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-rw-r--r--async/scheduler.h43
-rw-r--r--async/time_scheduler.h76
-rw-r--r--cortex_m/critical_section.h21
3 files changed, 140 insertions, 0 deletions
diff --git a/async/scheduler.h b/async/scheduler.h
index 0196aa5..bae4890 100644
--- a/async/scheduler.h
+++ b/async/scheduler.h
@@ -1,6 +1,9 @@
#pragma once
#include <coroutine>
+#include <optional>
+
+#include <cortex_m/critical_section.h>
struct schedulable {
schedulable* next = nullptr;
@@ -161,3 +164,43 @@ struct task : public schedulable {
task(std::coroutine_handle<promise_type> h) : schedulable(h) {}
};
+
+struct async_flag : public schedulable {
+ bool ready;
+
+ async_flag() : ready(false) {}
+
+ bool await_ready() {
+ return ready;
+ }
+
+ bool await_suspend(std::coroutine_handle<> h) {
+ critical_section lock;
+
+ if(ready) {
+ return false;
+ } else {
+ awaiter = h;
+ return true;
+ }
+ }
+
+ void await_resume() {
+ critical_section lock;
+
+ awaiter = nullptr;
+ ready = false;
+ }
+
+ void set() {
+ if(ready) {
+ return;
+ }
+
+ ready = true;
+
+ if(awaiter) {
+ scheduler.schedule(*this);
+ }
+ }
+};
diff --git a/async/time_scheduler.h b/async/time_scheduler.h
new file mode 100644
index 0000000..e09de16
--- /dev/null
+++ b/async/time_scheduler.h
@@ -0,0 +1,76 @@
+#pragma once
+
+#include <chrono>
+
+#include "scheduler.h"
+
+template <typename Duration = std::chrono::milliseconds>
+struct time_scheduler_t {
+ struct wakeup_future : public schedulable {
+ time_scheduler_t& tsched;
+ Duration time;
+ wakeup_future(time_scheduler_t& tsched, Duration time) : tsched(tsched), time(time) {}
+
+ bool await_ready() {
+ return tsched.now >= time;
+ }
+
+ bool await_suspend(std::coroutine_handle<> h) {
+ if(tsched.now >= time) {
+ return false;
+ } else {
+ awaiter = h;
+ tsched.push_wakeup(this);
+ return true;
+ }
+ }
+
+ void await_resume() {}
+
+ void resume() {
+ scheduler.schedule(*this);
+ }
+ };
+
+ Duration now;
+
+ wakeup_future* wakeup_queue;
+
+ void push_wakeup(wakeup_future* fut) {
+ wakeup_future** p = &wakeup_queue;
+
+ while((*p) && (*p)->time <= fut->time) {
+ p = reinterpret_cast<wakeup_future**>(&(*p)->next);
+ }
+
+ fut->next = *p;
+ *p = fut;
+ }
+
+ async_flag tick_flag;
+
+ void tick() {
+ tick_flag.set();
+ }
+
+ task wakeup_task() {
+ while(1) {
+ co_await tick_flag;
+ now++;
+
+ while(wakeup_queue && wakeup_queue->time <= now) {
+ auto fut = wakeup_queue;
+ wakeup_queue = static_cast<wakeup_future*>(fut->next);
+ fut->resume();
+ }
+ }
+ }
+
+ wakeup_future sleep_until(Duration time) {
+ return {*this, time};
+ }
+
+ wakeup_future sleep(Duration duration) {
+ return sleep_until(now + duration);
+ }
+};
diff --git a/cortex_m/critical_section.h b/cortex_m/critical_section.h
new file mode 100644
index 0000000..6b611a8
--- /dev/null
+++ b/cortex_m/critical_section.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <cstdint>
+
+struct critical_section {
+ uint32_t primask;
+
+ critical_section() {
+ asm volatile("mrs %0, primask" : "=r" (primask));
+
+ asm volatile("cpsid i");
+
+ asm volatile("dmb");
+ }
+
+ ~critical_section() {
+ asm volatile("dmb");
+
+ asm volatile("msr primask, %0" :: "r" (primask));
+ }
+};