#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#define DEV "/dev/i2c/0"

// Status register bits
#define STATUS_DIR 0x80
#define STATUS_TSB 0x40
#define STATUS_SBR 0x20
#define STATUS_RST 0x10
#define STATUS_LL  0x08
#define STATUS_SD  0x04
#define STATUS_PPD 0x02
#define STATUS_1WB 0x01

typedef unsigned long long int owaddress;

int i2cdev;

void i2c_write(unsigned char* cmd, int buflen) {
    if (write(i2cdev, cmd, buflen) != buflen)
        perror("cmd_write");
}

unsigned char ow_wait() {
	unsigned char buf = 0xFF;
	
	do {
		read(i2cdev, &buf, 1);
	} while (buf & STATUS_1WB);
	
	return buf;
}

void ow_reset() {
    unsigned char status;
    
    i2c_write("\xF0", 1); // Device reset
    i2c_write("\xD2\xF0", 2); // Config write
    i2c_write("\xB4", 1); // 1 wire reset
    
    status = ow_wait();
    
    printf("Initialization complete, ");
    
    if (status & STATUS_SD)
        printf("bus is shorted\n");
    else if (status & STATUS_PPD)
        printf("presence pulse detected\n");
    else
        printf("no devices detected\n");
}

void ow_backtostart() {
	i2c_write("\xB4", 1); // 1 wire reset
	ow_wait();
	i2c_write("\xA5\xF0", 2); // Search bus
	ow_wait();
}

unsigned char ow_triplet(int direction) {
	unsigned char buf[2], status;
	
	buf[0] = 0x78;
	buf[1] = direction ? 0x80 : 0x00;
	i2c_write(buf, 2);
	status = ow_wait();
	
// 	printf(", dgo %d, dwent %d, first %d, second %d",
// 	       direction ? 1 : 0, status & STATUS_DIR ? 1 : 0,
// 	       status & STATUS_SBR ? 1 : 0, status & STATUS_TSB ? 1 :0);
	
	return status;
}

void ow_selectaddr(owaddress addr) {
	i2c_write("\xB4", 1); // 1 wire reset
	ow_wait();
	
	unsigned char buf[2];
	int i;
	
	i2c_write("\xA5\x55", 2); // Match rom
	ow_wait();
	
	for (i = 0; i < 8; i++) {
		buf[0] = 0xA5;
		buf[1] = addr & 0xFF;
		i2c_write(buf, 2);
		ow_wait();
		
		addr = addr >> 8;
	}
}

int ow_crc(owaddress addr) {
	int i, bit_in;
	unsigned char crc = 0x00;
	
	for (i = 0; i < 64; i++) {
		bit_in = addr & 0x01;
		addr = addr >> 1;
		
		if (crc & 0x01)
			bit_in = 1 - bit_in;
		
		crc = crc >> 1;
		
		if (bit_in)
			crc ^= 0x80 | 0x08 | 0x04;
	}
	
	printf("Result crc 0x%02x addr 0x%llx\n", crc, addr);
	
	if (crc == 0)
		return 1;
	else
		return 0;
}

float ow_temp_ds18s20(owaddress addr) {
	unsigned char stratchpad[9];
	int i;
	
	ow_selectaddr(addr);
	
	i2c_write("\xD2\xB4", 2); // Enable SPU
	i2c_write("\xA5\x44", 2); // Convert_T
	usleep(800000);
	i2c_write("\xD2\xF0", 2); // Disable SPU
	
	ow_selectaddr(addr);
	
	i2c_write("\xA5\xBE", 2); // Read stratchpad
	ow_wait();
	
	printf("Stratchpad ");
	
	for (i = 0; i < 9; i++) {
		i2c_write("\x96", 1);
		ow_wait();
		i2c_write("\xE1\xE1", 2);
		if (read(i2cdev, stratchpad + i, 1) != 1)
			perror("i2c_read");
		
		printf("%02x ", *(stratchpad + i));
	}
	
	printf("\n");
	
	
	int temp_read, count_remain, count_per_c;
	float result;
	
	temp_read = stratchpad[0] >> 1;
	if (stratchpad[1])
		temp_read = - temp_read;
	
	count_remain = stratchpad[6];
	count_per_c = stratchpad[7];
	
	result = temp_read - 0.25 + ((float) count_per_c - count_remain) / count_per_c;
	
	return result;
}

void ow_scan() {
	owaddress path_here, path_follow, path_follow_next = 0;
	int depth, status, done = 0;
	
	// We kind of walk a binary tree depth-first
	
	while(!done) {
		ow_backtostart();
		depth = 0;
		path_here = 0;
		path_follow = path_follow_next;
		done = 1;
		
		printf("New loop\n");
		
		while (depth < 64) {
// 			printf("Depth %d", depth);
			status = ow_triplet(path_follow & (1 << depth));
			
			if (status & STATUS_DIR) {
				path_here |= (owaddress) 1 << depth;
			} else if ((status & (STATUS_SBR | STATUS_TSB)) == 0x00) {
				// Two devices at this bit, and we went left
				// Next time: follow path this far, then turn right
				
				done = 0;
				path_follow_next = ((((owaddress) 1 << depth) - 1) & path_here) | ((owaddress) 1 << depth);
			}
			
			depth++;
		}
		
		int c = ow_crc(path_here);
		printf("GOT ADDRESS!!!!!!!: 0x%016llx %s\n", path_here, c ? "valid" : "INVALID!");
		
		if ((path_here & 0xFF) == 0x10)
			printf("Temperature %0.2f\n", ow_temp_ds18s20(path_here));
	}
}



int main() {
    i2cdev = open(DEV, O_RDWR);
    if (i2cdev < 0) {
        perror("open");
        exit(1);
    }
    
    ioctl(i2cdev, I2C_SLAVE, 0x18);
    
    ow_reset();
    
    ow_scan();

    return 0;
}