Intermec CN2B Manual do Utilizador descarregar pdf (Página 202)

Chapter 7 — Programming

184 CN2B Mobile Computer User’s Manual

Alpha (Green) Plane

The alpha plane contains values from the keypad when the keypad has been

placed in alpha mode by pressing the green [Alpha] key, such as:

Press the Keys To Enter This

[Alpha] [1] Caps

[Alpha] [5] j

[Alpha] [9] w

Locating the Registry Settings for Your Key Values

Key values for each plane are stored in the registry. All units ship with a

default key mapping loaded in the registry. Applications that change the

default mapping need to read the appropriate key from the registry into an

array of words, modify the values required and then write the updated val

ues back into the registry. The registry access can be done with standard

Microsoft API calls, such as RegOpenKeyEx(), RegQueryValueEx(), and

RegSetValueEx(). These registry keys contain the plane mappings:

• The unshifted plane mapping can be found in the registry at:

HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\KEYBD\Vkey

• The orange plane mapping can be found in the registry at:

HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\KEYBD\VkeyGold

• The alpha plane mapping can be found in the registry at:

HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\KEYBD\VkeyAlpha

How Key Values Are Stored in the Registry

To know which fields to update in the registry, you must know what Scan

Codes are assigned to each physical key (see page 185). The Scan Code is

used at the lowest level of the system to let the keypad driver know which

physical key is pressed. The keypad driver takes that scan code and looks it

up in a table (a copy of the table in the registry) to determine the values to

pass to the operating system.

Each registry key is just an array that describes to the keypad driver what

value needs to be passed for each physical key. The key values are indexed

by the scan code, this is a zero-based index. For example in the unshifted

plane, the [4] key has a scan code of 0x06. This means that the seventh

word under the “Vkey” registry key has the value for the [4] key. Taking a

sample of the “Vkey” registry key shows the following values:

00,00,0B,05,02,03,C1,07,04,03,BE,00,34,00,00,00,. . .

The value is 34,00. The values are in reverse byte order because that is the

way the processor handles data. When writing an application, nothing

needs to be done to swap the bytes, as this will happen automatically when

the data is read into a byte value. This is something you just need to be

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