/*
 * Various 1 wire routines
 * Search routine is copied from the Dallas owpd library with mods.
 *
 * $Id$
 *
 * Copyright (c) 2004
 *      Daniel O'Connor <darius@dons.net.au>.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <stdio.h>
#include <avr/io.h>
#include <avr/pgmspace.h>

#include "1wire.h"
#include "1wire-delay.h"

void		uart_putsP(const char *addr);
void		uart_puts(const char *addr);
void		uart_getc();
int		uart_putc(char c);

static uint8_t OW_LastDevice = 0;
static uint8_t OW_LastDiscrepancy = 0;
static uint8_t OW_LastFamilyDiscrepancy = 0;

static void
OWdelay(void) {
      asm volatile (
	  "ldi r21, 50\n\t"
	  "_OWdelay:\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "nop\n\t"
	  "dec r21\n\t"
	  "brne _OWdelay\n\t"
	  ::: "r21");
}

/*-----------------------------------------------------------------------------
 * Generate a 1-Wire reset, return 1 if no presence detect was found,
 * return 0 otherwise.
 * (NOTE: Does not handle alarm presence from DS2404/DS1994)
 */
int
OWTouchReset(void) {
    uint8_t	result;

    asm volatile (
	/* Delay G (0 usec) */
	"\n\t"
	/* Drive bus low */
	"cbi %[out], %[opin]\n\t"
	"sbi %[ddr], %[opin]\n\t"
	/* Delay H (480 usec) */
	"ldi r21, 120\n\t"
	"loopH:\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"dec r21\n\t"
	"brne loopH\n\t"
	/* Release bus */
	"cbi %[ddr], %[opin]\n\t"
	/* Delay I (70 usec) */
	"ldi r21, 35\n\t"
	"loopI:\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n\t"
	"dec r21\n\t"
	"brne loopI\n\t"
	/* Sample for presense */
	"ldi %[result], 0\n\t"
	"sbi %[ddr], 1\n\t"
	"sbi %[out], 1\n\t"
	/* 1 == no presence */
	"sbic %[in], %[ipin]\n\t"
	"ldi %[result], 1\n\t"
	"cbi %[out], 1\n\t"

	: [result] "=r" (result)			/* Outputs */
	: [out]  "I" (_SFR_IO_ADDR(OWIREOUTPORT)),	/* Inputs */
	  [ddr]  "I" (_SFR_IO_ADDR(OWIREDDR)),
	  [opin] "I" (OWIREOUTPIN),
	  [in]   "I" (_SFR_IO_ADDR(OWIREINPORT)),
	  [ipin] "I" (OWIREINPIN)
	: "r21");				/* Clobbers */

    return(result);
}

/*-----------------------------------------------------------------------------
 * Send a 1-wire write bit.
 */
void
OWWriteBit(int bit) {
    OWdelay();
    if (bit) {
	OWIREOUTPORT &= ~(_BV(OWIREOUTPIN));
	OWIREDDR |= _BV(OWIREOUTPIN);
	DELAY_A;
	OWIREDDR &= ~(_BV(OWIREOUTPIN));
	DELAY_B;
    } else {
	OWIREOUTPORT &= ~(_BV(OWIREOUTPIN));
	OWIREDDR |= _BV(OWIREOUTPIN);
	DELAY_C;
	OWIREDDR &= ~(_BV(OWIREOUTPIN));
	DELAY_D;
    }
}

/*-----------------------------------------------------------------------------
 * Read a bit from the 1-wire bus and return it.
 */
int
OWReadBit(void) {
    OWdelay();

    OWIREOUTPORT &= ~(_BV(OWIREOUTPIN));
    OWIREDDR |= _BV(OWIREOUTPIN);
    DELAY_A;
    OWIREDDR &= ~(_BV(OWIREOUTPIN));
    DELAY_E;
    return(OWIREINPORT & _BV(OWIREINPIN) ? 1 : 0);
}

/*-----------------------------------------------------------------------------
 * Write a byte to the 1-wire bus
 */
void
OWWriteByte(uint8_t data) {
    int i;
    
    /* Send LSB first */
    for (i = 0; i < 8; i++) {
	OWWriteBit(data & 0x01);
	data >>= 1;
    }
}

/*-----------------------------------------------------------------------------
 * Read a byte from the 1-wire bus
 */
int
OWReadByte(void) {
    int i, result = 0;
    
    for (i = 0; i < 8; i++) {
	result >>= 1;
	if (OWReadBit())
	    result |= 0x80;
    }
    return(result);
}

/*-----------------------------------------------------------------------------
 * Write a 1-wire data byte and return the sampled result.
 */
int
OWTouchByte(uint8_t data) {
    int i, result = 0;
    
    for (i = 0; i < 8; i++) {
	result >>= 1;
	
	/* If sending a 1 then read a bit, otherwise write a 0 */
	if (data & 0x01) {
	    if (OWReadBit())
		result |= 0x80;
	} else
	    OWWriteBit(0);
	
	data >>= 1;
    }

    return(result);
}

/*-----------------------------------------------------------------------------
 * Write a block of bytes to the 1-wire bus and return the sampled result in
 * the same buffer
 */
void
OWBlock(uint8_t *data, int len) {
    int i;
    
    for (i = 0; i < len; i++)
	data[i] = OWTouchByte(data[i]);
}


/*-----------------------------------------------------------------------------
 * Send a 1 wire command to a device, or all if no ROM ID provided
 */
void
OWSendCmd(uint8_t *ROM, uint8_t cmd) {
    int		i;

    OWTouchReset();
    
    if (ROM == NULL)
	OWWriteByte(OW_SKIP_ROM_CMD);
    else {
	OWWriteByte(OW_MATCH_ROM_CMD);
	for (i = 0; i < 8; i++)
	    OWWriteByte(ROM[i]);
    }

