text: /*
   * This file is part of the MiniPython project, http://minipython.org/
   *
   * The MIT License (MIT)
   *
   * Copyright (c) 2015 Kevin Thomas
   *
   * 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.
   */
  
  extern "C" {
  
  #include <errno.h>
  #include "pinmap.h"
  #include "serial_api.h"
  #include "py/runtime.h"
  #include "py/stream.h"
  #include "py/mphal.h"
  #include "microbit/modmicrobit.h"
  
  // There is only one UART peripheral and it's already used by stdio (and
  // connected to USB serial).  So to access the UART we go through the
  // mp_hal_stdio functions.  The init method can reconfigure the underlying
  // UART peripheral to a different baudrate and/or pins.
  
  typedef struct _microbit_uart_obj_t {
      mp_obj_base_t base;
  } microbit_uart_obj_t;
  
  // timeout (in ms) to wait between characters when reading
  STATIC uint16_t microbit_uart_timeout_char = 0;
  
  STATIC mp_obj_t microbit_uart_init(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
      static const mp_arg_t allowed_args[] = {
          { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = 9600} },
          { MP_QSTR_bits,     MP_ARG_INT, {.u_int = 8} },
          { MP_QSTR_parity,   MP_ARG_OBJ, {.u_obj = mp_const_none} },
          { MP_QSTR_stop,     MP_ARG_INT, {.u_int = 1} },
          { MP_QSTR_pins,     MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none } },
          { MP_QSTR_tx,       MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none } },
          { MP_QSTR_rx,       MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none } },
      };
  
      // parse args
      //microbit_uart_obj_t *self = (microbit_uart_obj_t*)pos_args[0];
      mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
      mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
  
      SerialParity parity;
      if (args[2].u_obj == mp_const_none) {
          parity = ParityNone;
      } else {
          parity = (SerialParity)mp_obj_get_int(args[2].u_obj);
      }
  
      // default pins are the internal USB-UART pins
      PinName p_tx = TGT_TX;
      PinName p_rx = TGT_RX;
  
      // set tx/rx pins if they are given
      if (args[5].u_obj != mp_const_none) {
          p_tx = (PinName)microbit_obj_get_pin_name(args[5].u_obj);
      }
      if (args[6].u_obj != mp_const_none) {
          p_rx = (PinName)microbit_obj_get_pin_name(args[6].u_obj);
      }
  
      // support for legacy "pins" argument
      if (args[4].u_obj != mp_const_none) {
          mp_obj_t *pins;
          mp_obj_get_array_fixed_n(args[4].u_obj, 2, &pins);
          p_tx = (PinName)microbit_obj_get_pin_name(pins[0]);
          p_rx = (PinName)microbit_obj_get_pin_name(pins[1]);
      }
  
      // initialise the uart
      // Note: we don't want to call serial_init() because it sends a single 0x00
      // character on the line during initialisation.  This function has anyway
      // already been called by the MicroBitSerial constructor so it's enough to
      // just reconfigure the pins here, as would have been done by serial_init().
      serial_t serial;
      serial.uart = NRF_UART0;
      NRF_GPIO->DIR |= (1 << p_tx);
      NRF_GPIO->DIR &= ~(1 << p_rx);
      NRF_UART0->PSELTXD = p_tx;
      NRF_UART0->PSELRXD = p_rx;
      pin_mode(p_tx, PullUp);
      pin_mode(p_rx, PullUp);
      serial_baud(&serial, args[0].u_int);
      serial_format(&serial, args[1].u_int, parity, args[3].u_int);
  
      // set the character read timeout based on the baudrate and 13 bits
      microbit_uart_timeout_char = 13000 / args[0].u_int + 1;
  
      return mp_const_none;
  }
  MP_DEFINE_CONST_FUN_OBJ_KW(microbit_uart_init_obj, 1, microbit_uart_init);
  
