/****************************************************************************/
/*     program name : RNX2CRX                                               */
/*                                                                          */
/*     RINEX file compression program for UNIX/MS-DOS system.               */
/*     convert the RINEX format to Compact RINEX format                     */
/*     Created by Yuki HATANAKA / Geospatial Information Authority of Japan */
/*                                                                          */
/*     ver.                                                                 */
/*     4.0.0       2007-02-05 test version   Y. Hatanaka                    */
/*                  - CRINEX 1/3 for RINEX 2.x/3.x                          */
/*     4.0.1       2007-05-08                                               */
/*                  - elimination of supports for VMS and SUN OS 4.1.x      */
/*                  - output not to the current directory but the same      */
/*                    directory as the input file.                          */
/*                  - the same code for DOS and UNIX                        */
/*     4.0.2       2007-06-07                                               */
/*                  - fixing incompatibility of argument and format         */
/*                    string of printf.                                     */
/*     4.0.3       2007-06-21                                               */
/*                  - nothing was changed from 4.0.2 except for the         */
/*                    version string to be the same as crx2rnx.c            */
/*     4.0.4       2009-06-31                Y. Hatanaka                    */
/*                  - rename function getline to ggetline                   */
/*                  - correct typos in error messages                       */
/*     4.0.5       2012-07-1x                Y. Hatanaka                    */
/*                  - check length of input file name                       */
/*                  - minor changes to suppress warning messages            */
/*                    at compilation.                                       */
/*                  - initialize "dummy" in main routine                    */
/*     4.0.6       2014-03-24                Y. Hatanaka                    */
/*                  - "include" statements are moved to the top.            */
/*                  - Manipulation of file names in the new file naming     */
/*                    convention (*.rnx/crx) is added.                      */
/*     4.0.7       2016-04-14                Y. Hatanaka                    */
/*                  - increase the following constants                      */
/*                       MAXSAT        90     -> 100                        */
/*                       MAXTYPE       50     -> 100                        */
/*                       MAXCLM        1024   -> 2048                       */
/*                       MAX_BUFF_SIZE 131072 -> 204800                     */
/*     4.0.8       2019-07-12                Y. Hatanaka                    */
/*                  - Correction of a bug which eliminates clock offset     */
/*                    data periodically when used with the option "-e".     */
/*                  - New option "-d" is added to delete input file after   */
/*                    successful conversion.                                */
/*     4.1.0       2021-12-16                Y. Hatanaka                    */
/*                  - RINEX ver.4.xx files are accepted and converted to    */
/*                    Compact RINEX ver. 3 format                           */
/*                  - Following bugs are fixed:                             */
/*                    + Error in case the number of special records exceeds */
/*                      99 in RINEX ver.2 files                             */
/*                    + Error in case clock offset is padded with spaces    */
/*                      in RINEX ver. 3 or 4 files.                         */
/*                    + Error in case a bad GNSS type is detected even if   */
/*                      option -s is specified.                             */
/*                                                                          */
/*     Copyright (c) 2007 Geospatial Information Authority of Japan         */
/*                                                                          */
/****************************************************************************/

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <time.h>

#define VERSION  "ver.4.1.0"

/**** Exit codes are defined here.   ****/
#define EXIT_WARNING 2

#ifndef EXIT_FAILURE
#define EXIT_FAILURE 1
#endif

#ifndef EXIT_SUCCESS
#define EXIT_SUCCESS 0
#endif

/*** define macro to flush or clear the output buffer ***/
#define FLUSH_BUFF printf("%s",top_buff), *(p_buff = top_buff)='\0'
#define CLEAR_BUFF *(p_buff = top_buff) = '\0'

#define CRX_VERSION1 "1.0"    /* CRINEX version for RINEX 2.x */
#define CRX_VERSION2 "3.0"    /* CRINEX version for RINEX 3.x */
#define PROGNAME "RNX2CRX"
#define MAXSAT    100         /* Maximum number of satellites observed at one epoch */
#define MAXTYPE   100         /* Maximum number of data types for a GNSS system */
#define MAXCLM   2048         /* Maximum columns in one line   (>MAXTYPE*19+3)  */
#define MAX_BUFF_SIZE 204800  /* Maximum size of output buffer (>MAXSAT*(MAXTYPE*19+4)+60 */
#define ARC_ORDER 3           /* order of difference to take    */

/* define data structure for fields of clock offset and observation records */
/* Those data will be handled as integers after eliminating decimal points.  */
/* Since their size may exceeds range between LONG_MIN and LONG_MAX,         */
/* they will be read with being divided properly into upper and lower digits */
typedef struct clock_format{
    long u[ARC_ORDER+1];      /* upper X digits */
    long l[ARC_ORDER+1];      /* lower 8 digits (can be 9-10 digits for deltas)*/
} clock_format;

typedef struct data_format{
    long u[ARC_ORDER+1];      /* upper X digits */
    long l[ARC_ORDER+1];      /* lower 5 digits (can be 6-7 digits for deltas) */
    int order;
} data_format;

