bare5_2

examples/bare5.rs

@@ -57,12 +57,17 @@ mod stm32f40x {
     // width  (field width)
     // value  (new value that the field should take)
     //
-    // impl VolatileCell<u32> {
-    //     #[inline(always)]
-    //     pub fn modify(&self, offset: u8, width: u8, value: u32) {
-    //         // your code here
-    //     }
-    // }
+    impl VolatileCell<u32> {
+        #[inline(always)]
+        pub fn modify(&self, offset: u8, width: u8, value: u32) {
+            let currentVal = self.read();
+            let b = 0b11111111;
+            let mask = !( (b << offset + width) | !(b << offset) );
+            let maskedVal = mask & (value << offset);
+            let modVal = (currentVal & !mask) | maskedVal;
+            self.write(modVal);
+        }
+    }
 
     #[repr(C)]
     #[allow(non_snake_case)]
@@ -141,27 +146,27 @@ fn wait(i: u32) {
 }
 
 // simple test of Your `modify`
-//fn test() {
-// let t:VolatileCell<u32> = unsafe {  core::mem::uninitialized() };
-// t.write(0);
-// assert!(t.read() == 0);
-// t.modify(3, 3, 0b10101);
-// //
-// //     10101
-// //    ..0111000
-// //    ---------
-// //    000101000
-// assert!(t.read() == 0b101 << 3);
-// t.modify(4, 3, 0b10001);
-// //    000101000
-// //      111
-// //      001
-// //    000011000
-// assert!(t.read() == 0b011 << 3);
+fn test() {
+let t:VolatileCell<u32> = unsafe {  core::mem::uninitialized() };
+t.write(0);
+assert!(t.read() == 0);
+t.modify(3, 3, 0b10101);
+//
+//     10101
+//    ..0111000
+//    ---------
+//    000101000
+assert!(t.read() == 0b101 << 3);
+t.modify(4, 3, 0b10001);
+//    000101000
+//      111
+//      001
+//    000011000
+assert!(t.read() == 0b011 << 3);
 
 // if << is used, your code will panic in dev (debug), but not in release mode
-// t.modify(32, 3, 1);
-//}
+t.modify(32, 3, 1);
+}
 
 // system startup, can be hidden from the user
 #[entry]