src/util.rs

@@ -1,7 +1,9 @@
 use crate::{ByteConversionError, SizeMissmatch};
-use core::fmt::Debug;
+use core::fmt::{Debug, Display, Formatter};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::error::Error;
 
 pub trait ToBeBytes {
     type ByteArray: AsRef<[u8]>;
@@ -74,6 +76,43 @@ pub trait UnsignedEnum {
 
 pub trait UnsignedEnumExt: UnsignedEnum + Debug + Copy + Clone + PartialEq + Eq {}
 
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum UnsignedByteFieldError {
+    /// Value is too large for specified width of byte field. The first value contains the width,
+    /// the second value contains the detected value.
+    ValueTooLargeForWidth((usize, u64)),
+    /// Only 1, 2, 4 and 8 are allow width values. Optionally contains the expected width if
+    /// applicable, for example for conversions.
+    InvalidWidth(usize, Option<usize>),
+    ByteConversionError(ByteConversionError),
+}
+
+impl From<ByteConversionError> for UnsignedByteFieldError {
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversionError(value)
+    }
+}
+
+impl Display for UnsignedByteFieldError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            Self::ByteConversionError(e) => {
+                write!(f, "low level byte conversion error: {e}")
+            }
+            Self::InvalidWidth(val, _) => {
+                write!(f, "invalid width {val}, only 1, 2, 4 and 8 are allowed.")
+            }
+            Self::ValueTooLargeForWidth((width, value)) => {
+                write!(f, "value {value} too large for width {width}")
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for UnsignedByteFieldError {}
+
 /// Type erased variant.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
@@ -87,30 +126,30 @@ impl UnsignedByteField {
         Self { width, value }
     }
 
-    pub fn new_from_be_bytes(width: usize, buf: &[u8]) -> Result<Self, ByteConversionError> {
+    pub fn new_from_be_bytes(width: usize, buf: &[u8]) -> Result<Self, UnsignedByteFieldError> {
         if width > buf.len() {
             return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
                 found: buf.len(),
                 expected: width,
-            }));
+            })
+            .into());
         }
         match width {
-            0 => Ok(Self::new(0, 0)),
-            1 => Ok(Self::new(1, buf[0] as u64)),
+            0 => Ok(Self::new(width, 0)),
+            1 => Ok(Self::new(width, buf[0] as u64)),
             2 => Ok(Self::new(
-                2,
+                width,
                 u16::from_be_bytes(buf[0..2].try_into().unwrap()) as u64,
             )),
             4 => Ok(Self::new(
-                2,
+                width,
                 u32::from_be_bytes(buf[0..4].try_into().unwrap()) as u64,
             )),
             8 => Ok(Self::new(
-                2,
+                width,
                 u64::from_be_bytes(buf[0..8].try_into().unwrap()),
             )),
-            // TODO: I don't know whether it is a good idea to panic here.
-            _ => panic!("invalid width"),
+            _ => Err(UnsignedByteFieldError::InvalidWidth(width, None)),
         }
     }
 }
@@ -156,18 +195,18 @@ impl UnsignedEnum for UnsignedByteField {
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct GenericUnsignedByteField<TYPE> {
-    val: TYPE,
+    value: TYPE,
 }
 
 impl<TYPE> GenericUnsignedByteField<TYPE> {
     pub fn new(val: TYPE) -> Self {
-        Self { val }
+        Self { value: val }
     }
 }
 
 impl<TYPE: ToBeBytes> UnsignedEnum for GenericUnsignedByteField<TYPE> {
     fn len(&self) -> usize {
-        self.val.written_len()
+        self.value.written_len()
     }
 
     fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<(), ByteConversionError> {
@@ -177,7 +216,7 @@ impl<TYPE: ToBeBytes> UnsignedEnum for GenericUnsignedByteField<TYPE> {
                 expected: self.len(),
             }));
         }
-        buf[0..self.len()].copy_from_slice(self.val.to_be_bytes().as_ref());
+        buf[0..self.len()].copy_from_slice(self.value.to_be_bytes().as_ref());
         Ok(())
     }
 }
@@ -190,16 +229,16 @@ pub type UnsignedU64 = GenericUnsignedByteField<u64>;
 
 impl From<UnsignedU8> for UnsignedByteField {
     fn from(value: UnsignedU8) -> Self {
-        Self::new(1, value.val as u64)
+        Self::new(1, value.value as u64)
     }
 }
 
 impl TryFrom<UnsignedByteField> for UnsignedU8 {
-    type Error = ();
+    type Error = UnsignedByteFieldError;
 
