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device.go
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device.go
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package i2c
import "github.com/mastercactapus/embedded/serial"
type Bus interface {
Tx(addr uint16, w, r []byte) error
}
type Device struct {
bus Bus
addr uint16
}
var _ serial.Transmitter = (*Device)(nil)
type WriterTo interface {
WriteTo([]byte, uint16) (int, error)
}
type ReaderFrom interface {
ReadFrom([]byte, uint16) (int, error)
}
type (
ByteWriterTo interface{ WriteByteTo(byte, uint16) error }
ByteReaderFrom interface{ ReadByteFrom(uint16) (byte, error) }
)
// NewDevice returns a new Device with the given bus and address.
func NewDevice(bus Bus, addr uint16) *Device {
return &Device{bus: bus, addr: addr}
}
// Tx is a convenience method that sends a write and read request to the device,
// it uses a reapeated START contidition meaning the bus is not released
// between the two calls. Otherwise it is the same as calling Write then Read.
func (d *Device) Tx(w, r []byte) (err error) {
return d.bus.Tx(d.addr, w, r)
}
func (d *Device) Write(w []byte) (int, error) {
if wt, ok := d.bus.(WriterTo); ok {
return wt.WriteTo(w, d.addr)
}
err := d.bus.Tx(d.addr, w, nil)
if err != nil {
return 0, err
}
return len(w), nil
}
func (d *Device) Read(r []byte) (int, error) {
if rf, ok := d.bus.(ReaderFrom); ok {
return rf.ReadFrom(r, d.addr)
}
err := d.bus.Tx(d.addr, nil, r)
if err != nil {
return 0, err
}
return len(r), nil
}
func (d *Device) WriteByte(b byte) error {
if w, ok := d.bus.(ByteWriterTo); ok {
return w.WriteByteTo(b, d.addr)
}
_, err := d.Write([]byte{b})
return err
}
func (d *Device) ReadByte() (byte, error) {
if r, ok := d.bus.(ByteReaderFrom); ok {
return r.ReadByteFrom(d.addr)
}
var b [1]byte
_, err := d.Read(b[:])
return b[0], err
}