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// #################################################################################################

// # << NEORV32: neorv32_uart.c - Universal Asynchronous Receiver/Transmitter (UART) HW Driver >>  #

// # ********************************************************************************************* #

// # BSD 3-Clause License                                                                          #

// #                                                                                               #

// # Copyright (c) 2022, Stephan Nolting. All rights reserved.                                     #

// #                                                                                               #

// # Redistribution and use in source and binary forms, with or without modification, are          #

// # permitted provided that the following conditions are met:                                     #

// #                                                                                               #

// # 1. Redistributions of source code must retain the above copyright notice, this list of        #

// #    conditions and the following disclaimer.                                                   #

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// # 3. Neither the name of the copyright holder nor the names of its contributors may be used to  #

// #    endorse or promote products derived from this software without specific prior written      #

// #    permission.                                                                                #

// #                                                                                               #

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// # ********************************************************************************************* #

// # The NEORV32 Processor - https://github.com/stnolting/neorv32              (c) Stephan Nolting #

// #################################################################################################

/**********************************************************************//**

 * @file neorv32_uart.c

 * @brief Universal asynchronous receiver/transmitter (UART0/UART1) HW driver source file.

 *

 * @warning UART0 (primary UART) is used as default user console interface for all NEORV32 software framework/library functions.

 *

 * @note These functions should only be used if the UART0/UART1 unit was synthesized (IO_UART0_EN = true / IO_UART1_EN = true).

 **************************************************************************/

#include "neorv32.h"

#include "neorv32_uart.h"

#include <string.h>

#include <stdarg.h>

/// \cond

// Private functions

static void __neorv32_uart_itoa(uint32_t x, char *res) __attribute__((unused)); // GCC: do not output a warning when this variable is unused

static void __neorv32_uart_tohex(uint32_t x, char *res) __attribute__((unused)); // GCC: do not output a warning when this variable is unused

static void __neorv32_uart_touppercase(uint32_t len, char *ptr) __attribute__((unused)); // GCC: do not output a warning when this variable is unused

/// \endcond

// #################################################################################################

// Override default STDIO functions

// #################################################################################################

/**********************************************************************//**

 * Send char via UART0

 *

 * @param[in] Char to be send.

 * @return Char that has been sent.

 **************************************************************************/

int putchar(int ch) {

  neorv32_uart0_putc((char)ch);

  return ch;

}

/**********************************************************************//**

 * Read char from UART0.

 *

 * @return Read char.

 **************************************************************************/

int getchar(void) {

  return (int)neorv32_uart0_getc();

}

// #################################################################################################

// Primary UART (UART0)

// #################################################################################################

/**********************************************************************//**

 * Check if UART0 unit was synthesized.

 *

 * @return 0 if UART0 was not synthesized, 1 if UART0 is available.

 **************************************************************************/

int neorv32_uart0_available(void) {

  if (NEORV32_SYSINFO.SOC & (1 << SYSINFO_SOC_IO_UART0)) {

    return 1;

  }

  else {

    return 0;

  }

}

/**********************************************************************//**

 * Enable and configure primary UART (UART0).

 *

 * @note The 'UART0_SIM_MODE' compiler flag will configure UART0 for simulation mode: all UART0 TX data will be redirected to simulation output. Use this for simulations only!

 * @note To enable simulation mode add <USER_FLAGS+=-DUART0_SIM_MODE> when compiling.

 *

 * @warning The baud rate is computed using INTEGER operations (truncation errors might occur).

 *

 * @param[in] baudrate Targeted BAUD rate (e.g. 9600).

 * @param[in] parity Parity configuration (00=off, 10=even, 11=odd), see #NEORV32_UART_PARITY_enum.

 * @param[in] flow_con Hardware flow control configuration (00=off, 01=RTS, 10=CTS, 11=RTS/CTS), see #NEORV32_UART_FLOW_CONTROL_enum.

