release

[unix-history] / usr / src / usr.bin / pascal / pdx / runtime / entry.c

/*-
* Copyright (c) 1980 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*      This product includes software developed by the University of
*      California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#ifndef lint
static char sccsid[] = "@(#)entry.c     5.2 (Berkeley) 4/16/91";
#endif /* not lint */

/*
* routines to deal with the entry addresses of blocks
*/

#include "defs.h"
#include "runtime.h"
#include "frame.rep"
#include "machine.h"
#include "process.h"
#include "sym.h"
#include "source.h"
#include "object.h"
#include "process/pxinfo.h"
#include "process/process.rep"

/*
* Return the address of the beginning of the procedure/function
* associated with the given frame.
*/

ADDRESS entry(frp)
register FRAME *frp;
{
       return(frp->blockp - 2 - ENDOFF);
}

/*
* Find the entry address of the caller of the current block.
* This is only called in connection with breakpoints.
*
* This routine assumes it is at the very beginning of the block.
*/

ADDRESS caller_addr()
{
       FRAME *frp;

       if ((frp = curframe()) == NIL) {
               panic("caller_addr(main program)");
       }
       frp = nextframe(frp);
       if (frp == NIL) {
               return(codeloc(program));
       } else {
               return(entry(frp));
       }
}

/*
* Find the return address of the current procedure/function.
*
* There are two special cases:
*
*      we're right at the beginning of the main program
*      we're right at the beginning of some procedure or function
*
* The first one is handled by returning the last instruction in
* the object code.  In the second case, we get the return address
* directly from the process' stack.
*/

ADDRESS return_addr()
{
       ADDRESS addr;
       FRAME *frp, frame;

       if (pc == codeloc(program)) {
               addr = lastaddr();
       } else {
               frp = curframe();
               if (frp == NIL) {
                       dread(&frame, (ADDRESS) process->sp, sizeof(FRAME));
                       addr = frame.save_pc - ENDOFF;
               } else {
                       addr = frp->save_pc;
               }
       }
       return addr;
}

/*
* Calculate the entry address for a procedure or function parameter,
* given the address of the descriptor.
*/

ADDRESS fparamaddr(a)
ADDRESS a;
{
       ADDRESS r;

       dread(&r, a, sizeof(r));
       return (r - ENDOFF);
}