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

// # << NEORV32: neorv32_rte.c - NEORV32 Runtime Environment >>                                    #

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

// # BSD 3-Clause License                                                                          #

// #                                                                                               #

// # Copyright (c) 2021, Stephan Nolting. All rights reserved.                                     #

// #                                                                                               #

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

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// #    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_rte.c

 * @author Stephan Nolting

 * @brief NEORV32 Runtime Environment.

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

#include "neorv32.h"

#include "neorv32_rte.h"

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

 * The >private< trap vector look-up table of the NEORV32 RTE.

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

static uint32_t __neorv32_rte_vector_lut[NEORV32_RTE_NUM_TRAPS] __attribute__((unused)); // trap handler vector table

// private functions

static void __attribute__((__interrupt__)) __neorv32_rte_core(void) __attribute__((aligned(16))) __attribute__((unused));

static void __neorv32_rte_debug_exc_handler(void)     __attribute__((unused));

static void __neorv32_rte_print_true_false(int state) __attribute__((unused));

static void __neorv32_rte_print_hex_word(uint32_t num);

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

 * Setup NEORV32 runtime environment.

 *

 * @note This function installs a debug handler for ALL exception and interrupt sources, which

 * gives detailed information about the exception/interrupt. Actual handler can be installed afterwards

 * via neorv32_rte_exception_install(uint8_t id, void (*handler)(void)).

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

void neorv32_rte_setup(void) {

  // configure trap handler base address

  uint32_t mtvec_base = (uint32_t)(&__neorv32_rte_core);

  neorv32_cpu_csr_write(CSR_MTVEC, mtvec_base);

  // install debug handler for all sources

  uint8_t id;

  for (id = 0; id < (sizeof(__neorv32_rte_vector_lut)/sizeof(__neorv32_rte_vector_lut[0])); id++) {

    neorv32_rte_exception_uninstall(id); // this will configure the debug handler

  }

}

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

 * Install exception handler function to NEORV32 runtime environment.

 *

 * @note Interrupt sources have to be explicitly enabled by the user via the CSR.mie bits via neorv32_cpu_irq_enable(uint8_t irq_sel)

 * and the global interrupt enable bit mstatus.mie via neorv32_cpu_eint(void).

 *

 * @param[in] id Identifier (type) of the targeted exception. See #NEORV32_RTE_TRAP_enum.

 * @param[in] handler The actual handler function for the specified exception (function MUST be of type "void function(void);").

 * @return 0 if success, 1 if error (invalid id or targeted exception not supported).

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

int neorv32_rte_exception_install(uint8_t id, void (*handler)(void)) {

  // id valid?

  if ((id >= RTE_TRAP_I_MISALIGNED) && (id <= CSR_MIE_FIRQ15E)) {

    __neorv32_rte_vector_lut[id] = (uint32_t)handler; // install handler

    return 0;

  }

  return 1;

}

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

 * Uninstall exception handler function from NEORV32 runtime environment, which was

 * previously installed via neorv32_rte_exception_install(uint8_t id, void (*handler)(void)).

 *

 * @note Interrupt sources have to be explicitly disabled by the user via the CSR.mie bits via neorv32_cpu_irq_disable(uint8_t irq_sel)

 * and/or the global interrupt enable bit mstatus.mie via neorv32_cpu_dint(void).

 *

 * @param[in] id Identifier (type) of the targeted exception. See #NEORV32_RTE_TRAP_enum.

 * @return 0 if success, 1 if error (invalid id or targeted exception not supported).

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

int neorv32_rte_exception_uninstall(uint8_t id) {

  // id valid?

  if ((id >= RTE_TRAP_I_MISALIGNED) && (id <= CSR_MIE_FIRQ15E)) {

    __neorv32_rte_vector_lut[id] = (uint32_t)(&__neorv32_rte_debug_exc_handler); // use dummy handler in case the exception is accidently triggered

    return 0;

  }

  return 1;

}

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

 * This is the core of the NEORV32 RTE.

 *

 * @note This function must no be explicitly used by the user.

 * @note The RTE core uses mscratch CSR to store the trap-causing mepc for further (user-defined) processing.

 *

 * @warning When using the the RTE, this function is the ONLY function that can use the 'interrupt' attribute!