 **************************************************************************/

void neorv32_uart0_setup(uint32_t baudrate, uint8_t parity, uint8_t flow_con) {

  NEORV32_UART0.CTRL = 0; // reset

  uint32_t clock = NEORV32_SYSINFO.CLK;

  uint16_t i = 0; // BAUD rate divisor

  uint8_t p = 0; // initial prsc = CLK/2

  // raw clock prescaler

#ifndef make_bootloader

  // use div instructions

  i = (uint16_t)(clock / (2*baudrate));

#else

  // division via repeated subtraction (minimal size, only for bootloader)

  while (clock >= 2*baudrate) {

    clock -= 2*baudrate;

    i++;

  }

#endif

  // find baud prescaler (12-bit wide))

  while (i >= 0x0fff) {

    if ((p == 2) || (p == 4))

      i >>= 3;

    else

      i >>= 1;

    p++;

  }

  uint32_t clk_prsc = (uint32_t)p;

  clk_prsc = clk_prsc << UART_CTRL_PRSC0;

  uint32_t baud_prsc = (uint32_t)i;

  baud_prsc = baud_prsc - 1;

  baud_prsc = baud_prsc << UART_CTRL_BAUD00;

  uint32_t uart_en = 1;

  uart_en = uart_en << UART_CTRL_EN;

  uint32_t parity_config = (uint32_t)(parity & 3);

  parity_config = parity_config << UART_CTRL_PMODE0;

  uint32_t flow_control = (uint32_t)(flow_con & 3);

  flow_control = flow_control << UART_CTRL_RTS_EN;

  /* Enable UART0 for SIM mode. */

  /* USE THIS ONLY FOR SIMULATION! */

#ifdef UART_SIM_MODE

  #warning <UART_SIM_MODE> is obsolete (but still supported for compatibility). Please consider using the new flag <UART0_SIM_MODE>.

#endif

#if defined UART0_SIM_MODE || defined UART_SIM_MODE

  #warning UART0_SIM_MODE (primary UART) enabled! Sending all UART0.TX data to text.io simulation output instead of real UART0 transmitter. Use this for simulations only!

  uint32_t sim_mode = 1 << UART_CTRL_SIM_MODE;

#else

  uint32_t sim_mode = 0;

#endif

  NEORV32_UART0.CTRL = clk_prsc | baud_prsc | uart_en | parity_config | sim_mode | flow_control;

}

/**********************************************************************//**

 * Disable UART0.

 **************************************************************************/

void neorv32_uart0_disable(void) {

  NEORV32_UART0.CTRL &= ~((uint32_t)(1 << UART_CTRL_EN));

}

/**********************************************************************//**

 * Enable UART0.

 **************************************************************************/

void neorv32_uart0_enable(void) {

  NEORV32_UART0.CTRL |= ((uint32_t)(1 << UART_CTRL_EN));

}

/**********************************************************************//**

 * Send single char via UART0.

 *

 * @note This function is blocking.

 *

 * @param[in] c Char to be send.

 **************************************************************************/

void neorv32_uart0_putc(char c) {

  // wait for previous transfer to finish

  while ((NEORV32_UART0.CTRL & (1<<UART_CTRL_TX_FULL)) != 0); // wait for space in TX FIFO

  NEORV32_UART0.DATA = ((uint32_t)c) << UART_DATA_LSB;

}

/**********************************************************************//**

 * Check if UART0 TX is busy (transmitter busy or data left in TX buffer).

 *

 * @note This function is blocking.

 *

 * @return 0 if idle, 1 if busy

 **************************************************************************/

int neorv32_uart0_tx_busy(void) {

  uint32_t ctrl = NEORV32_UART0.CTRL;

  if (((ctrl & (1<<UART_CTRL_TX_BUSY)) != 0) ||  // TX engine busy

      ((ctrl & (1<<UART_CTRL_TX_EMPTY)) == 0)) { // TX buffer not empty

    return 1;

  }

  return 0;

}

/**********************************************************************//**

 * Get char from UART0.

 *

 * @note This function is blocking and does not check for UART frame/parity errors.

 *

 * @return Received char.

 **************************************************************************/

char neorv32_uart0_getc(void) {

  uint32_t d = 0;

  while (1) {

    d = NEORV32_UART0.DATA;

    if ((d & (1<<UART_DATA_AVAIL)) != 0) { // char received?

      return (char)d;

    }

  }

}

/**********************************************************************//**

 * Get char from UART0 (and check errors).

 *

 * @note This function is non-blocking and checks for frame and parity errors.

 *

 * @param[in,out] data Received char.

 * @return Status code:

 *  0 = char received without errors

 * -1 = nothing received

 * -2 = char received with frame error

 * -3 = char received with parity error

 * -4 = char received with overrun error.

