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Annotation of 43BSD/ucb/pascal/pdx/machine/setbp.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1980 Regents of the University of California.
        !             3:  * All rights reserved.  The Berkeley software License Agreement
        !             4:  * specifies the terms and conditions for redistribution.
        !             5:  */
        !             6: 
        !             7: #ifndef lint
        !             8: static char sccsid[] = "@(#)setbp.c    5.1 (Berkeley) 6/6/85";
        !             9: #endif not lint
        !            10: /*
        !            11:  * Breakpoint/machine interface.
        !            12:  */
        !            13: 
        !            14: #include "defs.h"
        !            15: #include <signal.h>
        !            16: #include "machine.h"
        !            17: #include "process.h"
        !            18: #include "main.h"
        !            19: #include "pxops.h"
        !            20: #include "process/process.rep"
        !            21: 
        !            22: #define BP_OP          O_BPT           /* breakpoint trap */
        !            23: #define BP_ERRNO       SIGILL          /* signal received at a breakpoint */
        !            24: 
        !            25: /*
        !            26:  * Setting a breakpoint at a location consists of saving
        !            27:  * the half-word at the location and poking a BP_OP there.
        !            28:  *
        !            29:  * We save the locations and half-words on a list for use in unsetting.
        !            30:  */
        !            31: 
        !            32: typedef struct savelist SAVELIST;
        !            33: 
        !            34: struct savelist {
        !            35:        ADDRESS location;
        !            36:        short save;
        !            37:        short refcount;
        !            38:        SAVELIST *link;
        !            39: };
        !            40: 
        !            41: LOCAL SAVELIST *savelist;
        !            42: 
        !            43: /*
        !            44:  * Set a breakpoint at the given address.  Only save the half-word there
        !            45:  * if it's not already a breakpoint.
        !            46:  */
        !            47: 
        !            48: setbp(addr)
        !            49: ADDRESS addr;
        !            50: {
        !            51:        short w;
        !            52:        short save;
        !            53:        register SAVELIST *newsave, *s;
        !            54: 
        !            55:        if (option('b')) {
        !            56:                printf("setting breakpoint at %d\n", addr);
        !            57:                fflush(stdout);
        !            58:        }
        !            59:        for (s = savelist; s != NIL; s = s->link) {
        !            60:                if (s->location == addr) {
        !            61:                        s->refcount++;
        !            62:                        return;
        !            63:                }
        !            64:        }
        !            65:        iread(&save, addr, sizeof(save));
        !            66:        newsave = alloc(1, SAVELIST);
        !            67:        newsave->location = addr;
        !            68:        newsave->save = save;
        !            69:        newsave->refcount = 1;
        !            70:        newsave->link = savelist;
        !            71:        savelist = newsave;
        !            72:        w = BP_OP;
        !            73:        iwrite(&w, addr, sizeof(w));
        !            74: }
        !            75: 
        !            76: /*
        !            77:  * Unset a breakpoint; unfortunately we have to search the SAVELIST
        !            78:  * to find the saved value.  The assumption is that the SAVELIST will
        !            79:  * usually be quite small.
        !            80:  */
        !            81: 
        !            82: unsetbp(addr)
        !            83: ADDRESS addr;
        !            84: {
        !            85:        register SAVELIST *s, *prev;
        !            86: 
        !            87:        if (option('b')) {
        !            88:                printf("unsetting breakpoint at %d\n", addr);
        !            89:                fflush(stdout);
        !            90:        }
        !            91:        prev = NIL;
        !            92:        for (s = savelist; s != NIL; s = s->link) {
        !            93:                if (s->location == addr) {
        !            94:                        iwrite(&s->save, addr, sizeof(s->save));
        !            95:                        s->refcount--;
        !            96:                        if (s->refcount == 0) {
        !            97:                                if (prev == NIL) {
        !            98:                                        savelist = s->link;
        !            99:                                } else {
        !           100:                                        prev->link = s->link;
        !           101:                                }
        !           102:                                dispose(s);
        !           103:                        }
        !           104:                        return;
        !           105:                }
        !           106:                prev = s;
        !           107:        }
        !           108:        panic("unsetbp: couldn't find address %d", addr);
        !           109: }
        !           110: 
        !           111: /*
        !           112:  * Predicate to test if the reason the process stopped was because
        !           113:  * of a breakpoint.
        !           114:  */
        !           115: 
        !           116: BOOLEAN isbperr()
        !           117: {
        !           118:        register PROCESS *p;
        !           119: 
        !           120:        p = process;
        !           121:        return(p->status==STOPPED && p->signo==BP_ERRNO);
        !           122: }

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