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

static void __attribute__((__interrupt__)) __attribute__((aligned(16)))  __neorv32_rte_core(void) {

  register uint32_t rte_mepc = neorv32_cpu_csr_read(CSR_MEPC);

  neorv32_cpu_csr_write(CSR_MSCRATCH, rte_mepc); // store for later

  register uint32_t rte_mcause = neorv32_cpu_csr_read(CSR_MCAUSE);

  // compute return address

  if (((int32_t)rte_mcause) >= 0) { // modify pc only if exception (MSB cleared)

    // get low half word of faulting instruction

    register uint32_t rte_trap_inst;

    asm volatile ("lh %[result], 0(%[input_i])" : [result] "=r" (rte_trap_inst) : [input_i] "r" (rte_mepc));

    if ((rte_trap_inst & 3) == 3) { // faulting instruction is uncompressed instruction

      rte_mepc += 4;

    }

    else { // faulting instruction is compressed instruction

      rte_mepc += 2;

    }

    // store new return address

    neorv32_cpu_csr_write(CSR_MEPC, rte_mepc);

  }

  // find according trap handler

  register uint32_t rte_handler = (uint32_t)(&__neorv32_rte_debug_exc_handler);

  switch (rte_mcause) {

    case TRAP_CODE_I_MISALIGNED: rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_I_MISALIGNED]; break;

    case TRAP_CODE_I_ACCESS:     rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_I_ACCESS]; break;

    case TRAP_CODE_I_ILLEGAL:    rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_I_ILLEGAL]; break;

    case TRAP_CODE_BREAKPOINT:   rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_BREAKPOINT]; break;

    case TRAP_CODE_L_MISALIGNED: rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_L_MISALIGNED]; break;

    case TRAP_CODE_L_ACCESS:     rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_L_ACCESS]; break;

    case TRAP_CODE_S_MISALIGNED: rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_S_MISALIGNED]; break;

    case TRAP_CODE_S_ACCESS:     rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_S_ACCESS]; break;

    case TRAP_CODE_UENV_CALL:    rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_UENV_CALL]; break;

    case TRAP_CODE_MENV_CALL:    rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_MENV_CALL]; break;

    case TRAP_CODE_NMI:          rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_NMI]; break;

    case TRAP_CODE_MSI:          rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_MSI]; break;

    case TRAP_CODE_MTI:          rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_MTI]; break;

    case TRAP_CODE_MEI:          rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_MEI]; break;

    case TRAP_CODE_FIRQ_0:       rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_0]; break;

    case TRAP_CODE_FIRQ_1:       rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_1]; break;

    case TRAP_CODE_FIRQ_2:       rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_2]; break;

    case TRAP_CODE_FIRQ_3:       rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_3]; break;

    case TRAP_CODE_FIRQ_4:       rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_4]; break;

    case TRAP_CODE_FIRQ_5:       rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_5]; break;

    case TRAP_CODE_FIRQ_6:       rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_6]; break;

    case TRAP_CODE_FIRQ_7:       rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_7]; break;

    case TRAP_CODE_FIRQ_8:       rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_8]; break;

    case TRAP_CODE_FIRQ_9:       rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_9]; break;

    case TRAP_CODE_FIRQ_10:      rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_10]; break;

    case TRAP_CODE_FIRQ_11:      rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_11]; break;

    case TRAP_CODE_FIRQ_12:      rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_12]; break;

    case TRAP_CODE_FIRQ_13:      rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_13]; break;

    case TRAP_CODE_FIRQ_14:      rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_14]; break;

    case TRAP_CODE_FIRQ_15:      rte_handler = __neorv32_rte_vector_lut[RTE_TRAP_FIRQ_15]; break;

    default: break;

  }

  // execute handler

  void (*handler_pnt)(void);

  handler_pnt = (void*)rte_handler;

  (*handler_pnt)();

}

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

 * NEORV32 runtime environment: Debug exception handler, printing various exception/interrupt information via UART.

 * @note This function is used by neorv32_rte_exception_uninstall(void) only.