/* define global variables */
long ep_count = 0;
long ep_reset = 0;
long nl_count = 0;
int rinex_version;          /* =2, 3 or 4 */
int nsat,ntype,ntype_gnss[UCHAR_MAX],ntype_record[MAXSAT],clk_order = -1;
int exit_status = EXIT_SUCCESS;
int skip_strange_epoch = 0; /* default : stop with error */
int delete_if_no_error = 0; /* default : not delete */
int n_infile = 0;           /* number of input file (must be 0 or 1) */

/*
clock_format clk1,clk0 = {0,0,0,0,0,0,0,0};
*/
clock_format clk1,clk0 = {{0,0,0,0},{0,0,0,0}};
data_format dy0[MAXSAT][MAXTYPE], dy1[MAXSAT][MAXTYPE];
char flag0[MAXSAT][MAXTYPE*2], flag[MAXSAT][MAXTYPE*2];
char out_buff[MAX_BUFF_SIZE] = {'x','\0'};  /**** a character is put as a stopper to avoid memory overflow ****/
char *top_buff=&out_buff[1],*p_buff;        /**** therefore, actual buffer start from the second character ****/
char infile[MAXCLM];                        /**** name of input file ****/
size_t C1  = sizeof("");               /* size of one character */
size_t C2  = sizeof(" ");              /* size of 2-character string */
size_t C3  = sizeof("  ");             /* size of 3-character string */
size_t C14 = sizeof("             ");  /* size of 14-character string */

char oldline[MAXCLM] = {'&','\0'};
int nsat_old = 0;

/* declaration of functions */
void parse_args(int argc, char *argv[]);
void header(void);
int  get_next_epoch(char *p_line);
void skip_to_next(char *p_line);
void initialize_all(char *oldline,int *nsat_old, int count);
void put_event_data(char *p_line);
void read_clock(char *line,int shift_cl);
void process_clock(void);
int  set_sat_table(char *p_new, char *p_old, int nsat_old,int *sattbl);
int  read_more_sat(int n, char *p);
void data(int *sattbl);
char *strdiff(char *s1, char *s2, char *ds);
int  ggetline(data_format *py1, char *flag, char *sat_id, int *ntype_rec);
void read_value(char *p, long *pu, long *pl);
void take_diff(data_format *py1, data_format *py0);
void putdiff(long dddu, long dddl);
void put_clock(long du, long dl, int clk_order);
int  read_chk_line(char *line);
void error_exit(int error_no, char *string);
void no_error_exit();

/*---------------------------------------------------------------------*/
int main(int argc, char *argv[]){
    char newline[MAXCLM];
    char dummy[2] = {'\0','\0'};
    char *p,*p_event,*p_nsat,*p_satlst,*p_satold,*p_clock;
    int sattbl[MAXSAT],i,j,shift_clk;
       /* sattbl[i]: order (at the previous epoch) of i-th satellite */
       /* (at the current epoch). -1 is set for the new satellites   */

    parse_args(argc,argv);
    for(i=0;i<UCHAR_MAX;i++) ntype_gnss[i] = -1;  /** -1 unless GNSS type is defined **/
    header();
    if (rinex_version==2){
        p_event  = &newline[28];  /** pointer to event flag **/
        p_nsat   = &newline[29];  /** pointer to n_sat **/
        p_satlst = &newline[32];  /** pointer to satellite list **/
        p_satold = &oldline[32];  /** pointer to n_sat of the previous epoch **/
        p_clock  = &newline[68];  /** pointer to clock offset data **/
        shift_clk = 1;
    }else{
        p_event  = &newline[31];
        p_nsat   = &newline[32];
        p_satlst = &newline[41];
        p_satold = &oldline[41];
        p_clock  = &newline[41];
        shift_clk = 4;
    }

    for(CLEAR_BUFF;;FLUSH_BUFF){
        SKIP:
        if( ! get_next_epoch(newline) ) no_error_exit();

        /*** if event flag > 1, then (1)output event data  */
        /*** (2)initialize all data arcs, and continue to next epoch ***/
        if( atoi(strncpy(dummy,p_event,C1)) > 1) {
            put_event_data(newline);
            initialize_all(oldline,&nsat_old,0);
            continue;
        }

        if( ep_reset > 0 && ++ep_count > ep_reset ) initialize_all(oldline,&nsat_old,1);

        if(strchr(newline,'\0') > p_clock){
            read_clock(p_clock,shift_clk);        /**** read clock offset ****/
        }else{
            clk_order = -1;                       /*** reset data arc for clock offset ***/
        }

        nsat = atoi(p_nsat);
        if(nsat > MAXSAT) error_exit(8,newline);
        if(nsat > 12 && rinex_version == 2) read_more_sat(nsat,p_satlst);  /*** read continuation lines ***/

