text: #include <stdint.h>
  #include <stdio.h>
  #include <string.h>
  #include <stdlib.h>
  
  #include "py/nlr.h"
  #include "py/parse.h"
  #include "py/lexer.h"
  #include "py/runtime.h"
  #include "py/stackctrl.h"
  #include "py/gc.h"
  #include "gccollect.h"
  #include "pyexec.h"
  #include "readline.h"
  #include "lexermemzip.h"
  
  #include "Arduino.h"
  #include MICROPY_HAL_H
  
  #include "servo.h"
  #include "usb.h"
  #include "led.h"
  #include "uart.h"
  #include "pin.h"
  #include "pybstdio.h"
  
  
  extern uint32_t _heap_start;
  
  void flash_error(int n) {
      for (int i = 0; i < n; i++) {
          led_state(PYB_LED_BUILTIN, 1);
          delay(250);
          led_state(PYB_LED_BUILTIN, 0);
          delay(250);
      }
  }
  
  void NORETURN __fatal_error(const char *msg) {
      for (volatile uint delay = 0; delay < 10000000; delay++) {
      }
      led_state(1, 1);
      led_state(2, 1);
      led_state(3, 1);
      led_state(4, 1);
      stdout_tx_strn("\nFATAL ERROR:\n", 14);
      stdout_tx_strn(msg, strlen(msg));
      for (uint i = 0;;) {
          led_toggle(((i++) & 3) + 1);
          for (volatile uint delay = 0; delay < 10000000; delay++) {
          }
          if (i >= 16) {
              // to conserve power
              __WFI();
          }
      }
  }
  
  void nlr_jump_fail(void *val) {
      printf("FATAL: uncaught exception %p\n", val);
      __fatal_error("");
  }
  
  void __assert_func(const char *file, int line, const char *func, const char *expr) {
  
      printf("Assertion failed: %s, file %s, line %d\n", expr, file, line);
      __fatal_error("");
  }
  
  mp_obj_t pyb_analog_read(mp_obj_t pin_obj) {
      uint pin = mp_obj_get_int(pin_obj);
      int val = analogRead(pin);
      return MP_OBJ_NEW_SMALL_INT(val);
  }
  
  mp_obj_t pyb_analog_write(mp_obj_t pin_obj, mp_obj_t val_obj) {
      uint pin = mp_obj_get_int(pin_obj);
      int val = mp_obj_get_int(val_obj);
      analogWrite(pin, val);
      return mp_const_none;
  }
  
  mp_obj_t pyb_analog_write_resolution(mp_obj_t res_obj) {
      int res = mp_obj_get_int(res_obj);
      analogWriteResolution(res);
      return mp_const_none;
  }
  
  mp_obj_t pyb_analog_write_frequency(mp_obj_t pin_obj, mp_obj_t freq_obj) {
      uint pin = mp_obj_get_int(pin_obj);
      int freq = mp_obj_get_int(freq_obj);
      analogWriteFrequency(pin, freq);
      return mp_const_none;
  }
  
  #if 0
  // get lots of info about the board
  static mp_obj_t pyb_info(void) {
      // get and print unique id; 96 bits
      {
          byte *id = (byte*)0x40048058;
          printf("ID=%02x%02x%02x%02x:%02x%02x%02x%02x:%02x%02x%02x%02x\n", id[0], id[1], id[2], id[3], id[4], id[5], id[6], id[7], id[8], id[9], id[10], id[11]);
      }
  
      // get and print clock speeds
      printf("CPU=%u\nBUS=%u\nMEM=%u\n", F_CPU, F_BUS, F_MEM);
  
      // to print info about memory
      {
          printf("_sdata=%p\n", &_sdata);
          printf("_edata=%p\n", &_edata);
          printf("_sbss=%p\n", &_sbss);
          printf("_ebss=%p\n", &_ebss);
          printf("_estack=%p\n", &_estack);
          printf("_etext=%p\n", &_etext);
          printf("_heap_start=%p\n", &_heap_start);
      }
  
      // GC info
      {
          gc_info_t info;
          gc_info(&info);
          printf("GC:\n");
          printf("  %u total\n", info.total);
          printf("  %u used %u free\n", info.used, info.free);
          printf("  1=%u 2=%u m=%u\n", info.num_1block, info.num_2block, info.max_block);
      }
  