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

static void __neorv32_rte_debug_exc_handler(void) {

  if (neorv32_uart0_available() == 0) {

    return; // handler cannot output anything if UART0 is not implemented

  }

  char tmp;

  // intro

  neorv32_uart_print("<RTE> ");

  // cause

  register uint32_t trap_cause = neorv32_cpu_csr_read(CSR_MCAUSE);

  tmp = (char)(trap_cause & 0xf);

  if (tmp >= 10) {

    tmp = 'a' + (tmp - 10);

  }

  else {

    tmp = '0' + tmp;

  }

  switch (trap_cause) {

    case TRAP_CODE_I_MISALIGNED: neorv32_uart_print("Instruction address misaligned"); break;

    case TRAP_CODE_I_ACCESS:     neorv32_uart_print("Instruction access fault"); break;

    case TRAP_CODE_I_ILLEGAL:    neorv32_uart_print("Illegal instruction"); break;

    case TRAP_CODE_BREAKPOINT:   neorv32_uart_print("Breakpoint"); break;

    case TRAP_CODE_L_MISALIGNED: neorv32_uart_print("Load address misaligned"); break;

    case TRAP_CODE_L_ACCESS:     neorv32_uart_print("Load access fault"); break;

    case TRAP_CODE_S_MISALIGNED: neorv32_uart_print("Store address misaligned"); break;

    case TRAP_CODE_S_ACCESS:     neorv32_uart_print("Store access fault"); break;

    case TRAP_CODE_UENV_CALL:    neorv32_uart_print("Environment call from U-mode"); break;

    case TRAP_CODE_MENV_CALL:    neorv32_uart_print("Environment call from M-mode"); break;

    case TRAP_CODE_MSI:          neorv32_uart_print("Machine software interrupt"); break;

    case TRAP_CODE_MTI:          neorv32_uart_print("Machine timer interrupt"); break;

    case TRAP_CODE_MEI:          neorv32_uart_print("Machine external interrupt"); break;

    case TRAP_CODE_FIRQ_0:

    case TRAP_CODE_FIRQ_1:

    case TRAP_CODE_FIRQ_2:

    case TRAP_CODE_FIRQ_3:

    case TRAP_CODE_FIRQ_4:

    case TRAP_CODE_FIRQ_5:

    case TRAP_CODE_FIRQ_6:

    case TRAP_CODE_FIRQ_7:

    case TRAP_CODE_FIRQ_8:

    case TRAP_CODE_FIRQ_9:

    case TRAP_CODE_FIRQ_10:

    case TRAP_CODE_FIRQ_11:

    case TRAP_CODE_FIRQ_12:

    case TRAP_CODE_FIRQ_13:

    case TRAP_CODE_FIRQ_14:

    case TRAP_CODE_FIRQ_15:      neorv32_uart_print("Fast interrupt "); neorv32_uart_putc(tmp); break;

    default:                     neorv32_uart_print("Unknown trap cause: "); __neorv32_rte_print_hex_word(trap_cause); break;

  }

  // instruction address

  neorv32_uart_print(" @ PC=");

  __neorv32_rte_print_hex_word(neorv32_cpu_csr_read(CSR_MSCRATCH)); // rte core stores actual mepc to mscratch

  // additional info

  neorv32_uart_print(", MTVAL=");

  __neorv32_rte_print_hex_word(neorv32_cpu_csr_read(CSR_MTVAL));

  neorv32_uart_print(" </RTE>");

}

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

 * NEORV32 runtime environment: Print hardware configuration information via UART

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

void neorv32_rte_print_hw_config(void) {

  if (neorv32_uart0_available() == 0) {

    return; // cannot output anything if UART0 is not implemented

  }

  uint32_t tmp;

  int i;

  char c;

  neorv32_uart_printf("\n\n<<< Processor Configuration Overview >>>\n");

  // Processor - general stuff

  neorv32_uart0_printf("\n=== << General >> ===\n"

                       "Clock:         %u Hz\n"

                       "User ID:       0x%x\n", SYSINFO_CLK, SYSINFO_USER_CODE);

  neorv32_uart0_printf("Full HW reset: "); __neorv32_rte_print_true_false(SYSINFO_FEATURES & (1 << SYSINFO_FEATURES_HW_RESET));

  neorv32_uart0_printf("Boot Config.:  Boot ");

  if (SYSINFO_FEATURES & (1 << SYSINFO_FEATURES_BOOTLOADER)) {

    neorv32_uart0_printf("via Bootloader\n");

  }

  else {

    neorv32_uart0_printf("from memory (@ 0x%x)\n", SYSINFO_ISPACE_BASE);

  }

  neorv32_uart0_printf("On-chip debug: "); __neorv32_rte_print_true_false(SYSINFO_FEATURES & (1 << SYSINFO_FEATURES_OCD));

