add read/write features to Field

src/utils/field.rs

@@ -1,5 +1,7 @@
 //! Implement the Field structure.
 
+use core::ptr::{read_volatile, write_volatile};
+
 /// Structure representing the location of a register.
 /// This structure does not provide any kind of safety, it
 /// is only descriptif.
@@ -23,7 +25,6 @@ pub struct Field {
     mask: u32
 }
 
-// TODO: test
 impl Field {
     /// Constructor for a Field.
     /// The field is defined by the `size` bits at `offset` bits after
@@ -65,7 +66,6 @@ impl Field {
     }
 
     /// Return the offset of the field in relation to the address, in bits.
-    #[allow(dead_code)]
     pub const fn get_offset(&self) -> usize {
         self.offset
     }
@@ -80,6 +80,39 @@ impl Field {
     pub const fn get_mask(&self) -> u32 {
         self.mask
     }
+
+    /// Set the value of the field in the provided u32.
+    #[inline]
+    pub fn read_and_write_to_u32(&self, val: u32, register: u32) -> u32 {
+        assert_eq!(val & !(self.mask >> self.offset), 0, "Value greater than the field");
+        register & !self.mask | (val << self.offset)
+    }
+
+    /// Get the value of the field from the provided u32.
+    #[inline]
+    pub fn read_from_u32(&self, register: u32) -> u32 {
+        (register & self.mask) >> self.offset
+    }
+
+    /// Write the value in memory.
+    pub fn read_and_write(&self, val: u32) {
+        let register = unsafe { read_volatile(self.address as *mut u32) };
+        let register = self.read_and_write_to_u32(val, register);
+        unsafe { write_volatile(self.address as *mut u32, register) };
+    }
+
+    /// Write the value in memory but override every other value of the 
+    /// u32 (replace them by 0s).
+    pub fn write_without_read(&self, val: u32) {
+        let register = self.read_and_write_to_u32(val, 0);
+        unsafe { write_volatile(self.address as *mut u32, register) };
+    }
+
+    /// Read the value from memory.
+    pub fn read(&self) -> u32 {
+        let register = unsafe { read_volatile(self.address as *mut u32) };
+        self.read_from_u32(register)
+    }
 }
 
 #[cfg(test)]
@@ -87,8 +120,114 @@ mod test {
     use super::*;
 
     #[test]
-    fn test() {
-        let f = Field::new(0, 0, 1);
-        assert_eq!(1, f.get_mask());
+    fn test_get_address() {
+        // Test when the address is alligned
+        assert_eq!(
+            Field::new(0x1234_5678, 0, 1).get_address(),
+            0x1234_5678,
+        );
+    }
+
+    #[test]
+    fn test_get_offset() {
+        assert_eq!(
+            Field::new(0x1234_5678, 18, 1).get_offset(),
+            18,
+        );
+    }
+
+    #[test]
+    fn test_get_size() {
+        assert_eq!(
+            Field::new(0x1234_5678, 18, 1).get_size(),
+            1,
+        );
+    }
+
+    #[test]
+    fn test_alignment_enforcement() {
+        let field = Field::new(0x1111_1110, 0, 1);
+        assert_eq!(field.get_address(), 0x1111_1110);
+        assert_eq!(field.get_offset(), 0);
+
+        let field = Field::new(0x1111_1111, 0, 1);
+        assert_eq!(field.get_address(), 0x1111_1110);
+        assert_eq!(field.get_offset(), 8);
+
+        let field = Field::new(0x1111_1112, 0, 1);
+        assert_eq!(field.get_address(), 0x1111_1110);
+        assert_eq!(field.get_offset(), 16);
+
+        let field = Field::new(0x1111_1113, 0, 1);
+        assert_eq!(field.get_address(), 0x1111_1110);
+        assert_eq!(field.get_offset(), 24);
+    }
+
+    #[test]
+    fn test_closeness_enforcement() {
+        let field = Field::new(0x1111_1110, 32, 1);
+        assert_eq!(field.get_address(), 0x1111_1114);
+        assert_eq!(field.get_offset(), 0);
+
+        let field = Field::new(0x1111_1111, 32, 1);
+        assert_eq!(field.get_address(), 0x1111_1114);
+        assert_eq!(field.get_offset(), 8);
+
+        let field = Field::new(0x1111_1112, 32+16, 1);
+        assert_eq!(field.get_address(), 0x1111_1118);
+        assert_eq!(field.get_offset(), 0);
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_prevent_overlaps() {
+        let _ = Field::new(0, 24, 16);
+    }
+
+    #[test]
+    fn test_get_mask() {
+        assert_eq!(
+            Field::new(0, 0, 1).get_mask(),
+            0b0000_0001,
+        );
+        assert_eq!(
+            Field::new(0, 0, 3).get_mask(),
+            0b0000_0111,
+        );
+        assert_eq!(
+            Field::new(0, 4, 1).get_mask(),
+            0b0001_0000,
+        );
+        assert_eq!(
+            Field::new(0, 4, 3).get_mask(),
+            0b0111_0000,
+        );
+    }
+
+    #[test]
+    fn test_read_and_write_to_u32() {
+        let field = Field::new(0, 3, 4);
+        let val = 0b0101_0101;
+        assert_eq!(
+            field.read_and_write_to_u32(0b0101, val),
+            0b0010_1101,
+        );
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_read_and_write_to_u32_too_big() {
+        let field = Field::new(0, 0, 3);
+        let _ = field.read_and_write_to_u32(0b1111, 0);
+    }
+
+    #[test]
+    fn test_read_from_u32() {
+        let field = Field::new(0, 3, 4);
+        let val = 0b1100_1111;
+        assert_eq!(
+            field.read_from_u32(val),
+            0b1001,
+        );
     }
 }