-    fn try_from(value: UnsignedByteField) -> Result<Self, ()> {
-        if value.value > 2_u64.pow(8) - 1 {
-            return Err(());
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 1 {
+            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(1)));
         }
         Ok(Self::new(value.value as u8))
     }
@@ -207,16 +246,16 @@ impl TryFrom<UnsignedByteField> for UnsignedU8 {
 
 impl From<UnsignedU16> for UnsignedByteField {
     fn from(value: UnsignedU16) -> Self {
-        Self::new(2, value.val as u64)
+        Self::new(2, value.value as u64)
     }
 }
 
 impl TryFrom<UnsignedByteField> for UnsignedU16 {
-    type Error = ();
+    type Error = UnsignedByteFieldError;
 
-    fn try_from(value: UnsignedByteField) -> Result<Self, ()> {
-        if value.value > 2_u64.pow(16) - 1 {
-            return Err(());
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 2 {
+            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(2)));
         }
         Ok(Self::new(value.value as u16))
     }
@@ -224,16 +263,16 @@ impl TryFrom<UnsignedByteField> for UnsignedU16 {
 
 impl From<UnsignedU32> for UnsignedByteField {
     fn from(value: UnsignedU32) -> Self {
-        Self::new(4, value.val as u64)
+        Self::new(4, value.value as u64)
     }
 }
 
 impl TryFrom<UnsignedByteField> for UnsignedU32 {
-    type Error = ();
+    type Error = UnsignedByteFieldError;
 
-    fn try_from(value: UnsignedByteField) -> Result<Self, ()> {
-        if value.value > 2_u64.pow(32) - 1 {
-            return Err(());
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 4 {
+            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(4)));
         }
         Ok(Self::new(value.value as u32))
     }
@@ -241,17 +280,277 @@ impl TryFrom<UnsignedByteField> for UnsignedU32 {
 
 impl From<UnsignedU64> for UnsignedByteField {
     fn from(value: UnsignedU64) -> Self {
-        Self::new(8, value.val)
+        Self::new(8, value.value)
     }
 }
 
 impl TryFrom<UnsignedByteField> for UnsignedU64 {
-    type Error = ();
+    type Error = UnsignedByteFieldError;
 
