From fc890e991ed960c0f2f052f2664fc07a005f4ed3 Mon Sep 17 00:00:00 2001
From: Brian Cully <bjc@kublai.com>
Date: Fri, 28 Oct 2022 16:26:43 -0400
Subject: =?UTF-8?q?log:=20move=20architecture-specifics=20to=20=E2=80=98ar?=
 =?UTF-8?q?ch=E2=80=99=20sub-module?=
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---
 src/log.rs | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/src/log.rs b/src/log.rs
index 7eb15e4..ccc9ebc 100644
--- a/src/log.rs
+++ b/src/log.rs
@@ -3,11 +3,6 @@ use core::{
     fmt::{write, Arguments},
 };
 
-use stm32f1xx_hal::{
-    serial::Tx,
-    pac::USART1,
-};
-
 use cortex_m::interrupt::{self, Mutex};
 
 #[macro_export]
@@ -25,9 +20,9 @@ macro_rules! logln {
     }
 }
 
-static TX: Mutex<RefCell<Option<Tx<USART1>>>> = Mutex::new(RefCell::new(None));
+static TX: Mutex<RefCell<Option<arch::Writer>>> = Mutex::new(RefCell::new(None));
 
-pub fn init(tx: Tx<USART1>) {
+pub fn init(tx: arch::Writer) {
     interrupt::free(|cs| {
         TX.borrow(cs).replace(Some(tx));
     });
@@ -35,6 +30,23 @@ pub fn init(tx: Tx<USART1>) {
 
 pub fn log_args(args: Arguments) {
     interrupt::free(|cs| {
-        TX.borrow(cs).borrow_mut().as_mut().map(|tx| write(tx, args));
+        TX.borrow(cs)
+            .borrow_mut()
+            .as_mut()
+            .map(|tx| write(tx, args));
     });
 }
+
+/*
+ * Because the logger needs to have a size in order to be allocated
+ * statically, we need to pull in architecture-specific details about
+ * the implementation.
+ *
+ * By putting everything in an `arch` module, we can more easily swap
+ * things out at compile time with feature flags, or a similar
+ * mechanism.
+ */
+mod arch {
+    use stm32f1xx_hal::{pac::USART1, serial::Tx};
+    pub type Writer = Tx<USART1>;
+}
-- 
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