Table of Contents

Name

dumpkeymap - Dianostic dump of a .keymapping file

Synopsis

dumpkeymap [options] [-] [file...]

Description

dumpkeymap prints a textual representation of each Apple/NeXT .keymapping file mentioned on the command-line. If no files are mentioned and if the local machine is an Apple or NeXT installation, then the key mapping currently in use by the WindowServer and the AppKit is printed instead.

Options

-h --help
Display general program instructions and option summary.
-k --help-keymapping
Display a detailed description of the internal layout of a .keymapping file. This is the same information as that presented in the Key Mapping Description section of this document.
-o --help-output
Display an explanation of the output generated by dumpkeymap when dissecting a .keymapping file. This is the same information as that presented in the Output Description section of this document.
-f --help-files
Display a summary of the various files and directories which are related to key mappings. This is the same information as that presented in the Files section of this document.
-d --help-diagnostics
Display a list of the various diagnostic messages which may be emitted by dumpkeymap. This is the same information as that presented in the Diagnostics section of this document.
-v --version
Display the dumpkeymap version number and warranty information.
- --
Inhibit processing of options at this point in the argument list. An occurrence of `-' or `--' in the argument list causes all following arguments to be treated as file names even if an argument begins with a `-' character.

Key Mapping Description

The following sections describe, in complete detail, the format of a raw key mapping resource, as well as the format of the .keymapping file which encapsulates one or more raw mappings.

Types and Data

The following type definitions are employed throughout this discussion:


typedef unsigned char byte;
typedef unsigned short word;
typedef unsigned long dword;

Additionally, the type definition `number' is used generically to indicate a numeric value. The actual size of the `number' type may be one or two bytes depending upon how the data is stored in the key map. Although most key maps use byte-sized numeric values, word-sized values are also allowed.

Multi-byte values in a key mapping file are stored in big-endian byte order.

Key Mapping File and Device Mapping

A key mapping file begins with a magic-number and continues with a variable number of device-specific key mappings.


struct KeyMappingFile {
    char magic_number[4];    // `KYM1'
    DeviceMapping maps[...]; // Variable number of maps
};


struct DeviceMapping {
    dword interface;  // Interface type
    dword handler_id; // Interface subtype
    dword map_size;   // Byte count of `map' (below)
    KeyMapping map; 
};

The value of `interface' represents a family of keyboard device types (such as Intel "PC, ADB, NeXT," Sun Type5, etc.), and is generally specified as one of the constant values "NX_EVS_DEVICE_INTERFACE_ADB, NX_EVS_DEVICE_INTERFACE_ACE," etc., which are are defined in IOHIDTypes.h on MacOS/X and Darwin, and in ev_types.h on MacOS/X Server, OpenStep, and NextStep.

The value of `handler_id' represents a specific keyboard layout within the much broader `interface' family. For instance, for a 101-key Intel PC keyboard (of type NX_EVS_DEVICE_INTERFACE_ACE ) the `handler_id' is '0', whereas for a 102-key keyboard it is `1'.

Together, `interface' and `handler_id' identify the exact keyboard hardware to which this mapping applies. Programs which display a visual representation of a keyboard layout, match `interface' and `handler_id' from the .keymapping file against the `interface' and `handler_id' values found in each .keyboard file.

Key Mapping

A key mapping completely defines the relationship of all scan codes with their associated functionality. A KeyMapping structure is embedded within the DeviceMapping structure in a KeyMappingFile. The key mapping currently in use by the WindowServer and AppKit is also represented by a KeyMapping structure, and can be referred to directly by calling NXGetKeyMapping() and accessing the `mapping' data member of the returned NXKeyMapping structure.


struct KeyMapping {
    word number_size;           // 0=1 byte, non-zero=2 bytes
    number num_modifier_groups; // Modifier groups
    ModifierGroup modifier_groups[...];
    number num_scan_codes;      // Scan groups
    ScanGroup scan_table[...]; 
    number num_sequence_lists;  // Sequence lists
    Sequence sequence_lists[...]; 
    number num_special_keys;    // Special keys
    SpecialKey special_key[...]; 
};

The `number_size' flag determines the size, in bytes, of all remaining numeric values (denoted by the type definition `number') within the key mapping. If its value is zero, then numbers are represented by a single byte. If it is non-zero, then numbers are represented by a word (two bytes).

Modifier Group

A modifier group defines all scan codes which map to a particular type of modifier, such as shift, control, etc.


enum Modifier {
    ALPHALOCK = 0,
    SHIFT,
    CONTROL,
    ALTERNATE,
    COMMAND,
    KEYPAD,
    HELP
};


struct ModifierGroup {
    number modifier;        // A Modifier constant
    number num_scan_codes; 
    number scan_codes[...]; // Variable number of scan codes
};

The scan_codes[] array contains a list of all scan codes which map to the specified modifier. The shift, command, and alternate modifiers are frequently mapped to two different scan codes, apiece, since these modifiers often appear on both the left and right sides of the keyboard.

