[U-Boot,v3,1/7] Add generic, reusable menu code

diff --git a/common/Makefile b/common/Makefile
index 224b7cc..d5bd983 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -170,6 +170,7 @@  COBJS-$(CONFIG_CMD_KGDB) += kgdb.o kgdb_stubs.o
 COBJS-$(CONFIG_KALLSYMS) += kallsyms.o
 COBJS-$(CONFIG_LCD) += lcd.o
 COBJS-$(CONFIG_LYNXKDI) += lynxkdi.o
+COBJS-$(CONFIG_MENU) += menu.o
 COBJS-$(CONFIG_MODEM_SUPPORT) += modem.o
 COBJS-$(CONFIG_UPDATE_TFTP) += update.o
 COBJS-$(CONFIG_USB_KEYBOARD) += usb_kbd.o
diff --git a/common/menu.c b/common/menu.c
new file mode 100644
index 0000000..9bcd906
--- /dev/null
+++ b/common/menu.c
@@ -0,0 +1,266 @@ 
+/*
+ * Copyright 2010-2011 Calxeda, Inc.
+ *
+ * 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 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <common.h>
+#include <malloc.h>
+#include <errno.h>
+#include <linux/list.h>
+
+#include "menu.h"
+
+struct menu_item {
+	char *key;
+	void *data;
+	struct list_head list;
+};
+
+struct menu {
+	struct menu_item *default_item;
+	char *title;
+	int prompt;
+	void (*item_data_print)(void *);
+	struct list_head items;
+};
+
+static inline void *menu_items_iter(struct menu *m,
+		void *(*callback)(struct menu *, struct menu_item *, void *),
+		void *extra)
+{
+	struct list_head *pos, *n;
+	struct menu_item *item;
+	void *ret;
+
+	list_for_each_safe(pos, n, &m->items) {
+		item = list_entry(pos, struct menu_item, list);
+
+		ret = callback(m, item, extra);
+
+		if (ret)
+			return ret;
+	}
+
+	return NULL;
+}
+
+static inline void *menu_item_print(struct menu *m,
+				struct menu_item *item,
+				void *extra)
+{
+	if (!m->item_data_print)
+		printf("%s\n", item->key);
+	else
+		m->item_data_print(item->data);
+
+	return NULL;
+}
+
+static inline void *menu_item_destroy(struct menu *m,
+				struct menu_item *item,
+				void *extra)
+{
+	if (item->key)
+		free(item->key);
+
+	free(item);
+
+	return NULL;
+}
+
+static inline void menu_display(struct menu *m)
+{
+	if (m->title)
+		printf("%s:\n", m->title);
+
+	menu_items_iter(m, menu_item_print, NULL);
+}
+
+static inline void *menu_item_key_match(struct menu *m,
+				struct menu_item *item,
+				void *extra)
+{
+	char *item_key = extra;
+
+	if (!item_key || !item->key) {
+		if (item_key == item->key)
+			return item;
+
+		return NULL;
+	}
+
+	if (strcmp(item->key, item_key) == 0)
+		return item;
+
+	return NULL;
+}
+
+static inline struct menu_item *menu_item_by_key(struct menu *m,
+							char *item_key)
+{
+	return menu_items_iter(m, menu_item_key_match, item_key);
+}
+
+static inline int menu_use_default(struct menu *m)
+{
+	return !m->prompt;
+}
+
+static inline int menu_default_choice(struct menu *m, void **choice)
+{
+	if (m->default_item) {
+		*choice = m->default_item->data;
+		return 1;
+	}
+
+	return -ENOENT;
+}
+
+static inline int menu_interactive_choice(struct menu *m, void **choice)
+{
+	char cbuf[CONFIG_SYS_CBSIZE];
+	struct menu_item *choice_item = NULL;
+	int readret;
+
+	while (!choice_item) {
+		cbuf[0] = '\0';
+
+		menu_display(m);
+
+		readret = readline_into_buffer("Enter choice: ", cbuf);
+
+		if (readret >= 0) {
+			choice_item = menu_item_by_key(m, cbuf);
+
+			if (!choice_item)
+				printf("%s not found\n", cbuf);
+		} else {
+			printf("^C\n");
+			return -EINTR;
+		}
+	}
+
+	*choice = choice_item->data;
+
+	return 1;
+}
+
+int menu_default_set(struct menu *m, char *item_key)
+{
+	struct menu_item *item;
+
+	if (!m)
+		return -EINVAL;
+
+	item = menu_item_by_key(m, item_key);
+
+	if (!item)
+		return -ENOENT;
+
+	m->default_item = item;
+
+	return 1;
+}
+
+int menu_get_choice(struct menu *m, void **choice)
+{
+	if (!m || !choice)
+		return -EINVAL;
+
+	if (menu_use_default(m))
+		return menu_default_choice(m, choice);
+
+	return menu_interactive_choice(m, choice);
+}
+
+/*
+ * note that this replaces the data of an item if it already exists, but
+ * doesn't change the order of the item.
