mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-10-03 18:09:02 -04:00
150 lines
2.8 KiB
C++
150 lines
2.8 KiB
C++
//
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// FILE: FastShiftIn.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.3.0
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// PURPOSE: Fast ShiftIn for 74HC165 register, AVR optimized
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// DATE: 2013-09-29
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// URL: https://github.com/RobTillaart/FastShiftIn
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//
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// HISTORY: see changelog.md
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#include "FastShiftIn.h"
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FastShiftIn::FastShiftIn(uint8_t dataIn, uint8_t clockPin, uint8_t bitOrder)
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{
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_bitOrder = bitOrder;
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_value = 0;
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pinMode(dataIn, INPUT);
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pinMode(clockPin, OUTPUT);
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// https://www.arduino.cc/reference/en/language/functions/advanced-io/shiftin/
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digitalWrite(clockPin, LOW); // assume rising pulses from clock
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#if defined(ARDUINO_ARCH_AVR) || defined(ARDUINO_ARCH_MEGAAVR)
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uint8_t _port = digitalPinToPort(dataIn);
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_dataInRegister = portInputRegister(_port);
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_dataInBit = digitalPinToBitMask(dataIn);
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_port = digitalPinToPort(clockPin);
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_clockRegister = portOutputRegister(_port);
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_clockBit = digitalPinToBitMask(clockPin);
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#else
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_dataPinIn = dataIn;
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_clockPin = clockPin;
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#endif
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}
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int FastShiftIn::read()
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{
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if (_bitOrder == LSBFIRST)
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{
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return readLSBFIRST();
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}
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return readMSBFIRST();
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}
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int FastShiftIn::readLSBFIRST()
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{
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#if defined(ARDUINO_ARCH_AVR) || defined(ARDUINO_ARCH_MEGAAVR)
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uint8_t rv = 0;
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uint8_t cbmask1 = _clockBit;
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uint8_t cbmask2 = ~_clockBit;
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uint8_t inmask1 = _dataInBit;
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for (uint8_t m = 1; m > 0; m <<= 1)
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{
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uint8_t oldSREG = SREG;
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noInterrupts();
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// clock pulse HIGH
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*_clockRegister |= cbmask1;
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// read one bit
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if ((*_dataInRegister & inmask1) > 0) rv |= m;
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// clock pulse LOW
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*_clockRegister &= cbmask2;
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SREG = oldSREG;
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}
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_value = rv;
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return rv;
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#else
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// reference implementation
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_value = shiftIn(_dataPinIn, _clockPin, LSBFIRST);
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return _value;
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#endif
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}
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int FastShiftIn::readMSBFIRST()
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{
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#if defined(ARDUINO_ARCH_AVR) || defined(ARDUINO_ARCH_MEGAAVR)
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uint8_t rv = 0;
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uint8_t cbmask1 = _clockBit;
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uint8_t cbmask2 = ~_clockBit;
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uint8_t inmask1 = _dataInBit;
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for (uint8_t m = 0x80; m > 0; m >>= 1)
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{
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uint8_t oldSREG = SREG;
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noInterrupts();
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// clock pulse HIGH
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*_clockRegister |= cbmask1;
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// read one bit
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if ((*_dataInRegister & inmask1) > 0) rv |= m;
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// clock pulse LOW
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*_clockRegister &= cbmask2;
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SREG = oldSREG;
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}
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_value = rv;
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return rv;
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#else
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// reference implementation
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_value = shiftIn(_dataPinIn, _clockPin, MSBFIRST);
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return _value;
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#endif
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}
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int FastShiftIn::lastRead(void)
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{
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return _value;
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};
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bool FastShiftIn::setBitOrder(const uint8_t bitOrder)
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{
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if ((bitOrder == LSBFIRST) || (bitOrder == MSBFIRST))
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{
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_bitOrder = bitOrder;
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return true;
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};
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return false;
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}
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uint8_t FastShiftIn::getBitOrder(void)
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{
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return _bitOrder;
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};
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// -- END OF FILE --
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