text: /*
  Copyright (c) 2007, Jim Studt  (original old version - many contributors since)
  
  The latest version of this library may be found at:
    http://www.pjrc.com/teensy/td_libs_OneWire.html
  
  OneWire has been maintained by Paul Stoffregen (paul@pjrc.com) since
  January 2010.
  
  DO NOT EMAIL for technical support, especially not for ESP chips!
  All project support questions must be posted on public forums
  relevant to the board or chips used.  If using Arduino, post on
  Arduino's forum.  If using ESP, post on the ESP community forums.
  There is ABSOLUTELY NO TECH SUPPORT BY PRIVATE EMAIL!
  
  Github's issue tracker for OneWire should be used only to report
  specific bugs.  DO NOT request project support via Github.  All
  project and tech support questions must be posted on forums, not
  github issues.  If you experience a problem and you are not
  absolutely sure it's an issue with the library, ask on a forum
  first.  Only use github to report issues after experts have
  confirmed the issue is with OneWire rather than your project.
  
  Back in 2010, OneWire was in need of many bug fixes, but had
  been abandoned the original author (Jim Studt).  None of the known
  contributors were interested in maintaining OneWire.  Paul typically
  works on OneWire every 6 to 12 months.  Patches usually wait that
  long.  If anyone is interested in more actively maintaining OneWire,
  please contact Paul (this is pretty much the only reason to use
  private email about OneWire).
  
  OneWire is now very mature code.  No changes other than adding
  definitions for newer hardware support are anticipated.
  
  Version 2.3:
    Unknown chip fallback mode, Roger Clark
    Teensy-LC compatibility, Paul Stoffregen
    Search bug fix, Love Nystrom
  
  Version 2.2:
    Teensy 3.0 compatibility, Paul Stoffregen, paul@pjrc.com
    Arduino Due compatibility, http://arduino.cc/forum/index.php?topic=141030
    Fix DS18B20 example negative temperature
    Fix DS18B20 example's low res modes, Ken Butcher
    Improve reset timing, Mark Tillotson
    Add const qualifiers, Bertrik Sikken
    Add initial value input to crc16, Bertrik Sikken
    Add target_search() function, Scott Roberts
  
  Version 2.1:
    Arduino 1.0 compatibility, Paul Stoffregen
    Improve temperature example, Paul Stoffregen
    DS250x_PROM example, Guillermo Lovato
    PIC32 (chipKit) compatibility, Jason Dangel, dangel.jason AT gmail.com
    Improvements from Glenn Trewitt:
    - crc16() now works
    - check_crc16() does all of calculation/checking work.
    - Added read_bytes() and write_bytes(), to reduce tedious loops.
    - Added ds2408 example.
    Delete very old, out-of-date readme file (info is here)
  
  Version 2.0: Modifications by Paul Stoffregen, January 2010:
  http://www.pjrc.com/teensy/td_libs_OneWire.html
    Search fix from Robin James
      http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1238032295/27#27
    Use direct optimized I/O in all cases
    Disable interrupts during timing critical sections
      (this solves many random communication errors)
    Disable interrupts during read-modify-write I/O
    Reduce RAM consumption by eliminating unnecessary
      variables and trimming many to 8 bits
    Optimize both crc8 - table version moved to flash
  
  Modified to work with larger numbers of devices - avoids loop.
  Tested in Arduino 11 alpha with 12 sensors.
  26 Sept 2008 -- Robin James
  http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1238032295/27#27
  
  Updated to work with arduino-0008 and to include skip() as of
  2007/07/06. --RJL20
  
  Modified to calculate the 8-bit CRC directly, avoiding the need for
  the 256-byte lookup table to be loaded in RAM.  Tested in arduino-0010
  -- Tom Pollard, Jan 23, 2008
  
  Jim Studt's original library was modified by Josh Larios.
  
