mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-10-03 18:09:02 -04:00
102 lines
3.4 KiB
Markdown
102 lines
3.4 KiB
Markdown
|
|
[](https://github.com/marketplace/actions/arduino_ci)
|
|
[](https://github.com/RobTillaart/DEVNULL/actions/workflows/arduino-lint.yml)
|
|
[](https://github.com/RobTillaart/DEVNULL/actions/workflows/jsoncheck.yml)
|
|
[](https://github.com/RobTillaart/DEVNULL/issues)
|
|
|
|
[](https://github.com/RobTillaart/DEVNULL/blob/master/LICENSE)
|
|
[](https://github.com/RobTillaart/DEVNULL/releases)
|
|
[](https://registry.platformio.org/libraries/robtillaart/DEVNULL)
|
|
|
|
|
|
# DEVNULL
|
|
|
|
Arduino library for a /dev/null stream.
|
|
|
|
|
|
## Description
|
|
|
|
The library implements a stream class that mimics the **/dev/null**
|
|
device of a Linux system. You can write everything to it.
|
|
You can never read data from it as it always returns EOF (end of file);
|
|
|
|
The 0.1.0 version is a minimal implementation that can be optimized.
|
|
it implements the **write(const uint8_t data)** call and e.g. a float is still
|
|
converted to individual characters that are send one after another.
|
|
Strings and text send every byte.
|
|
|
|
The advantage is that printing takes time and e.g. one can use it to measure
|
|
the **print** class performance.
|
|
|
|
Performance can be increased by implementing all methods of the print interface
|
|
with only a return 0; (or at least **print(Type)** as the **println(T)** would only
|
|
call once extra for the "\n".
|
|
|
|
|
|
#### Related
|
|
|
|
- https://github.com/RobTillaart/DEVFULL
|
|
- https://github.com/RobTillaart/DEVNULL
|
|
- https://github.com/RobTillaart/DEVRANDOM
|
|
|
|
|
|
## Interface
|
|
|
|
```cpp
|
|
#include "DEVNULL.h"
|
|
```
|
|
|
|
- **DEVNULL()** constructor, sets the timeout to zero.
|
|
- **int available()** always return zero.
|
|
- **int peek()** always returns EOF.
|
|
- **int read()** always return EOF.
|
|
- **void flush()** does nothing but keeps some compilers happy.
|
|
- **size_t write(const uint8_t data)** implements print interface. returns 1.
|
|
- **size_t write( const uint8_t \*buffer, size_t size)** implements print interface.
|
|
Returns size.
|
|
- **int lastByte()** returns last byte written (debug and test purpose).
|
|
Returns -1 if no byte has been written yet.
|
|
|
|
|
|
## Operation
|
|
|
|
Use with care.
|
|
|
|
See examples.
|
|
|
|
|
|
## Future
|
|
|
|
#### Must
|
|
|
|
#### Should
|
|
|
|
#### Could
|
|
|
|
- add byte counter (uint32_t)
|
|
- investigate if DEVNULL can be used to harvest entropy?
|
|
- sum xor of all data + timestamp?
|
|
- enable / disable flag (complex)
|
|
- => /dev/entropy class?
|
|
- **flush()** could reset bottomLessPit to -1?
|
|
|
|
|
|
#### Wont
|
|
|
|
- add delay to mimic pause / tune behaviour for simulating devices
|
|
- microseconds
|
|
- delay per byte, esp long arrays might need other performance
|
|
- out of scope for /dev/null => separate class?
|
|
- implement Print class to increase performance?
|
|
- derived class?
|
|
|
|
|
|
## Support
|
|
|
|
If you appreciate my libraries, you can support the development and maintenance.
|
|
Improve the quality of the libraries by providing issues and Pull Requests, or
|
|
donate through PayPal or GitHub sponsors.
|
|
|
|
Thank you,
|
|
|