Import of the watch repository from Pebble

src/fw/kernel/util/stack_info.c

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "FreeRTOS.h"
+#include "task.h"
+
+#include "mcu/interrupts.h"
+
+extern uint32_t __isr_stack_start__[];
+
+uint32_t stack_free_bytes(void) {
+
+  // Get the current SP
+  register uint32_t SP __asm ("sp");
+  uint32_t cur_sp = SP;
+
+  // Default stack
+  uint32_t start = (uint32_t) __isr_stack_start__;
+
+  // On ISR stack?
+  if (!mcu_state_is_isr()) {
+    TaskHandle_t task_handle = xTaskGetCurrentTaskHandle();
+    if (task_handle != NULL) {
+      // task_handle is NULL before we start the first task
+      start = (uint32_t)ulTaskGetStackStart(task_handle);
+    }
+  }
+
+  return cur_sp - start;
+}