// The count of files inside a zip is truncated to fit in a uint16.
	// Gloss over this by reading headers until we encounter
	// a bad one, and then only report an ErrFormat or UnexpectedEOF if
	// the file count modulo 65536 is incorrect.
	for {
		f := &File{zip: r, zipr: rdr}
		err = readDirectoryHeader(f, buf)
		if err == ErrFormat || err == io.ErrUnexpectedEOF {
			break
		}
		if err != nil {
			return err
		}

			} else {
				value /= divisor
			}
		case '%':
			p.next()
			divisor := p.factor()
			if int64(value) < 0 {
				p.errorf("modulo of value with high bit set")
			}
			if divisor == 0 {
				p.errorf("modulo by zero")
			} else {
				value %= divisor
			}
		case lex.LSH:
			p.next()
			shift := p.factor()
			if int64(shift) < 0 {

<h4 id="Integer_overflow">Integer overflow</h4>

<p>
For <a href="#Numeric_types">unsigned integer</a> values, the operations <code>+</code>,
<code>-</code>, <code>*</code>, and <code>&lt;&lt;</code> are
computed modulo 2<sup><i>n</i></sup>, where <i>n</i> is the bit width of
the unsigned integer's type.
Loosely speaking, these unsigned integer operations
discard high bits upon overflow, and programs may rely on "wrap around".
</p>