Scan Group

There is one ScanGroup for each scan code generated by the given keyboard. This number is given by KeyMapping::num_scan_codes. The first scan group represents hardware scan code 0, the second represents scan code 1, etc.


enum ModifierMask {
    ALPHALOCK_MASK       = 1 << 0,
    SHIFT_MASK           = 1 << 1,
    CONTROL_MASK         = 1 << 2,
    ALTERNATE_MASK       = 1 << 3,
    CARRIAGE_RETURN_MASK = 1 << 4
};
#define NOT_BOUND 0xff


struct ScanGroup {
    number mask; 
    Character characters[...]; 
};

For each scan code, `mask' defines which modifier combinations generate characters. If `mask' is NOT_BOUND (0xff) then then this scan code does not generate any characters ever, and its characters[] array is zero length. Otherwise, the characters[] array contains one Character record for each modifier combination.

The number of records in characters[] is determined by computing (1 << bits_set_in_mask). In other words, if mask is zero, then zero bits are set, so characters[] contains only one record. If `mask' is "(SHIFT_MASK | CONTROL_MASK)," then two bits are set, so characters[] contains four records.

The first record always represents the character which is generated by that key when no modifiers are active. The remaining records represent characters generated by the various modifier combinations. Using the example with the shift and control masks set, record two would represent the character with the shift modifier active; record three, the control modifier active; and record four, both the shift and control modifiers active.

As a special case, ALPHALOCK_MASK implies SHIFT_MASK, though only ALPHALOCK_MASK appears in `mask'. In this case the same character is generated for both the shift and alpha-lock modifiers, but only needs to appear once in the characters[] array.

CARRIAGE_RETURN_MASK does not actually refer to a modifier key. Instead, it is used to distinguish the scan code which is given the special pseudo-designation of carriage return key. Typically, this mask appears solo in a ScanGroup record and only the two Character records for control-M and control-C follow. This flag may be a throwback to an earlier time or may be specially interpreted by the low-level keyboard driver, but its purpose is otherwise enigmatic.

Character

Each Character record indicates the character generated when this key is pressed, as well as the character set which contains the character. Well known character sets are `ASCII' and `Symbol'. The character set can also be one of the meta values FUNCTION_KEY or KEY_SEQUENCE. If it is FUNCTION_KEY then `char_code' represents a generally well-known function key such as those enumerated by FunctionKey. If the character set is KEY_SEQUENCE then `char_code' represents is a zero-base index into KeyMapping::sequence_lists[].


enum CharacterSet {
    ASCII        = 0x00,
    SYMBOL       = 0x01,
    ... 
    FUNCTION_KEY = 0xfe,
    KEY_SEQUENCE = 0xff
};


struct Character {
    number set;       // CharacterSet of generated character
    number char_code; // Actual character generated
};


enum FunctionKey {
    F1 = 0x20, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12,
    INSERT, DELETE, HOME, END, PAGE_UP, PAGE_DOWN, PRINT_SCREEN,
    SCROLL_LOCK, PAUSE, SYS_REQUEST, BREAK, RESET, STOP, MENU,
    USER, SYSTEM, PRINT, CLEAR_LINE, CLEAR_DISPLAY, INSERT_LINE,
    DELETE_LINE, INSERT_CHAR, DELETE_CHAR, PREV, NEXT, SELECT
};

Sequence

When Character::set contains the meta value KEY_SEQUENCE, the scan code is bound to a sequence of keys rather than a single character. A sequence is a series of modifiers and characters which are automatically generated when the associated key is depressed.


#define MODIFIER_KEY 0xff


struct Sequence {
    number num_chars; 
    Character characters[...]; 
};

Each generated Character is represented as previously described, with the exception that MODIFIER_KEY may appear in place of KEY_SEQUENCE. When the value of Character::set is MODIFIER_KEY then Character::char_code represents a modifier key rather than an actual character. If the modifier represented by `char_code' is non-zero, then it indicates that the associated modifier key has been depressed. In this case, the value is one of the constants enumerated by Modifier ("SHIFT, CONTROL, ALTERNATE," etc.). If the value is zero then it means that the modifier keys have been released.

