From: Scott Worley <scottworley@scottworley.com>
Date: Sun, 8 Oct 2023 07:13:36 +0000 (-0700)
Subject: client: Don't sleep in interrupt context
X-Git-Tag: v0.1.0~58
X-Git-Url: http://git.scottworley.com/tattlekey/commitdiff_plain/1427141a9ef3932472820452174859ab7539bcf0?hp=d1521eda56a4768dbf481aa6cf9e75c5a5a7e7f1

client: Don't sleep in interrupt context
---

diff --git a/client/tattlekey.c b/client/tattlekey.c
index 30f92a4..05488ea 100644
--- a/client/tattlekey.c
+++ b/client/tattlekey.c
@@ -1,33 +1,20 @@
 #include "pico/cyw43_arch.h"
 #include "pico/stdlib.h"
+#include "pico/util/queue.h"
 
 #include "blink.h"
 #include "button.h"
 #include "config.h"
 #include "net.h"
 
-static u16_t seq = 0;
+queue_t queue;
 
 static void button_pressed() {
-  /* TODO: This is interrupt context.  We need to get out of interrupt context
-   * quickly; we should not be doing significant work here, & definitely
-   * shouldn't be sleeping here.  We signal errors with blinking the LED, which
-   * involves sleeping, so this all has to move. */
-  send_report(seq++, 0);
-  signal(4, 200);
-}
-
-static void wait_forever() {
-  /* pico-examples/gpio/hello_gpio_irq/hello_gpio_irq.c implements wait-forever
-   * as "while (1);", but
-   * https://www.raspberrypi.com/documentation/pico-sdk/high_level.html#gaf469c6d691230e9d1008
-   * says sleeping uses less power, so we sleep.  */
-  while (1) {
-    /* https://www.raspberrypi.com/documentation/pico-sdk/hardware.html#rpip7ce2cdc1662dce59296b
-     * says the maximum sleep is 2^32 - 1 microseconds (~71.58 minutes), so we
-     * sleep in chunks. */
-    sleep_ms(1 << 31); /* 35.79 minutes */
-  }
+  /* This runs in interrupt context; don't linger.  */
+  char zero = '\0';
+  /* We don't check for failure (full queue) here because there's not much to be
+   * done about it. */
+  queue_try_add(&queue, &zero);
 }
 
 int main() {
@@ -41,7 +28,16 @@ int main() {
                                          CYW43_AUTH_WPA2_AES_PSK, 10000))
     signal_error_by_blinking();
   signal(3, 200);
+
+  queue_init(&queue, 1, 99);
+
   begin_listening_for_button_press(button_pressed);
 
-  wait_forever();
+  u16_t seq = 0;
+  while (1) {
+    char _;
+    queue_remove_blocking(&queue, &_);
+    send_report(seq++, 0);
+    signal(4, 200);
+  }
 }