Trait ObjectAccess

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pub trait ObjectAccess: Sync + Send {
Show 22 methods    // Required methods
    fn read(
        &self,
        sub: u8,
        offset: usize,
        buf: &mut [u8],
    ) -> Result<usize, AbortCode>;
    fn read_size(&self, sub: u8) -> Result<usize, AbortCode>;
    fn write(&self, sub: u8, data: &[u8]) -> Result<(), AbortCode>;
    fn object_code(&self) -> ObjectCode;
    fn sub_info(&self, sub: u8) -> Result<SubInfo, AbortCode>;

    // Provided methods
    fn begin_partial(&self, sub: u8) -> Result<(), AbortCode> { ... }
    fn write_partial(&self, _sub: u8, _buf: &[u8]) -> Result<(), AbortCode> { ... }
    fn end_partial(&self, _sub: u8) -> Result<(), AbortCode> { ... }
    fn max_sub_number(&self) -> u8 { ... }
    fn set_event_flag(&self, _sub: u8) -> Result<(), AbortCode> { ... }
    fn read_event_flag(&self, _sub: u8) -> bool { ... }
    fn clear_events(&self) { ... }
    fn access_type(&self, sub: u8) -> Result<AccessType, AbortCode> { ... }
    fn data_type(&self, sub: u8) -> Result<DataType, AbortCode> { ... }
    fn size(&self, sub: u8) -> Result<usize, AbortCode> { ... }
    fn current_size(&self, sub: u8) -> Result<usize, AbortCode> { ... }
    fn read_u32(&self, sub: u8) -> Result<u32, AbortCode> { ... }
    fn read_u16(&self, sub: u8) -> Result<u16, AbortCode> { ... }
    fn read_u8(&self, sub: u8) -> Result<u8, AbortCode> { ... }
    fn read_i32(&self, sub: u8) -> Result<i32, AbortCode> { ... }
    fn read_i16(&self, sub: u8) -> Result<i16, AbortCode> { ... }
    fn read_i8(&self, sub: u8) -> Result<i8, AbortCode> { ... }
}

Expand description

A trait for accessing objects

Any struct which implements an object in the object dictionary must implement this trait

Required Methods§

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fn read( &self, sub: u8, offset: usize, buf: &mut [u8], ) -> Result<usize, AbortCode>

Read raw bytes from a subobject

If the specified read goes out of range (i.e. offset + buf.len() > current_size) an error is returned. All implementers are required to allow reading a subset of the object bytes, i.e. offset may be non-zero, and/or the buf length may be shorter than the object data

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fn read_size(&self, sub: u8) -> Result<usize, AbortCode>

Get the number of bytes available for a read

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fn write(&self, sub: u8, data: &[u8]) -> Result<(), AbortCode>

Write raw bytes to a subobject

The length of data must match the size of the object, or else it will fail with either AbortCode::DataTypeMismatchLengthLow or AbortCode::DataTypeMismatchLengthHigh.

If the sub is does not exist, it shall fail with AbortCode::NoSuchSubIndex.

If the sub exists but is not writeable, it shall fail with AbortCode::ReadOnly.

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fn object_code(&self) -> ObjectCode

Get the type of this object

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fn sub_info(&self, sub: u8) -> Result<SubInfo, AbortCode>

Get metadata about a sub object

Provided Methods§

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fn begin_partial(&self, sub: u8) -> Result<(), AbortCode>

Initialize a new partial write

This must be called before performing calls to partial_write.

A default implementation is provided which returns an appropriate error:

AbortCode::NoSuchSubIndex if the sub object does not exist
AbortCode::ReadOnly if the sub object is read-only
AbortCode::UnsupportedAccess if the sub object does not support partial writes

Objects which support partial writing must override the default implementation.

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fn write_partial(&self, _sub: u8, _buf: &[u8]) -> Result<(), AbortCode>

Perform a partial write of bytes to a subobject

Most objects do not support partial writes. But in some cases, such as DOMAINs, or very large string objects, it is unavoidable and these must support it.

Partial writes MUST be done sequentially, and implementers may assume that this is the case. Executing multiple concurrent partial writes to the same sub object is not supported. It is up to the application to ensure that this is not done.

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fn end_partial(&self, _sub: u8) -> Result<(), AbortCode>

Finalize a previous partial write

This must always be called after using partial_write, after all partial_write calls have been completed.

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fn max_sub_number(&self) -> u8

Get the highest sub index available in this object

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fn set_event_flag(&self, _sub: u8) -> Result<(), AbortCode>

Set an event flag for the specified sub object on this object

Event flags are used for triggering PDOs. This is optional, as not all objects support PDOs or PDO triggering.

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fn read_event_flag(&self, _sub: u8) -> bool

Read an event flag for the specified sub object

This is optional as not all objects support events

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fn clear_events(&self)

Clear event flags for all sub objects

This is optional as not all objects support events

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fn access_type(&self, sub: u8) -> Result<AccessType, AbortCode>

Get the access type of a specific sub object

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fn data_type(&self, sub: u8) -> Result<DataType, AbortCode>

Get the data type of a specific sub object

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fn size(&self, sub: u8) -> Result<usize, AbortCode>

Get the maximum size of an sub object

For most sub objects, this matches the current_size, but for strings the size of the currently stored value (returned by current_size()) may be smaller.

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fn current_size(&self, sub: u8) -> Result<usize, AbortCode>

Get the current size of a sub object

Note that this is not necessarily the allocated size of the object, as some objects (such as strings) may have values shorter than their maximum size. As such, this gives the maximum number of bytes which may be read, but not necessarily the number of bytes which may be written.

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