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+>General principles</TITLE
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+><A
+NAME="HAL-GENERAL-PRINCIPLES">Chapter 8. General principles</H1
+><P
+>The HAL has been implemented according to the following general
+principles:</P
+><P
+></P
+><OL
+TYPE="1"
+><LI
+><P
+> The HAL is implemented in C and assembler, although the
+ eCos kernel is largely implemented in C++.
+ This is to permit the HAL the widest possible
+ applicability.</P
+></LI
+><LI
+><P
+>All interfaces to the HAL are implemented by
+ CPP macros. This allows them to be implemented as inline
+ C code, inline assembler or function calls to external C
+ or assembler code. This allows the most efficient
+ implementation to be selected without affecting the
+ interface. It also allows them to be redefined if the
+ platform or variant HAL needs to replace or enhance a definition
+ from the architecture HAL.</P
+></LI
+><LI
+><P
+>The HAL provides simple, portable mechanisms for dealing
+with the hardware of a wide range of architectures and platforms.
+It is always possible to bypass the HAL and program the hardware
+directly, but this may lead to a loss of portability. </P
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