        /**** get observation ****/
        for(i=0,p=p_satlst ; i<nsat ; i++,p+=3) {
            if( ggetline(dy1[i],flag[i],p,&ntype_record[i]) ) {
                CLEAR_BUFF;
                exit_status = EXIT_WARNING;
                goto SKIP;
            }
        }
        *p = '\0';    /*** terminate satellite list ***/

        if(set_sat_table(p_satlst,p_satold,nsat_old,sattbl) ){
            CLEAR_BUFF;
            exit_status = EXIT_WARNING;
            continue;
        }

        /***********************************************************/
        /**** print change of the line & clock offset difference ****/
        /**** and data difference                               ****/
        /***********************************************************/
        p_buff = strdiff(oldline,newline,p_buff);
        if(clk_order > -1) {
            if(clk_order > 0) process_clock();            /**** process clock offset ****/
            put_clock(clk1.u[clk_order],clk1.l[clk_order],clk_order);
        }else{
            *p_buff++ = '\n';
        }
        data(sattbl); *p_buff = '\0';
        /**************************************/
        /**** save current epoch to buffer ****/
        /**************************************/
        nsat_old = nsat;
        sprintf(oldline,"%s",newline);
        clk0 = clk1;
        for(i=0;i<nsat;i++){
            strcpy(flag0[i],flag[i]);
            for(j=0;j<ntype_record[i];j++) dy0[i][j] = dy1[i][j];
        }
    }
}
/*---------------------------------------------------------------------*/
void parse_args(int argc, char *argv[]){
    char *p,outfile[MAXCLM],*progname;
    int force = 0, help = 0;
    int nfout = 0;  /*** =0 default output file name ***/
                    /*** =1 standard output          ***/
    FILE *ifp;

    progname = argv[0];
    argc--;argv++;
    for(;argc>0;argc--,argv++){
        if((*argv)[0] != '-'){
            strncpy(infile,*argv,C1*MAXCLM);
            n_infile++;
        }else if(strcmp(*argv,"-")   == 0){
            nfout = 1;                 /* output to standard output */
        }else if(strcmp(*argv,"-f")  == 0){
            force = 1;                 /* overwrite if the output file exists */
        }else if(strcmp(*argv,"-d")  == 0){
            delete_if_no_error = 1;    /* delete the original file if 
                                          no error in the conversion */
        }else if(strcmp(*argv,"-s")  == 0){
            skip_strange_epoch = 1;
        }else if(strcmp(*argv,"-e")  == 0){
            argc--;argv++;
            sscanf(*argv,"%ld",&ep_reset);
        }else if(strcmp(*argv,"-h")  == 0){
            help = 1;
        }else{
            help = 1;
        }
    }

    if(strlen(infile) == MAXCLM) error_exit(14,infile);
    if(help == 1 || n_infile > 1 || n_infile < 0) error_exit(1,progname);
    if(n_infile == 0) return;  /*** stdin & stdout will be used if input file name is not given ***/

    /***********************/
    /*** open input file ***/
    /***********************/
    p = strrchr(infile,'.');
    if(p == NULL || *(p+4) != '\0'
                 || ( toupper(*(p+3)) != 'O'
                      && strcmp(p+1,"RNX") != 0
                      && strcmp(p+1,"rnx") != 0 )
    ) error_exit(4,p);

    if((ifp=fopen(infile,"r")) == NULL) error_exit(5,infile);

    /************************/
    /*** open output file ***/
    /************************/
    if(nfout == 0){
        strcpy(outfile,infile);
        p = strrchr(outfile,'.');
        if     (*(p+3) == 'o') { *(p+3) = 'd';}
        else if(*(p+3) == 'O') { *(p+3) = 'D';}
        else if( strcmp(p+1,"rnx") == 0) { strcpy((p+1),"crx");}
        else if( strcmp(p+1,"RNX") == 0) { strcpy((p+1),"CRX");}

        if((freopen(outfile,"r",stdout)) != NULL && force == 0){
            fprintf(stderr,"The file %s already exists. Overwrite?(n)",outfile);
            if(getchar() != 'y') exit(EXIT_SUCCESS);
        }
        freopen(outfile,"w",stdout);
    }
    fclose(ifp);
    freopen(infile,"r",stdin);
}
/*---------------------------------------------------------------------*/
void header(void){
    char line[MAXCLM], line2[41], timestring[20];
    time_t tc = time(NULL);
    struct tm *tp;

    if( (tp = gmtime(&tc)) == NULL) tp = localtime(&tc);
    strftime(timestring, C1*20, "%d-%b-%y %H:%M", tp);

