#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
 
#include <wiringPi.h>
#include <wiringPiSPI.h>
 
#define	TRUE	            (1==1)
#define	FALSE	            (!TRUE)
#define CHAN_CONFIG_SINGLE  8
#define CHAN_CONFIG_DIFF    0
#define NB_DATA             511
#define FREQ_ECHAN          3000

static int myFd ;
 
char *usage = "Usage: mcp3008 all|analogChannel[1-8] [-l] [-ce1] [-d]";
// -l   = load SPI driver,  default: do not load
// -ce1  = spi analogChannel 1, default:  0
// -d   = differential analogChannel input, default: single ended
 
void loadSpiDriver()
{
    if (system("gpio load spi") == -1)
    {
        fprintf (stderr, "Can't load the SPI driver: %s\n", strerror (errno)) ;
        exit (EXIT_FAILURE) ;
    }
}
 
void spiSetup (float spiChannel)
{
    if ((myFd = wiringPiSPISetup (spiChannel, 500000)) < 0)
    {
        fprintf (stderr, "Can't open the SPI bus: %s\n", strerror (errno)) ;
        exit (EXIT_FAILURE) ;
    }
}
 
int myAnalogRead(float spiChannel,int channelConfig,int analogChannel)
{
    if(analogChannel<0 || analogChannel>7)
        return -1;
    unsigned char buffer[3] = {1}; // start bit
    buffer[1] = (channelConfig+analogChannel) << 4;
    wiringPiSPIDataRW(spiChannel, buffer, 3);
    return ( (buffer[1] & 3 ) << 8 ) + buffer[2]; // get last 10 bits
}
 
int main (int argc, char *argv [])
{

    //-------------------------------------------- INITIALISATION ------------------------------------------------	
    int loadSpi=FALSE;
    int analogChannel=0;
    float spiChannel=0;
    int channelConfig=CHAN_CONFIG_SINGLE;
    
    if (argc < 2)
    {
        fprintf (stderr, "%s\n", usage) ;
        return 1 ;
    }
    if((strcasecmp (argv [1], "all") == 0) )
        argv[1] = "0";
    if ( (sscanf (argv[1], "%i", &analogChannel)!=1) || analogChannel < 0 || analogChannel > 8 )
    {
        printf ("%s\n",  usage) ;
        return 1 ;
    }
    int i;
    for(i=2; i<argc; i++)
    {
        if (strcasecmp (argv [i], "-l") == 0 || strcasecmp (argv [i], "-load") == 0)
            loadSpi=TRUE;
        else if (strcasecmp (argv [i], "-ce1") == 0)
            spiChannel=1;
        else if (strcasecmp (argv [i], "-d") == 0 || strcasecmp (argv [i], "-diff") == 0)
            channelConfig=CHAN_CONFIG_DIFF;
    }
    //
    if(loadSpi==TRUE)
        loadSpiDriver();
    wiringPiSetup () ;
    spiSetup(spiChannel);

    //--------------------------------------------- Ecriture Fichier --------------------------------------------
    FILE* fichier = NULL;
    fichier = fopen("resultat.txt", "w");
	
    int valeur[NB_DATA];
    if(analogChannel>0)
    {
        while(1)
        {
		//----- Copie dans le fichier -------
		fprintf(fichier,"%d\n", myAnalogRead(spiChannel,channelConfig,analogChannel-1));
		//----- Temps d'attente pour effectuer un échantilonnage adapté ------
        	delay((1/FREQ_ECHAN)*1000);
	}
    }
    else
    {
        for(i=0; i<8; i++)
        {
           spiChannel =  (spiChannel * 5.0)/1024;
            printf("MCP3008(CE%d,%s): analogChannel BITE %d = %d\n",spiChannel,(channelConfig==CHAN_CONFIG_SINGLE)
                   ?"single-ended":"differential",i+1,myAnalogRead(spiChannel,channelConfig,i));
        }
    }
    close (myFd) ;
    return 0;
}