-    fn try_from(value: UnsignedByteField) -> Result<Self, ()> {
-        if value.value > 2_u64.pow(64) - 1 {
-            return Err(());
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 8 {
+            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(8)));
         }
         Ok(Self::new(value.value))
     }
 }
+
+#[cfg(test)]
+pub mod tests {
+    use crate::util::{
+        UnsignedByteField, UnsignedByteFieldError, UnsignedEnum, UnsignedU16, UnsignedU32,
+        UnsignedU64, UnsignedU8,
+    };
+    use std::format;
+
+    #[test]
+    fn test_simple_u8() {
+        let u8 = UnsignedU8::new(5);
+        assert_eq!(u8.len(), 1);
+        let mut buf: [u8; 8] = [0; 8];
+        u8.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(buf[0], 5);
+        for i in 1..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn test_simple_u16() {
+        let u16 = UnsignedU16::new(3823);
+        assert_eq!(u16.len(), 2);
+        let mut buf: [u8; 8] = [0; 8];
+        u16.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u16::from_be_bytes(buf[0..2].try_into().unwrap());
+        assert_eq!(raw_val, 3823);
+        for i in 2..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn test_simple_u32() {
+        let u32 = UnsignedU32::new(80932);
+        assert_eq!(u32.len(), 4);
+        let mut buf: [u8; 8] = [0; 8];
+        u32.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u32::from_be_bytes(buf[0..4].try_into().unwrap());
+        assert_eq!(raw_val, 80932);
+        for i in 4..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn test_simple_u64() {
+        let u64 = UnsignedU64::new(5999999);
+        assert_eq!(u64.len(), 8);
+        let mut buf: [u8; 8] = [0; 8];
+        u64.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u64::from_be_bytes(buf[0..8].try_into().unwrap());
+        assert_eq!(raw_val, 5999999);
+    }
+
+    #[test]
+    fn conversions_u8() {
+        let u8 = UnsignedU8::new(5);
+        let u8_type_erased = UnsignedByteField::from(u8);
+        assert_eq!(u8_type_erased.width, 1);
+        assert_eq!(u8_type_erased.value, 5);
+        let u8_conv_back = UnsignedU8::try_from(u8_type_erased).expect("conversion failed for u8");
+        assert_eq!(u8, u8_conv_back);
+        assert_eq!(u8_conv_back.value, 5);
+    }
+
+    #[test]
+    fn conversion_u8_fails() {
+        let field = UnsignedByteField::new(2, 60000);
+        let conv_fails = UnsignedU8::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
+                assert_eq!(width, 2);
+                assert_eq!(expected, 1);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u16() {
+        let u16 = UnsignedU16::new(64444);
+        let u16_type_erased = UnsignedByteField::from(u16);
+        assert_eq!(u16_type_erased.width, 2);
+        assert_eq!(u16_type_erased.value, 64444);
+        let u16_conv_back =
+            UnsignedU16::try_from(u16_type_erased).expect("conversion failed for u16");
+        assert_eq!(u16, u16_conv_back);
+        assert_eq!(u16_conv_back.value, 64444);
+    }
+
+    #[test]
+    fn conversion_u16_fails() {
+        let field = UnsignedByteField::new(4, 75000);
+        let conv_fails = UnsignedU16::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
+                assert_eq!(width, 4);
+                assert_eq!(expected, 2);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u32() {
+        let u32 = UnsignedU32::new(75000);
+        let u32_type_erased = UnsignedByteField::from(u32);
+        assert_eq!(u32_type_erased.width, 4);
+        assert_eq!(u32_type_erased.value, 75000);
+        let u32_conv_back =
+            UnsignedU32::try_from(u32_type_erased).expect("conversion failed for u32");
+        assert_eq!(u32, u32_conv_back);
+        assert_eq!(u32_conv_back.value, 75000);
+    }
+
+    #[test]
+    fn conversion_u32_fails() {
+        let field = UnsignedByteField::new(8, 75000);
+        let conv_fails = UnsignedU32::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
+                assert_eq!(width, 8);
+                assert_eq!(expected, 4);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u64() {
+        let u64 = UnsignedU64::new(5999999);
+        let u64_type_erased = UnsignedByteField::from(u64);
+        assert_eq!(u64_type_erased.width, 8);
+        assert_eq!(u64_type_erased.value, 5999999);
+        let u64_conv_back =
+            UnsignedU64::try_from(u64_type_erased).expect("conversion failed for u64");
+        assert_eq!(u64, u64_conv_back);
+        assert_eq!(u64_conv_back.value, 5999999);
+    }
+
+    #[test]
+    fn conversion_u64_fails() {
+        let field = UnsignedByteField::new(4, 60000);
+        let conv_fails = UnsignedU64::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
+                assert_eq!(width, 4);
+                assert_eq!(expected, 8);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn type_erased_u8_write() {
+        let u8 = UnsignedByteField::new(1, 5);
+        assert_eq!(u8.len(), 1);
+        let mut buf: [u8; 8] = [0; 8];
+        u8.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(buf[0], 5);
+        for i in 1..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn type_erased_u16_write() {
+        let u16 = UnsignedByteField::new(2, 3823);
+        assert_eq!(u16.len(), 2);
+        let mut buf: [u8; 8] = [0; 8];
+        u16.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u16::from_be_bytes(buf[0..2].try_into().unwrap());
+        assert_eq!(raw_val, 3823);
+        for i in 2..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn type_erased_u32_write() {
+        let u32 = UnsignedByteField::new(4, 80932);
+        assert_eq!(u32.len(), 4);
+        let mut buf: [u8; 8] = [0; 8];
+        u32.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u32::from_be_bytes(buf[0..4].try_into().unwrap());
+        assert_eq!(raw_val, 80932);
+        for i in 4..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn type_erased_u64_write() {
+        let u64 = UnsignedByteField::new(8, 5999999);
+        assert_eq!(u64.len(), 8);
+        let mut buf: [u8; 8] = [0; 8];
+        u64.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u64::from_be_bytes(buf[0..8].try_into().unwrap());
+        assert_eq!(raw_val, 5999999);
+    }
+
+    #[test]
+    fn type_erased_u8_construction() {
+        let buf: [u8; 2] = [5, 10];
+        let u8 = UnsignedByteField::new_from_be_bytes(1, &buf).expect("construction failed");
+        assert_eq!(u8.width, 1);
+        assert_eq!(u8.value, 5);
+    }
+
+    #[test]
+    fn type_erased_u16_construction() {
+        let buf: [u8; 2] = [0x10, 0x15];
+        let u16 = UnsignedByteField::new_from_be_bytes(2, &buf).expect("construction failed");
+        assert_eq!(u16.width, 2);
+        assert_eq!(u16.value, 0x1015);
+    }
+
+    #[test]
+    fn type_erased_u32_construction() {
+        let buf: [u8; 4] = [0x01, 0x02, 0x03, 0x04];
+        let u32 = UnsignedByteField::new_from_be_bytes(4, &buf).expect("construction failed");
+        assert_eq!(u32.width, 4);
+        assert_eq!(u32.value, 0x01020304);
+    }
+
+    #[test]
+    fn type_erased_u64_construction() {
+        let buf: [u8; 8] = [0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08];
+        let u64 = UnsignedByteField::new_from_be_bytes(8, &buf).expect("construction failed");
+        assert_eq!(u64.width, 8);
+        assert_eq!(u64.value, 0x0102030405060708);
+    }
+}