12316967ad
Convert README.menu to reStructured text and add it to the HTML documentation. Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
132 lines
3.4 KiB
ReStructuredText
132 lines
3.4 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
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.. Copyright 2010-2011 Calxeda, Inc.
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Menus
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=====
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U-Boot provides a set of interfaces for creating and using simple, text
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based menus. Menus are displayed as lists of labeled entries on the
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console, and an entry can be selected by entering its label.
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To use the menu code, enable CONFIG_MENU, and include "menu.h" where
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the interfaces should be available.
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Menus are composed of items. Each item has a key used to identify it in
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the menu, and an opaque pointer to data controlled by the consumer.
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If you want to show a menu, instead starting the shell, define
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CONFIG_AUTOBOOT_MENU_SHOW. You have to code the int menu_show(int bootdelay)
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function, which handle your menu. This function returns the remaining
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bootdelay.
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Interfaces
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----------
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.. code-block:: c
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#include "menu.h"
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/*
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* Consumers of the menu interfaces will use a struct menu * as the
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* handle for a menu. struct menu is only fully defined in menu.c,
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* preventing consumers of the menu interfaces from accessing its
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* contents directly.
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*/
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struct menu;
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/*
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* NOTE: See comments in common/menu.c for more detailed documentation on
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* these interfaces.
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*/
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/*
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* menu_create() - Creates a menu handle with default settings
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*/
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struct menu *menu_create(char *title, int timeout, int prompt,
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void (*item_data_print)(void *),
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char *(*item_choice)(void *),
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void *item_choice_data);
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/*
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* menu_item_add() - Adds or replaces a menu item
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*/
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int menu_item_add(struct menu *m, char *item_key, void *item_data);
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/*
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* menu_default_set() - Sets the default choice for the menu
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*/
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int menu_default_set(struct menu *m, char *item_key);
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/*
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* menu_default_choice() - Set *choice to point to the default item's data
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*/
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int menu_default_choice(struct menu *m, void **choice);
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/*
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* menu_get_choice() - Returns the user's selected menu entry, or the
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* default if the menu is set to not prompt or the timeout expires.
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*/
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int menu_get_choice(struct menu *m, void **choice);
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/*
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* menu_destroy() - frees the memory used by a menu and its items.
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*/
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int menu_destroy(struct menu *m);
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/*
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* menu_display_statusline(struct menu *m);
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* shows a statusline for every menu_display call.
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*/
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void menu_display_statusline(struct menu *m);
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Example Code
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------------
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This example creates a menu that always prompts, and allows the user
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to pick from a list of tools. The item key and data are the same.
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.. code-block:: c
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#include "menu.h"
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char *tools[] = {
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"Hammer",
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"Screwdriver",
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"Nail gun",
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NULL
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};
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char *pick_a_tool(void)
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{
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struct menu *m;
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int i;
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char *tool = NULL;
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m = menu_create("Tools", 0, 1, NULL);
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for(i = 0; tools[i]; i++) {
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if (menu_item_add(m, tools[i], tools[i]) != 1) {
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printf("failed to add item!");
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menu_destroy(m);
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return NULL;
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}
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}
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if (menu_get_choice(m, (void **)&tool) != 1)
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printf("Problem picking tool!\n");
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menu_destroy(m);
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return tool;
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}
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void caller(void)
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{
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char *tool = pick_a_tool();
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if (tool) {
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printf("picked a tool: %s\n", tool);
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use_tool(tool);
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}
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}
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