    /*** Check RINEX VERSION / TYPE ***/
    read_chk_line(line);
    if(strncmp(&line[60],"RINEX VERSION / TYPE",C1*20) != 0 ||
       strncmp(&line[20],"O",C1)     != 0 ) error_exit(15,line);

    rinex_version = atoi(line);
    if      ( rinex_version == 2 ){printf("%-20.20s",CRX_VERSION1);}
    else if ( rinex_version == 3 || rinex_version == 4 ){printf("%-20.20s",CRX_VERSION2);}
    else                          {error_exit(15,line);}
    printf("%-40.40s%-20.20s\n","COMPACT RINEX FORMAT","CRINEX VERS   / TYPE");

    sprintf(line2,"%s %s",PROGNAME,VERSION);
    printf("%-40.40s%-20.20sCRINEX PROG / DATE\n",line2,timestring);
    printf("%s\n",line);
    do{
        read_chk_line(line);
        printf("%s\n",line);
        if       (strncmp(&line[60],"# / TYPES OF OBSERV",C1*19) == 0 && line[5] != ' '){
            ntype = atoi(line);                                        /** for RINEX2 **/
        } else if(strncmp(&line[60],"SYS / # / OBS TYPES",C1*19) == 0){ /** for RINEX3 **/
            if (line[0] != ' ') ntype_gnss[(unsigned int)line[0]] = atoi(&line[3]);
            if (ntype_gnss[(unsigned int)line[0]] > MAXTYPE) error_exit(16,line);
        }
    }while( strncmp(&line[60],"END OF HEADER",C1*13) != 0);
}
/*---------------------------------------------------------------------*/
int  get_next_epoch(char *p_line){
/**** find next epoch line.                                                          ****/
/**** If the line seems to be abnormal, print warning message                        ****/
/**** and skip until next epoch is found                                             ****/
/**** return value  0 : end of the file                                              ****/
/****               1 : normal end                                                   ****/
/****               2 : trouble in the line                                          ****/
    char *p;

    nl_count++;
    if( fgets(p_line,MAXCLM,stdin) == NULL ) return 0;  /*** EOF: exit program successfully ***/

    if( (p = strchr(p_line,'\n')) == NULL) {
        if( *p_line == '\032' ) return 0;              /** DOS EOF **/
        if( *p_line != '\0' || feof(stdin) == 0 ) {
             if( ! skip_strange_epoch ) error_exit(12,p_line);
             skip_to_next(p_line);
             return 2;
        }
        fprintf(stderr,"WARNING: null characters are detected at the end of file --> neglected.\n");
        exit_status = EXIT_WARNING;
        return 0;
    }
    if( *(p-1) == '\r' ){*(--p)='\0';};                   /*** remove DOS CR/LF ***/
    while(*--p == ' ' && p>p_line){};*++p = '\0';         /*** chop blank ***/

    if (rinex_version == 2) {
        if( strlen(p_line)<29   || *p_line != ' '
                ||  *(p_line+27) != ' ' || ! isdigit(*(p_line+28))
                || (*(p_line+29) != ' ' && ! isdigit(*(p_line+29)) && *(p_line+29) != '\0') ) {
            /**** ------- something strange is found in the epoch line ****/
            if( ! skip_strange_epoch ) error_exit(6,p_line);
            if(*(p_line+18) != '.')  CLEAR_BUFF;
            skip_to_next(p_line);
            return 2;
        }
    }else{    /* rinex_version == 3 or 4 */
        if( *p_line != '>' ){
            if( ! skip_strange_epoch ) error_exit(6,p_line);
            CLEAR_BUFF;
            skip_to_next(p_line);
            return 2;
        }
        while(p < (p_line+41)) *p++ = ' '; /*** pad blank ***/
        *p = '\0';
    }
    return 1;
}
/*---------------------------------------------------------------------*/
void skip_to_next(char *p_line){
    fprintf(stderr," WARNING at line %ld: strange format. skip to next epoch.\n",nl_count);
    exit_status = EXIT_WARNING;

    if (rinex_version == 2) {
        do {                               /**** try to find next epoch line ****/
            read_chk_line(p_line);
           } while( strlen(p_line) <29 || *p_line!=' ' || *(p_line+3)  != ' ' 
                   || *(p_line+6)  != ' ' || *(p_line+9)  != ' ' 
                   || *(p_line+12) != ' ' || *(p_line+15) != ' '
                   || *(p_line+26) != ' ' || *(p_line+27) != ' ' 
                   || ! isdigit(*(p_line+28)) || ! isspace(*(p_line+29))
                   || (strlen(p_line)>68 && *(p_line+70)!='.') );
    }else{    /*** for RINEX3 ***/
        do {
            read_chk_line(p_line);
        } while( *p_line != '>');
    }
    initialize_all(oldline,&nsat_old,0);             /**** initialize all data ***/
}
/*---------------------------------------------------------------------*/
void initialize_all(char *oldline,int *nsat_old,int count){
    strcpy(oldline,"&");        /**** initialize the epoch data arc ****/
    clk_order = -1;             /**** initialize the clock data arc ****/
    *nsat_old = 0;              /**** initialize the all satellite arcs ****/
    ep_count = count;
}
/*---------------------------------------------------------------------*/
void put_event_data(char *p_line){
/**** This routine is called when event flag >1 is set.  ****/
/****      read # of event information lines and output  ****/
    int i,n;
    char *p;