Special Key

A special key is one which is scanned directly by the Mach kernel rather than by the WindowServer. In general, events are not generated for special keys.


enum SpecialKeyType {
    VOLUME_UP = 0,
    VOLUME_DOWN,
    BRIGHTNESS_UP,
    BRIGHTNESS_DOWN,
    ALPHA_LOCK,
    HELP,
    POWER,
    SECONDARY_ARROW_UP,
    SECONDARY_ARROW_DOWN
};


struct SpecialKey {
    number type;      // A SpecialKeyType constant
    number scan_code; // Actual scan code
};

Output

What follows is an explanation and description of the various pieces of information emitted by dumpkeymap.

For a more thorough discussion of any particular piece of information described here, refer to the detailed description of the internal layout of a key mapping provided by the Key Mapping Description section above.

Conventions

Depending upon context, some numeric values are displayed in decimal notation, whereas others are displayed in hexadecimal notation. Hexadecimal numbers are denoted by a `0x' prefix (for instance, `0x7b'), except when explicitly noted otherwise.

Key Mapping Source

The first piece of information presented about a particular key mapping is the source from which the data was gleaned. For a .keymapping file, the title "`KEYMAP FILE'" is emitted along with the path and name of the file in question. For the key mapping currently in use by the WindowServer and AppKit, the title "`ACTIVE KEYMAP'" is emitted instead.

Device Information

Each .keymapping file may contain one or more raw key mappings. For example, a file which maps keys to a Dvorak-style layout might contain raw mappings for Intel "PC, ADB, NeXT," and Sun Type5 keyboards.

For each raw mapping, the following information is emitted:

The `interface' and `handler_id' values, taken together, define a specific keyboard device. A .keyboard file, which describes the visual layout of a keyboard, also contains `interface' and `handler_id' identifiers. The .keyboard file corresponding to a particular key mapping can be found by matching the `interface' and `handler_id' values from each resource.

Modifiers

Each mapping may contain zero or more modifier records which associate hardware scan codes with modifier descriptions such as shift, control, alternate, etc. The title `MODIFIERS' is printed along with the count of modifier records which follow. For each modifier record, the modifier's name is printed along with a list of scan codes, in hexadecimal format, which generate that modifier value. For example:


MODIFIERS [4]
alternate: 0x1d 0x60
control: 0x3a
keypad: 0x52 0x53 ... 0x63 0x62
shift: 0x2a 0x36

Characters

Each mapping may contain zero or more character records which associate hardware scan codes with the actual characters generated by those scan codes in the presence or absence of various modifier combinations. The title `CHARACTERS' is printed along with the count of character records which follow. Here is a highly abbreviated example:


CHARACTERS [9]
scan 0x00: -AC-L  "a" "A" "^A" "^A" ca c7 "^A" "^A"
scan 0x07: -AC-L  "x" "X" "^X" "^X" 01/b4 01/ce "^X" "^X"
scan 0x0a: ---S-  "<" ">"
scan 0x13: -ACS-  "2" "@" "^@" "^@" b2 b3 "^@" "^@"
scan 0x24: R----  "^M" "^C"
scan 0x3e: -----  [F4]
scan 0x4a: -----  [page up]
scan 0x60: -----  {seq#3}
scan 0x68: not-bound

For each record, the hexadecimal value of the hardware scan code is printed, followed by a list of modifier flag combinations and the actual characters generated by this scan code with and without modifiers applied.

The modifier flags field is composed of a combination of single letter representations of the various modifier types. The letters stand for:


L - alpha-lock
S - shift
C - control
A - alternate
R - carriage-return

As a special case, the alpha-lock flag also implies the shift flag, so these two flags never appear together in the same record.

The combination of modifier flags determines the meaning and number of fields which follow. The first field after the modifier flags always represents the character that will be generated if no modifier keys are depressed. The remaining fields represent characters generated by the various modifier combinations. The order of the fields follows this general pattern:

The `R' flag does not actually refer to a modifier key. Instead, it is used to distinguish the scan code which is given the special pseudo-designation of carriage return key. Typically, this mask appears solo and only the two fields for control-M and control-C follow. This flag may be a throwback to an earlier time or may be specially interpreted by the low-level keyboard driver, but its purpose is otherwise enigmatic.

Recalling the example from above, the following fields can be identified:


scan 0x00: -AC-L  "a" "A" "^A" "^A" ca c7 "^A" "^A"

The notation used to represent a particular generated character varies.

Recalling a few examples from above, the following interpretations can be made:


scan 0x07: -AC-L  "x" "X" "^X" "^X" 01/b4 01/ce "^X" "^X"
scan 0x3e: -----  [F4]
scan 0x4a: -----  [page up]
scan 0x60: -----  {seq#3}

Finally, if a scan code is not bound to any characters, then it is annotated with the label `not-bound', as with example scan code 0x68 from above.