  Tom Pollard, pollard@alum.mit.edu, contributed around May 20, 2008
  
  Permission is hereby granted, free of charge, to any person obtaining
  a copy of this software and associated documentation files (the
  "Software"), to deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to
  the following conditions:
  
  The above copyright notice and this permission notice shall be
  included in all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  Much of the code was inspired by Derek Yerger's code, though I don't
  think much of that remains.  In any event that was..
      (copyleft) 2006 by Derek Yerger - Free to distribute freely.
  
  The CRC code was excerpted and inspired by the Dallas Semiconductor
  sample code bearing this copyright.
  //---------------------------------------------------------------------------
  // Copyright (C) 2000 Dallas Semiconductor Corporation, All Rights Reserved.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the "Software"),
  // to deal in the Software without restriction, including without limitation
  // the rights to use, copy, modify, merge, publish, distribute, sublicense,
  // and/or sell copies of the Software, and to permit persons to whom the
  // Software is furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY,  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  // IN NO EVENT SHALL DALLAS SEMICONDUCTOR BE LIABLE FOR ANY CLAIM, DAMAGES
  // OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  // OTHER DEALINGS IN THE SOFTWARE.
  //
  // Except as contained in this notice, the name of Dallas Semiconductor
  // shall not be used except as stated in the Dallas Semiconductor
  // Branding Policy.
  //--------------------------------------------------------------------------
  */
  
  #include <Arduino.h>
  #include "OneWire.h"
  #include "OneWire_direct_gpio.h"
  
  
  void OneWire::begin(uint8_t pin)
  {
  	pinMode(pin, INPUT);
  	bitmask = PIN_TO_BITMASK(pin);
  	baseReg = PIN_TO_BASEREG(pin);
  #if ONEWIRE_SEARCH
  	reset_search();
  #endif
  }
  
  
  // Perform the onewire reset function.  We will wait up to 250uS for
  // the bus to come high, if it doesn't then it is broken or shorted
  // and we return a 0;
  //
  // Returns 1 if a device asserted a presence pulse, 0 otherwise.
  //
  uint8_t OneWire::reset(void)
  {
  	IO_REG_TYPE mask IO_REG_MASK_ATTR = bitmask;
  	volatile IO_REG_TYPE *reg IO_REG_BASE_ATTR = baseReg;
  	uint8_t r;
  	uint8_t retries = 125;
  
  	noInterrupts();
  	DIRECT_MODE_INPUT(reg, mask);
  	interrupts();
  	// wait until the wire is high... just in case
  	do {
  		if (--retries == 0) return 0;
  		delayMicroseconds(2);
  	} while ( !DIRECT_READ(reg, mask));
  
  	noInterrupts();
  	DIRECT_WRITE_LOW(reg, mask);
  	DIRECT_MODE_OUTPUT(reg, mask);	// drive output low
  	interrupts();
  	delayMicroseconds(480);
  	noInterrupts();
  	DIRECT_MODE_INPUT(reg, mask);	// allow it to float
  	delayMicroseconds(70);
  	r = !DIRECT_READ(reg, mask);
  	interrupts();
  	delayMicroseconds(410);
  	return r;
  }
  
  //
  // Write a bit. Port and bit is used to cut lookup time and provide
  // more certain timing.
  //
  void OneWire::write_bit(uint8_t v)
  {
  	IO_REG_TYPE mask IO_REG_MASK_ATTR = bitmask;
  	volatile IO_REG_TYPE *reg IO_REG_BASE_ATTR = baseReg;
  
  	if (v & 1) {
  		noInterrupts();
  		DIRECT_WRITE_LOW(reg, mask);
  		DIRECT_MODE_OUTPUT(reg, mask);	// drive output low
  		delayMicroseconds(10);
  		DIRECT_WRITE_HIGH(reg, mask);	// drive output high
  		interrupts();
  		delayMicroseconds(55);
  	} else {
  		noInterrupts();
  		DIRECT_WRITE_LOW(reg, mask);
  		DIRECT_MODE_OUTPUT(reg, mask);	// drive output low
  		delayMicroseconds(65);
  		DIRECT_WRITE_HIGH(reg, mask);	// drive output high
  		interrupts();
  		delayMicroseconds(5);
  	}
  }
  