    if (rinex_version == 2 ) {
        if(*(p_line+26) == '.') error_exit(6,p_line);
        printf("&%s\n",(p_line+1));
        if( strlen(p_line) > 29 ){
            n = atoi((p_line+29));     /** n: number of lines to follow **/
            for(i=0;i<n;i++){
                read_chk_line(p_line);
                printf("%s\n",p_line);
                if(strncmp((p_line+60),"# / TYPES OF OBSERV",C1*19) == 0 && *(p_line+5) != ' ') {
                    *flag[0] = '\0';
                    ntype = atoi(p_line);
                    if (ntype > MAXTYPE) error_exit(16,p_line);
                }
            }
        }
    } else {
        if( strlen(p_line)<35 ||  *(p_line+29) == '.') error_exit(6,p_line);
        /* chop blanks that were padded in get_next_epoch */
        p = strchr(p_line+35,'\0');while(*--p == ' '){};*++p = '\0';
        printf("%s\n",p_line);
        n = atoi((p_line+32));         /** n: number of lines to follow **/
        for(i=0;i<n;i++){
            read_chk_line(p_line);
            printf("%s\n",p_line);
            if(strncmp((p_line+60),"SYS / # / OBS TYPES",C1*19) == 0 && *p_line != ' '){
                *flag[0] = '\0';
                ntype_gnss[(unsigned int)*p_line] = atoi((p_line+3));
                if (ntype_gnss[(unsigned int)*p_line] > MAXTYPE) error_exit(16,p_line);
            }
        }
    }
}
/*---------------------------------------------------------------------*/
void read_clock(char *p_clock,int shift_clk){
/****  read the clock offset value ****/
/**  *p_clock : pointer to beginning of clock data **/
    char *p_dot;      /** pointer for decimal point **/
    p_dot = p_clock + 2;
    if(*p_dot != '.')error_exit(7,p_clock);

    strncpy(p_dot,p_dot+1,C1*shift_clk);  /**** shift digits because of too  ****/
    *(p_dot+shift_clk) = '.';             /**** many digits for fractional part ****/
    sscanf(p_clock,"%ld.%ld",&clk1.u[0],&clk1.l[0]);
    if(*p_clock == '-' || *(p_clock+1) == '-') clk1.l[0] = -clk1.l[0];
    if(clk_order < ARC_ORDER) clk_order++;
    *p_clock = '\0';
}
/*---------------------------------------------------------------------*/
void process_clock(void){
    int i;
    for(i=0;i<clk_order;i++){
        clk1.u[i+1] = clk1.u[i]-clk0.u[i];
        clk1.l[i+1] = clk1.l[i]-clk0.l[i];
    }
}
/*---------------------------------------------------------------------*/
int  set_sat_table(char *p_new, char *p_old, int nsat_old,int *sattbl){
    /**** sattbl : order of the satellites in the previous epoch   ****/
    /**** if *sattbl is set to  -1, the data arc for the satellite ****/
    /**** will be initialized                                      ****/
    int i,j;
    char *ps;

    for (i=0;i< nsat;i++,p_new+=3){
        *sattbl = -1;
        ps = p_old;
        for(j=0;j<nsat_old;j++,ps+=3){
            if(strncmp(p_new,ps,C3) == 0){
                *sattbl = j;
                break;
            }
        }
        /*** check double entry ***/
        for(j=i+1,ps=p_new+3 ; j<nsat ; j++,ps+=3){
            if(strncmp(p_new,ps,C3) == 0){
                if( ! skip_strange_epoch ) error_exit(13,p_new);
                fprintf(stderr,"WARNING:Duplicated satellite in one epoch at line %ld. ... skip\n",nl_count);
                return 1;
            }
        }
        sattbl++;
    }
    return 0;
}
/*---------------------------------------------------------------------*/
int  read_more_sat(int n, char *p){
/**** read continuation line of satellite list (for RINEX2) ****/
    char line[MAXCLM];
    
    do {
        p += 36;
        if( read_chk_line(line) ) return 1;
         /**** append satellite table ****/
        if(line[2] == ' '){
            sprintf(p,"%s",&line[32]);
        }else{                        /*** for the files before clarification of format ***/
            sprintf(p,"%s",&line[0]); /*** by W.Gurtner (IGS mail #1577)                ***/
        }
        n -= 12;
    } while(n>12);
    return 0;
}
/*---------------------------------------------------------------------*/
void data(int *sattbl){
/********************************************************************/
/*  Function : output the 3rd order difference of data              */
/*       u : upper X digits of the data                             */
/*       l : lower 5 digits of the data                             */
/*            ( y = u*100 + l/1000 )                                */
/*   py->u : upper digits of the 3rd order difference of the data   */
/*   py->l : lower digits of the 3rd order difference of the data   */
/********************************************************************/
    data_format *py1;
    int  i,j,*i0;
    char *p;

