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# FastShiftInOut

Arduino library for **AVR** optimized shiftInOut (simultaneously).

Related libraries
- https://github.com/RobTillaart/FastShiftIn
- https://github.com/RobTillaart/FastShiftOut
- https://github.com/RobTillaart/ShiftInSlow
- https://github.com/RobTillaart/ShiftOutSlow


## Description

FastShiftInOut is a class that can send and receive bytes simultaneously.
In that sense it mimics a SPI bus.

Experimental.


## Performance

performance of **write()**

|  version  |  UNO (us)  |  ESP32 (us)  |
|:---------:|:----------:|:------------:|
|   0.1.0   |   181.08   |     4.32     |
|   0.1.1   |    26.84   |     4.32     |


## Interface

bitOrder = { LSBFIRST, MSBFIRST };

- **FastShiftInOut(uint8_t dataIn, uint8_t dataOut, uint8_t clockPin, uint8_t bitOrder = LSBFIRST)**
- **uint8_t write(uint8_t data)** reads and writes simultaneously.
- **uint8_t lastWritten(void)** returns last written value.
- **bool setBitOrder(uint8_t bitOrder)** idem.
- **uint8_t getBitOrder(void)** idem.
- **uint8_t writeLSBFIRST(uint8_t data)**
- **uint8_t writeMSBFIRST(uint8_t data)**


## Operation

See examples


## Future

#### must
- documentation

#### should
- performance measurements
- optimize for AVR

#### could
- **void ignoreRead()**
- add Print interface?