mirror of
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88 lines
3.0 KiB
Markdown
88 lines
3.0 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/DEVNULL/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/DEVNULL/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/DEVNULL/blob/master/LICENSE)
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[](https://github.com/RobTillaart/DEVNULL/releases)
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# DEVNULL
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Arduino library for a /dev/null stream.
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## Description
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The library implements a stream class that mimics the **/dev/null**
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device of a Linux system. You can write everything to it.
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You can never read data from it as it always returns EOF (end of file);
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The 0.1.0 version is a minimal implementation that can be optimized.
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it implements the **write(const uint8_t data)** call and e.g. a float is still
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converted to individual characters that are send one after another.
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Strings and text send every byte.
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The advantage is that printing takes time and e.g. one can use it to measure
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the **print** class performance.
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Performance can be increased by implementing all methods of the print interface
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with only a return 0; (or at least **print(Type)** as the **println(T)** would only
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call once extra for the "\n".
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## Versions
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#### 0.1.2
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- sets the timeout for reading to 0. No need to wait longer with DEVNULL.
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this improves the **find(...)** calls substantially.
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- added **size_t write( const uint8_t \*buffer, size_t size)** for faster string processing.
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#### 0.1.4
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- add **lastByte()** to check last byte written.
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- split of .cpp
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## Interface
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- **DEVNULL()** constructor, sets the timeout to zero.
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- **int available()** always return zero.
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- **int peek()** always returns EOF.
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- **int read()** always return EOF.
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- **void flush()** does nothing but keeps some compilers happy.
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- **size_t write(const uint8_t data)** implements print interface. returns 1.
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- **size_t write( const uint8_t \*buffer, size_t size)** implements print interface.
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Returns size.
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- **int lastByte()** returns last byte written (debug and test purpose).
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Returns -1 if no byte has been written yet.
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## Operation
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Use with care.
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See examples.
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## Future
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#### Could
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- add byte counter (uint32_t)
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- investigate if DEVNULL can be used to harvest entropy?
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- sum xor of all data + timestamp?
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- enable / disable flag (complex)
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- => /dev/entropy class?
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- **flush()** could reset bottomLessPit to -1?
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#### Wont
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- add delay to mimic pause / tune behaviour for simulating devices
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- microseconds
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- delay per byte, esp long arrays might need other performance
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- out of scope for /dev/null => separate class?
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- implement Print class to increase performance?
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- derived class?
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