Add base ada language files

1 files changed, 806 insertions, 0 deletions

diff --git a/gdb/ada-tasks.c b/gdb/ada-tasks.c
new file mode 100644
index 0000000..23dc105
--- /dev/null
+++ b/gdb/ada-tasks.c
@@ -0,0 +1,806 @@
+/* file ada-tasks.c: Ada tasking control for GDB
+   Copyright 1997 Free Software Foundation, Inc.
+   Contributed by Ada Core Technologies, Inc
+.
+   This file is part of GDB.
+
+   [$Id$]
+   Authors: Roch-Alexandre Nomine Beguin, Arnaud Charlet <charlet@gnat.com>
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+*/
+
+#include <ctype.h> 
+#include "defs.h" 
+#include "command.h" 
+#include "value.h"
+#include "language.h"
+#include "inferior.h"
+#include "symtab.h"
+#include "target.h"
+#include "gdbcore.h"
+
+#if (defined(__alpha__) && defined(__osf__) && !defined(__alpha_vxworks))
+#include <sys/procfs.h>
+#endif
+
+#if (defined(__alpha__) && defined(__osf__) && !defined(VXWORKS_TARGET))
+#include "gregset.h"
+#endif 
+
+#include "ada-lang.h"
+
+/* FIXME: move all this conditional compilation in description
+   files or in configure.in */
+
+#if defined (VXWORKS_TARGET)
+#define THREAD_TO_PID(tid,lwpid) (tid)
+
+#elif defined (linux)
+#define THREAD_TO_PID(tid,lwpid) (0)
+
+#elif (defined (sun) && defined (__SVR4))
+#define THREAD_TO_PID thread_to_pid
+
+#elif defined (sgi) || defined (__WIN32__) || defined (hpux)
+#define THREAD_TO_PID(tid,lwpid) ((int)lwpid)
+
+#else
+#define THREAD_TO_PID(tid,lwpid) (0)
+#endif
+
+#if defined(__alpha__) && defined(__osf__) && !defined(VXWORKS_TARGET)
+#define THREAD_FETCH_REGISTERS dec_thread_fetch_registers
+#define GET_CURRENT_THREAD dec_thread_get_current_thread
+extern int dec_thread_get_registers (gdb_gregset_t *, gdb_fpregset_t *);
+#endif
+
+#if defined (_AIX)
+#define THREAD_FETCH_REGISTERS aix_thread_fetch_registers
+#define GET_CURRENT_THREAD aix_thread_get_current_thread
+#endif
+
+#if defined(VXWORKS_TARGET)
+#define GET_CURRENT_THREAD() ((void*)inferior_pid)
+#define THREAD_FETCH_REGISTERS() (-1)
+
+#elif defined (sun) && defined (__SVR4)
+#define GET_CURRENT_THREAD solaris_thread_get_current_thread
+#define THREAD_FETCH_REGISTERS() (-1)
+extern void *GET_CURRENT_THREAD();
+
+#elif defined (_AIX) || (defined(__alpha__) && defined(__osf__))
+extern void *GET_CURRENT_THREAD();
+
+#elif defined (__WIN32__) || defined (hpux)
+#define GET_CURRENT_THREAD() (inferior_pid)
+#define THREAD_FETCH_REGISTERS() (-1)
+
+#else
+#define GET_CURRENT_THREAD() (NULL)
+#define THREAD_FETCH_REGISTERS() (-1)
+#endif
+
+#define KNOWN_TASKS_NAME "system__tasking__debug__known_tasks"
+
+#define READ_MEMORY(addr, var) read_memory (addr, (char*) &var, sizeof (var))
+/* external declarations */
+
+extern struct value* find_function_in_inferior (char *);
+
+/* Global visible variables */
+
+struct task_entry *task_list = NULL;
+int ada__tasks_check_symbol_table = 1;
+void *pthread_kern_addr = NULL;
+
+#if (defined(__alpha__) && defined(__osf__) && !defined(VXWORKS_TARGET))
+gdb_gregset_t gregset_saved;
+gdb_fpregset_t fpregset_saved;
+#endif
+
+/* The maximum number of tasks known to the Ada runtime */
+const int MAX_NUMBER_OF_KNOWN_TASKS = 1000;
