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https://github.com/RobTillaart/Arduino.git
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117 lines
2.9 KiB
C++
117 lines
2.9 KiB
C++
//
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// FILE: FastShiftOut.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.2.2
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// PURPOSE: shiftout that implements the Print interface
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// DATE: 2013-08-22
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// URL: https://github.com/RobTillaart/FastShiftOut
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//
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#include "FastShiftOut.h"
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FastShiftOut::FastShiftOut(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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pinMode(datapin, OUTPUT);
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pinMode(clockpin, OUTPUT);
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// https://www.arduino.cc/reference/en/language/functions/advanced-io/shiftout/
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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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_dataout = 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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_clockout = portOutputRegister(_clockport);
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_clockbit = digitalPinToBitMask(clockpin);
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#else // reference implementation
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// reuse these 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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size_t FastShiftOut::write(const uint8_t data)
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{
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_value = data;
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if (_bitorder == LSBFIRST)
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{
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return writeLSBFIRST(data);
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}
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return writeMSBFIRST(data);
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}
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size_t FastShiftOut::writeLSBFIRST(const uint8_t data)
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{
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#if defined(ARDUINO_ARCH_AVR) || defined(ARDUINO_ARCH_MEGAAVR)
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uint8_t cbmask1 = _clockbit;
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uint8_t cbmask2 = ~_clockbit;
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uint8_t dbmask1 = _databit;
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uint8_t dbmask2 = ~_databit;
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for (uint8_t i = 0, m = 1; i < 8; i++)
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{
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uint8_t oldSREG = SREG;
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noInterrupts();
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if ((data & m) == 0) *_dataout &= dbmask2;
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else *_dataout |= dbmask1;
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*_clockout |= cbmask1;
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*_clockout &= cbmask2;
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SREG = oldSREG;
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m <<= 1;
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}
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return 1;
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#else
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shiftOut(_databit, _clockbit, LSBFIRST, data);
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return 1;
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#endif
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}
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size_t FastShiftOut::writeMSBFIRST(const uint8_t data)
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{
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#if defined(ARDUINO_ARCH_AVR) || defined(ARDUINO_ARCH_MEGAAVR)
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uint8_t cbmask1 = _clockbit;
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uint8_t cbmask2 = ~_clockbit;
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uint8_t dbmask1 = _databit;
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uint8_t dbmask2 = ~_databit;
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for (uint8_t i = 0, n = 128; i < 8; i++)
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{
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uint8_t oldSREG = SREG;
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noInterrupts();
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if ((data & n) == 0) *_dataout &= dbmask2;
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else *_dataout |= dbmask1;
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*_clockout |= cbmask1;
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*_clockout &= cbmask2;
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SREG = oldSREG;
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n >>= 1;
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}
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return 1;
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#else // reference implementation // note this has no cli()
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shiftOut(_databit, _clockbit, MSBFIRST, data);
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return 1;
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#endif
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}
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bool FastShiftOut::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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