status-go/vendor/github.com/libp2p/go-msgio/num.go

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package msgio
import (
"encoding/binary"
"io"
)
// NBO is NetworkByteOrder
var NBO = binary.BigEndian
// WriteLen writes a length to the given writer.
func WriteLen(w io.Writer, l int) error {
ul := uint32(l)
return binary.Write(w, NBO, &ul)
}
// ReadLen reads a length from the given reader.
// if buf is non-nil, it reuses the buffer. Ex:
// l, err := ReadLen(r, nil)
// _, err := ReadLen(r, buf)
func ReadLen(r io.Reader, buf []byte) (int, error) {
if len(buf) < 4 {
buf = make([]byte, 4)
}
buf = buf[:4]
if _, err := io.ReadFull(r, buf); err != nil {
return 0, err
}
n := int(NBO.Uint32(buf))
return n, nil
}