bare5_2

examples/bare5.rs

@@ -56,13 +56,17 @@ mod stm32f40x {
     // offset (field offset)
     // 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 current_value = self.read();
+            let b = 0b11111111;
+            let mask = !( (b << offset + width) | !(b << offset) );
+            let masked_value = mask & (value << offset);
+            let modified_value = (current_value & !mask) | masked_value;
+            self.write(modified_value);
+        }
+    }
 
     #[repr(C)]
     #[allow(non_snake_case)]
@@ -141,27 +145,27 @@ 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]
@@ -177,24 +181,18 @@ fn main() -> ! {
 // user application
 fn idle(rcc: &mut RCC, gpioa: &mut GPIOA) {
     // power on GPIOA
-    let r = rcc.AHB1ENR.read(); // read
-    rcc.AHB1ENR.write(r | 1 << (0)); // set enable
-
+    rcc.AHB1ENR.modify(0, 1, 0b1);
     // configure PA5 as output
-    let r = gpioa.MODER.read() & !(0b11 << (5 * 2)); // read and mask
-    gpioa.MODER.write(r | 0b01 << (5 * 2)); // set output mode
-
+    gpioa.MODER.modify(5*2, 2, 0b01);
     loop {
         // set PA5 high
-        // gpioa.BSRRH.write(1 << 5); // set bit, output hight (turn on led)
-        gpioa.ODR.write(gpioa.ODR.read() | (1 << 5));
-
-        wait(10_000);
+        gpioa.ODR.modify(5, 1, 0b1);
+        //Modify wait by the speedup of a release build.
+        wait(1_119_982);
 
         // set PA5 low
-        // gpioa.BSRRL.write(1 << 5); // clear bit, output low (turn off led)
-        gpioa.ODR.write(gpioa.ODR.read() & !(1 << 5));
-        wait(10_000);
+        gpioa.ODR.modify(5, 1, 0b0);
+        wait(1_119_982);
     }
 }
 
@@ -227,7 +225,7 @@ fn idle(rcc: &mut RCC, gpioa: &mut GPIOA) {
 //    - field width (in bits, u8),
 //    - and value (u32).
 //
-//    Implement and check that running `test` gives you expected behavior.
+//    Implement and` gives you expected behavior.
 //
 //    Change the code into using your new API.
 //