BSD 4_3 release

[unix-history] / usr / src / ucb / pascal / pdx / machine / setbp.c

/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/

#ifndef lint
static char sccsid[] = "@(#)setbp.c     5.1 (Berkeley) 6/6/85";
#endif not lint
/*
* Breakpoint/machine interface.
*/

#include "defs.h"
#include <signal.h>
#include "machine.h"
#include "process.h"
#include "main.h"
#include "pxops.h"
#include "process/process.rep"

#define BP_OP           O_BPT           /* breakpoint trap */
#define BP_ERRNO        SIGILL          /* signal received at a breakpoint */

/*
* Setting a breakpoint at a location consists of saving
* the half-word at the location and poking a BP_OP there.
*
* We save the locations and half-words on a list for use in unsetting.
*/

typedef struct savelist SAVELIST;

struct savelist {
       ADDRESS location;
       short save;
       short refcount;
       SAVELIST *link;
};

LOCAL SAVELIST *savelist;

/*
* Set a breakpoint at the given address.  Only save the half-word there
* if it's not already a breakpoint.
*/

setbp(addr)
ADDRESS addr;
{
       short w;
       short save;
       register SAVELIST *newsave, *s;

       if (option('b')) {
               printf("setting breakpoint at %d\n", addr);
               fflush(stdout);
       }
       for (s = savelist; s != NIL; s = s->link) {
               if (s->location == addr) {
                       s->refcount++;
                       return;
               }
       }
       iread(&save, addr, sizeof(save));
       newsave = alloc(1, SAVELIST);
       newsave->location = addr;
       newsave->save = save;
       newsave->refcount = 1;
       newsave->link = savelist;
       savelist = newsave;
       w = BP_OP;
       iwrite(&w, addr, sizeof(w));
}

/*
* Unset a breakpoint; unfortunately we have to search the SAVELIST
* to find the saved value.  The assumption is that the SAVELIST will
* usually be quite small.
*/

unsetbp(addr)
ADDRESS addr;
{
       register SAVELIST *s, *prev;

       if (option('b')) {
               printf("unsetting breakpoint at %d\n", addr);
               fflush(stdout);
       }
       prev = NIL;
       for (s = savelist; s != NIL; s = s->link) {
               if (s->location == addr) {
                       iwrite(&s->save, addr, sizeof(s->save));
                       s->refcount--;
                       if (s->refcount == 0) {
                               if (prev == NIL) {
                                       savelist = s->link;
                               } else {
                                       prev->link = s->link;
                               }
                               dispose(s);
                       }
                       return;
               }
               prev = s;
       }
       panic("unsetbp: couldn't find address %d", addr);
}

/*
* Predicate to test if the reason the process stopped was because
* of a breakpoint.
*/

BOOLEAN isbperr()
{
       register PROCESS *p;

       p = process;
       return(p->status==STOPPED && p->signo==BP_ERRNO);
}