gpxe/src/hci/editstring.c

   1 /*
   2  * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 #include <assert.h>
  20 #include <string.h>
  21 #include <gpxe/keys.h>
  22 #include <gpxe/editstring.h>
  23
  24 /** @file
  25  *
  26  * Editable strings
  27  *
  28  */
  29
  30 static void insert_delete ( struct edit_string *string, size_t delete_len,
  31                             const char *insert_text )
  32                             __attribute__ (( nonnull (1) ));
  33 static void insert_character ( struct edit_string *string,
  34                                unsigned int character ) __nonnull;
  35 static void delete_character ( struct edit_string *string ) __nonnull;
  36 static void backspace ( struct edit_string *string ) __nonnull;
  37 static void kill_eol ( struct edit_string *string ) __nonnull;
  38
  39 /**
  40  * Insert and/or delete text within an editable string
  41  *
  42  * @v string            Editable string
  43  * @v delete_len        Length of text to delete from current cursor position
  44  * @v insert_text       Text to insert at current cursor position, or NULL
  45  */
  46 static void insert_delete ( struct edit_string *string, size_t delete_len,
  47                             const char *insert_text ) {
  48         size_t old_len, max_delete_len, insert_len, max_insert_len, new_len;
  49
  50         /* Calculate lengths */
  51         old_len = strlen ( string->buf );
  52         assert ( string->cursor <= old_len );
  53         max_delete_len = ( old_len - string->cursor );
  54         if ( delete_len > max_delete_len )
  55                 delete_len = max_delete_len;
  56         insert_len = ( insert_text ? strlen ( insert_text ) : 0 );
  57         max_insert_len = ( ( string->len - 1 ) - ( old_len - delete_len ) );
  58         if ( insert_len > max_insert_len )
  59                 insert_len = max_insert_len;
  60         new_len = ( old_len - delete_len + insert_len );
  61
  62         /* Fill in edit history */
  63         string->mod_start = string->cursor;
  64         string->mod_end = ( ( new_len > old_len ) ? new_len : old_len );
  65
  66         /* Move data following the cursor */
  67         memmove ( ( string->buf + string->cursor + insert_len ),
  68                   ( string->buf + string->cursor + delete_len ),
  69                   ( max_delete_len + 1 - delete_len ) );
  70
  71         /* Copy inserted text to cursor position */
  72         memcpy ( ( string->buf + string->cursor ), insert_text, insert_len );
  73         string->cursor += insert_len;
  74 }
  75
  76 /**
  77  * Insert character at current cursor position
  78  *
  79  * @v string            Editable string
  80  * @v character         Character to insert
  81  */
  82 static void insert_character ( struct edit_string *string,
  83                               unsigned int character ) {
  84         char insert_text[2] = { character, '\0' };
  85         insert_delete ( string, 0, insert_text );
  86 }
  87
  88 /**
  89  * Delete character at current cursor position
  90  *
  91  * @v string            Editable string
  92  */
  93 static void delete_character ( struct edit_string *string ) {
  94         insert_delete ( string, 1, NULL );
  95 }
  96
  97 /**
  98  * Delete character to left of current cursor position
  99  *
 100  * @v string            Editable string
 101  */
 102 static void backspace ( struct edit_string *string ) {
 103         if ( string->cursor > 0 ) {
 104                 string->cursor--;
 105                 delete_character ( string );
 106         }
 107 }
 108
 109 /**
 110  * Delete to end of line
 111  *
 112  * @v string            Editable string
 113  */
 114 static void kill_eol ( struct edit_string *string ) {
 115         insert_delete ( string, ~( ( size_t ) 0 ), NULL );
 116 }
 117
 118 /**
 119  * Edit editable string
 120  *
 121  * @v string            Editable string
 122  * @v key               Key pressed by user
 123  * @ret key             Key returned to application, or zero
 124  *
 125  * Handles keypresses and updates the content of the editable string.
 126  * Basic line editing facilities (delete/insert/cursor) are supported.
 127  * If edit_string() understands and uses the keypress it will return
 128  * zero, otherwise it will return the original key.
 129  *
 130  * This function does not update the display in any way.
 131  *
 132  * The string's edit history will be updated to allow the caller to
 133  * efficiently bring the display into sync with the string content.
 134  */
 135 int edit_string ( struct edit_string *string, int key ) {
 136         int retval = 0;
 137         size_t len = strlen ( string->buf );
 138
 139         /* Prepare edit history */
 140         string->last_cursor = string->cursor;
 141         string->mod_start = string->cursor;
 142         string->mod_end = string->cursor;
 143
 144         /* Interpret key */
 145         if ( ( key >= 0x20 ) && ( key <= 0x7e ) ) {
 146                 /* Printable character; insert at current position */
 147                 insert_character ( string, key );
 148         } else switch ( key ) {
 149         case KEY_BACKSPACE:
 150                 /* Backspace */
 151                 backspace ( string );
 152                 break;
 153         case KEY_DC:
 154         case CTRL_D:
 155                 /* Delete character */
 156                 delete_character ( string );
 157                 break;
 158         case CTRL_K:
 159                 /* Delete to end of line */
 160                 kill_eol ( string );
 161                 break;
 162         case KEY_HOME:
 163         case CTRL_A:
 164                 /* Start of line */
 165                 string->cursor = 0;
 166                 break;
 167         case KEY_END:
 168         case CTRL_E:
 169                 /* End of line */
 170                 string->cursor = len;
 171                 break;
 172         case KEY_LEFT:
 173         case CTRL_B:
 174                 /* Cursor left */
 175                 if ( string->cursor > 0 )
 176                         string->cursor--;
 177                 break;
 178         case KEY_RIGHT:
 179         case CTRL_F:
 180                 /* Cursor right */
 181                 if ( string->cursor < len )
 182                         string->cursor++;
 183                 break;
 184         default:
 185                 retval = key;
 186                 break;
 187         }
 188
 189         return retval;
 190 }