Software Keyboard

From Nintendo Switch Brew
Revision as of 09:48, 3 August 2018 by Thog (talk | contribs)
Jump to navigation Jump to search

The software keyboard expects to be passed three IStorages via PushInData.

Common Arguments

The first IStorage passed to this applet should contain the common library applet arguments. This is populated by nn::la::CommonArgumentsWriter and has the following format.

Offset Size Typical Value Notes
0x0 4 1 Common Arguments version
0x4 4 0x20 Common Arguments size
0x8 4 5 Library applet version (some kind of API version?)
0xC 4 0 Theme color
0x10 1 0 Play startup sound
0x18 8 N/A System tick (see svcGetSystemTick)
0x20 End of struct


The second IStorage passed to this applet should contain the configuration for the keyboard.

Offset Size Typical Value Notes
0x0 4 2
0x4 18 u"OK" UTF-16 text displayed in the submit button
0x16 2 0 UTF-16 "left optional symbol key"
0x18 2 0 UTF-16 "right optional symbol key"
0x1A 1 0
0x1C 4 0 Key set disable bitmask
0x20 4 1 Initial cursor position (0 = start of string, 1 = end of string)
0x24 130 u"" UTF-16 header text
0xA6 258 u"" UTF-16 sub text
0x1A8 514 u"" UTF-16 guide text
0x3AC 4 0 String length limit (defaults to 500?)
0x3B0 4 0
0x3B4 4 0 Password flag (0 = not password, 1 = password)
0x3B8 4 1
0x3BC 2 1
0x3BE 1 1 Draw background (0 = no, 1 = yes)
0x3C0 4 20 Offset of initial string in work buffer (or 0)
0x3C4 4 0 Size of initial string in work buffer (bytes)
0x3C8 4 2024 Offset of user dictionary in work buffer (or 0)
0x3CC 4 0 Length of user dictionary (number of entries)
0x3D0 1 0 #Text check enable
0x3D8 8 0 #Text check callback function address. Not sure why this is included here
0x3E0 End of struct

If the length limit is <= 32, the text entry box will be a single row and show the header/sub text. Otherwise, it will use multiple rows and the header/sub text will not be shown.

Each entry in the user dictionary is 100 bytes long.

Key Set Disable Bitmask

Various bits in this field disable certain keys on the keyboard. This list is incomplete.

0x02: disable ' '
0x04: disable '@'
0x08: disable '%'
0x10: disable '\' and '/'
0x40: disable numbers
0x80: used for download codes

Work Buffer

This is the third IStorage passed to this applet. It is a transfer memory storage. The transfer memory should have size 0x1000 (0xd000 in certain cases) and permissions 0.

The layout of the work buffer doesn't seem to matter as long as the offsets in the #KeyboardConfig are adjusted, but official code lays it out like this.

Offset Size Notes
20 (decimal) Unknown UTF-16 initial string
2024 (decimal) Unknown User dictionary

Text Check

If text checking is enabled in #KeyboardConfig, text will be checked when the submit button is pressed. First, swkbd sends the text via PushInteractiveOutData.

Offset Size Notes
0x0 0x4 Buffer size
0x4 Variable UTF-16 text
0x7d4 Size of storage

The application then has an opportunity to validate or reject the text. It creates a new IStorage, writes the response to it, and sends it via PushInteractiveInData.

Offset Size Notes
0x0 0x4 Status (0 = OK, 1 = bad)
0x4 Variable UTF-16 error message (shown in a dialog box)
0x7d4 Size of storage


When either the submit button is pressed and input has been validated, or the user cancels the text entry, swkbd will push its response and exit. The response IStorage has the following format.

Offset Size Notes
0x0 0x4 Result code (0 = OK, 1 = Cancel)
0x4 Variable UTF-16 text
0x7d8 Size of storage