  // CPU configuration

  neorv32_uart0_printf("\n=== << CPU >> ===\n");

  // ID

  neorv32_uart0_printf("Hart ID:           0x%x\n"

                       "Vendor ID:         0x%x\n", neorv32_cpu_csr_read(CSR_MHARTID), neorv32_cpu_csr_read(CSR_MVENDORID));

  tmp = neorv32_cpu_csr_read(CSR_MARCHID);

  neorv32_uart0_printf("Architecture ID:   0x%x", tmp);

  if (tmp == NEORV32_ARCHID) {

    neorv32_uart0_printf(" (NEORV32)");

  }

  // hardware version

  neorv32_uart0_printf("\nImplementation ID: 0x%x (", neorv32_cpu_csr_read(CSR_MIMPID));

  neorv32_rte_print_hw_version();

  neorv32_uart0_putc(')');

  // CPU architecture and endianness

  neorv32_uart0_printf("\nArchitecture:      ");

  tmp = neorv32_cpu_csr_read(CSR_MISA);

  tmp = (tmp >> 30) & 0x03;

  if (tmp == 1) {

    neorv32_uart0_printf("rv32-little");

  }

  else {

    neorv32_uart0_printf("unknown");

  }

  // CPU extensions

  neorv32_uart0_printf("\nISA extensions:    ");

  tmp = neorv32_cpu_csr_read(CSR_MISA);

  for (i=0; i<26; i++) {

    if (tmp & (1 << i)) {

      c = (char)('A' + i);

      neorv32_uart0_putc(c);

      neorv32_uart0_putc(' ');

    }

  }

  // Z* CPU extensions (from custom "mzext" CSR)

  tmp = neorv32_cpu_csr_read(CSR_MZEXT);

  if (tmp & (1<<CSR_MZEXT_ZICSR)) {

    neorv32_uart0_printf("Zicsr ");

  }

  if (tmp & (1<<CSR_MZEXT_ZIFENCEI)) {

    neorv32_uart0_printf("Zifencei ");

  }

  if (tmp & (1<<CSR_MZEXT_ZMMUL)) {

    neorv32_uart0_printf("Zmmul ");

  }

  if (tmp & (1<<CSR_MZEXT_ZFINX)) {

    neorv32_uart0_printf("Zfinx ");

  }

  if (tmp & (1<<CSR_MZEXT_ZXNOCNT)) {

    neorv32_uart0_printf("Zxnocnt(!) ");

  }

  if (tmp & (1<<CSR_MZEXT_ZXSCNT)) {

    neorv32_uart0_printf("Zxscnt(!) ");

  }

  if (tmp & (1<<CSR_MZEXT_DEBUGMODE)) {

    neorv32_uart0_printf("Debug-Mode ");

  }

  // check physical memory protection

  neorv32_uart0_printf("\nPMP:               ");

  uint32_t pmp_num_regions = neorv32_cpu_pmp_get_num_regions();

  if (pmp_num_regions != 0)  {

    neorv32_uart0_printf("%u regions, %u bytes minimal granularity\n", pmp_num_regions, neorv32_cpu_pmp_get_granularity());

  }

  else {

    neorv32_uart0_printf("not implemented\n");

  }

  // check hardware performance monitors

  neorv32_uart0_printf("HPM Counters:      %u counters, %u-bit wide\n", neorv32_cpu_hpm_get_counters(), neorv32_cpu_hpm_get_size());

  // Memory configuration

  neorv32_uart0_printf("\n=== << Memory Configuration >> ===\n");

  neorv32_uart0_printf("Instr. base address:  0x%x\n", SYSINFO_ISPACE_BASE);

  // IMEM

  neorv32_uart0_printf("Internal IMEM:        ");

  if (SYSINFO_FEATURES & (1 << SYSINFO_FEATURES_MEM_INT_IMEM)) {

    neorv32_uart0_printf("yes, %u bytes\n", SYSINFO_IMEM_SIZE);

  }

  else {

    neorv32_uart0_printf("no\n");