    for(i=0,i0 = sattbl ; i<nsat ; i++,i0++){
        for(j=0,py1=dy1[i] ; j<ntype_record[i] ; j++,py1++){
            if( py1->order >= 0 ){       /*** if the numerical data field is non-blank ***/
                if(*i0 < 0 || dy0[*i0][j].order == -1){
                    /**** initialize the data arc ****/
                    py1->order = 0; p_buff += sprintf(p_buff,"%d&",ARC_ORDER);
                }else{
                    take_diff(py1,&(dy0[*i0][j]));
                    if(labs( py1->u[py1->order]) > 100000){
                        /**** initialization of the arc for large cycle slip  ****/
                        py1->order = 0; p_buff += sprintf(p_buff,"%d&",ARC_ORDER);
                    }
                }
                putdiff(py1->u[py1->order],py1->l[py1->order]);
            }else if(*i0 >= 0 && rinex_version == 2){
                /**** CRINEX1 (RINEX2) initialize flags for blank field, not put '&' ****/
                flag0[*i0][j*2] = flag0[*i0][j*2+1] = ' ';
            }
            if(j < ntype_record[i]-1) *p_buff++ = ' ';   /** ' ' :field separator **/
        }
        *(p_buff++) = ' ';  /* write field separator */
        if(*i0 < 0){             /* if new satellite initialize all LLI & SN flags */
            if(rinex_version == 2){
                p_buff = strdiff("",    flag[i],p_buff);
            }else{          /*  replace space with '&' for CRINEX3(RINEX3)  */
                for(p=flag[i]; *p != '\0' ; p++) *p_buff++ = (*p == ' ')? '&':*p;
                *p_buff++ = '\n'; *p_buff = '\0';
            }
        }else{
            p_buff = strdiff(flag0[*i0],flag[i],p_buff);
        }
    }
}
/*---------------------------------------------------------------------*/
char *strdiff(char *s1, char *s2, char *ds){
/********************************************************************/
/**   copy only the difference of string s2 from string s1         **/
/**   '&' is marked when some character changed to a space         **/
/**   trailing blank is eliminated and '/n' is added               **/
/********************************************************************/
    for(; *s1 != '\0'  && *s2 != '\0' ; s2++){
        if(*s2 == *(s1++))
            *ds++ = ' ';
        else if(*s2 == ' ')
            *ds++ = '&';
        else
            *ds++ = *s2;
    }
    strcpy(ds,s1);
    for(;*ds;ds++){ if(*ds != ' ') *ds = '&'; }
    while(*s2) *ds++ = *s2++;

    for(ds-- ; *ds == ' ' ; ds--);    /*** find pointer of last non-space character ***/
    *++ds = '\n'; *++ds = '\0';       /*** chop spaces at the end of the line ***/
    return ds;
}
/*---------------------------------------------------------------------*/
int  ggetline(data_format *py1, char *flag, char *sat_id, int *ntype_rec){
/**** read data line for one satellite and       ****/
/**** set data difference and flags to variables ****/
    char line[MAXCLM],*p,*pmax,*p_1st_rec;
    int i,j,nfield,max_field;

    if( read_chk_line(line) ) return 1;
    if(rinex_version == 2 ) {             /** for RINEX2 **/
        max_field = 5;                             /** maximum data types in one line **/
        *ntype_rec = ntype;                        /** # of data types for the satellite **/
        p_1st_rec = line;                          /** pointer to the start of the first record **/
    }else{                                /** for RINEX3 **/
        strncpy(sat_id,line,C3);                   /** put satellite ID to the list of satellites **/
        max_field = *ntype_rec = ntype_gnss[(unsigned int)line[0]];  /*** # of data types for the GNSS system ***/
        if(max_field<0) {
           if( ! skip_strange_epoch ) error_exit(21,line);
           fprintf(stderr,"WARNING at line %ld. : GNSS type '%c' is not defined in the header. ... skip\n",nl_count,(unsigned int)line[0]);
           return 1;
        }
        p_1st_rec = line+3;
    }
    for(i=0;i<*ntype_rec;i+=max_field){                 /* for each line */
        nfield = (*ntype_rec-i < max_field ? *ntype_rec-i:max_field); /*** expected # of data fields in the line ***/
        pmax = p_1st_rec + 16*nfield;

        /*** Cut or pad spaces. Detect error if there is any character after *pmax ***/
        p = strchr(line,'\0');
        if(p < pmax ) {
            while(p<pmax) *p++ = ' ';*p='\0';
        }else{
	    for(*p = ' ' ; p > pmax && *p == ' ' ; p--){};
            if(p > pmax) {
                if( ! skip_strange_epoch ) error_exit(9,line);
                fprintf(stderr,"WARNING: mismatch of number of the data types at line %ld. ... skip\n",nl_count);
                return 1;
            }
        }

