From 31723faee9a643b0405741f35aeb096a8a4dbb6d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Carl=20=C3=96sterberg?= <carl.vilhelms.osterberg@gmail.com>
Date: Fri, 5 Mar 2021 16:30:51 +0100
Subject: [PATCH] tasks done
---
examples/rtic_bare4.rs | 10 +++++++---
examples/rtic_bare5.rs | 13 +++++++------
2 files changed, 14 insertions(+), 9 deletions(-)
diff --git a/examples/rtic_bare4.rs b/examples/rtic_bare4.rs
index f6e3e29..8f01d93 100644
--- a/examples/rtic_bare4.rs
+++ b/examples/rtic_bare4.rs
@@ -57,10 +57,12 @@ const APP: () = {
#[init]
fn init(_cx: init::Context) {
// power on GPIOA
+ //6.3.11
let r = read_u32(RCC_AHB1ENR); // read
write_u32(RCC_AHB1ENR, r | 1); // set enable
// configure PA5 as output
+ //8.4.1
let r = read_u32(GPIOA_MODER) & !(0b11 << (5 * 2)); // read and mask
write_u32(GPIOA_MODER, r | 0b01 << (5 * 2)); // set output mode
@@ -100,7 +102,7 @@ const APP: () = {
//
// What was the error message and explain why.
//
-// error[E0133]: call to unsafe function is unsafe and requires unsafe function or block
+// error[E0133]: call to unsafe function is unsafe and requires unsafe function or block.
// A volatile read to register clashes with rusts memory safety, therefor we must tell the compiler
// that we know what we are doing and just go with it.
//
@@ -127,9 +129,11 @@ const APP: () = {
//
// If we try to access GPIOA_MODER before its powered we wont be able to write to it.
//
-// Without the non-reordering property of `write_volatile/read_volatile` could that happen in theory
+// With the reordering property of `write_volatile/read_volatile` could that happen in theory
// (argue from the point of data dependencies).
//
-// ** your answer here **
+// Maybe some read operation which is a load from memory gets optimizied into
+// being moved around because in pipelineing mode a load takes an extra
+// clock cycle.
//
// Commit your answers (bare4_3)
diff --git a/examples/rtic_bare5.rs b/examples/rtic_bare5.rs
index b62fad2..4defae4 100644
--- a/examples/rtic_bare5.rs
+++ b/examples/rtic_bare5.rs
@@ -64,8 +64,9 @@ mod stm32f40x {
mask = mask >> (32-width);
mask = mask << offset;
let altered = mask & (value << offset);
- //hprintln!("Altered {:b}", !altered).ok();
- //hprintln!("Old {:b}", (self.read()&!mask)).ok();
+ hprintln!("Mask {:b}", mask).ok();
+ hprintln!("Altered {:b}", altered).ok();
+ hprintln!("Old {:b}", (self.read()&!mask)).ok();
self.write((self.read()&!mask) | altered);
}
}
@@ -159,16 +160,16 @@ fn test_modify() {
// ..0111000
// ---------
// 000101000
- //hprintln!("Current {:b}", t.read()).ok();
- //hprintln!("Correct {:b}", 0b101 << 3).ok();
+ hprintln!("Current {:b}", t.read()).ok();
+ hprintln!("Correct {:b}", 0b101 << 3).ok();
assert!(t.read() == 0b101 << 3);
t.modify(4, 3, 0b10001);
// 000101000
// 111
// 001
// 000011000
- //hprintln!("Current {:b}", t.read()).ok();
- //hprintln!("Correct {:b}", 0b011 << 3).ok();
+ hprintln!("Current {:b}", t.read()).ok();
+ hprintln!("Correct {:b}", 0b011 << 3).ok();
assert!(t.read() == 0b011 << 3);
//
// add more tests here if you like
--
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