+
+/* the current task */
+int current_task = -1, current_task_id = -1, current_task_index;
+void *current_thread, *current_lwp;
+
+char *ada_task_states[] =
+{
+  "Unactivated",
+  "Runnable",
+  "Terminated",
+  "Child Activation Wait",
+  "Accept Statement",
+  "Waiting on entry call",
+  "Async Select Wait",
+  "Delay Sleep",
+  "Child Termination Wait",
+  "Wait Child in Term Alt",
+  "",
+  "",
+  "",
+  "",
+  "Asynchronous Hold"
+};
+
+/* Global internal types */
+
+static char *ada_long_task_states[] =
+{
+  "Unactivated",
+  "Runnable",
+  "Terminated",
+  "Waiting for child activation",
+  "Blocked in accept statement",
+  "Waiting on entry call",
+  "Asynchronous Selective Wait",
+  "Delay Sleep",
+  "Waiting for children termination",
+  "Waiting for children in terminate alternative",
+  "",
+  "",
+  "",
+  "",
+  "Asynchronous Hold"
+};
+
+/* Global internal variables */
+
+static int highest_task_num = 0;
+int thread_support = 0; /* 1 if the thread library in use is supported */
+static int gdbtk_task_initialization = 0;
+
+static int add_task_entry (p_task_id, index)
+     void *p_task_id;
+     int index;
+{
+  struct task_entry *new_task_entry = NULL;
+  struct task_entry *pt;
+
+  highest_task_num++;
+  new_task_entry = malloc (sizeof (struct task_entry));
+  new_task_entry->task_num = highest_task_num;
+  new_task_entry->task_id = p_task_id;
+  new_task_entry->known_tasks_index = index;
+  new_task_entry->next_task = NULL;
+  pt = task_list;
+  if (pt)
+    {
+      while (pt->next_task)
+	pt = pt->next_task;
+      pt->next_task = new_task_entry;
+      pt->stack_per = 0;
+    }
+  else task_list = new_task_entry;
+  return new_task_entry->task_num;
+}
+
+int 
+get_entry_number (p_task_id)
+     void *p_task_id;
+{
+  struct task_entry *pt;
+
+  pt = task_list;
+  while (pt != NULL)
+    {
+      if (pt->task_id == p_task_id)
+	return pt->task_num;
+      pt = pt->next_task;
+    }
+  return 0;
+}
+
+static struct task_entry *get_thread_entry_vptr (thread)
+     void *thread;
+{
+  struct task_entry *pt;
+
+  pt = task_list;
+  while (pt != NULL)
+    {
+      if (pt->thread == thread)
+      return pt;
+      pt = pt->next_task;
+    }
+  return 0;
+}
+
+static struct task_entry *get_entry_vptr (p_task_num)
+     int p_task_num;
+{
+  struct task_entry *pt;
+
+  pt = task_list;
+  while (pt)
+    {
+      if (pt->task_num == p_task_num)
+	return pt;
+      pt = pt->next_task;
+    }
+  return NULL;
+}
+
+void init_task_list ()
+{
+  struct task_entry *pt, *old_pt;
+
+  pt = task_list;
+  while (pt)
+    {
+      old_pt = pt;
+      pt = pt->next_task;
+      free (old_pt);
+    };
+  task_list = NULL;
+  highest_task_num = 0;
+}
+
+int valid_task_id (task)
+     int task;
+{
+  return get_entry_vptr (task) != NULL;
+}
+
+void *get_self_id ()
+{
+  struct value* val;
+  void *self_id;
+  int result;
+  struct task_entry *ent;
+  extern int do_not_insert_breakpoints;
+
+#if !((defined(sun) && defined(__SVR4)) || defined(VXWORKS_TARGET) || defined(__WIN32__))
+  if (thread_support)
+#endif
+    {
+      ent = get_thread_entry_vptr (GET_CURRENT_THREAD ());
