int run_command(command_context_t *context, command_t *c, char *words[], int num_words);
 
 static void tcl_output(void *privData, const char *file, int line, const char *function, const char *string)
-{              
+{
        Jim_Obj *tclOutput=(Jim_Obj *)privData;
 
        Jim_AppendString(interp, tclOutput, string, strlen(string));
        char **words;
 
        target_call_timer_callbacks_now();
-       LOG_USER_N("%s", ""); /* Keep GDB connection alive*/ 
-       
+       LOG_USER_N("%s", ""); /* Keep GDB connection alive*/
+
        c = interp->cmdPrivData;
        LOG_DEBUG("script_command - %s", c->name);
 
                        break;
                }
                words[i] = strdup(w);
-               if (words[i] == NULL) 
+               if (words[i] == NULL)
                {
                        return JIM_ERR;
                }
                 */
                context = global_cmd_ctx;
        }
-       
+
        /* capture log output and return it */
        Jim_Obj *tclOutput = Jim_NewStringObj(interp, "", 0);
        /* a garbage collect can happen, so we need a reference count to this object */
        Jim_IncrRefCount(tclOutput);
-       
+
        log_add_callback(tcl_output, tclOutput);
-       
+
        retval = run_command(context, c, words, nwords);
-       
+
        log_remove_callback(tcl_output, tclOutput);
 
        /* We dump output into this local variable */
        {
                *return_retval = retval;
        }
-       
+
        return (retval==ERROR_OK)?JIM_OK:JIM_ERR;
 }
 
 command_t* register_command(command_context_t *context, command_t *parent, char *name, int (*handler)(struct command_context_s *context, char* name, char** args, int argc), enum command_mode mode, char *help)
 {
        command_t *c, *p;
-       
+
        if (!context || !name)
                return NULL;
-                               
+
        c = malloc(sizeof(command_t));
-       
+
        c->name = strdup(name);
        c->parent = parent;
        c->children = NULL;
        if (!help)
                help="";
        c->next = NULL;
-       
+
        /* place command in tree */
        if (parent)
        {
                        context->commands = c;
                }
        }
-       
+
        /* just a placeholder, no handler */
        if (c->handler==NULL)
                return c;
 
        /* If this is a two level command, e.g. "flash banks", then the
         * "unknown" proc in startup.tcl must redirect to  this command.
-        * 
+        *
         * "flash banks" is translated by "unknown" to "flash_banks"
         * if such a proc exists
         */
        const char *full_name=alloc_printf("ocd_%s%s%s", t1, t2, t3);
        Jim_CreateCommand(interp, full_name, script_command, c, NULL);
        free((void *)full_name);
-       
+
        /* we now need to add an overrideable proc */
        const char *override_name=alloc_printf("proc %s%s%s {args} {if {[catch {eval \"ocd_%s%s%s $args\"}]==0} {return \"\"} else { return -code error }", t1, t2, t3, t1, t2, t3);
-       Jim_Eval_Named(interp, override_name, __FILE__, __LINE__ );     
+       Jim_Eval_Named(interp, override_name, __FILE__, __LINE__ );
        free((void *)override_name);
-       
+
        /* accumulate help text in Tcl helptext list.  */
     Jim_Obj *helptext=Jim_GetGlobalVariableStr(interp, "ocd_helptext", JIM_ERRMSG);
     if (Jim_IsShared(helptext))
         helptext = Jim_DuplicateObj(interp, helptext);
        Jim_Obj *cmd_entry=Jim_NewListObj(interp, NULL, 0);
-       
+
        Jim_Obj *cmd_list=Jim_NewListObj(interp, NULL, 0);
 
        /* maximum of two levels :-) */
        if (c->parent!=NULL)
        {
                Jim_ListAppendElement(interp, cmd_list, Jim_NewStringObj(interp, c->parent->name, -1));
-       } 
+       }
        Jim_ListAppendElement(interp, cmd_list, Jim_NewStringObj(interp, c->name, -1));
-       
+
        Jim_ListAppendElement(interp, cmd_entry, cmd_list);
        Jim_ListAppendElement(interp, cmd_entry, Jim_NewStringObj(interp, help, -1));
        Jim_ListAppendElement(interp, helptext, cmd_entry);
 int unregister_all_commands(command_context_t *context)
 {
        command_t *c, *c2;
-       
+
        if (context == NULL)
                return ERROR_OK;
-       
+
        while(NULL != context->commands)
        {
                c = context->commands;
-               
+
                while(NULL != c->children)
                {
                        c2 = c->children;
                        free(c2);
                        c2 = NULL;
                }
-               
+
                context->commands = context->commands->next;
-               
+
                free(c->name);
                c->name = NULL;
                free(c);
-               c = NULL;               
+               c = NULL;
        }
-       
+
        return ERROR_OK;
 }
 
 int unregister_command(command_context_t *context, char *name)
 {
        command_t *c, *p = NULL, *c2;
-       
+
        if ((!context) || (!name))
                return ERROR_INVALID_ARGUMENTS;
-       
+
        /* find command */
        for (c = context->commands; c; c = c->next)
        {
                        {
                                context->commands = c->next;
                        }
-                       
+
                        /* unregister children */
                        if (c->children)
                        {
                                        free(c2);
                                }
                        }
-                       
+
                        /* delete command */
                        free(c->name);
                        free(c);
                }
-               
+
                /* remember the last command for unlinking */
                p = c;
        }
-       
+
        return ERROR_OK;
 }
 
 void command_print_n(command_context_t *context, char *format, ...)
 {
        char *string;
-       
+
        va_list ap;
        va_start(ap, format);
 
