cyfral.c

/*
 * cyfral.c
 *
 * Created: 08.02.2016 20:39:55
 *  Author: Elektron
 */ 
#include <avr/io.h>
#include <util/delay.h>
#include "cyfral.h"

#define AVG_U_SUM 100
#define AVG_T_SUM 100

uint8_t cl_buffer[14];

uint8_t cl_decode(uint8_t* data)
{
	uint8_t start = 0;
	for(uint8_t i=0;i<8;i++) data[i] = 0;
	
	for(uint8_t temp=0;start<112;start++){							//íàõîäèì ñòàðòîâîå ñëîâî
		temp = temp<<1;
		if((cl_buffer[start/8]>>(start%8)) & 0x01) temp |= 0x01;
		else temp &= ~(0x01);
		temp &= 0x0F;
		if(temp == 0x01 && start > 2){start -= 3;break;}
	}
	for(uint8_t i=0;i<36;i++){										//ïðîâåðÿåì ïðàâèëüíîñòü äàííûõ
		uint8_t temp = 0;
		if((cl_buffer[(start+i)/8]>>((start+i)%8)) & 0x01) temp |= 0x01;
		if(((cl_buffer[(start+i+36)/8]>>((start+i+36)%8)) & 0x01) != temp) return CL_NO_KEY;
	}
	for(uint8_t i=0;i<32;i+=4){										//äåêîäèðóåì äàííûå
		uint8_t temp = 0;
		for(uint8_t bit=0;bit<4;bit++){
			temp = temp<<1;
			if((cl_buffer[(start+i+bit+4)/8]>>((start+i+bit+4)%8)) & 0x01) temp |= 0x01;
		}
		
		switch(temp){
			case 0b00001110: temp = 0b11000000;break;
			case 0b00001101: temp = 0b10000000;break;
			case 0b00001011: temp = 0b01000000;break;
			case 0b00000111: temp = 0b00000000;break;
			default: return CL_NO_KEY;
		}
		data[2-(i/16)] |= temp >> ((i%16)/2);
	}
	data[3] = 0x01;
	return CL_READ_OK;
}

uint8_t cl_read(uint8_t* data)
{
	uint16_t sum = 0;
	uint8_t avg_t = 0, avg_u = 0;
	
	ADMUX = (0 << REFS1)|(1 << REFS0) 					// îïîðíîå íàïðÿæåíèå AVCC
	|(1 << ADLAR)										// ñìåùåíèå ðåçóëüòàòà (âëåâî ïðè 1, ÷èòàåì 8 áèò èç ADCH)
	|(CL_ADC);	 										// âõîä CL_ADC
	_delay_us(20);
	
	for(uint8_t i=0;i<14;i++)cl_buffer[i] = 0;				//÷èñòèì ìàññèâ ïðèåìà

	for(uint8_t i=0;i<AVG_U_SUM;i++){						//îïðåäåëÿåì ñðåäíåå íàïðÿæåíèå
		sum += ADCH;
		_delay_us(10);
	}
	avg_u = sum / AVG_U_SUM;
	sum = 0;
	for(uint8_t u=0,i=0;i<AVG_T_SUM;i++){					//îïðåäåëÿåì äëèòåëüíîñòü öèêëà ãåíåðàòîðà êëþ÷à
		for(uint8_t t=0;t<200;t++){
			if(ADCH < avg_u && u){sum += t; u = 0;break;}
			if(ADCH > avg_u && !u){sum += t; u = 1;break;}
			_delay_us(4);
		}
	}
	avg_t = sum / AVG_T_SUM;
	if(avg_t < 5 || avg_t > 23) return CL_NO_KEY;
	
	for(uint8_t i=0;i<112;i++){								//ïèøåì â áóôåð ïðèåìà ñòàðòîâîå ñëîâî è êîä êëþ÷à òðèæäû
		uint8_t t;
		for (t=0;t<=150;t++){
			if(ADCH > avg_u) break;
			_delay_us(4);
		}
		if(t == 150) return CL_NO_KEY;
		
		for (t=0;t<=150;t++){
			if(ADCH < avg_u) break;
			_delay_us(4);
		}
		if(t == 150) return CL_NO_KEY;
		
		if(t > avg_t) cl_buffer[i/8] |= 0x01<<(i%8);
	}		
	
	return cl_decode(data);
}