+      return ent ? ent->task_id : 0;
+    }
+
+  /* FIXME: calling a function in the inferior with a multithreaded application
+     is not reliable, so return NULL if there is no safe way to get the current
+     task */
+  return NULL;
+}
+
+int get_current_task ()
+{
+  int result;
+  
+  /* FIXME: language_ada should be defined in defs.h */
+  /*  if (current_language->la_language != language_ada) return -1; */
+
+  result = get_entry_number (get_self_id ());
+
+  /* return -1 if not found */
+  return result == 0 ? -1 : result;
+}
+
+/* Print detailed information about specified task */
+
+static void
+info_task (arg, from_tty)
+     char *arg;
+     int from_tty;
+{
+  void *temp_task;
+  struct task_entry *pt, *pt2;
+  void *self_id, *caller;
+  struct task_fields atcb, atcb2;
+  struct entry_call call;
+  int bounds [2];
+  char image [256];
+  int num;
+
+  /* FIXME: language_ada should be defined in defs.h */
+  /*  if (current_language->la_language != language_ada) 
+    { 
+      printf_filtered ("The current language does not support tasks.\n"); 
+      return; 
+    } 
+  */
+  pt = get_entry_vptr (atoi (arg));
+  if (pt == NULL)
+    {
+      printf_filtered ("Task %s not found.\n", arg); 
+      return; 
+    }
+
+  temp_task = pt->task_id;
+
+  /* read the atcb in the inferior */
+  READ_MEMORY ((CORE_ADDR) temp_task, atcb);
+
+  /* print the Ada task id */
+  printf_filtered ("Ada Task: %p\n", temp_task);
+
+  /* print the name of the task */
+  if (atcb.image.P_ARRAY != NULL) {
+    READ_MEMORY ((CORE_ADDR) EXTRACT_ADDRESS (atcb.image.P_BOUNDS), bounds);
+    bounds [1] = EXTRACT_INT (bounds [1]);
+    read_memory ((CORE_ADDR) EXTRACT_ADDRESS (atcb.image.P_ARRAY),
+                 (char*) &image, bounds [1]);
+    printf_filtered ("Name: %.*s\n", bounds [1], image);
+  }
+  else printf_filtered ("<no name>\n");
+
+  /* print the thread id */
+
+  if ((long) pt->thread < 65536)
+    printf_filtered ("Thread: %ld\n", (long int) pt->thread);
+  else
+    printf_filtered ("Thread: %p\n", pt->thread);
+
+  if ((long) pt->lwp != 0)
+    {
+      if ((long) pt->lwp < 65536)
+        printf_filtered ("LWP: %ld\n", (long int) pt->lwp);
+      else
+        printf_filtered ("LWP: %p\n", pt->lwp);
+    }
+
+  /* print the parent gdb task id */
+  num = get_entry_number (EXTRACT_ADDRESS (atcb.parent));
+  if (num != 0)
+    {
+      printf_filtered ("Parent: %d", num);
+      pt2 = get_entry_vptr (num);
+      READ_MEMORY ((CORE_ADDR) pt2->task_id, atcb2);
+
+      /* print the name of the task */
+      if (atcb2.image.P_ARRAY != NULL) {
+        READ_MEMORY ((CORE_ADDR) EXTRACT_ADDRESS (atcb2.image.P_BOUNDS),
+                     bounds);
+        bounds [1] = EXTRACT_INT (bounds [1]);
+        read_memory ((CORE_ADDR) EXTRACT_ADDRESS (atcb2.image.P_ARRAY),
+                     (char*) &image, bounds [1]);
+        printf_filtered (" (%.*s)\n", bounds [1], image);
+      }
+      else
+        printf_filtered ("\n");
+    }
+  else
+    printf_filtered ("No parent\n");
+
+  /* print the base priority of the task */
+  printf_filtered ("Base Priority: %d\n", EXTRACT_INT (atcb.priority));
