diff -r 89d6a7a84779 -r 25a17d01db0c Symbian3/PDK/Source/GUID-C661B40F-1439-587F-9E8E-DB2DFC79C040.dita --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Symbian3/PDK/Source/GUID-C661B40F-1439-587F-9E8E-DB2DFC79C040.dita Fri Jan 22 18:26:19 2010 +0000 @@ -0,0 +1,31 @@ + + + + + +HAL GroupsDescription of HAL groups to add new attributes. +

You can extend HAL +groups to add new attributes and new types of hardware.

+
Extending an existing hardware type

Each HAL group +has an associated set of function numbers. For example, the enumerators of TDisplayHalFunction, +in u32std.h define the functions associated with the +HAL group EHalGroupDisplay.

In this specific case, +new state can be represented by a new function number, and by changing the HAL +handler implementation to deal with the new function number.

It +is important to note that any new function numbers should not follow consecutively +from those defined by Symbian. Instead, choose high values so that they are +guaranteed not to clash with any future Symbian extensions. Symbian will always +use new values that follow consecutively from previous Symbian defined values.

+
New hardware type

Although up to 32 HAL groups +can be defined, Symbian OS does not use all 32. This leaves some values that +can be used for new hardware.

In this case choose a HAL group number +at the high end of the range, so that it is guaranteed not to clash with any +future Symbian extensions. Symbian will always use new values that follow +consecutively from previous Symbian defined values.

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