#include <malloc.h>
#include <stdio.h>

main()
/******************************************************************/
/* extract_image: This program allows a user to read in a data    */
/*    file written as integer*2, extract a specific portion of    */
/*    that file, and write out the resulting portion.             */ 
/******************************************************************/
{
      FILE *inf, *opf, *fopen();
      static char *cdata,hdr[10000];
      static int *idata;
      static short int *sdata;
      static float *fdata;
      int *ivector();
      short int *isvector();
      char *cvector();
      float *vector();
      short int istat,ival;
      int i,j,k,l,c,nlat,nlon,nbnd,nbmin,nbmax;
      int sl,ss,sb,nl,ns,nb,dtype,dlen,hlen;
      char ans,ans2,s[10];
      char infile[60],outfile[60];

      printf(" Please enter the input file name: ");
      gets(infile);
      while ((inf = fopen(infile,"r")) == NULL) {
        printf(" Error in opening the input file, please try again! \n");
        printf(" Please enter the input file name: ");
        gets(infile);
      }
      printf(" Please enter the data type: (i-int, s-short, c-char, f-float)");
      gets(s);
      if (s[0] == 'i' || s[0] == 'I') {
        dtype = 0;
        dlen = 4;
      }
      else if (s[0] == 's' || s[0] == 'S') {
        dtype = 1;
        dlen = 2;
      }
      else if (s[0] == 'c' || s[0] == 'C') {
        dtype = 2;
        dlen = 1;
      }
      else if (s[0] == 'f' || s[0] == 'F') {
        dtype = 3;
        dlen = 4;
      }
      hlen=0;
      printf(" Please enter the header length (default=0): ");
      gets(s);
      if (s[0] != '\0') hlen = atoi(s);
      printf(" Please enter the number of lines: ");
      gets(s);
      nlat = atoi(s);
      printf(" Please enter the number of pixels per line: ");
      gets(s);
      nlon = atoi(s);
      printf(" Please enter the number of bands: ");
      gets(s);
      nbnd = atoi(s);
      printf(" Please enter the output file name: ");
      gets(outfile);
      while ((opf = fopen(outfile,"w")) == NULL) {
        printf(" Error in opening the output file, please try again! \n");
        printf(" Please enter the output file name: ");
        gets(outfile);
      }
      printf(" Please enter the starting line to extract: ");
      gets(s);
      sl = atoi(s);
      printf(" Please enter the starting sample to extract: ");
      gets(s);
      ss = atoi(s);
      printf(" Please enter the starting band to extract: ");
      gets(s);
      sb = atoi(s);
      printf(" Please enter the number of lines to extract: ");
      gets(s);
      nl = atoi(s);
      printf(" Please enter the number of samples to extract: ");
      gets(s);
      ns = atoi(s);
      printf(" Please enter the number of bands to extract: ");
      gets(s);
      nb = atoi(s);

/**************************/
/*  Allocate data array   */
/**************************/
      if (dtype == 0)
        idata=ivector(nlat*nlon);
      else if (dtype == 1)
        sdata=isvector(nlat*nlon);
      else if (dtype == 2)
        cdata=cvector(nlat*nlon);
      else if (dtype == 3)
        fdata=vector(nlat*nlon);

/****************************/
/*  begin processing        */
/****************************/
      fread(hdr,1,hlen,inf);
      for (l=0; l<nbnd; l++) {
        if (dtype == 0) 
          fread(idata,dlen,nlat*nlon,inf);
        else if (dtype == 1)
          fread(sdata,dlen,nlat*nlon,inf);
        else if (dtype == 2)
          fread(cdata,dlen,nlat*nlon,inf);
        else if (dtype == 3)
          fread(fdata,dlen,nlat*nlon,inf);
        if (l+1 >= sb) {
          if (l+1 > sb+nb-1) exit(1);
          for (j=sl-1; j<sl+nl-1; j++) {
            if (dtype == 0) 
              fwrite(&idata[j*nlon+ss-1],dlen,ns,opf);
            else if (dtype == 1)
              fwrite(&sdata[j*nlon+ss-1],dlen,ns,opf);
            else if (dtype == 2)
              fwrite(&cdata[j*nlon+ss-1],dlen,ns,opf);
            else if (dtype == 3)
              fwrite(&fdata[j*nlon+ss-1],dlen,ns,opf);
          }
        }
      }

} /* End of program */

short wordin (inf,rvptr)
FILE *inf;
short int *rvptr;
{   short int retval;
    short int ateof=0;
    short int c;

    if(inf == NULL || (c=getc(inf))==EOF || (retval = c<<8, c=getc(inf))==EOF) {
        retval = -1L;
        ateof = 1;
    }
    else 
      retval |= c;

    *rvptr = retval;
    return ateof;
}

short wordout (opf,rvptr)
FILE *opf;
short int *rvptr;
{   short int retval;
    short int ateof=0;
    short int c;

    c = (*rvptr>>8)&0xff;
    if (opf != NULL) {
       putc(c,opf);
       c = *rvptr&0xff;
       putc(c,opf);
       retval = 0L; }
    else
       retval = -1L;
    return retval;
}

strcpy(s,t)
char s[],t[];
{
   int i;
   
   i = 0;
   while ((s[i] = t[i]) != '\0') i++;
}

toupper(c)
char c;
{
   if (c >= 'a' && c <= 'z') c = c - 'a' + 'A';
   return c;
}