+
+  /* print the current state of the task */
+
+  /* check if this task is accepting a rendezvous */
+  if (atcb.call == NULL)
+    caller = NULL;
+  else {
+    READ_MEMORY ((CORE_ADDR) EXTRACT_ADDRESS (atcb.call), call);
+    caller = EXTRACT_ADDRESS (call.self);
+  }
+ 
+  if (caller != NULL)
+    {
+      num = get_entry_number (caller);
+      printf_filtered ("Accepting rendezvous with %d", num);
+
+      if (num != 0)
+	{
+	  pt2 = get_entry_vptr (num);
+	  READ_MEMORY ((CORE_ADDR) pt2->task_id, atcb2);
+
+	  /* print the name of the task */
+	  if (atcb2.image.P_ARRAY != NULL) {
+	    READ_MEMORY ((CORE_ADDR) EXTRACT_ADDRESS (atcb2.image.P_BOUNDS),
+                         bounds);
+            bounds [1] = EXTRACT_INT (bounds [1]);
+	    read_memory ((CORE_ADDR) EXTRACT_ADDRESS (atcb2.image.P_ARRAY),
+                         (char*) &image, bounds [1]);
+	    printf_filtered (" (%.*s)\n", bounds [1], image);
+	  }
+	  else
+	    printf_filtered ("\n");
+	}
+      else
+	printf_filtered ("\n");
+    }
+  else
+    printf_filtered ("State: %s\n", ada_long_task_states [atcb.state]);
+}
+
+#if 0
+
+/* A useful function that shows the alignment of all the fields in the
+   tasks_fields structure
+ */
+
+print_align ()
+{
+  struct task_fields tf;
+  void *tf_base             = &(tf);
+  void *tf_state            = &(tf.state);
+  void *tf_entry_num        = &(tf.entry_num);
+  void *tf_parent           = &(tf.parent);
+  void *tf_priority         = &(tf.priority);
+  void *tf_current_priority = &(tf.current_priority);
+  void *tf_image            = &(tf.image);
+  void *tf_call             = &(tf.call);
+  void *tf_thread           = &(tf.thread);
+  void *tf_lwp              = &(tf.lwp);
+  printf_filtered ("\n");
+  printf_filtered ("(tf_base = 0x%x)\n", tf_base);
+  printf_filtered ("task_fields.entry_num        at %3d (0x%x)\n", tf_entry_num - tf_base, tf_entry_num);
+  printf_filtered ("task_fields.state            at %3d (0x%x)\n", tf_state - tf_base, tf_state);
+  printf_filtered ("task_fields.parent           at %3d (0x%x)\n", tf_parent - tf_base, tf_parent);
+  printf_filtered ("task_fields.priority         at %3d (0x%x)\n", tf_priority - tf_base, tf_priority);
+  printf_filtered ("task_fields.current_priority at %3d (0x%x)\n", tf_current_priority - tf_base, tf_current_priority);
+  printf_filtered ("task_fields.image            at %3d (0x%x)\n", tf_image - tf_base, tf_image);
+  printf_filtered ("task_fields.call             at %3d (0x%x)\n", tf_call - tf_base, tf_call);
+  printf_filtered ("task_fields.thread           at %3d (0x%x)\n", tf_thread - tf_base, tf_thread);
+  printf_filtered ("task_fields.lwp              at %3d (0x%x)\n", tf_lwp - tf_base, tf_lwp);
+  printf_filtered ("\n"); 
+}
+#endif
+
+/* Print information about currently known tasks */
+
+static void
+info_tasks (arg, from_tty)
+     char *arg;
+     int from_tty;
+{
+  struct value* val;
+  int i, task_number, state;
+  void *temp_task, *temp_tasks [MAX_NUMBER_OF_KNOWN_TASKS];
+  struct task_entry *pt;
+  void *self_id, *caller, *thread_id=NULL;
+  struct task_fields atcb;
+  struct entry_call call;