  //
  // Read a bit. Port and bit is used to cut lookup time and provide
  // more certain timing.
  //
  uint8_t OneWire::read_bit(void)
  {
  	IO_REG_TYPE mask IO_REG_MASK_ATTR = bitmask;
  	volatile IO_REG_TYPE *reg IO_REG_BASE_ATTR = baseReg;
  	uint8_t r;
  
  	noInterrupts();
  	DIRECT_MODE_OUTPUT(reg, mask);
  	DIRECT_WRITE_LOW(reg, mask);
  	delayMicroseconds(3);
  	DIRECT_MODE_INPUT(reg, mask);	// let pin float, pull up will raise
  	delayMicroseconds(10);
  	r = DIRECT_READ(reg, mask);
  	interrupts();
  	delayMicroseconds(53);
  	return r;
  }
  
  //
  // Write a byte. The writing code uses the active drivers to raise the
  // pin high, if you need power after the write (e.g. DS18S20 in
  // parasite power mode) then set 'power' to 1, otherwise the pin will
  // go tri-state at the end of the write to avoid heating in a short or
  // other mishap.
  //
  void OneWire::write(uint8_t v, uint8_t power /* = 0 */) {
      uint8_t bitMask;
  
      for (bitMask = 0x01; bitMask; bitMask <<= 1) {
  	OneWire::write_bit( (bitMask & v)?1:0);
      }
      if ( !power) {
  	noInterrupts();
  	DIRECT_MODE_INPUT(baseReg, bitmask);
  	DIRECT_WRITE_LOW(baseReg, bitmask);
  	interrupts();
      }
  }
  
  void OneWire::write_bytes(const uint8_t *buf, uint16_t count, bool power /* = 0 */) {
    for (uint16_t i = 0 ; i < count ; i++)
      write(buf[i]);
    if (!power) {
      noInterrupts();
      DIRECT_MODE_INPUT(baseReg, bitmask);
      DIRECT_WRITE_LOW(baseReg, bitmask);
      interrupts();
    }
  }
  
  //
  // Read a byte
  //
  uint8_t OneWire::read() {
      uint8_t bitMask;
      uint8_t r = 0;
  
      for (bitMask = 0x01; bitMask; bitMask <<= 1) {
  	if ( OneWire::read_bit()) r |= bitMask;
      }
      return r;
  }
  
  void OneWire::read_bytes(uint8_t *buf, uint16_t count) {
    for (uint16_t i = 0 ; i < count ; i++)
      buf[i] = read();
  }
  
  //
  // Do a ROM select
  //
  void OneWire::select(const uint8_t rom[8])
  {
      uint8_t i;
  
      write(0x55);           // Choose ROM
  
      for (i = 0; i < 8; i++) write(rom[i]);
  }
  
  //
  // Do a ROM skip
  //
  void OneWire::skip()
  {
      write(0xCC);           // Skip ROM
  }
  
  void OneWire::depower()
  {
  	noInterrupts();
  	DIRECT_MODE_INPUT(baseReg, bitmask);
  	interrupts();
  }
  
  #if ONEWIRE_SEARCH
  
  //
  // You need to use this function to start a search again from the beginning.
  // You do not need to do it for the first search, though you could.
  //
  void OneWire::reset_search()
  {
    // reset the search state
    LastDiscrepancy = 0;
    LastDeviceFlag = false;
    LastFamilyDiscrepancy = 0;
    for(int i = 7; ; i--) {
      ROM_NO[i] = 0;
      if ( i == 0) break;
    }
  }
  
  // Setup the search to find the device type 'family_code' on the next call
  // to search(*newAddr) if it is present.
  //
  void OneWire::target_search(uint8_t family_code)
  {
     // set the search state to find SearchFamily type devices
     ROM_NO[0] = family_code;
     for (uint8_t i = 1; i < 8; i++)
        ROM_NO[i] = 0;
     LastDiscrepancy = 64;
     LastFamilyDiscrepancy = 0;
     LastDeviceFlag = false;
  }
  