+ */
+int menu_item_add(struct menu *m, char *item_key, void *item_data)
+{
+	struct menu_item *item;
+
+	if (!m)
+		return -EINVAL;
+
+	item = menu_item_by_key(m, item_key);
+
+	if (item) {
+		item->data = item_data;
+		return 1;
+	}
+
+	item = malloc(sizeof *item);
+	if (!item)
+		return -ENOMEM;
+
+	item->key = strdup(item_key);
+
+	if (!item->key) {
+		free(item);
+		return -ENOMEM;
+	}
+
+	item->data = item_data;
+
+	list_add_tail(&item->list, &m->items);
+
+	return 1;
+}
+
+struct menu *menu_create(char *title, int prompt,
+				void (*item_data_print)(void *))
+{
+	struct menu *m;
+
+	m = malloc(sizeof *m);
+
+	if (!m)
+		return NULL;
+
+	m->default_item = NULL;
+	m->prompt = prompt;
+	m->item_data_print = item_data_print;
+
+	if (title) {
+		m->title = strdup(title);
+		if (!m->title) {
+			free(m);
+			return NULL;
+		}
+	} else
+		m->title = NULL;
+
+
+	INIT_LIST_HEAD(&m->items);
+
+	return m;
+}
+
+int menu_destroy(struct menu *m)
+{
+	if (!m)
+		return -EINVAL;
+
+	menu_items_iter(m, menu_item_destroy, NULL);
+
+	if (m->title)
+		free(m->title);
+
+	free(m);
+
+	return 1;
+}
diff --git a/doc/README.menu b/doc/README.menu
new file mode 100644
index 0000000..bca44be
--- /dev/null
+++ b/doc/README.menu
@@ -0,0 +1,158 @@ 
+/*
+ * Copyright 2010-2011 Calxeda, Inc.
+ *
+ * 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 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, see <http://www.gnu.org/licenses/>.
+ */
+
+U-boot provides a set of interfaces for creating and using simple, text
+based menus. Menus are displayed as lists of labeled entries on the
+console, and an entry can be selected by entering its label.
+
+To use the menu code, enable CONFIG_MENU, and include "menu.h" where
+the interfaces should be available.
+
+Menus are composed of items. Each item has a key used to identify it in
+the menu, and an opaque pointer to data controlled by the consumer.
+
+Interfaces
+----------
+#include "menu.h"
+
+struct menu;
+
+struct menu *menu_create(char *title, int prompt,
+				void (*item_data_print)(void *));
+int menu_item_add(struct menu *m, char *item_key, void *item_data);
+int menu_default_set(struct menu *m, char *item_key);
+int menu_get_choice(struct menu *m, void **choice);
+int menu_destroy(struct menu *m);
+
+menu_create() - Creates a menu handle with default settings
+
+  title - If not NULL, points to a string that will be displayed before
+  the list of menu items. It will be copied to internal storage, and is
+  safe to discard after passing to menu_create().
+
+  prompt - If 0, don't ask for user input. If 1, the user will be ed for
+  promptinput.