+  int bounds [2];
+  char image [256];
+  int size;
+  char car;
+
+#if defined(__alpha__) && defined(__osf__) && !defined(VXWORKS_TARGET)
+  pthreadTeb_t thr;
+  gdb_gregset_t regs;
+#endif
+
+  static struct symbol *sym;
+  static struct minimal_symbol *msym;
+  static void *known_tasks_addr = NULL;
+
+  int init_only = gdbtk_task_initialization;
+  gdbtk_task_initialization = 0;
+
+  task_number = 0;
+
+  if (PIDGET(inferior_ptid) == 0)
+    {
+      printf_filtered ("The program is not being run under gdb. ");
+      printf_filtered ("Use 'run' or 'attach' first.\n");
+      return;
+    }
+
+  if (ada__tasks_check_symbol_table)
+    {
+      thread_support = 0;
+#if (defined(__alpha__) && defined(__osf__) & !defined(VXWORKS_TARGET)) || \
+    defined (_AIX)
+      thread_support = 1;
+#endif
+
+      msym = lookup_minimal_symbol (KNOWN_TASKS_NAME, NULL, NULL);
+      if (msym != NULL)
+	known_tasks_addr = (void *) SYMBOL_VALUE_ADDRESS (msym);
+      else
+#ifndef VXWORKS_TARGET
+	return; 
+#else
+	{
+	  if (target_lookup_symbol (KNOWN_TASKS_NAME, &known_tasks_addr) != 0)
+	    return;
+	}
+#endif
+
+      ada__tasks_check_symbol_table = 0;
+    }
+
+  if (known_tasks_addr == NULL)
+    return;
+
+#if !((defined(sun) && defined(__SVR4)) || defined(VXWORKS_TARGET) || defined(__WIN32__) || defined (hpux))
+  if (thread_support)
+#endif
+    thread_id = GET_CURRENT_THREAD ();
+
+  /* then we get a list of tasks created */
+
+  init_task_list ();
+
+  READ_MEMORY ((CORE_ADDR) known_tasks_addr, temp_tasks);
+
+  for (i=0; i<MAX_NUMBER_OF_KNOWN_TASKS; i++)
+    {
+      temp_task = EXTRACT_ADDRESS (temp_tasks[i]);
+
+      if (temp_task != NULL)
+        {
+          task_number = get_entry_number (temp_task);
+          if (task_number == 0)
+	    task_number = add_task_entry (temp_task, i);
+        }
+    }      
+
+  /* Return without printing anything if this function was called in
+     order to init GDBTK tasking. */
+
+  if (init_only) return;
+
+  /* print the header */
+
+#if defined(__alpha__) && defined(__osf__) && !defined(VXWORKS_TARGET)
+  printf_filtered
+   ("  ID       TID P-ID Pri Stack  %% State                  Name\n");
+#else
+  printf_filtered ("  ID       TID P-ID Pri State                  Name\n");
+#endif
+
+  /* Now that we have a list of task id's, we can print them */
+  pt = task_list;
+  while (pt)
+    {
+      temp_task = pt->task_id;
+
+      /* read the atcb in the inferior */
+      READ_MEMORY ((CORE_ADDR) temp_task, atcb);
+
+      /* store the thread id for future use */
+      pt->thread = EXTRACT_ADDRESS (atcb.thread);
+
+#if defined (linux)
+      pt->lwp = (void *) THREAD_TO_PID (atcb.thread, 0);
+#else
+      pt->lwp = EXTRACT_ADDRESS (atcb.lwp);
+#endif
+
+      /* print a star if this task is the current one */
+      if (thread_id)
+#if defined (__WIN32__) || defined (SGI) || defined (hpux)
+	printf_filtered (pt->lwp == thread_id ? "*" : " ");
+#else
+	printf_filtered (pt->thread == thread_id ? "*" : " ");
+#endif
+
+      /* print the gdb task id */
+      printf_filtered ("%3d", pt->task_num);
+
+      /* print the Ada task id */