  }

  // DMEM

  neorv32_uart0_printf("Data base address:    0x%x\n", SYSINFO_DSPACE_BASE);

  neorv32_uart0_printf("Internal DMEM:        ");

  if (SYSINFO_FEATURES & (1 << SYSINFO_FEATURES_MEM_INT_DMEM)) { neorv32_uart0_printf("yes, %u bytes\n", SYSINFO_DMEM_SIZE); }

  else {  neorv32_uart0_printf("no\n"); }

  // i-cache

  neorv32_uart0_printf("Internal i-cache:     ");

  __neorv32_rte_print_true_false(SYSINFO_FEATURES & (1 << SYSINFO_FEATURES_ICACHE));

  if (SYSINFO_FEATURES & (1 << SYSINFO_FEATURES_ICACHE)) {

    neorv32_uart0_printf("- ");

    uint32_t ic_block_size = (SYSINFO_CACHE >> SYSINFO_CACHE_IC_BLOCK_SIZE_0) & 0x0F;

    if (ic_block_size) {

      ic_block_size = 1 << ic_block_size;

    }

    else {

      ic_block_size = 0;

    }

    uint32_t ic_num_blocks = (SYSINFO_CACHE >> SYSINFO_CACHE_IC_NUM_BLOCKS_0) & 0x0F;

    if (ic_num_blocks) {

      ic_num_blocks = 1 << ic_num_blocks;

    }

    else {

      ic_num_blocks = 0;

    }

    uint32_t ic_associativity = (SYSINFO_CACHE >> SYSINFO_CACHE_IC_ASSOCIATIVITY_0) & 0x0F;

    ic_associativity = 1 << ic_associativity;

    neorv32_uart0_printf("%u bytes: %u set(s), %u block(s) per set, %u bytes per block", ic_associativity*ic_num_blocks*ic_block_size, ic_associativity, ic_num_blocks, ic_block_size);

    if (ic_associativity == 1) {

      neorv32_uart0_printf(" (direct-mapped)\n");

    }

    else if (((SYSINFO_CACHE >> SYSINFO_CACHE_IC_REPLACEMENT_0) & 0x0F) == 1) {

      neorv32_uart0_printf(" (LRU replacement policy)\n");

    }

    else {

      neorv32_uart0_printf("\n");

    }

  }

  neorv32_uart0_printf("Ext. bus interface:   ");

  __neorv32_rte_print_true_false(SYSINFO_FEATURES & (1 << SYSINFO_FEATURES_MEM_EXT));

  neorv32_uart0_printf("Ext. bus Endianness:  ");

  if (SYSINFO_FEATURES & (1 << SYSINFO_FEATURES_MEM_EXT_ENDIAN)) {

    neorv32_uart0_printf("big\n");

  }

  else {

    neorv32_uart0_printf("little\n");

  }

  // peripherals

  neorv32_uart0_printf("\n=== << Peripherals >> ===\n");

  tmp = SYSINFO_FEATURES;

  neorv32_uart0_printf("GPIO   - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_GPIO));

  neorv32_uart0_printf("MTIME  - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_MTIME));

  neorv32_uart0_printf("UART0  - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_UART0));

  neorv32_uart0_printf("UART1  - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_UART1));

  neorv32_uart0_printf("SPI    - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_SPI));

  neorv32_uart0_printf("TWI    - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_TWI));

  neorv32_uart0_printf("PWM    - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_PWM));

  neorv32_uart0_printf("WDT    - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_WDT));

  neorv32_uart0_printf("TRNG   - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_TRNG));

  neorv32_uart0_printf("CFS    - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_CFS));

  neorv32_uart0_printf("SLINK  - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_SLINK));

  neorv32_uart0_printf("NEOLED - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_NEOLED));

  neorv32_uart0_printf("XIRQ   - "); __neorv32_rte_print_true_false(tmp & (1 << SYSINFO_FEATURES_IO_XIRQ));

}

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

 * NEORV32 runtime environment: Private function to print yes or no.

 * @note This function is used by neorv32_rte_print_hw_config(void) only.

 *

 * @param[in] state Print 'yes' when !=0, print '0' when 0

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

static void __neorv32_rte_print_true_false(int state) {

  if (state) {

    neorv32_uart0_print("yes\n");

  }

  else {

    neorv32_uart0_print("no\n");

  }

}

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

 * NEORV32 runtime environment: Private function to print 32-bit number

 * as 8-digit hexadecimal value (with "0x" suffix).

 *

 * @param[in] num Number to print as hexadecimal.

