--- freem/src/mdebug.c	2025/01/19 02:04:04	1.1
+++ freem/src/mdebug.c	2025/04/30 14:41:03	1.6
@@ -1,23 +1,11 @@
 /*
- *                            *
- *                           * *
- *                          *   *
- *                     ***************
- *                      * *       * *
- *                       *  MUMPS  *
- *                      * *       * *
- *                     ***************
- *                          *   *
- *                           * *
- *                            *
- *
- *   mdebug.c
+ *   $Id: mdebug.c,v 1.6 2025/04/30 14:41:03 snw Exp $
  *    debugger enhancements
  *
  *  
- *   Author: Serena Willis <jpw@coherent-logic.com>
+ *   Author: Serena Willis <snw@coherent-logic.com>
  *    Copyright (C) 1998 MUG Deutschland
- *    Copyright (C) 2020 Coherent Logic Development LLC
+ *    Copyright (C) 2020, 2025 Coherent Logic Development LLC
  *
  *
  *   This file is part of FreeM.
@@ -35,11 +23,57 @@
  *   You should have received a copy of the GNU Affero Public License
  *   along with FreeM.  If not, see <https://www.gnu.org/licenses/>.
  *
+ *   $Log: mdebug.c,v $
+ *   Revision 1.6  2025/04/30 14:41:03  snw
+ *   Further debugger work
+ *
+ *   Revision 1.5  2025/04/29 18:46:17  snw
+ *   Begin work on interactive debugger
+ *
+ *   Revision 1.4  2025/04/28 19:38:55  snw
+ *   Add trace mode
+ *
+ *   Revision 1.3  2025/03/09 19:50:47  snw
+ *   Second phase of REUSE compliance and header reformat
+ *
+ *
+ * SPDX-FileCopyrightText:  (C) 2025 Coherent Logic Development LLC
+ * SPDX-License-Identifier: AGPL-3.0-or-later
  **/
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
+
+#include "config.h"
+
+#ifdef HAVE_LIBREADLINE
+#  if defined(HAVE_READLINE_READLINE_H)
+#    include <readline/readline.h>
+#  elif defined(HAVE_READLINE_H)
+#    include <readline.h>
+#  else /* !defined(HAVE_READLINE_H) */
+extern char *readline ();
+#  endif /* !defined(HAVE_READLINE_H) */
+/*char *cmdline = NULL;*/
+#else /* !defined(HAVE_READLINE_READLINE_H) */
+  /* no readline */
+#endif /* HAVE_LIBREADLINE */
+
+#ifdef HAVE_READLINE_HISTORY
+#  if defined(HAVE_READLINE_HISTORY_H)
+#    include <readline/history.h>
+#  elif defined(HAVE_HISTORY_H)
+#    include <history.h>
+#  else /* !defined(HAVE_HISTORY_H) */
+extern void add_history ();
+extern int write_history ();
+extern int read_history ();
+#  endif /* defined(HAVE_READLINE_HISTORY_H) */
+  /* no history */
+#endif /* HAVE_READLINE_HISTORY */
+
 
 #include "mpsdef.h"
 #include "mdebug.h"
@@ -67,6 +101,137 @@ void dbg_init (void)
 