+#ifndef VXWORKS_TARGET
+      printf_filtered (" %9lx", (long) temp_task);
+#else
+#ifdef TARGET_64
+      printf_filtered (" %#9lx", (unsigned long)pt->thread & 0x3ffffffffff);
+#else
+      printf_filtered (" %#9lx", (long)pt->thread);
+#endif
+#endif
+
+      /* print the parent gdb task id */
+      printf_filtered
+        (" %4d", get_entry_number (EXTRACT_ADDRESS (atcb.parent)));
+
+      /* print the base priority of the task */
+      printf_filtered (" %3d", EXTRACT_INT (atcb.priority));
+
+#if defined(__alpha__) && defined(__osf__) && !defined(VXWORKS_TARGET)
+      if (pt->task_num == 1 || atcb.state == Terminated)
+	{
+          printf_filtered ("  Unknown");
+	  goto next;
+	}
+
+      read_memory ((CORE_ADDR)atcb.thread, &thr, sizeof (thr));
+      current_thread = atcb.thread;
+      regs.regs [SP_REGNUM] = 0;
+      if (dec_thread_get_registers (&regs, NULL) == 0) {
+	pt->stack_per = (100 * ((long)thr.__stack_base -
+	regs.regs [SP_REGNUM])) / thr.__stack_size;
+	/* if the thread is terminated but still there, the
+	stack_base/size values are erroneous. Try to patch it */
+	if (pt->stack_per < 0 || pt->stack_per > 100) pt->stack_per = 0;
+      }
+
+      /* print information about stack space used in the thread */
+      if (thr.__stack_size < 1024*1024)
+	{
+	  size = thr.__stack_size / 1024;
+	  car = 'K';
+	}
+      else if (thr.__stack_size < 1024*1024*1024)
+	{
+	  size = thr.__stack_size / 1024 / 1024;
+	  car = 'M';
+	}
+      else /* Who knows... */
+	{
+	  size = thr.__stack_size / 1024 / 1024 / 1024;
+	  car = 'G';
+	}
+      printf_filtered (" %4d%c %2d", size, car, pt->stack_per);
+next:
+#endif
+
+      /* print the current state of the task */
+
+      /* check if this task is accepting a rendezvous */
+      if (atcb.call == NULL)
+	caller = NULL;
+      else {
+	READ_MEMORY ((CORE_ADDR) EXTRACT_ADDRESS (atcb.call), call);
+	caller = EXTRACT_ADDRESS (call.self);
+      }
+ 
+      if (caller != NULL)
+	printf_filtered (" Accepting RV with %-4d", get_entry_number (caller));
+      else
+	{
+	  state = atcb.state;
+#if defined (__WIN32__) || defined (SGI) || defined (hpux)
+	  if (state == Runnable && (thread_id && pt->lwp == thread_id))
+#else
+	  if (state == Runnable && (thread_id && pt->thread == thread_id))
+#endif
+	    /* Replace "Runnable" by "Running" if this is the current task */
+	    printf_filtered (" %-22s", "Running");
+	  else
+	    printf_filtered (" %-22s", ada_task_states [state]);
+	}
+
+      /* finally, print the name of the task */
+      if (atcb.image.P_ARRAY != NULL) {
+        READ_MEMORY ((CORE_ADDR) EXTRACT_ADDRESS (atcb.image.P_BOUNDS), bounds);
+        bounds [1] = EXTRACT_INT (bounds [1]);
+        read_memory ((CORE_ADDR) EXTRACT_ADDRESS (atcb.image.P_ARRAY),
+                     (char*)&image, bounds [1]);
+        printf_filtered (" %.*s\n", bounds [1], image);
+      }
+      else printf_filtered (" <no name>\n");
+
+      pt = pt->next_task;
+    }
+}
+
+/* Task list initialization for GDB-Tk.  We basically use info_tasks()
+   to initialize our variables, but abort that function before we
+   actually print anything. */
