BSD 4_1c_2 release

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

/* Copyright (c) 1982 Regents of the University of California */

static char sccsid[] = "@(#)entry.c 1.1 1/18/82";

/*
* 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);
}