    OWWriteByte(cmd);
}

/*-----------------------------------------------------------------------------
 * Search algorithm from App note 187 (and 162)
 *
 * Returns 1 when something is found, 0 if nothing present
 */
int
OWFirst(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only) {
    /* Reset state */
    OW_LastDiscrepancy = 0;
    OW_LastDevice = 0;
    OW_LastFamilyDiscrepancy = 0;
    
    /* Go looking */
    return (OWNext(ROM, do_reset, alarm_only));
}

/* Returns 1 when something is found, 0 if nothing left */
int
OWNext(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only) {
    uint8_t	bit_test, search_direction, bit_number;
    uint8_t	last_zero, rom_byte_number, next_result;
    uint8_t	rom_byte_mask;
    uint8_t	lastcrc8, crcaccum;
    char	errstr[30];

    /* Init for search */
   bit_number = 1;
   last_zero = 0;
   rom_byte_number = 0;
   rom_byte_mask = 1;
   next_result = 0;
   lastcrc8 = 0;
   crcaccum = 0;

   /* if the last call was not the last one */
   if (!OW_LastDevice) {
       /* check if reset first is requested */
       if (do_reset) {
	   /* reset the 1-wire
	    * if there are no parts on 1-wire, return 0 */
#if OW_DEBUG
	   uart_putsP(PSTR("Resetting\n\r"));
#endif
         if (OWTouchReset()) {
	     /* reset the search */
	     OW_LastDiscrepancy = 0;
	     OW_LastFamilyDiscrepancy = 0;
#if OW_DEBUG
	     uart_putsP(PSTR("No devices on bus\n\r"));
#endif
	     return 0;
         }
       }

       /* If finding alarming devices issue a different command */
      if (alarm_only)
	  OWWriteByte(OW_SEARCH_ALRM_CMD);	/* issue the alarming search command */
      else
	  OWWriteByte(OW_SEARCH_ROM_CMD);	/* issue the search command */

      /* pause before beginning the search */
      OWdelay();
      OWdelay();
      OWdelay();
      
      /* loop to do the search */
      do {
	  /* read a bit and its compliment */
	  bit_test = OWReadBit() << 1;
	  bit_test |= OWReadBit();

#if OW_DEBUG
	  sprintf_P(errstr, PSTR("bit_test = %d\n\r"), bit_test);
	  uart_puts(errstr);
#endif

	  /* check for no devices on 1-wire */
	  if (bit_test == 3) {
	      sprintf_P(errstr, PSTR("bit_test = %d\n\r"), bit_test);
	      uart_puts(errstr);
	      break;
	  }
	  else {
	      /* all devices coupled have 0 or 1 */
	      if (bit_test > 0)
		  search_direction = !(bit_test & 0x01);  /* bit write value for search */
	      else {
		  /* if this discrepancy is before the Last Discrepancy
		   * on a previous OWNext then pick the same as last time */
		  if (bit_number < OW_LastDiscrepancy)
		      search_direction = ((ROM[rom_byte_number] & rom_byte_mask) > 0);
		  else
		      /* if equal to last pick 1, if not then pick 0 */
			 search_direction = (bit_number == OW_LastDiscrepancy);

		  /* if 0 was picked then record its position in LastZero */
		  if (search_direction == 0) {
		      last_zero = bit_number;

		      /* check for Last discrepancy in family */
		      if (last_zero < 9)
			  OW_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[rom_byte_number] |= rom_byte_mask;
	      else
		  ROM[rom_byte_number] &= ~rom_byte_mask;

	      /* serial number search direction write bit */
	      OWWriteBit(search_direction);

	      /* increment the byte counter bit_number
	       * and shift the mask rom_byte_mask */
	      bit_number++;
	      rom_byte_mask <<= 1;

	      /* if the mask is 0 then go to new ROM byte rom_byte_number
	       * and reset mask */
	      if (rom_byte_mask == 0) {
		  OWCRC(ROM[rom_byte_number], &crcaccum);  /* accumulate the CRC */
		  lastcrc8 = crcaccum;
		  
		  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 (!(bit_number < 65) || lastcrc8) {
	  if (lastcrc8) {
	      sprintf_P(errstr, PSTR("Bad CRC (%d)\n\r"), lastcrc8);
	      uart_puts(errstr);
	      next_result = 0;
	  } else {
	      /*  search successful so set LastDiscrepancy,LastDevice,next_result */
	      OW_LastDiscrepancy = last_zero;
	      OW_LastDevice = (OW_LastDiscrepancy == 0);
#if OW_DEBUG
	      sprintf_P(errstr, PSTR("Last device = %d\n\r"), OW_LastDevice);
	      uart_puts(errstr);
#endif
	      next_result = 1;
	  }
      }
   }

   /* if no device found then reset counters so next 'next' will be
    * like a first */
   if (!next_result || !ROM[0]) {
       OW_LastDiscrepancy = 0;
       OW_LastDevice = 0;
       OW_LastFamilyDiscrepancy = 0;
       next_result = 0;
   }

   return next_result;

}

uint8_t PROGMEM dscrc_table[] = { 
    0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
    157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
    35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
    190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
    70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
    219, 133,103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
    101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
    248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
    140,210, 48, 110, 237, 179, 81, 15, 78, 16, 242,  172, 47, 113,147, 205,
    17, 79, 173, 243, 112, 46, 204, 146, 211,141, 111, 49, 178, 236, 14, 80,
    175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82,176, 238,
    50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
    202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
    87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
    233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
    116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53
};

void
OWCRC(uint8_t x, uint8_t *crc) {
    *crc = pgm_read_byte(&dscrc_table[(*crc) ^ x]);
}