  STATIC mp_obj_t microbit_uart_any(mp_obj_t self_in) {
      (void)self_in;
      if (mp_hal_stdin_rx_any()) {
          return mp_const_true;
      } else {
          return mp_const_false;
      }
  }
  MP_DEFINE_CONST_FUN_OBJ_1(microbit_uart_any_obj, microbit_uart_any);
  
  STATIC const mp_map_elem_t microbit_uart_locals_dict_table[] = {
      { MP_OBJ_NEW_QSTR(MP_QSTR_init), (mp_obj_t)&microbit_uart_init_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_any), (mp_obj_t)&microbit_uart_any_obj },
  
      { MP_OBJ_NEW_QSTR(MP_QSTR_read), (mp_obj_t)&mp_stream_read_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_readline), (mp_obj_t)&mp_stream_unbuffered_readline_obj},
      { MP_OBJ_NEW_QSTR(MP_QSTR_readinto), (mp_obj_t)&mp_stream_readinto_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_write), (mp_obj_t)&mp_stream_write_obj },
  
      { MP_OBJ_NEW_QSTR(MP_QSTR_ODD), MP_OBJ_NEW_SMALL_INT(ParityOdd) },
      { MP_OBJ_NEW_QSTR(MP_QSTR_EVEN), MP_OBJ_NEW_SMALL_INT(ParityEven) },
  };
  
  STATIC MP_DEFINE_CONST_DICT(microbit_uart_locals_dict, microbit_uart_locals_dict_table);
  
  // Waits at most timeout_ms for at least 1 char to become ready for reading.
  // Returns true if something available, false if not.
  STATIC bool microbit_uart_rx_wait(uint32_t timeout_ms) {
      uint32_t start = mp_hal_ticks_ms();
      for (;;) {
          if (mp_hal_stdin_rx_any()) {
              return true; // have at least 1 character waiting
          }
          if (mp_hal_ticks_ms() - start >= timeout_ms) {
              return false; // timeout
          }
      }
  }
  
  STATIC mp_uint_t microbit_uart_read(mp_obj_t self_in, void *buf_in, mp_uint_t size, int *errcode) {
      (void)self_in;
      byte *buf = (byte*)buf_in;
      (void)errcode;
  
      // make sure we want at least 1 char
      if (size == 0) {
          return 0;
      }
  
      // check there is at least 1 char available
      if (!mp_hal_stdin_rx_any()) {
          *errcode = EAGAIN;
          return MP_STREAM_ERROR;
      }
  
      // read the data
      byte *orig_buf = buf;
      for (;;) {
          *buf++ = mp_hal_stdin_rx_chr();
          if (--size == 0 || !microbit_uart_rx_wait(microbit_uart_timeout_char)) {
              // return number of bytes read
              return buf - orig_buf;
          }
      }
  }
  
  STATIC mp_uint_t microbit_uart_write(mp_obj_t self_in, const void *buf_in, mp_uint_t size, int *errcode) {
      (void)self_in;
      const char *buf = (const char*)buf_in;
      (void)errcode;
      mp_hal_stdout_tx_strn(buf, size);
      return size;
  }
  
  STATIC const mp_stream_p_t microbit_uart_stream_p = {
      .read = microbit_uart_read,
      .write = microbit_uart_write,
      .ioctl = NULL,
      .is_text = false,
  };
  
  const mp_obj_type_t microbit_uart_type = {
      { &mp_type_type },
      .name = MP_QSTR_MicroBitUART,
      .print = NULL,
      .make_new = NULL,
      .call = NULL,
      .unary_op = NULL,
      .binary_op = NULL,
      .attr = NULL,
      .subscr = NULL,
      .getiter = NULL,
      .iternext = NULL,
      .buffer_p = {NULL},
      .protocol = &microbit_uart_stream_p,
      .parent = NULL,
      .locals_dict = (mp_obj_dict_t*)&microbit_uart_locals_dict,
  };
  
  microbit_uart_obj_t microbit_uart_obj = {
      {&microbit_uart_type},
  };
  
  }
  