+
+  item_data_print - If not NULL, will be called for each item when
+  the menu is displayed, with the pointer to the item's data passed
+  as the argument. If NULL, each item's key will be printed instead.
+  Since an item's key is what must be entered to select an item, the
+  item_data_print function should make it obvious what the key for each
+  entry is.
+
+  Returns a pointer to the menu if successful, or NULL if there is
+  insufficient memory available to create the menu.
+
+
+menu_item_add() - Adds or replaces a menu item
+
+  m - Points to a menu created by menu_create().
+
+  item_key - Points to a string that will uniquely identify the item.
+  The string will be copied to internal storage, and is safe to discard
+  after passing to menu_item_add.
+
+  item_data - An opaque pointer associated with an item. It is never
+  dereferenced internally, but will be passed to the item_data_print,
+  and will be returned from menu_get_choice if the menu item is
+  selected.
+
+  Returns 1 if successful, -EINVAL if m is NULL, or -ENOMEM if there is
+  insufficient memory to add the menu item.
+
+
+menu_default_set() - Sets the default choice for the menu. This is safe
+to call more than once.
+
+  m - Points to a menu created by menu_create().
+
+  item_key - Points to a string that, when compared using strcmp,
+  matches the key for an existing item in the menu.
+
+  Returns 1 if successful, -EINVAL if m is NULL, or -ENOENT if no item
+  with a key matching item_key is found.
+
+
+menu_get_choice() - Returns the user's selected menu entry, or the
+default if the menu is set to not prompt. This is safe to call more than
+once.
+
+  m - Points to a menu created by menu_create().
+
+  choice - Points to a location that will store a pointer to the
+  selected menu item. If no item is selected or there is an error, no
+  value will be written at the location it points to.
+
+  Returns 1 if successful, -EINVAL if m or choice is NULL, -ENOENT if no
+  default has been set and the menu is set to not prompt, or -EINTR if
+  the user exits the menu via ctrl+c.
+
+
+menu_destroy() - frees the memory used by a menu and its items.
+
+  m - Points to a menu created by menu_create().
+
+  Returns 1 if successful, or -EINVAL if m is NULL.
+
+
+Example
+-------
+This example creates a menu that always prompts, and allows the user
+to pick from a list of tools.  The item key and data are the same.
+
+#include "menu.h"
+
+char *tools[] = {
+	"Hammer",
+	"Screwdriver",
+	"Nail gun",
+	NULL
+};
+
+char *pick_a_tool(void)
+{
+	struct menu *m;
+	int i;
+	char *tool = NULL;
+
+	m = menu_create("Tools", 1, NULL);
+
+	for(i = 0; tools[i]; i++) {
+		if (menu_item_add(m, tools[i], tools[i]) != 1) {
+			printf("failed to add item!");
+			menu_destroy(m);
+			return NULL;
+                }
+	}
+
+	if (menu_get_choice(m, (void **)&tool) != 1)
+		printf("Problem picking tool!\n");
+
+	menu_destroy(m);
+
+	return tool;
+}
+
+void caller(void)
+{
+	char *tool = pick_a_tool();
+
+	if (tool) {
+		printf("picked a tool: %s\n", tool);
+		use_tool(tool);
+	}
+}
diff --git a/include/menu.h b/include/menu.h
new file mode 100644
index 0000000..d47e1a0
--- /dev/null
+++ b/include/menu.h
@@ -0,0 +1,30 @@ 
+/*
+ * Copyright 2010-2011 Calxeda, Inc.
+ *
+ * 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 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __MENU_H__
+#define __MENU_H__
+
+struct menu;
+
+struct menu *menu_create(char *title, int prompt,
+				void (*item_data_print)(void *));
+int menu_default_set(struct menu *m, char *item_key);
+int menu_get_choice(struct menu *m, void **choice);
+int menu_item_add(struct menu *m, char *item_key, void *item_data);
+int menu_destroy(struct menu *m);
+
+#endif /* __MENU_H__ */