/*
 *     Copyright (C) 2010 Jiri Pittner <jiri@pittnerovi.com>
 *
 *     This program is free software: you can redistribute it and/or modify
 *     it under the terms of the GNU General Public License as published by
 *     the Free Software Foundation, either version 3 of the License, or
 *     (at your option) any later version.

       This program is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *     GNU General Public License for more details.
 *
 *     You should have received a copy of the GNU General Public License
 *     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *  
*/



#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/select.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <math.h>

#include "keeloq.c"

//set modulation depth here
float l_zero= 0.;
float l_one = 1.;

void delay_ms(int fd,unsigned int sr,unsigned int t )
{
unsigned long count = sr*(double)t/1000.;
while(count-- >0) write(fd,&l_zero,sizeof(float));
}


//outputs a stream of floats at given sample rate to be used for ASK or FSK modulation in gnuradio
void transmit(int fd, unsigned int sr, uint8_t *outcode, uint8_t outcodelen)
{
unsigned int te = .0004*sr; //basic pulse element
int i,j;

float *l_zero_array = malloc(te*sizeof(float));
float *l_one_array = malloc(te*sizeof(float));
for(i=0; i<te; ++i) l_zero_array[i]=l_zero;
for(i=0; i<te; ++i) l_one_array[i]=l_one;

//preamble
for(i=0; i<12; ++i) 
	{
	write(fd,l_zero_array,te*sizeof(float));
	write(fd,l_one_array,te*sizeof(float));
	}

//header
for(i=0; i<10; ++i)  write(fd,l_zero_array,te*sizeof(float));

//pwm encoded bits
uint8_t obitcount=0, obytecount=0;
for(i=0; i<=outcodelen; ++i)
	{
	unsigned char bit = outcode[obytecount]& (1<<obitcount);
        write(fd,l_one_array,te*sizeof(float));
	if(i==outcodelen) break;
	write(fd,bit?l_zero_array:l_one_array,te*sizeof(float));
	write(fd,l_zero_array,te*sizeof(float));
	if(++obitcount==8) {obitcount=0;++obytecount;}
	}

free(l_zero_array);
free(l_one_array);
}


int main(int argc, char **argv)
{
if(argc!=2) {fprintf(stderr,"Usage: %s outputfile\n",argv[0]); exit(1);}


int fd ; 
fd=open(argv[1],O_WRONLY|O_CREAT,0777);
if(fd<0) {perror("cannot open output file"); exit(errno);};


#define MAXOUTCODELEN 256
uint8_t outcode[MAXOUTCODELEN];
uint8_t outcodelen;

KEELOQ_CODE keeloq_crypt=0x123456789abcdef0LL;
//encrypt something
{
uint16_t counter=1111;
outcode[0]=counter&0xff;
outcode[1]=counter>>8;
outcode[2]=0x78;
outcode[3]=0x23;
encrypt((uint32_t *)outcode,&keeloq_crypt);
outcode[4]=0x53;
outcode[5]=0x4d;
outcode[6]=0x08;
outcode[7]=0x20;
outcode[8]=0x02;
outcodelen=65;
}

int i;
printf("TX code: ");
for(i=0; i<9; ++i) printf("%02x ",outcode[i]);
printf("\n");

unsigned int sr=50000; //sampling rate

//just a test - transmit constant data repeatedly
while(1)
	{
	transmit(fd,sr,outcode,65);
	delay_ms(fd,sr,500); //every 500 ms
	}




close(fd);
}