#include <stdio.h>

void PrintUsage(void)
{
 printf("
 FolderChg Tool
 By Malcolm Smith

 Takes a calculator variable on the PC
 and changes the folder it will download
 into on the calculator.

 USAGE:
 folderchg infile outfile foldername [description]
 infile = Input filename
 outfile = Output filename
 foldername = Desired calculator folder name
 description = Description string, up to 40 characters.
 ");
}

int main(int argc, char *argv[])
{
FILE *in,*out;
long a;
char temp;
long total;
char description[40]={' '};
char folder[8]={' '};

  if(argc!=5 && argc!=4)
  {PrintUsage();return;}
  if(!strcmp(argv[1],argv[2]))
  {
   printf("Error: Input and output filenames must be different.\n");
   PrintUsage();
   return;
  }

  if(argc==5)
  {
   strncpy(description,argv[4],40);
  }

  strncpy(folder,argv[3],8);

in = fopen(argv[1],"rb");
out = fopen(argv[2],"wb");

if(!in || !out) return;

total=0;
while(!feof(in))
{
 fgetc(in);
 total++;
}
rewind(in);
total -= (10+8+40);

for(a=0;a<10;a++)     //8=calc signature, 2=magic hex code
{
 temp = fgetc(in);
 fputc(temp,out);
}
for(a=0;a<8;a++) //folder name
{
 fgetc(in);
 fputc(folder[a],out);
}
for(a=0;a<40;a++) //description string
{
 temp = fgetc(in);
 if(argc!=5)
 description[a] = temp;
 fputc(description[a],out);
}

for(a=0;a<total-1;a++)
{
 temp = fgetc(in);
 fputc(temp,out);
}



fclose(in);
fclose(out);
  return 0;
}