        /*** parse the line (read value into py1) ***/
        for(j=0,p=p_1st_rec; j<nfield; j++,p+=16,py1++){
            if( *(p+10) == '.' ){
                *flag++ = *(p+14);
                *flag++ = *(p+15);
                *(p+14) = '\0';
                read_value(p,&(py1->u[0]),&(py1->l[0]));
                py1->order = 0;
            }else if( strncmp(p,"              ",C14) == 0 ){
                if( rinex_version == 2 && strncmp((p+14),"  ",C2) != 0 ) error_exit(20,line);
                *flag++ = *(p+14);
                *flag++ = *(p+15);
                py1->order = -1;
            }else{
                if( ! skip_strange_epoch ) error_exit(10,p);
                fprintf(stderr,"WARNING: abnormal data field at line %ld....skip\n",nl_count);
                return 1;
            }
        }
        if(i+max_field < *ntype_rec){
            if( read_chk_line(line) ) return 1;   /* read continuation line */
        }
    }
    *flag = '\0';
    return 0;
}
/*---------------------------------------------------------------------*/
void read_value(char *p, long *pu, long *pl){
/**** divide the data into lower 5 digits and upper digits     ****/
/**** input p :  pointer to one record (14 characters + '\0')  ****/
/**** output  *pu, *pl: upper and lower digits the data        ****/

    char *p7,*p8,*p9;
    p7 = p +7;
    p8 = p7+1;
    p9 = p8+1;

    *(p9+1) = *p9;            /* shift two digits: ex. 123.456 -> 1223456,  -.345 ->   -345 */
    *p9 = *p8;                /*                       -12.345 -> -112345, -1.234 -> --1234 */
    *pl = atol(p9);           /*                         0.123 ->  . 0123, -0.123 -> --0123 */
    
    if(*p7 == ' '){
        *pu = 0;
    }else if(*p7 == '-'){
        *pu = 0;
        *pl = -*pl;
    }else{
        *p8 = '.';
        *pu = atol(p);
        if(*pu < 0) *pl = -*pl;
    }
}
/*---------------------------------------------------------------------*/
void take_diff(data_format *py1, data_format *py0){
    int k;

    py1->order = py0->order;
    if(py1->order < ARC_ORDER) (py1->order)++;
    if(py1->order > 0){
        for(k=0;k<py1->order;k++){
            py1->u[k+1] = py1->u[k] - py0->u[k];
            py1->l[k+1] = py1->l[k] - py0->l[k];
        }
    }
}
/*---------------------------------------------------------------------*/
void putdiff(long dddu, long dddl){

    dddu += dddl/100000 ; dddl %= 100000;
    if(dddu<0 && dddl>0){
        dddu++ ; dddl -= 100000;
    }else if(dddu>0 && dddl<0){
       	dddu-- ; dddl += 100000;
    }

