Implement value conversions over type parameter

1 files changed, 92 insertions, 0 deletions

diff --git a/src/conversion.rs b/src/conversion.rs
new file mode 100644
index 0000000..20d04c7
--- /dev/null
+++ b/src/conversion.rs
@@ -0,0 +1,92 @@
+
+use { ic, private, Error };
+
+#[doc(hidden)]
+pub trait ConvertThreshold<E> : private::Sealed {
+    fn convert_threshold(value: i16) -> Result<u16, Error<E>>;
+}
+
+impl<E> ConvertThreshold<E> for ic::Resolution12Bit {
+    fn convert_threshold(value: i16) -> Result<u16, Error<E>> {
+        if value < -2048 || value > 2047 {
+            return Err(Error::InvalidInputData);
+        }
+        Ok((value << 4) as u16)
+    }
+}
+
+impl<E> ConvertThreshold<E> for ic::Resolution16Bit {
+    fn convert_threshold(value: i16) -> Result<u16, Error<E>> {
+        Ok(value as u16)
+    }
+}
+
+#[doc(hidden)]
+pub trait ConvertMeasurement : private::Sealed {
+    fn convert_measurement(register_data: u16) -> i16;
+}
+
+impl ConvertMeasurement for ic::Resolution12Bit {
+    fn convert_measurement(register_data: u16) -> i16 {
+        let value = register_data;
+        let is_negative = (value & 0b1000_0000_0000_0000) != 0;
+        if is_negative {
+            let value = 0b1111_0000_0000_0000 | (value >> 4);
+            value as i16
+        }
+        else {
+            (value >> 4) as i16
+        }
+    }
+}
+
+impl ConvertMeasurement for ic::Resolution16Bit {
+    fn convert_measurement(register_data: u16) -> i16 {
+        register_data as i16
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn convert_measurement_12_bits() {
+        assert_eq!(    0, ic::Resolution12Bit::convert_measurement(0));
+        assert_eq!( 2047, ic::Resolution12Bit::convert_measurement(0x7FFF));
+        assert_eq!(-2048, ic::Resolution12Bit::convert_measurement(0x8000));
+        assert_eq!(   -1, ic::Resolution12Bit::convert_measurement(0xFFFF));
+    }
+
+    #[test]
+    fn convert_measurement_16_bits() {
+        assert_eq!(     0, ic::Resolution16Bit::convert_measurement(0));
+        assert_eq!( 32767, ic::Resolution16Bit::convert_measurement(0x7FFF));
+        assert_eq!(-32768, ic::Resolution16Bit::convert_measurement(0x8000));
+        assert_eq!(    -1, ic::Resolution16Bit::convert_measurement(0xFFFF));
+    }
+
+    fn assert_invalid_input_data<E>(result: Result<u16, Error<E>>) {
+        match result {
+            Err(Error::InvalidInputData) => (),
+            _ => panic!("InvalidInputData error was not returned.")
+        }
+    }
+
+    #[test]
+    fn convert_threshold_12_bits() {
+        assert_invalid_input_data::<()>(ic::Resolution12Bit::convert_threshold(2048));
+        assert_invalid_input_data::<()>(ic::Resolution12Bit::convert_threshold(-2049));
+        assert_eq!(     0, <ic::Resolution12Bit as ConvertThreshold<()>>::convert_threshold(0).unwrap());
+        assert_eq!(0x7FF0, <ic::Resolution12Bit as ConvertThreshold<()>>::convert_threshold(2047).unwrap());
+        assert_eq!(0x8000, <ic::Resolution12Bit as ConvertThreshold<()>>::convert_threshold(-2048).unwrap());
+        assert_eq!(0xFFF0, <ic::Resolution12Bit as ConvertThreshold<()>>::convert_threshold(-1).unwrap());
+    }
+
+    #[test]
+    fn convert_threshold_16_bits() {
+        assert_eq!(0x7FFF, <ic::Resolution16Bit as ConvertThreshold<()>>::convert_threshold(32767).unwrap());
+        assert_eq!(0x8000, <ic::Resolution16Bit as ConvertThreshold<()>>::convert_threshold(-32768).unwrap());
+    }
+}