hard to understand code for the representation of tab

[Patrice Dumas]

Hello,

This is not important, but in the info code, in info/util.c in the
printed_representation function, which returns a pointer to string that
is the printed representation of character (or other logical unit) if it
were printed at a given screen column.

l 226 for tab there is a code that I do not understand at all,
  *pchars = ((pl_chars + 8) & 0xf8) - pl_chars;

A bit more context for the variables:
pl_chars: size_t the string column the printed representation of character
   should be printed at
rep: text buffer corresponding to the returned value
pchars: int gets the number of screen columns taken up by the return value
pbytes: int gets the number of bytes in returned string

here is more context for the code:

      else if (*cur_ptr == '\t')
        {
          int i = 0;

          *pchars = ((pl_chars + 8) & 0xf8) - pl_chars;
          *pbytes = *pchars;

          /* We must output spaces instead of the tab because a tab may
             not clear characters already on the screen. */
          for (i = 0; i < *pbytes; i++)
            text_buffer_add_char (rep, ' ');
          return text_buffer_base (rep);
        }

-- 
Pat