source: vendor/gcc/3.3.4/libf2c/libI77/uio.c

#include "config.h"
#include "f2c.h"
#include "fio.h"
#include <sys/types.h>
uiolen f__reclen;

int
do_us (ftnint * number, char *ptr, ftnlen len)
{
  if (f__reading)
    {
      f__recpos += (int) (*number * len);
      if (f__recpos > f__reclen)
        err (f__elist->cierr, 110, "do_us");
      if (fread (ptr, (size_t) len, (size_t) (*number), f__cf) != (size_t) *number)
        err (f__elist->ciend, EOF, "do_us");
      return (0);
    }
  else
    {
      f__reclen += *number * len;
      (void) fwrite (ptr, (size_t) len, (size_t) (*number), f__cf);
      return (0);
    }
}
integer
do_ud (ftnint * number, char *ptr, ftnlen len)
{
  f__recpos += (int) (*number * len);
  if (f__recpos > f__curunit->url && f__curunit->url != 1)
    err (f__elist->cierr, 110, "do_ud");
  if (f__reading)
    {
#ifdef Pad_UDread
      size_t i;
      if (!(i = fread (ptr, (size_t) len, (size_t) (*number), f__cf))
          && !(f__recpos - *number * len))
        err (f__elist->cierr, EOF, "do_ud");
      if (i < (size_t) *number)
        memset (ptr + i * len, 0, (*number - i) * len);
      return 0;
#else
      if (fread (ptr, (size_t) len, (size_t) (*number), f__cf) != *number)
        err (f__elist->cierr, EOF, "do_ud");
      else
        return (0);
#endif
    }
  (void) fwrite (ptr, (size_t) len, (size_t) (*number), f__cf);
  return (0);
}

integer
do_uio (ftnint * number, char *ptr, ftnlen len)
{
  if (f__sequential)
    return (do_us (number, ptr, len));
  else
    return (do_ud (number, ptr, len));
}