Merge pull request #3 from gavincabbage/gavincabbage-readbytes

Gavincabbage readbytes

controller/hd44780/hd44780_test.go

@@ -131,6 +131,7 @@ type mockI2CBus struct {
 	closed bool
 }
 
+func (bus *mockI2CBus) ReadBytes(addr byte, num int) ([]byte, error)      { return []byte{0x00}, nil }
 func (bus *mockI2CBus) ReadByte(addr byte) (byte, error)                  { return 0x00, nil }
 func (bus *mockI2CBus) WriteBytes(addr byte, value []byte) error          { return nil }
 func (bus *mockI2CBus) ReadFromReg(addr, reg byte, value []byte) error    { return nil }

host/generic/i2cbus.go

@@ -101,6 +101,28 @@ func (b *i2cBus) ReadByte(addr byte) (byte, error) {
 	return bytes[0], nil
 }
 
+func (b *i2cBus) ReadBytes(addr byte, num int) ([]byte, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if err := b.init(); err != nil {
+		return []byte{0}, err
+	}
+
+	if err := b.setAddress(addr); err != nil {
+		return []byte{0}, err
+	}
+
+	bytes := make([]byte, num)
+	n, _ := b.file.Read(bytes)
+
+	if n != num {
+		return []byte{0}, fmt.Errorf("i2c: Unexpected number (%v) of bytes read", n)
+	}
+
+	return bytes, nil
+}
+
 func (b *i2cBus) WriteByte(addr, value byte) error {
 	b.mu.Lock()
 	defer b.mu.Unlock()

i2c.go

@@ -6,6 +6,8 @@ package embd
 type I2CBus interface {
 	// ReadByte reads a byte from the given address.
 	ReadByte(addr byte) (value byte, err error)
+	// ReadBytes reads a slice of bytes from the given address.
+	ReadBytes(addr byte, num int) (value []byte, err error)
 	// WriteByte writes a byte to the given address.
 	WriteByte(addr, value byte) error
 	// WriteBytes writes a slice bytes to the given address.