eCos Reference Manual
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# Chapter 4. HAL Interfaces

This section describes the main HAL interfaces.

# Base Definitions

These are definitions that characterize the properties of the base architecture that are used to compile the portable parts of the kernel. They are concerned with such things a portable type definitions, endianness, and labeling.

These definitions are supplied by the `cyg/hal/basetype.h` header file which is supplied by the architecture HAL. It is included automatically by `cyg/infra/cyg_type.h`.

## Byte order

CYG_BYTEORDER

  This defines the byte order of the target and must be set to either CYG_LSBFIRST or CYG_MSBFIRST.

## Label Translation

`CYG_LABEL_NAME(name)`

  This is a wrapper used in some C and C++ files which use labels defined in assembly code or the linker script. It need only be defined if the default implementation in `cyg/infra/cyg_type.h`, which passes the name argument unaltered, is inadequate. It should be paired with `CYG_LABEL_DEFN()`.

`CYG_LABEL_DEFN(name)`

  This is a wrapper used in assembler sources and linker scripts which define labels. It need only be defined if the default implementation in `cyg/infra/cyg_type.h`, which passes the name argument unaltered, is inadequate. The most usual alternative definition of this macro prepends an underscore to the label name.

## Base types

    	cyg_halint8
    	cyg_halint16
    	cyg_halint32
    	cyg_halint64
    	cyg_halcount8
    	cyg_halcount16
    	cyg_halcount32
    	cyg_halcount64
    	cyg_halbool

These macros define the C base types that should be used to define variables of the given size. They only need to be defined if the default types specified in `cyg/infra/cyg_type.h` cannot be used. Note that these are only the base types, they will be composed with signed and unsigned to form full type specifications.

## Atomic types

    	cyg_halatomic CYG_ATOMIC

These types are guaranteed to be read or written in a single uninterruptible operation. It is architecture defined what size this type is, but it will be at least a byte.

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