even-bytes

even-bytes.c

#!/usr/bin/env C -m
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

void even_bytes(const int bytes)
{
  int c;
  do
  {
    for (int i = 0; i < bytes; i++)
    {
      c = fgetc(stdin);
      if (feof(stdin))
      {
        goto done;
      }
      fputc(c, stdout);
    }
    for (int i = 0; i < bytes; i++)
    {
      c = fgetc(stdin);
      if (feof(stdin))
      {
        goto done;
      }
    }
  }
  while (c != EOF);
done:
  fclose(stdout);
}

void usage()
{
  printf("Usage: even-bytes\n");
  printf("  even-bytes <bytes per> < in > out\n");
}

int main(int argc, char **argv)
{
  int bytes = 1;

  if (argc > 1) {
    bytes = atoi(argv[1]);
  }

  if (argc < 1)
  {
    usage();
    return 0;
  }
  even_bytes(bytes);

  return 0;
}