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107 lines
4.3 KiB
Markdown
107 lines
4.3 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/Multiplex/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/Multiplex/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/Multiplex/blob/master/LICENSE)
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[](https://github.com/RobTillaart/Multiplex/releases)
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# Multiplex
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Arduino Library implementing a (Print) stream multiplexer.
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## Description
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Multiplex is a library in which one can add multiple Print streams.
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If one prints to the multiplexer the data is sent to all the streams that were added.
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The maximum number of streams to add is 4.
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This value is defined in the **multiplex.h file** with `#define MAX_MULTIPLEX`.
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This value can be set to 254 MAX as the number 255 / 0xFF is used as a NOT_FOUND flag.
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Streams can be enabled or disabled by calling `enable()/disable()` passing either an index (based on the order
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in which `add` was called; 0 is first) or a pointer to the `Print`
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object that was passed to `add(Print *)` by calling `enableStream()/disableStream()`
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It is not possible to remove a stream from the multiplexer (yet), as this would affect the indices used.
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Solution is to reset and repopulate for now.
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**Note**: 0.2.2 has **experimental** remove support.
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## Interface
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### Constructor
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- **Multiplex(uint8_t max_multiplex = 4)** constructor,
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sets the maximum number of streams to 4 by default.
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MAX number is 254 as 255 (0xFF) is used as a flag for **NOT FOUND**.
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- **~Multiplex()** destructor
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- **void reset()** resets the count in the multiplexer to zero streams.
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### Core
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- **size_t write(uint8_t c)** workhorse of the Print interface.
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Writes a character to all enabled streams.
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- **size_t write(const uint8_t \* buffer, size_t size)**
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Writes a buffer of size characters to all enabled streams.
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- **bool add(Print \* stream)** add another Print stream.
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Returns false if no space left.
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Use the **index(Stream)** to get the actual index of the stream.
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#### Experimental 0.2.2
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Removing a stream is experimental.
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It changes the internal indices used, so if you want to use **remove()** in your sketch, you
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should only use the functions with a stream as parameter as these will always work correctly.
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Alternative is to request the **index(Stream)** after you called **remove()** and update your indices.
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- **bool remove(Print \* stream)** remove a Print stream.
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Returns false if not in the multiplexer.
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- **bool remove(uint8_t index)** remove a stream by its internal index.
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Returns false if index is out of range.
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### Control
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- **uint8_t count()** returns number of streams added, MAX 4 in initial release
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- **uint8_t size()** returns size which is 4 in the current release.
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- **uint8_t free()** returns number of free slots.
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Note: the index based functions are (slightly) faster than the stream based functions.
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How much faster depends on **MAX_MULTIPLEX** as the stream based functions do a lookup in every call.
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- **bool enable(uint8_t index)** enable the stream at index.
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Returns true on success, false otherwise.
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- **bool enableStream(Stream \* stream)** enable the stream.
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Returns true on success, false otherwise.
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- **bool disable(uint8_t index)** disable the stream at index.
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Returns true on success, false otherwise.
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- **bool disableStream(Stream \* stream)** disable the stream.
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Returns true on success, false otherwise.
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- **bool isEnabled(uint8_t index)** returns true if the stream at index is enabled,
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false otherwise.
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- **bool isEnabledStream(Stream \* stream)** returns true if the stream is enabled,
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false otherwise.
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- **uint8_t index(Print \*stream)** returns the index of the stream if it was added,
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otherwise it returns 0xFF == 255.
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Can be used to check if a stream is added to the multiplexer.
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- **Print \* stream(uint8_t index)** returns the stream at index or NULL otherwise.
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Convenience function.
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## Future
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- set size in constructor - dynamic memory
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- pack enabled flag in one or more bytes
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- add names?
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## Operation
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See examples
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