12  * new string. When new item is added then first it is compared if it is not
14  * buffer to store the new item, oldest one is removed until there is a room.
21  * chunks (when ring buffer wraps). To ensure that item is in a single chunk,
22  * item includes padding. If continues area for new item cannot be allocated
25  * If item does not fit at the end of the ring buffer padding is added: *
27  * | header    | "history item" |                                   | padding |
31  * If item fits in the ring buffer available space then there is no padding:
33  * |                 | header     | "history item" |                          |
37  * As an optimization, the added padding is attributed to the preceding item
38  * instead of the current item. This way the padding will be freed one item
56 	struct shell_history_item *h_item; /* history item */  in z_shell_history_get()
57 	sys_dnode_t *l_item; /* list item */  in z_shell_history_get()
96 			struct shell_history_item *item,  in add_to_head()  argument
99 	item->len = len;  in add_to_head()
100 	item->padding = padding;  in add_to_head()
101 	memcpy(item->data, src, len);  in add_to_head()
102 	sys_dlist_prepend(&history->list, &item->dnode);  in add_to_head()
108 	sys_dnode_t *l_item; /* list item */  in remove_from_tail()
137 	sys_dnode_t *l_item; /* list item */  in z_shell_history_put()