  //
  // Perform a search. If this function returns a '1' then it has
  // enumerated the next device and you may retrieve the ROM from the
  // OneWire::address variable. If there are no devices, no further
  // devices, or something horrible happens in the middle of the
  // enumeration then a 0 is returned.  If a new device is found then
  // its address is copied to newAddr.  Use OneWire::reset_search() to
  // start over.
  //
  // --- Replaced by the one from the Dallas Semiconductor web site ---
  //--------------------------------------------------------------------------
  // Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
  // search state.
  // Return TRUE  : device found, ROM number in ROM_NO buffer
  //        FALSE : device not found, end of search
  //
  bool OneWire::search(uint8_t *newAddr, bool search_mode /* = true */)
  {
     uint8_t id_bit_number;
     uint8_t last_zero, rom_byte_number;
     bool    search_result;
     uint8_t id_bit, cmp_id_bit;
  
     unsigned char rom_byte_mask, search_direction;
  
     // initialize for search
     id_bit_number = 1;
     last_zero = 0;
     rom_byte_number = 0;
     rom_byte_mask = 1;
     search_result = false;
  
     // if the last call was not the last one
     if (!LastDeviceFlag) {
        // 1-Wire reset
        if (!reset()) {
           // reset the search
           LastDiscrepancy = 0;
           LastDeviceFlag = false;
           LastFamilyDiscrepancy = 0;
           return false;
        }
  
        // issue the search command
        if (search_mode == true) {
          write(0xF0);   // NORMAL SEARCH
        } else {
          write(0xEC);   // CONDITIONAL SEARCH
        }
  
        // loop to do the search
        do
        {
           // read a bit and its complement
           id_bit = read_bit();
           cmp_id_bit = read_bit();
  
           // check for no devices on 1-wire
           if ((id_bit == 1) && (cmp_id_bit == 1)) {
              break;
           } else {
              // all devices coupled have 0 or 1
              if (id_bit != cmp_id_bit) {
                 search_direction = id_bit;  // bit write value for search
              } else {
                 // if this discrepancy if before the Last Discrepancy
                 // on a previous next then pick the same as last time
                 if (id_bit_number < LastDiscrepancy) {
                    search_direction = ((ROM_NO[rom_byte_number] & rom_byte_mask) > 0);
                 } else {
                    // if equal to last pick 1, if not then pick 0
                    search_direction = (id_bit_number == LastDiscrepancy);
                 }
                 // if 0 was picked then record its position in LastZero
                 if (search_direction == 0) {
                    last_zero = id_bit_number;
  
                    // check for Last discrepancy in family
                    if (last_zero < 9)
                       LastFamilyDiscrepancy = last_zero;
                 }
              }
  
              // set or clear the bit in the ROM byte rom_byte_number
              // with mask rom_byte_mask
              if (search_direction == 1)
                ROM_NO[rom_byte_number] |= rom_byte_mask;
              else
                ROM_NO[rom_byte_number] &= ~rom_byte_mask;
  
              // serial number search direction write bit
              write_bit(search_direction);
  
              // increment the byte counter id_bit_number
              // and shift the mask rom_byte_mask
              id_bit_number++;
              rom_byte_mask <<= 1;
  
              // if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
              if (rom_byte_mask == 0) {
                  rom_byte_number++;
                  rom_byte_mask = 1;
              }
           }
        }
        while(rom_byte_number < 8);  // loop until through all ROM bytes 0-7
  
        // if the search was successful then
        if (!(id_bit_number < 65)) {
           // search successful so set LastDiscrepancy,LastDeviceFlag,search_result
           LastDiscrepancy = last_zero;
  
           // check for last device
           if (LastDiscrepancy == 0) {
              LastDeviceFlag = true;
           }
           search_result = true;
        }
     }
  
