add src/hello.c to augment new command tutorial

The hello module provides the 'hello' command, printing a greetings
to the command console.  It can grow to serve as pedagogical example
of services that OpenOCD developers should use: a runnable style guide.

src/Makefile.am

@@ -12,7 +12,9 @@ endif
 openocd_SOURCES = $(MAINFILE)
 openocd_LDADD = libopenocd.la
 
-libopenocd_la_SOURCES = openocd.c
+libopenocd_la_SOURCES = \
+	hello.c \
+	openocd.c
 
 # set the include path found by configure
 AM_CPPFLAGS = \

src/hello.c

@@ -0,0 +1,57 @@
+/***************************************************************************
+ *   Copyright (C) 2009 Zachary T Welch <zw@superlucidity.net>             *
+ *                                                                         *
+ *   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.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ ***************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include "log.h"
+
+static COMMAND_HELPER(handle_hello_args, const char **sep, const char **name)
+{
+	if (argc > 1)
+	{
+		LOG_ERROR("%s: too many arguments", CMD_NAME);
+		return ERROR_COMMAND_SYNTAX_ERROR;
+	}
+	if (1 == argc)
+	{
+		*sep = " ";
+		*name = args[0];
+	}
+	else
+		*sep = *name = "";
+
+	return ERROR_OK;
+}
+COMMAND_HANDLER(handle_hello_command)
+{
+	const char *sep, *name;
+	int retval = CALL_COMMAND_HANDLER(handle_hello_args, &sep, &name);
+	if (ERROR_OK == retval)
+		command_print(cmd_ctx, "Greetings%s%s!", sep, name);
+	return retval;
+}
+
+int hello_register_commands(struct command_context_s *cmd_ctx)
+{
+	struct command_s *cmd = register_command(cmd_ctx, NULL, "hello",
+			&handle_hello_command, COMMAND_ANY,
+			"option");
+	return cmd ? ERROR_OK : -ENOMEM;
+}

src/openocd.c

@@ -177,6 +177,9 @@ COMMAND_HANDLER(handle_init_command)
 
 command_context_t *global_cmd_ctx;
 
+/// src/hello.c gives a simple example for writing new command modules
+int hello_register_commands(struct command_context_s *cmd_ctx);
+
 /* NB! this fn can be invoked outside this file for non PC hosted builds */
 command_context_t *setup_command_handler(void)
 {
@@ -188,6 +191,7 @@ command_context_t *setup_command_handler(void)
 					 COMMAND_EXEC, "show OpenOCD version");
 
 	/* register subsystem commands */
+	hello_register_commands(cmd_ctx);
 	server_register_commands(cmd_ctx);
 	telnet_register_commands(cmd_ctx);
 	gdb_register_commands(cmd_ctx);