    if(dddu == 0){
        p_buff += sprintf(p_buff,"%ld",dddl);
    }else{
        p_buff += sprintf(p_buff,"%ld%5.5ld",dddu,labs(dddl));
    }
}
/*---------------------------------------------------------------------*/
void put_clock(long du, long dl, int c_order){
/***********************************/
/****  output clock diff. data  ****/
/***********************************/
    du += dl/100000000 ; dl %= 100000000;
    if(du<0 && dl>0){
        du++ ; dl -= 100000000;
    }else if(du>0 && dl<0){
        du-- ; dl += 100000000;
    }
    if(c_order == 0) p_buff += sprintf(p_buff,"%d&",ARC_ORDER);
    if(du == 0){
        p_buff += sprintf(p_buff,"%ld\n",dl);
    }else{
        p_buff += sprintf(p_buff,"%ld%8.8ld\n",du,labs(dl));
    }
}
/*---------------------------------------------------------------------*/
int  read_chk_line(char *line){
    char *p;
/***************************************/
/* Read and check one line.            */
/* The end of the line should be '\n'. */
/***************************************/
    nl_count++;
    if( fgets(line,MAXCLM,stdin) == NULL ) error_exit(11,line);
    if( (p = strchr(line,'\n')) == NULL) {
        if( fgetc(stdin) == EOF ) {
            error_exit(11,line);
        }else{
            if( ! skip_strange_epoch ) error_exit(12,line);
            fprintf(stderr,"WARNING: null character is found or the line is too long (>%d) at line %ld.\n",MAXCLM,nl_count);
            return 1;
        }
    }
    if( *(p-1) == '\r' )p--;   /*** check DOS CR/LF ***/
    while(*--p == ' ' && p>line){}; *++p = '\0';   /** Chop blank **/
    return 0;
}
/*---------------------------------------------------------------------*/
void error_exit(int error_no, char *string){
    if(error_no == 1 ){
        fprintf(stderr,"Usage: %s [file] [-] [-f] [-e # of epochs] [-s] [-d] [-h]\n",string);
        fprintf(stderr,"    stdin and stdout are used if input file name is not given.\n");
        fprintf(stderr,"    -       : output to stdout\n");
        fprintf(stderr,"    -f      : force overwrite of output file\n");
        fprintf(stderr,"    -e #    : initialize the compression operation at every # epochs\n");
        fprintf(stderr,"              When some part of the Compact RINEX file is lost, the data\n");
        fprintf(stderr,"              can not be recovered thereafter until all the data arc are\n");
        fprintf(stderr,"              initialized for differential operation. This option may be used to\n");
        fprintf(stderr,"              increase chances to recover parts of data by using an option of\n");
        fprintf(stderr,"              CRX2RNX(ver. 4.0 or after) with cost of increase of file size.\n");
        fprintf(stderr,"    -s      : warn and skip strange epochs (default: stop with error status)\n");
        fprintf(stderr,"    -d      : delete the input file if conversion finishes without errors\n");
        fprintf(stderr,"              (i.e. exit code = %d or %d).\n",EXIT_SUCCESS,EXIT_WARNING);
        fprintf(stderr,"              This option does nothing if stdin is used for the input.\n");
        fprintf(stderr,"    -h      : display this message\n\n");
        fprintf(stderr,"    exit code = %d (success)\n",EXIT_SUCCESS);
        fprintf(stderr,"              = %d (error)\n",  EXIT_FAILURE);
        fprintf(stderr,"              = %d (warning)\n",EXIT_WARNING);
        fprintf(stderr,"    [version : %s]\n",VERSION);
        exit(EXIT_FAILURE);
    }
    if(error_no == 4 ){
        fprintf(stderr,"ERROR : invalid file name  %s\n",string);
        fprintf(stderr,"The extension of the input file name should be [.??o] or [.rnx].\n");
        fprintf(stderr,"To convert the files whose name is not fit to the above conventions,\n");
        fprintf(stderr,"use of this program as a filter is also possible. \n");
        fprintf(stderr,"    for example)  cat file.in | %s - > file.out\n",PROGNAME);
        exit(EXIT_FAILURE);
    }
    if(error_no == 5 ){
        fprintf(stderr,"ERROR : can't open %s\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 6 ){
        fprintf(stderr,"ERROR when reading line %ld.\n",nl_count);
        fprintf(stderr,"     start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 7 ){
        fprintf(stderr,"ERROR at line %ld: invalid format for clock offset.\n",nl_count);
        fprintf(stderr,"     start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 8 ){
        fprintf(stderr,"ERROR at line %ld : number of satellites exceed the maximum(%d).\n",nl_count,MAXSAT);
        fprintf(stderr,"     start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 9 ){
        fprintf(stderr,"ERROR at line %ld : mismatch of number of the data types.\n",nl_count);
        fprintf(stderr,"     start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 10){
        fprintf(stderr,"ERROR at line %ld : abnormal data field.\n",nl_count);
        fprintf(stderr,"     start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 11){
        fprintf(stderr,"ERROR : The RINEX file seems to be truncated in the middle.\n");
        fprintf(stderr,"        The conversion is interrupted after reading line %ld :\n",nl_count);
        fprintf(stderr,"        start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 12 ){
        fprintf(stderr,"ERROR at line %ld. : null character is found or the line is too long (>%d).\n",nl_count,MAXCLM);
        fprintf(stderr,"     start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 13 ){
        fprintf(stderr,"ERROR at line %ld. : Duplicated satellite in one epoch.\n",nl_count);
        fprintf(stderr,"     start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 14 ){
        fprintf(stderr,"ERROR at line %ld. : Length of file name exceed MAXCLM(%d).\n",nl_count,MAXCLM);
        fprintf(stderr,"     start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 15 ){
        fprintf(stderr,"The first line is :\n%s\n\n",string);
        fprintf(stderr,"ERROR : The file format is not valid. This program is applicable\n");
        fprintf(stderr,"        only to RINEX Version 2/3/4 Observation file.\n");
        exit(EXIT_FAILURE);
    }
    if(error_no == 16 ){
        fprintf(stderr,"ERROR at line %ld. : Number of data types exceed MAXTYPE(%d).\n",nl_count,MAXTYPE);
        fprintf(stderr,"     start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 20 ){
        fprintf(stderr,"ERROR at line %ld. : data is blank but there is flag.\n",nl_count);
        fprintf(stderr,"     start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
    if(error_no == 21 ){
        fprintf(stderr,"ERROR at line %ld. : GNSS type '%c' is not defined in the header.\n",nl_count,(unsigned int)string[0]);
        fprintf(stderr,"     start>%s<end\n",string);
        exit(EXIT_FAILURE);
    }
}
/*---------------------------------------------------------------------*/
void no_error_exit() {
    if (delete_if_no_error && exit_status != 2 && n_infile == 1)  remove(infile);
    exit(exit_status);
}