Need help in understanding a loop

Code:

// Dumps raw memory in hex byte and printable split format
void dump(const unsigned char *data_buffer, const unsigned int length) {
   unsigned char byte;
   unsigned int i, j;
   for(i=0; i < length; i++) {
      byte = data_buffer[i];
      printf("%02x ", data_buffer[i]);  // Display byte in hex.
      if(((i%16)==15) || (i==length-1)) {
         for(j=0; j < 15-(i%16); j++)
            printf("   ");
         printf("| ");
         for(j=(i-(i%16)); j <= i; j++) {  // Display printable bytes from line.
            byte = data_buffer[j];
            if((byte > 31) && (byte < 127)) // Outside printable char range
               printf("%c", byte);
            else
               printf(".");
         }
         printf("\n"); // End of the dump line (each line is 16 bytes)
      } // End if
   } // End for
}

Hey guys i Found this code on the Net somewhere.
What it does it is written on the top of it .

I am facing problems understanding this function :-

Code:

if(((i%16)==15) || (i==length-1)) {
         for(j=0; j < 15-(i%16); j++)
            printf("   ");
         printf("| ");
         for(j=(i-(i%16)); j <= i; j++) {  // Display printable bytes from line.
            byte = data_buffer[j];
            if((byte > 31) && (byte < 127)) // Outside printable char range
               printf("%c", byte);
            else
               printf(".");

I am not getting what is exactly happening in this loop!!!

Need you help guys please explain me this..