 **************************************************************************/

int neorv32_uart0_getc_safe(char *data) {

  uint32_t uart_rx = NEORV32_UART0.DATA;

  // get received byte (if there is any)

  *data = (char)uart_rx;

  // check if no data available at all

  if ((uart_rx & (1<<UART_DATA_AVAIL)) == 0) {

   return -1;

  }

  // check for frame error

  if (uart_rx & (1<<UART_DATA_FERR)) {

    return -2;

  }

  // check for parity error

  if (uart_rx & (1<<UART_DATA_PERR)) {

    return -3;

  }

  // check for overrun error

  if (uart_rx & (1<<UART_DATA_OVERR)) {

    return -4;

  }

  return 0; // all fine

}

/**********************************************************************//**

 * Check if UART0 has received a char.

 *

 * @note This function is non-blocking.

 * @note Use neorv32_uart0_char_received_get(void) to get the char.

 *

 * @return =!0 when a char has been received.

 **************************************************************************/

int neorv32_uart0_char_received(void) {

  if ((NEORV32_UART0.DATA & (1<<UART_DATA_AVAIL)) != 0) {

    return 1;

  }

  else {

    return 0;

  }

}

/**********************************************************************//**

 * Get a received char from UART0.

 *

 * @note This function is non-blocking.

 * @note Should only be used in combination with neorv32_uart_char_received(void).

 *

 * @return Received char.

 **************************************************************************/

char neorv32_uart0_char_received_get(void) {

  return (char)NEORV32_UART0.DATA;

}

/**********************************************************************//**

 * Print string (zero-terminated) via UART0. Print full line break "\r\n" for every '\n'.

 *

 * @note This function is blocking.

 *

 * @param[in] s Pointer to string.

 **************************************************************************/

void neorv32_uart0_print(const char *s) {

  char c = 0;

  while ((c = *s++)) {

    if (c == '\n') {

      neorv32_uart0_putc('\r');

    }

    neorv32_uart0_putc(c);

  }

}

/**********************************************************************//**

 * Custom version of 'printf' function using UART0.

 *

 * @note This function is blocking.

 *

 * @param[in] format Pointer to format string.

 *

 * <TABLE>

 * <TR><TD>%s</TD><TD>String (array of chars, zero-terminated)</TD></TR>

 * <TR><TD>%c</TD><TD>Single char</TD></TR>

 * <TR><TD>%d/%i</TD><TD>32-bit signed number, printed as decimal</TD></TR>

 * <TR><TD>%u</TD><TD>32-bit unsigned number, printed as decimal</TD></TR>

 * <TR><TD>%x</TD><TD>32-bit number, printed as 8-char hexadecimal - lower-case</TD></TR>

 * <TR><TD>%X</TD><TD>32-bit number, printed as 8-char hexadecimal - upper-case</TD></TR>

 * <TR><TD>%p</TD><TD>32-bit pointer, printed as 8-char hexadecimal - lower-case</TD></TR>

 * </TABLE>

 **************************************************************************/

void neorv32_uart0_printf(const char *format, ...) {

  char c, string_buf[11];

  int32_t n;

  va_list a;

  va_start(a, format);

  while ((c = *format++)) {

    if (c == '%') {

      c = *format++;

      switch (c) {

        case 's': // string

          neorv32_uart0_print(va_arg(a, char*));

          break;

        case 'c': // char

          neorv32_uart0_putc((char)va_arg(a, int));

          break;

        case 'i': // 32-bit signed

        case 'd':

          n = (int32_t)va_arg(a, int32_t);

          if (n < 0) {

            n = -n;

            neorv32_uart0_putc('-');

          }

          __neorv32_uart_itoa((uint32_t)n, string_buf);

          neorv32_uart0_print(string_buf);

          break;

        case 'u': // 32-bit unsigned

          __neorv32_uart_itoa(va_arg(a, uint32_t), string_buf);

          neorv32_uart0_print(string_buf);

          break;

        case 'x': // 32-bit hexadecimal

        case 'p':

        case 'X':

          __neorv32_uart_tohex(va_arg(a, uint32_t), string_buf);

          if (c == 'X') {

            __neorv32_uart_touppercase(11, string_buf);

          }

          neorv32_uart0_print(string_buf);

          break;

        default: // unsupported format

          neorv32_uart0_putc('%');

          neorv32_uart0_putc(c);

          break;

      }

    }

    else {

      if (c == '\n') {

        neorv32_uart0_putc('\r');

      }

      neorv32_uart0_putc(c);

    }

  }

  va_end(a);

}

/**********************************************************************//**

 * Simplified custom version of 'scanf' function for UART0.