Sequences

A scan code (modified and unmodified) can be bound to a key sequence rather than generating a single character or acting as a modifier. When it is bound to a key sequence, a series of character invocations and modifier actions are automatically generated rather than a single keystroke.

Each mapping may contain zero or more key sequence records. The title `SEQUENCES' is printed along with the count of sequence records which follow. For example:


SEQUENCES [3]
sequence 0: "f" "o" "o"
sequence 1: {alternate} "b" "a" "r" {unmodify}
sequence 2: [home] "b" "a" "z"

The notation used to represent the sequence of generated characters is identical to the notation already described in the Characters section above, with the exception that modifier actions may be interposed between generated characters. Such modifier actions are represented by the modifier's name enclosed in braces. The special name `{unmodify}' indicates the release of the modifier keys.

Thus, the sequences in the above example can be interpreted as follows:

Special Keys

Certain keyboards feature keys which perform some type of special purpose function rather than generating a character or acting as a modifier. For instance, Apple keyboards often contain a power key, and NeXT keyboards have historically featured screen brightness and volume control keys.

Each mapping may contain zero or more special-key records which associate hardware scan codes with such special purpose functions. The title `SPECIALS' is printed along with the count of records which follow. For each record, the special function's name is printed along with a list of scan codes, in hexadecimal format, which are bound to that function. For example:


SPECIALS [6]
alpha-lock: 0x39
brightness-down: 0x79
brightness-up: 0x74
power: 0x7f
sound-down: 0x77
sound-up: 0x73

Files

A key mapping file which precisely defines the relationship of all hardware-specific keyboard scan-codes with their associated functionality.

A file describing the physical layout of keys on a particular type of keyboard. Each `key' token in this file defines the position and shape of the key on the keyboard, as well as the associated scan code which that key generates. A .keymapping file, on the other hand, defines the characters which are generated by a particular scan code depending upon the state of the various modifier keys (such as shift, control, etc.). The `interface' and `handler_id' values from a .keymapping file are matched against those in each .keyboard file in order to associate a particular .keyboard file with a key mapping. Various GUI programs use the .keyboard file to display a visual representation of a keyboard for the user. Since these files are just plain text, they can be easily viewed and interpreted without the aid of a specialized program, thus dumpkeymap leaves these files alone.

/System/Library/Keyboards
/Network/Library/Keyboards
/Local/Library/Keyboards
/Library/Keyboards

Repositories for .keymapping and .keyboard files for MacOS/X, Darwin, and MacOS/X Server.

/NextLibrary/Keyboards
/LocalLibrary/Keyboards

Repositories for .keymapping and .keyboard files for OpenStep and NextStep.

Repository for personal .keymapping and .keyboard files.

Diganostics

The following diagnostic messages may be issued to the standard error stream.
Unrecognized option.
An unrecognized option was specified on the command-line. Invoke dumpkeymap with the --help option to view a list of valid options.
Insufficient data in keymapping data stream.
The key mapping file or data stream is corrupt. Either the file has been incorrectly truncated or a field, such as those which indicates the number of variable records which follow, contains a corrupt value.

The following diagnostic messages have significance only when trying to print .keymapping files mentioned on the command-line.

Bad magic number.
The mentioned file is not a .keymapping file. The file's content does not start with the string `KYM1'.
Unable to open key mapping file.
The call to fopen() failed; probably because the specified path is invalid or dumpkeymap does not have permission to read the file.
Unable to determine key mapping file size.
The call to fstat() failed, thus memory can not be allocated for loading the file.
Unable to read key mapping file.
The call to fread() failed.

The following diagnostic messages have significance only when trying to print the currently active key mapping when no .keymapping files have been mentioned on the command-line.

Unable to open event status driver.
The call to NXOpenEventStatus() failed.
Bad key mapping length.
The call to NXKeyMappingLength() returned a bogus value.
Unable to get current key mapping.
The call to NXGetKeyMapping() failed.

The following diagnostic messages have significance only when using dumpkeymap on a non-Apple/NeXT platform.

Must specify at least one .keymapping file.
No .keymapping files were mentioned on the command-line. On non-Apple/NeXT platforms, there is no concept of a currently active .keymapping file, so at least one file must be mentioned on the command-line.

Author

Eric Sunshine <sunshine@sunshineco.com> wrote dumpkeymap and this document, the dumpkeymap user's manual. Both dumpkeymap and this document are copyright 1999,2000 by Eric Sunshine <sunshine@sunshineco.com>. All rights reserved.

The implementation of dumpkeymap is based upon information gathered on September 3, 1997 by Eric Sunshine <sunshine@sunshineco.com> and Paul S. McCarthy <zarnuk@zarnuk.com> during an effort to reverse engineer the format of the NeXT .keymapping file.

Version 4 -- 1 December 2000


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