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device8.go
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device8.go
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package tester
// I2CDevice represents a mock I2C device on a mock I2C bus with 8-bit registers.
type I2CDevice8 struct {
c Failer
// addr is the i2c device address.
addr uint8
// Registers holds the device registers. It can be inspected
// or changed as desired for testing.
Registers [MaxRegisters]uint8
// If Err is non-nil, it will be returned as the error from the
// I2C methods.
Err error
}
// NewI2CDevice returns a new mock I2C device.
//
// For compatibility, this creates an instance of NewI2CDevice8
func NewI2CDevice(c Failer, addr uint8) *I2CDevice8 {
return NewI2CDevice8(c, addr)
}
// NewI2CDevice8 returns a new mock I2C device.
func NewI2CDevice8(c Failer, addr uint8) *I2CDevice8 {
return &I2CDevice8{
c: c,
addr: addr,
}
}
// Addr returns the Device address.
func (d *I2CDevice8) Addr() uint8 {
return d.addr
}
// ReadRegister implements I2C.ReadRegister.
func (d *I2CDevice8) readRegister(r uint8, buf []byte) error {
if d.Err != nil {
return d.Err
}
if len(buf) == 0 {
d.c.Fatalf("no register buffer to read into")
}
d.assertRegisterRange(r, buf)
copy(buf, d.Registers[r:])
return nil
}
// WriteRegister implements I2C.WriteRegister.
func (d *I2CDevice8) writeRegister(r uint8, buf []byte) error {
if d.Err != nil {
return d.Err
}
d.assertRegisterRange(r, buf)
copy(d.Registers[r:], buf)
return nil
}
// Tx implements I2C.Tx.
func (bus *I2CDevice8) Tx(w, r []byte) error {
switch len(w) {
case 0:
bus.c.Fatalf("i2c mock: need a write byte")
return nil
case 1:
return bus.readRegister(w[0], r)
default:
if len(r) > 0 || len(w) == 1 {
bus.c.Fatalf("i2c mock: unsupported lengths in Tx(%d, %d)", len(w), len(r))
}
return bus.writeRegister(w[0], w[1:])
}
}
// assertRegisterRange asserts that reading or writing the given
// register and subsequent registers is in range of the available registers.
func (d *I2CDevice8) assertRegisterRange(r uint8, buf []byte) {
if int(r) >= len(d.Registers) {
d.c.Fatalf("register read/write [%#x, %#x] start out of range", r, int(r)+len(buf))
}
if int(r)+len(buf) > len(d.Registers) {
d.c.Fatalf("register read/write [%#x, %#x] end out of range", r, int(r)+len(buf))
}
}