 *

 * @note This function is blocking.

 *

 * @param[in,out] buffer Pointer to array of chars to store string.

 * @param[in] max_size Maximum number of chars to sample.

 * @param[in] echo Echo UART input when 1.

 * @return Number of chars read.

 **************************************************************************/

int neorv32_uart0_scan(char *buffer, int max_size, int echo) {

  char c = 0;

  int length = 0;

  while (1) {

    c = neorv32_uart0_getc();

    if (c == '\b') { // BACKSPACE

      if (length != 0) {

        if (echo) {

          neorv32_uart0_print("\b \b"); // delete last char in console

        }

        buffer--;

        length--;

      }

    }

    else if (c == '\r') // carriage return

      break;

    else if ((c >= ' ') && (c <= '~') && (length < (max_size-1))) {

      if (echo) {

        neorv32_uart0_putc(c); // echo

      }

      *buffer++ = c;

      length++;

    }

  }

  *buffer = '\0'; // terminate string

  return length;

}

// #################################################################################################

// Secondary UART (UART1)

// #################################################################################################

/**********************************************************************//**

 * Check if UART1 unit was synthesized.

 *

 * @return 0 if UART1 was not synthesized, 1 if UART1 is available.

 **************************************************************************/

int neorv32_uart1_available(void) {

  if (NEORV32_SYSINFO.SOC & (1 << SYSINFO_SOC_IO_UART1)) {

    return 1;

  }

  else {

    return 0;

  }

}

/**********************************************************************//**

 * Enable and configure secondary UART (UART1).

 *

 * @note The 'UART1_SIM_MODE' compiler flag will configure UART1 for simulation mode: all UART1 TX data will be redirected to simulation output. Use this for simulations only!

 * @note To enable simulation mode add <USER_FLAGS+=-DUART1_SIM_MODE> when compiling.

 *

 * @warning The baud rate is computed using INTEGER operations (truncation errors might occur).

 *

 * @param[in] baudrate Targeted BAUD rate (e.g. 9600).

 * @param[in] parity Parity configuration (00=off, 10=even, 11=odd), see #NEORV32_UART_PARITY_enum.

 * @param[in] flow_con Hardware flow control configuration (00=off, 01=RTS, 10=CTS, 11=RTS/CTS), see #NEORV32_UART_FLOW_CONTROL_enum.

 **************************************************************************/

void neorv32_uart1_setup(uint32_t baudrate, uint8_t parity, uint8_t flow_con) {

  NEORV32_UART1.CTRL = 0; // reset

  uint32_t clock = NEORV32_SYSINFO.CLK;

  uint16_t i = 0; // BAUD rate divisor

  uint8_t p = 0; // initial prsc = CLK/2

  // raw clock prescaler

#ifndef make_bootloader

  // use div instructions

  i = (uint16_t)(clock / (2*baudrate));

#else

  // division via repeated subtraction (minimal size, only for bootloader)

  while (clock >= 2*baudrate) {

    clock -= 2*baudrate;

    i++;

  }

#endif

  // find baud prescaler (12-bit wide))

  while (i >= 0x0fff) {

    if ((p == 2) || (p == 4))

      i >>= 3;

    else

      i >>= 1;

    p++;

  }

  uint32_t clk_prsc = (uint32_t)p;

  clk_prsc = clk_prsc << UART_CTRL_PRSC0;

  uint32_t baud_prsc = (uint32_t)i;

  baud_prsc = baud_prsc - 1;

  baud_prsc = baud_prsc << UART_CTRL_BAUD00;

  uint32_t uart_en = 1;

  uart_en = uart_en << UART_CTRL_EN;

  uint32_t parity_config = (uint32_t)(parity & 3);

  parity_config = parity_config << UART_CTRL_PMODE0;

  uint32_t flow_control = (uint32_t)(flow_con & 3);

  flow_control = flow_control << UART_CTRL_RTS_EN;

  /* Enable UART1 for SIM mode. */

  /* USE THIS ONLY FOR SIMULATION! */

#ifdef UART1_SIM_MODE

  #warning UART1_SIM_MODE (secondary UART) enabled! Sending all UART1.TX data to text.io simulation output instead of real UART1 transmitter. Use this for simulations only!

  uint32_t sim_mode = 1 << UART_CTRL_SIM_MODE;

#else

  uint32_t sim_mode = 0;

#endif

  NEORV32_UART1.CTRL = clk_prsc | baud_prsc | uart_en | parity_config | sim_mode | flow_control;

}

/**********************************************************************//**

 * Disable UART1.

