/****************************************************/
/*                                                  */
/*             Sample  program KAK_read             */
/*                                                  */
/*  This C program read the monthly file of Kakioka */
/*  one-second resolution geomagnetic data for      */
/*  given date and time (year, month, day, hour,min)*/
/*  and simply write the data on the display.       */
/*                                                  */
/*                  Coded by T. Takeuchi (Nov. 1998)*/
/*                                                  */
/****************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#ifndef EXIT_SUCCESS
#define EXIT_SUCCESS 0
#define EXIT_FAILURE 1
#endif

typedef struct {
   unsigned char year[2]  ;
   unsigned char month[2] ;
   unsigned char day[2]   ;
   unsigned char hour[2]  ;
   unsigned char minute[2] ;
   unsigned char sday[2] ;
   unsigned char sminute[2] ;
}  day_time_part ;

typedef struct {
   unsigned char offF[2] ;
   unsigned char offH[2] ;
   unsigned char offZ[2] ;
   unsigned char offD[2] ; 
}  offset_part ;

typedef struct {
   unsigned char F[2] ;
   unsigned char H[2] ;
   unsigned char Z[2] ;
   unsigned char D[2] ; 
} data_part ;

void Print_Usage(void) ;
void Print_Head(long YEAR, long MM, long DD) ;

/****************************************************/
/*                    MAIN                          */
/****************************************************/

void main(int argc, char *argv[])
{
    FILE *data_fp ;
    char data_fname[80] ;
    int  i ;
    long YYMMDD, YEAR, MM, DD, hhmm, hh, mm ;
    long seek ;
    day_time_part day_time ;
    offset_part   offset ;
    data_part     data ;

    /**** INITIAL SETUP ***/

    if (argc != 4){
      Print_Usage() ;
    }
    if ( strlen( argv[1] ) != 6 ){
      Print_Usage() ;
    }
    if ( strlen( argv[2] ) != 4 ){
      Print_Usage() ;
    }

    YYMMDD = atol(argv[1]) ;
    YEAR   = 1900 + YYMMDD / 10000 ;
    MM     = (YYMMDD % 10000) / 100 ; 
    DD     = YYMMDD % 100 ;
    hhmm   = atol(argv[2]) ;
    hh     = hhmm / 100 ;
    mm     = hhmm % 100 ;  
    sprintf(data_fname, argv[3]) ;

    /*** READ DATA ***/ 

    if ((data_fp = fopen(data_fname, "rb")) == NULL){
      fprintf(stderr, "File \'%s\' could not be opened.\n", data_fname) ;
      exit( EXIT_FAILURE ) ;
    }

    Print_Head(YEAR, MM, DD) ;

    seek = (((DD - 1) * 24  + hh) * 60 + mm) * 512 ;
    fseek(data_fp, seek, SEEK_SET) ;
    fread(&day_time, 14, 1, data_fp);
    fseek(data_fp, 2, SEEK_CUR) ;
    fread(&offset, 8, 1, data_fp) ;
    fseek(data_fp, 8, SEEK_CUR) ;

    if (( (day_time.year[0]*256 + day_time.year[1]) != YEAR) ||
        ( (day_time.month[0]*256 + day_time.month[1]) != MM)){
      fprintf(stderr, "\nWrong File Name.\n\n") ;
       exit( EXIT_FAILURE ) ;
    }
 
    for (i = 0 ; i <= 59 ; i++){
       fread(&data, 8, 1, data_fp) ;
       printf("%2.2hd:%2.2hd:%2.2d  %9.3f  %9.3f  %9.3f  %9.3f\n",
               day_time.hour[0] * 256 + day_time.hour[1],
               day_time.minute[0] * 256 + day_time.minute[1],
               i,
               (offset.offF[0] * 256 + offset.offF[1]) * 10 +
               (data.F[0] * 256 + data.F[1]) * 0.01,  
               (offset.offH[0] * 256 + offset.offH[1]) * 10 +
               (data.H[0] * 256 + data.H[1]) * 0.01,  
               (offset.offZ[0] * 256 + offset.offZ[1]) * 10 +
               (data.Z[0] * 256 + data.Z[1]) * 0.01,  
               (offset.offD[0] * 256 + offset.offD[1]) * 10 +
               (data.D[0] * 256 + data.D[1]) * 0.001) ;  
    } 

    fclose(data_fp) ;
}

/****************************************************/
/*                 Print Usage                      */
/****************************************************/

void Print_Usage()
{ 
    fprintf(stderr, "\nUsage: KAK_read YYMMDD hhmm [fname]\n") ;
    fprintf(stderr,  "(ex)KAK_read 950101 1200 /data/1995/kak9505.sec\n\n") ;
    exit( EXIT_FAILURE ) ;
}

/****************************************************/
/*                 Print Head                       */
/****************************************************/

void Print_Head(long YEAR, long MM, long DD)
{
    printf("\n") ;
    printf("=====================================================\n") ;
    printf("                KAK(1sec) Sample Read\n") ;
    printf("=====================================================\n") ;
    printf("  F  : Total force                       [nanoteslas]\n") ;
    printf("  H  : Horizontal intensity (Northward)  [nanoteslas]\n") ;
    printf("  Z  : Vertical intensity   (Downward)   [nanoteslas]\n")  ;
    printf("  D  : Declination          (Westward)   [minutes]\n")  ;
    printf("\n") ;
    printf(" Day : %4.4ld.%2.2ld.%2.2ld\n", YEAR, MM, DD) ;
    printf("----------------------------------------------------\n") ;
    printf("hh:mm:ss      F          H          Z          D\n") ;
}