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