 **************************************************************************/

void neorv32_uart1_disable(void) {

  NEORV32_UART1.CTRL &= ~((uint32_t)(1 << UART_CTRL_EN));

}

/**********************************************************************//**

 * Enable UART1.

 **************************************************************************/

void neorv32_uart1_enable(void) {

  NEORV32_UART1.CTRL |= ((uint32_t)(1 << UART_CTRL_EN));

}

/**********************************************************************//**

 * Send single char via UART1.

 *

 * @note This function is blocking.

 *

 * @param[in] c Char to be send.

 **************************************************************************/

void neorv32_uart1_putc(char c) {

  // wait for previous transfer to finish

  while ((NEORV32_UART1.CTRL & (1<<UART_CTRL_TX_FULL)) != 0); // wait for space in TX FIFO

  NEORV32_UART1.DATA = ((uint32_t)c) << UART_DATA_LSB;

}

/**********************************************************************//**

 * Check if UART1 TX is busy (transmitter busy or data left in TX buffer).

 *

 * @note This function is blocking.

 *

 * @return 0 if idle, 1 if busy

 **************************************************************************/

int neorv32_uart1_tx_busy(void) {

  uint32_t ctrl = NEORV32_UART1.CTRL;

  if (((ctrl & (1<<UART_CTRL_TX_BUSY)) != 0) ||  // TX engine busy

      ((ctrl & (1<<UART_CTRL_TX_EMPTY)) == 0)) { // TX buffer not empty

    return 1;

  }

  return 0;

}

/**********************************************************************//**

 * Get char from UART1.

 *

 * @note This function is blocking and does not check for UART frame/parity errors.

 *

 * @return Received char.

 **************************************************************************/

char neorv32_uart1_getc(void) {

  uint32_t d = 0;

  while (1) {

    d = NEORV32_UART1.DATA;

    if ((d & (1<<UART_DATA_AVAIL)) != 0) { // char received?

      return (char)d;

    }

  }

}

/**********************************************************************//**

 * Get char from UART1 (and check errors).

 *

 * @note This function is non-blocking and checks for frame and parity errors.

 *

 * @param[in,out] data Received char.

 * @return Status code:

 *  0 = char received without errors

 * -1 = nothing received

 * -2 = char received with frame error

 * -3 = char received with parity error

 * -4 = char received with overrun error.

 **************************************************************************/

int neorv32_uart1_getc_safe(char *data) {

  uint32_t uart_rx = NEORV32_UART1.DATA;

  // get received byte (if there is any)

  *data = (char)uart_rx;

  // check if no data available at all

  if ((uart_rx & (1<<UART_DATA_AVAIL)) == 0) {

   return -1;

  }

  // check for frame error

  if (uart_rx & (1<<UART_DATA_FERR)) {

    return -2;

  }

  // check for parity error

  if (uart_rx & (1<<UART_DATA_PERR)) {

    return -3;

  }

  // check for overrun error

  if (uart_rx & (1<<UART_DATA_OVERR)) {

    return -4;

  }

  return 0; // all fine

}

/**********************************************************************//**

 * Check if UART1 has received a char.

 *

 * @note This function is non-blocking.

 * @note Use neorv32_uart0_char_received_get(void) to get the char.

 *

 * @return =!0 when a char has been received.

 **************************************************************************/

int neorv32_uart1_char_received(void) {

  if ((NEORV32_UART1.DATA & (1<<UART_DATA_AVAIL)) != 0) {

    return 1;

  }

  else {

    return 0;

  }

}

/**********************************************************************//**

 * Get a received char from UART1.

 *

 * @note This function is non-blocking.

 * @note Should only be used in combination with neorv32_uart_char_received(void).

 *

 * @return Received char.

 **************************************************************************/

char neorv32_uart1_char_received_get(void) {

  return (char)NEORV32_UART1.DATA;

}