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

void __neorv32_rte_print_hex_word(uint32_t num) {

  static const char hex_symbols[16] = "0123456789ABCDEF";

  neorv32_uart0_print("0x");

  int i;

  for (i=0; i<8; i++) {

    uint32_t index = (num >> (28 - 4*i)) & 0xF;

    neorv32_uart0_putc(hex_symbols[index]);

  }

}

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

 * NEORV32 runtime environment: Print the processor version in human-readable format.

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

void neorv32_rte_print_hw_version(void) {

  uint32_t i;

  char tmp, cnt;

  if (neorv32_uart0_available() == 0) {

    return; // cannot output anything if UART0 is not implemented

  }

  for (i=0; i<4; i++) {

    tmp = (char)(neorv32_cpu_csr_read(CSR_MIMPID) >> (24 - 8*i));

    // serial division

    cnt = 0;

    while (tmp >= 16) {

      tmp = tmp - 16;

      cnt++;

    }

    if (cnt) {

      neorv32_uart0_putc('0' + cnt);

    }

    neorv32_uart0_putc('0' + tmp);

    if (i < 3) {

      neorv32_uart0_putc('.');

    }

  }

}

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

 * NEORV32 runtime environment: Print project credits

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

void neorv32_rte_print_credits(void) {

  if (neorv32_uart0_available() == 0) {

    return; // cannot output anything if UART0 is not implemented

  }

  neorv32_uart0_print("The NEORV32 RISC-V Processor\n"

                      "(c) Stephan Nolting\n"

                      "BSD 3-Clause License\n"

                      "https://github.com/stnolting/neorv32\n\n");

}

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

 * NEORV32 runtime environment: Print project logo

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

void neorv32_rte_print_logo(void) {

  const uint32_t logo_data_c[11][4] =

  {

    {0b00000000000000000000000000000000,0b00000000000000000000000000000000,0b00000000000000000000000110000000,0b00000000000000000000000000000000},

    {0b00000000000000000000000000000000,0b00000000000000000000000000000000,0b00000000000000000000000110000000,0b00110001100011000000000000000000},

    {0b01100000110001111111110001111111,0b10000111111110001100000011000111,0b11111000011111111000000110000000,0b11111111111111110000000000000000},

    {0b11110000110011000000000011000000,0b11001100000011001100000011001100,0b00001100110000001100000110000011,0b11000000000000111100000000000000},

    {0b11011000110011000000000011000000,0b11001100000011001100000011000000,0b00001100000000011000000110000000,0b11000111111000110000000000000000},

    {0b11001100110011111111100011000000,0b11001111111110001100000011000000,0b11111000000001100000000110000011,0b11000111111000111100000000000000},

    {0b11000110110011000000000011000000,0b11001100001100000110000110000000,0b00001100000110000000000110000000,0b11000111111000110000000000000000},

    {0b11000011110011000000000011000000,0b11001100000110000011001100001100,0b00001100011000000000000110000011,0b11000000000000111100000000000000},

    {0b11000001100001111111110001111111,0b10001100000011000000110000000111,0b11111000111111111100000110000000,0b11111111111111110000000000000000},

    {0b00000000000000000000000000000000,0b00000000000000000000000000000000,0b00000000000000000000000110000000,0b00110001100011000000000000000000},

    {0b00000000000000000000000000000000,0b00000000000000000000000000000000,0b00000000000000000000000110000000,0b00000000000000000000000000000000}

  };

  int u,v,w;

  uint32_t tmp;

  if (neorv32_uart0_available() == 0) {

    return; // cannot output anything if UART0 is not implemented

  }

  for (u=0; u<11; u++) {

    neorv32_uart0_print("\n");

    for (v=0; v<4; v++) {

      tmp = logo_data_c[u][v];

      for (w=0; w<32; w++){

        if (((int32_t)tmp) < 0) { // check MSB

          neorv32_uart0_putc('#');

        }

        else {

          neorv32_uart0_putc(' ');

        }

        tmp <<= 1;

      }

    }

  }

  neorv32_uart0_print("\n");

}

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

 * NEORV32 runtime environment: Print project license

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

void neorv32_rte_print_license(void) {

  if (neorv32_uart0_available() == 0) {

    return; // cannot output anything if UART0 is not implemented

  }

  neorv32_uart_print(

  "\n"

  "BSD 3-Clause License\n"

  "\n"