newdup.c

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

#define INPUT "Rgn02.txt"
#define WIDTH 8 /* 6 bytes + CRLF */

unsigned char there[(2<<15)*16*16*2];
static inline int num(unsigned char *reg)
{
  register unsigned int val =
    (reg[0]&31) |
    ((reg[1]&31)<<5) |
    ((reg[2]&31)<<10) |
    ((reg[3]&15)<<15) |
    ((reg[4]&15)<<19) |
    ((reg[5]&15)<<23);

  return there[(unsigned int)val>>3] ^= (1<< (val & 7));
}

int main(void)
{
  struct stat st;
  if(!stat(INPUT, &st)) {
    off_t size = st.st_size;
    char *data = malloc(size+1);
    FILE *f = fopen(INPUT, "rb");
    if(f) {
      if(size == fread(data, 1, size, f)) {
        int fields = size/WIDTH;
        int i;
        for(i=0; i<fields; i++) {
          if(!num(&data[i*WIDTH])) {
            printf("%u\n", i);
          }
        }
      }
      fclose(f);
    }
  }
  return 0;
}