  #if 0
      // free space on flash
      {
          DWORD nclst;
          FATFS *fatfs;
          f_getfree("0:", &nclst, &fatfs);
          printf("LFS free: %u bytes\n", (uint)(nclst * fatfs->csize * 512));
      }
  #endif
  
      return mp_const_none;
  }
  
  #endif
  
  #define RAM_START (0x1FFF8000) // fixed for chip
  #define HEAP_END  (0x20006000) // tunable
  #define RAM_END   (0x20008000) // fixed for chip
  
  #if 0
  
  void gc_helper_get_regs_and_clean_stack(mp_uint_t *regs, mp_uint_t heap_end);
  
  mp_obj_t pyb_gc(void) {
      gc_collect();
      return mp_const_none;
  }
  
  mp_obj_t pyb_gpio(int n_args, mp_obj_t *args) {
      //assert(1 <= n_args && n_args <= 2);
  
      uint pin = mp_obj_get_int(args[0]);
      if (pin > CORE_NUM_DIGITAL) {
          goto pin_error;
      }
  
      if (n_args == 1) {
          // get pin
          pinMode(pin, INPUT);
          return MP_OBJ_NEW_SMALL_INT(digitalRead(pin));
      }
      
      // set pin
      pinMode(pin, OUTPUT);
      digitalWrite(pin, mp_obj_is_true(args[1]));
      return mp_const_none;
  
  pin_error:
      nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "pin %d does not exist", pin));
  }
  
  MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_gpio_obj, 1, 2, pyb_gpio);
  
  #if 0
  mp_obj_t pyb_hid_send_report(mp_obj_t arg) {
      mp_obj_t *items = mp_obj_get_array_fixed_n(arg, 4);
      uint8_t data[4];
      data[0] = mp_obj_get_int(items[0]);
      data[1] = mp_obj_get_int(items[1]);
      data[2] = mp_obj_get_int(items[2]);
      data[3] = mp_obj_get_int(items[3]);
      usb_hid_send_report(data);
      return mp_const_none;
  }
  #endif
  
  #endif // 0
  
  STATIC mp_obj_t pyb_config_source_dir = MP_OBJ_NULL;
  STATIC mp_obj_t pyb_config_main = MP_OBJ_NULL;
  STATIC mp_obj_t pyb_config_usb_mode = MP_OBJ_NULL;
  
  mp_obj_t pyb_source_dir(mp_obj_t source_dir) {
      if (MP_OBJ_IS_STR(source_dir)) {
          pyb_config_source_dir = source_dir;
      }
      return mp_const_none;
  }
  
  MP_DEFINE_CONST_FUN_OBJ_1(pyb_source_dir_obj, pyb_source_dir);
  
  mp_obj_t pyb_main(mp_obj_t main) {
      if (MP_OBJ_IS_STR(main)) {
          pyb_config_main = main;
      }
      return mp_const_none;
  }
  
  MP_DEFINE_CONST_FUN_OBJ_1(pyb_main_obj, pyb_main);
  
  STATIC mp_obj_t pyb_usb_mode(mp_obj_t usb_mode) {
      if (MP_OBJ_IS_STR(usb_mode)) {
          pyb_config_usb_mode = usb_mode;
      }
      return mp_const_none;
  }
  
  MP_DEFINE_CONST_FUN_OBJ_1(pyb_usb_mode_obj, pyb_usb_mode);
  
  #if 0
  
  mp_obj_t pyb_delay(mp_obj_t count) {
      delay(mp_obj_get_int(count));
      return mp_const_none;
  }
  
  mp_obj_t pyb_led(mp_obj_t state) {
      led_state(PYB_LED_BUILTIN, mp_obj_is_true(state));
      return state;
  }
  
  #endif  // 0
  
  #if 0
  char *strdup(const char *str) {
      uint32_t len = strlen(str);
      char *s2 = m_new(char, len + 1);
      memcpy(s2, str, len);
      s2[len] = 0;
      return s2;
  }
  #endif
  
  int main(void) {
      // TODO: Put this in a more common initialization function.
      // Turn on STKALIGN which keeps the stack 8-byte aligned for interrupts
      // (per EABI)
      #define SCB_CCR_STKALIGN (1 << 9)
      SCB_CCR |= SCB_CCR_STKALIGN;
  
      mp_stack_set_limit(10240);
  
      pinMode(LED_BUILTIN, OUTPUT);
      led_init();
  