+
+int
+gdbtk_tcl_tasks_initialize ()
+{
+  gdbtk_task_initialization = 1;
+  info_tasks ("", gdb_stdout);
+
+  return (task_list != NULL);
+}
+
+static void
+info_tasks_command (arg, from_tty)
+     char *arg;
+     int from_tty;
+{
+   if (arg == NULL || *arg == '\000')
+      info_tasks (arg, from_tty);
+   else
+      info_task (arg, from_tty);
+}
+
+/* Switch from one thread to another. */
+
+static void
+switch_to_thread (ptid_t ptid)
+
+{
+  if (ptid_equal (ptid, inferior_ptid))
+    return;
+
+  inferior_ptid = ptid;
+  flush_cached_frames ();
+  registers_changed ();
+  stop_pc = read_pc ();
+  select_frame (get_current_frame ());
+}
+
+/* Switch to a specified task. */
+
+static int task_switch (tid, lwpid)
+     void *tid, *lwpid;
+{
+  int res = 0, pid;
+
+  if (thread_support)
+    {
+      flush_cached_frames ();
+
+      if (current_task != current_task_id)
+	{
+	  res = THREAD_FETCH_REGISTERS ();
+	}
+      else
+	{
+#if (defined(__alpha__) && defined(__osf__) && !defined(VXWORKS_TARGET))
+	  supply_gregset (&gregset_saved);
+	  supply_fpregset (&fpregset_saved);
+#endif
+	}
+
+      if (res == 0) stop_pc = read_pc();
+      select_frame (get_current_frame ());
+      return res;
+    }
+
+  return -1;
+}
+
+static void task_command (tidstr, from_tty)
+     char *tidstr;
+     int from_tty;
+{
+  int num;
+  struct task_entry *e;
+
+  if (!tidstr)
+    error ("Please specify a task ID.  Use the \"info tasks\" command to\n"
+           "see the IDs of currently known tasks.");
+
+  num = atoi (tidstr);
+  e = get_entry_vptr (num);
+
+  if (e == NULL)
+    error ("Task ID %d not known.  Use the \"info tasks\" command to\n"
+           "see the IDs of currently known tasks.", num);
+
+  if (current_task_id == -1)
+    {
+#if (defined(__alpha__) && defined(__osf__) && !defined(VXWORKS_TARGET))
+      fill_gregset (&gregset_saved, -1);
+      fill_fpregset (&fpregset_saved, -1);
+#endif
+      current_task_id = get_current_task ();
+    }
+
+  current_task = num;
+  current_task_index = e->known_tasks_index;
+  current_thread = e->thread;
+  current_lwp = e->lwp;
+  if (task_switch (e->thread, e->lwp) == 0)
+    {
+      /* FIXME: find_printable_frame should be defined in frame.h, and
+	 implemented in ada-lang.c */
+      /*      find_printable_frame (selected_frame, frame_relative_level (selected_frame));*/
+      printf_filtered ("[Switching to task %d]\n", num);
+      print_stack_frame (selected_frame, frame_relative_level (selected_frame), 1);
+    }
+  else
+    printf_filtered ("Unable to switch to task %d\n", num);
+}
+
+void
+_initialize_tasks ()
+{
+  static struct cmd_list_element *task_cmd_list = NULL;
+  extern struct cmd_list_element *cmdlist;
+
+  add_info (
+        "tasks", info_tasks_command,
+	"Without argument: list all known Ada tasks, with status information.\n"
+	"info tasks n: print detailed information of task n.\n");
+
+  add_prefix_cmd ("task", class_run, task_command,
+                  "Use this command to switch between tasks.\n\
+ The new task ID must be currently known.", &task_cmd_list, "task ", 1,
+                  &cmdlist);
+}