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https://github.com/RobTillaart/Arduino.git
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132 lines
2.8 KiB
C++
132 lines
2.8 KiB
C++
//
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// FILE: FastShiftIn.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.2.2
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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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#include "FastShiftIn.h"
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FastShiftIn::FastShiftIn(const uint8_t datapin, const uint8_t clockpin, const uint8_t bitOrder)
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{
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_bitorder = bitOrder;
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_value = 0;
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pinMode(datapin, 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 _datatimer = digitalPinToTimer(datapin);
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// if (_datatimer != NOT_ON_TIMER) turnOffPWM(_datatimer); TODO
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uint8_t _dataport = digitalPinToPort(datapin);
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_datain = portOutputRegister(_dataport);
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_databit = digitalPinToBitMask(datapin);
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// uint8_t _clocktimer = digitalPinToTimer(clockpin);
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// if (_clocktimer != NOT_ON_TIMER) turnOffPWM(_clocktimer);
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uint8_t _clockport = digitalPinToPort(clockpin);
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_clockin = portOutputRegister(_clockport);
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_clockbit = digitalPinToBitMask(clockpin);
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#else
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// reference implementation
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// reuse these local vars as pin to save some space
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_databit = datapin;
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_clockbit = 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 value = 0;
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uint8_t cbmask1 = _clockbit;
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uint8_t cbmask2 = ~_clockbit;
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uint8_t dbmask = _databit;
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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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*_clockin |= cbmask1;
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if ((*_datain & dbmask) > 0)
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{
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value |= m;
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}
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*_clockin &= cbmask2;
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SREG = oldSREG;
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}
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_value = value;
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return _value;
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#else
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// reference implementation
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_value = shiftIn(_databit, _clockbit, 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 value = 0;
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uint8_t cbmask1 = _clockbit;
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uint8_t cbmask2 = ~cbmask1;
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uint8_t dbmask = _databit;
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for (uint8_t n = 128; n > 0; n >>= 1)
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{
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uint8_t oldSREG = SREG;
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noInterrupts();
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*_clockin |= cbmask1;
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if ((*_datain & dbmask) > 0)
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{
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value |= n;
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}
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*_clockin &= cbmask2;
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SREG = oldSREG;
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}
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_value = value;
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return _value;
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#else
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// reference implementation
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_value = shiftIn(_databit, _clockbit, MSBFIRST);
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return _value;
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#endif
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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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// -- END OF FILE --
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