  //    int first_soft_reset = true;
  
  soft_reset:
  
      led_state(PYB_LED_BUILTIN, 1);
  
      // GC init
      gc_init(&_heap_start, (void*)HEAP_END);
  
      // Micro Python init
      mp_init();
      mp_obj_list_init(mp_sys_path, 0);
      mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR_)); // current dir (or base dir of the script)
      mp_obj_list_init(mp_sys_argv, 0);
  
      readline_init0();
  
      pin_init0();
  
  #if 0
      // add some functions to the python namespace
      {
          mp_store_name(MP_QSTR_help, mp_make_function_n(0, pyb_help));
          mp_obj_t m = mp_obj_new_module(MP_QSTR_pyb);
          mp_store_attr(m, MP_QSTR_info, mp_make_function_n(0, pyb_info));
          mp_store_attr(m, MP_QSTR_source_dir, mp_make_function_n(1, pyb_source_dir));
          mp_store_attr(m, MP_QSTR_main, mp_make_function_n(1, pyb_main));
          mp_store_attr(m, MP_QSTR_gc, mp_make_function_n(0, pyb_gc));
          mp_store_attr(m, MP_QSTR_delay, mp_make_function_n(1, pyb_delay));
          mp_store_attr(m, MP_QSTR_led, mp_make_function_n(1, pyb_led));
          mp_store_attr(m, MP_QSTR_LED, (mp_obj_t)&pyb_led_type);
          mp_store_attr(m, MP_QSTR_analogRead, mp_make_function_n(1, pyb_analog_read));
          mp_store_attr(m, MP_QSTR_analogWrite, mp_make_function_n(2, pyb_analog_write));
          mp_store_attr(m, MP_QSTR_analogWriteResolution, mp_make_function_n(1, pyb_analog_write_resolution));
          mp_store_attr(m, MP_QSTR_analogWriteFrequency, mp_make_function_n(2, pyb_analog_write_frequency));
  
          mp_store_attr(m, MP_QSTR_gpio, (mp_obj_t)&pyb_gpio_obj);
          mp_store_attr(m, MP_QSTR_Servo, mp_make_function_n(0, pyb_Servo));
          mp_store_name(MP_QSTR_pyb, m);
      }
  #endif
  
      if (!pyexec_file("/boot.py")) {
          flash_error(4);
      }
  
      // Turn bootup LED off
      led_state(PYB_LED_BUILTIN, 0);
  
      // run main script
      {
          vstr_t *vstr = vstr_new();
          vstr_add_str(vstr, "/");
          if (pyb_config_main == MP_OBJ_NULL) {
              vstr_add_str(vstr, "main.py");
          } else {
              vstr_add_str(vstr, mp_obj_str_get_str(pyb_config_main));
          }
          if (!pyexec_file(vstr_null_terminated_str(vstr))) {
              flash_error(3);
          }
          vstr_free(vstr);
      }
  
      // enter REPL
      // REPL mode can change, or it can request a soft reset
      for (;;) {
          if (pyexec_mode_kind == PYEXEC_MODE_RAW_REPL) {
              if (pyexec_raw_repl() != 0) {
                  break;
              }
          } else {
              if (pyexec_friendly_repl() != 0) {
                  break;
              }
          }
      }
  
      printf("PYB: soft reboot\n");
  
  //    first_soft_reset = false;
      goto soft_reset;
  }
  
  // stub out __libc_init_array. It's called by mk20dx128.c and is used to call
  // global C++ constructors. Since this is a C-only projects, we don't need to
  // call constructors.
  void __libc_init_array(void) {
  }
  
  // ultoa is used by usb_init_serialnumber. Normally ultoa would be provided
  // by nonstd.c from the teensy core, but it conflicts with some of the
  // MicroPython functions in string0.c, so we provide ultoa here.
  char * ultoa(unsigned long val, char *buf, int radix) 	
  {
  	unsigned digit;
  	int i=0, j;
  	char t;
  
  	while (1) {
  		digit = val % radix;
  		buf[i] = ((digit < 10) ? '0' + digit : 'A' + digit - 10);
  		val /= radix;
  		if (val == 0) break;
  		i++;
  	}
  	buf[i + 1] = 0;
  	for (j=0; j < i; j++, i--) {
  		t = buf[j];
  		buf[j] = buf[i];
  		buf[i] = t;
  	}
  	return buf;
  }
  