     // if no device found then reset counters so next 'search' will be like a first
     if (!search_result || !ROM_NO[0]) {
        LastDiscrepancy = 0;
        LastDeviceFlag = false;
        LastFamilyDiscrepancy = 0;
        search_result = false;
     } else {
        for (int i = 0; i < 8; i++) newAddr[i] = ROM_NO[i];
     }
     return search_result;
    }
  
  #endif
  
  #if ONEWIRE_CRC
  // The 1-Wire CRC scheme is described in Maxim Application Note 27:
  // "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products"
  //
  
  #if ONEWIRE_CRC8_TABLE
  // Dow-CRC using polynomial X^8 + X^5 + X^4 + X^0
  // Tiny 2x16 entry CRC table created by Arjen Lentz
  // See http://lentz.com.au/blog/calculating-crc-with-a-tiny-32-entry-lookup-table
  static const uint8_t PROGMEM dscrc2x16_table[] = {
  	0x00, 0x5E, 0xBC, 0xE2, 0x61, 0x3F, 0xDD, 0x83,
  	0xC2, 0x9C, 0x7E, 0x20, 0xA3, 0xFD, 0x1F, 0x41,
  	0x00, 0x9D, 0x23, 0xBE, 0x46, 0xDB, 0x65, 0xF8,
  	0x8C, 0x11, 0xAF, 0x32, 0xCA, 0x57, 0xE9, 0x74
  };
  
  // Compute a Dallas Semiconductor 8 bit CRC. These show up in the ROM
  // and the registers.  (Use tiny 2x16 entry CRC table)
  uint8_t OneWire::crc8(const uint8_t *addr, uint8_t len)
  {
  	uint8_t crc = 0;
  
  	while (len--) {
  		crc = *addr++ ^ crc;  // just re-using crc as intermediate
  		crc = pgm_read_byte(dscrc2x16_table + (crc & 0x0f)) ^
  		pgm_read_byte(dscrc2x16_table + 16 + ((crc >> 4) & 0x0f));
  	}
  
  	return crc;
  }
  #else
  //
  // Compute a Dallas Semiconductor 8 bit CRC directly.
  // this is much slower, but a little smaller, than the lookup table.
  //
  uint8_t OneWire::crc8(const uint8_t *addr, uint8_t len)
  {
  	uint8_t crc = 0;
  
  	while (len--) {
  #if defined(__AVR__)
  		crc = _crc_ibutton_update(crc, *addr++);
  #else
  		uint8_t inbyte = *addr++;
  		for (uint8_t i = 8; i; i--) {
  			uint8_t mix = (crc ^ inbyte) & 0x01;
  			crc >>= 1;
  			if (mix) crc ^= 0x8C;
  			inbyte >>= 1;
  		}
  #endif
  	}
  	return crc;
  }
  #endif
  
  #if ONEWIRE_CRC16
  bool OneWire::check_crc16(const uint8_t* input, uint16_t len, const uint8_t* inverted_crc, uint16_t crc)
  {
      crc = ~crc16(input, len, crc);
      return (crc & 0xFF) == inverted_crc[0] && (crc >> 8) == inverted_crc[1];
  }
  
  uint16_t OneWire::crc16(const uint8_t* input, uint16_t len, uint16_t crc)
  {
  #if defined(__AVR__)
      for (uint16_t i = 0 ; i < len ; i++) {
          crc = _crc16_update(crc, input[i]);
      }
  #else
      static const uint8_t oddparity[16] =
          { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 };
  
      for (uint16_t i = 0 ; i < len ; i++) {
        // Even though we're just copying a byte from the input,
        // we'll be doing 16-bit computation with it.
        uint16_t cdata = input[i];
        cdata = (cdata ^ crc) & 0xff;
        crc >>= 8;
  
        if (oddparity[cdata & 0x0F] ^ oddparity[cdata >> 4])
            crc ^= 0xC001;
  
        cdata <<= 6;
        crc ^= cdata;
        cdata <<= 1;
        crc ^= cdata;
      }
  #endif
      return crc;
  }
  #endif
  
  #endif
  