        {
                /* we want this collected in the log + we also want to pick it up as a tcl return
                 * value.
-                * 
+                *
                 * The latter bit isn't precisely neat, but will do for now.
                 */
                LOG_USER_N("%s", string);
                strcat(string, "\n"); /* alloc_vprintf guaranteed the buffer to be at least one char longer */
                /* we want this collected in the log + we also want to pick it up as a tcl return
                 * value.
-                * 
+                *
                 * The latter bit isn't precisely neat, but will do for now.
                 */
                LOG_USER_N("%s", string);
                LOG_ERROR("Illegal mode for command");
                return ERROR_FAIL;
        }
-       
+
        int retval = c->handler(context, c->name, words + start_word + 1, num_words - start_word - 1);
        if (retval == ERROR_COMMAND_SYNTAX_ERROR)
        {
                /* we do not print out an error message because the command *should*
                 * have printed out an error
                 */
-               LOG_DEBUG("Command failed with error code %d", retval); 
+               LOG_DEBUG("Command failed with error code %d", retval);
        }
-       
-       return retval; 
+
+       return retval;
 }
 
 int command_run_line(command_context_t *context, char *line)
                if (retcode == JIM_OK)
                {
                        retcode = Jim_Eval_Named(interp, line, __FILE__, __LINE__ );
-                       
+
                        Jim_DeleteAssocData(interp, "retval");
-               }       
+               }
                Jim_DeleteAssocData(interp, "context");
        }
        if (retcode == JIM_ERR) {
                if (retval==ERROR_OK)
                {
                        /* It wasn't a low level OpenOCD command that failed */
-                       return ERROR_FAIL; 
+                       return ERROR_FAIL;
                }
                return retval;
        } else if (retcode == JIM_EXIT) {
                                if (chunk > 256)
                                        chunk = 256;
                                strncpy(buff, result+i, chunk);
-                               buff[chunk] = 0; 
+                               buff[chunk] = 0;
                                LOG_USER_N("%s", buff);
                        }
                        LOG_USER_N("%s", "\n");
 {
        free(context);
        context = NULL;
-       
+
        return ERROR_OK;
 }
 
                return JIM_ERR;
        Jim_Obj *result = Jim_NewStringObj(interp, full_path, strlen(full_path));
        free(full_path);
-       
+
        Jim_SetResult(interp, result);
        return JIM_OK;
 }
                ptr += x;
                nbytes -= x;
        }
-       
+
        return n;
 }
 
        interp->cb_vfprintf = openocd_jim_vfprintf;
        interp->cb_fflush = openocd_jim_fflush;
        interp->cb_fgets = openocd_jim_fgets;
-       
+
        add_default_dirs();
 
 #ifdef JIM_EMBEDDED
        }
 
        register_command(context, NULL, "sleep", handle_sleep_command,
-                                        COMMAND_ANY, "sleep for <n> milliseconds");
-       
+                                        COMMAND_ANY, "<n> [busy] - sleep for n milliseconds. \"busy\" means busy wait");
+
        register_command(context, NULL, "fast", handle_fast_command,
                                         COMMAND_ANY, "fast <enable/disable> - place at beginning of config files. Sets defaults to fast and dangerous.");
-       
+
        return context;
 }
 
 int handle_sleep_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 {
        unsigned long duration = 0;
-       
-       if (argc == 1)
+       int busy = 0;
+
+       if (argc==1)
+       {
+
+       } else if (argc==2)
+       {
+               if (strcmp(args[1], "busy")!=0)
+                       return ERROR_COMMAND_SYNTAX_ERROR;
+               busy = 1;
+       } else
+       {
+               return ERROR_COMMAND_SYNTAX_ERROR;
+       }
+
+       duration = strtoul(args[0], NULL, 0);
+
+       if (busy)
+       {
+               busy_sleep(duration);
+       } else
        {
-               duration = strtoul(args[0], NULL, 0);
                alive_sleep(duration);
        }
 
 {
        if (argc!=1)
                return ERROR_COMMAND_SYNTAX_ERROR;
-       
+
        fast_and_dangerous = strcmp("enable", args[0])==0;
-       
+
        return ERROR_OK;
 }
 
-void process_jim_events(void) 
+void process_jim_events(void)
 {
 #ifdef JIM_EMBEDDED
        static int recursion = 0;
 
-       if (!recursion) 
+       if (!recursion)
        {
                recursion++;
                Jim_ProcessEvents (interp, JIM_ALL_EVENTS|JIM_DONT_WAIT);
 {
        Jim_CreateCommand(interp, name, cmd, NULL, NULL);
 
-       /* FIX!!! it would be prettier to invoke add_help_text... 
+       /* FIX!!! it would be prettier to invoke add_help_text...
           accumulate help text in Tcl helptext list.  */
        Jim_Obj *helptext=Jim_GetGlobalVariableStr(interp, "ocd_helptext", JIM_ERRMSG);
        if (Jim_IsShared(helptext))
                helptext = Jim_DuplicateObj(interp, helptext);
-    
+
        Jim_Obj *cmd_entry=Jim_NewListObj(interp, NULL, 0);
-       
+
        Jim_Obj *cmd_list=Jim_NewListObj(interp, NULL, 0);
        Jim_ListAppendElement(interp, cmd_list, Jim_NewStringObj(interp, name, -1));
-       
+
        Jim_ListAppendElement(interp, cmd_entry, cmd_list);
        Jim_ListAppendElement(interp, cmd_entry, Jim_NewStringObj(interp, help, -1));
        Jim_ListAppendElement(interp, helptext, cmd_entry);