text: /*
   * This file is part of the MicroPython project, http://micropython.org/
   *
   * The MIT License (MIT)
   *
   * Copyright (c) 2018 Scott Shawcroft for Adafruit Industries
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  #include "stack.h"
  
  #include "py/mpconfig.h"
  #include "py/runtime.h"
  #include "supervisor/cpu.h"
  #include "supervisor/port.h"
  #include "supervisor/shared/safe_mode.h"
  
  extern uint32_t _estack;
  
  // Requested size.
  static uint32_t next_stack_size = CIRCUITPY_DEFAULT_STACK_SIZE;
  static uint32_t current_stack_size = 0;
  // Actual location and size, may be larger than requested.
  static uint32_t *stack_limit = NULL;
  static size_t stack_length = 0;
  
  #define EXCEPTION_STACK_SIZE 1024
  
  static void allocate_stack(void) {
  
      if (port_has_fixed_stack()) {
          stack_limit = port_stack_get_limit();
          stack_length = (port_stack_get_top() - stack_limit) * sizeof(uint32_t);
          current_stack_size = stack_length;
      } else {
          mp_uint_t regs[10];
          mp_uint_t sp = cpu_get_regs_and_sp(regs);
  
          mp_uint_t c_size = (uint32_t)port_stack_get_top() - sp;
          supervisor_allocation *stack_alloc = allocate_memory(c_size + next_stack_size + EXCEPTION_STACK_SIZE, true, false);
          if (stack_alloc == NULL) {
              stack_alloc = allocate_memory(c_size + CIRCUITPY_DEFAULT_STACK_SIZE + EXCEPTION_STACK_SIZE, true, false);
              current_stack_size = CIRCUITPY_DEFAULT_STACK_SIZE;
          } else {
              current_stack_size = next_stack_size;
          }
          stack_limit = stack_alloc->ptr;
          stack_length = get_allocation_length(stack_alloc);
      }
  
      *stack_limit = STACK_CANARY_VALUE;
  }
  
  inline bool stack_ok(void) {
      return stack_limit == NULL || *stack_limit == STACK_CANARY_VALUE;
  }
  
  inline void assert_heap_ok(void) {
      if (!stack_ok()) {
          reset_into_safe_mode(HEAP_OVERWRITTEN);
      }
  }
  
  void stack_init(void) {
      allocate_stack();
  }
  
  void stack_resize(void) {
      if (stack_limit == NULL) {
          return;
      }
      if (next_stack_size == current_stack_size) {
          *stack_limit = STACK_CANARY_VALUE;
          return;
      }
      free_memory(allocation_from_ptr(stack_limit));
      stack_limit = NULL;
      allocate_stack();
  }
  
  uint32_t *stack_get_bottom(void) {
      return stack_limit;
  }
  
  size_t stack_get_length(void) {
      return stack_length;
  }
  
  void set_next_stack_size(uint32_t size) {
      next_stack_size = size;
  }
  
  uint32_t get_current_stack_size(void) {
      return current_stack_size;
  }
  