 }
 
+int debugger (int entry_mode, char *curcode)
+{
+    
+#if defined(HAVE_LIBREADLINE)    
+    static int first_entry = TRUE;
+    static int stepmode = STEPMODE_NONE;
+    
+    char *dbg_buf;
+    char dbg_prompt[256];
+    HIST_ENTRY **dbg_hist;
+    int dbg_hist_idx;
+    HIST_ENTRY *dbg_hist_ent;
+    char rouname_buf[256];
+    char *savptr;
+    char *dbg_cmd;
+    int do_prompt = FALSE;
+    register int i;
+    
+    set_io (UNIX);
+    
+    if (first_entry) {
+        first_entry = FALSE;
+        
+        printf ("\nEntering debug mode; M commands unavailable.\n");
+        printf ("Type 'exit' to return to direct mode; 'help' for help.\n\n");
+
+        do_prompt = TRUE;
+    }
+    else {
+        switch (entry_mode) {
+            
+            case DEBENTRY_CMD:
+                if (stepmode == STEPMODE_CMD) {
+                    do_prompt = TRUE;
+                }
+                else {
+                    do_prompt = FALSE;
+                }
+                    
+                break;
+                    
+            case DEBENTRY_LINE:
+                if (stepmode == STEPMODE_CMD || stepmode == STEPMODE_LINE) {
+                    do_prompt = TRUE;
+                }
+                else {
+                    do_prompt = FALSE;
+                }
+                
+                break;
+                
+            case DEBENTRY_BREAKPOINT:
+                do_prompt = TRUE;
+                break;
+                
+            case DEBENTRY_SIGINT:
+                break;
+        }
+    }
+
+
+    if (!do_prompt) return TRUE;
+
+    while (1) {
+        
+        //stcpy (rouname_buf, rou_name);
+        getraddress (rouname_buf, nstx);
+        stcnv_m2c (rouname_buf);
+        
+        snprintf (dbg_prompt, sizeof (dbg_prompt) - 1, "%s $STACK=%d [DEBUG]> ", rouname_buf, nstx);
+
+        if ((stepmode == STEPMODE_LINE) || (stepmode == STEPMODE_CMD)) {
+            char codbuf[512];
+            stcpy (codbuf, curcode);
+            stcnv_m2c (codbuf);
+            
+            printf ("%s\n", codbuf);
+        }
+        dbg_buf = readline (dbg_prompt);
+
+        if (!dbg_buf) continue;
+
+        savptr = dbg_buf;
+        dbg_cmd = strtok_r (dbg_buf, " ", &savptr);
+        
+        if ((strcmp (dbg_cmd, "exit") == 0) || (strcmp (dbg_cmd, "quit") == 0)) {
+            first_entry = TRUE;
+            stepmode = STEPMODE_NONE;
+            printf ("\n\nExiting debug mode.\n\n");
+            set_io (MUMPS);
+            return FALSE;
+        }
+        else if ((strcmp (dbg_cmd, "step") == 0) || (strcmp (dbg_cmd, "s") == 0)) {
+            stepmode = STEPMODE_CMD;
+            return TRUE;
+        }
+        else if ((strcmp (dbg_cmd, "next") == 0) || (strcmp (dbg_cmd, "n") == 0)) {
+            stepmode = STEPMODE_LINE;
+            return TRUE;
+        }
+        else if ((strcmp (dbg_cmd, "continue") == 0) || (strcmp (dbg_cmd, "cont") == 0) || (strcmp(dbg_cmd, "c") == 0)) {
+            stepmode = STEPMODE_CONT;
+            return TRUE;
+        }
+        else if ((strcmp (dbg_cmd, "backtrace") == 0) || (strcmp (dbg_cmd, "bt") == 0)) {
+            char tmpbuf[256];
+
+            printf ("%-10s%s\n", "$STACK", "(CMND)ENTRY");
+            printf ("%-10s%s\n", "======", "===========");
+            
+            
+            for (i = 1; i <= nstx; i++) getraddress (callerr[i], i);
+            for (i = nstx; i > 0; i--) {
+                stcpy (tmpbuf, callerr[i]);
+                stcnv_m2c (tmpbuf);
+                printf ("%-10d%s\n", i, tmpbuf);
+            }
+        }
+        else {
+            printf ("DEBUG:  invalid command\r\n");
+        }
+        
+    }
+
+    return TRUE;
+#else
+    return FALSE;
+#endif
+
+}
+
 dbg_watch *dbg_add_watch (char *varnam)
 {
     register int i;
@@ -243,5 +408,5 @@ void dbg_fire_watch (char *varnam) {
 	w->chgct++;
 	w->firect++;
 	dbg_pending_watches++;
-
+        
 }