[sw/lib] initialize all variables (and arrays)

sw/lib/source/neorv32_aux.c

@@ -26,7 +26,7 @@
  **************************************************************************/
 uint64_t neorv32_aux_date2unixtime(date_t* date) {
 
-  uint32_t y, m, d, t;
+  uint32_t y = 0, m = 0, d = 0, t = 0;
 
   // range checks
   if (date->year < 1970) {
@@ -83,7 +83,7 @@ uint64_t neorv32_aux_date2unixtime(date_t* date) {
  **************************************************************************/
 void neorv32_aux_unixtime2date(uint64_t unixtime, date_t* date) {
 
-  uint32_t a, b, c, d, e, f;
+  uint32_t a = 0, b = 0, c = 0, d = 0, e = 0, f = 0;
 
   // invalid
   if (unixtime < 1) {
@@ -213,9 +213,14 @@ uint32_t neorv32_aux_xorshift32(void) {
 void neorv32_aux_itoa(char *buffer, uint32_t num, uint32_t base) {
 
   const char digits[16] = {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};
-  char tmp[33];
-  char *tmp_ptr;
-  unsigned int i;
+  char __attribute__((aligned(4))) tmp[36]; // optimize stack layout
+  char *tmp_ptr = 0;
+  unsigned int i = 0;
+
+  // prevent uninitialized stack bytes
+  for (i=0; i<sizeof(tmp); i++) {
+    tmp[i] = 0;
+  }
 
   if ((base < 2) || (base > 16)) { // invalid base?
     *buffer = '\0';
@@ -258,8 +263,8 @@ void neorv32_aux_print_hw_config(void) {
     return; // cannot output anything if UART0 is not implemented
   }
 
-  uint32_t tmp;
-  int i;
+  uint32_t tmp = 0;
+  int i = 0;
 
   neorv32_uart0_printf("\n\n<< NEORV32 Processor Configuration >>\n\n");
 
@@ -540,8 +545,8 @@ void neorv32_aux_print_hw_config(void) {
  **************************************************************************/
 void neorv32_aux_print_hw_version(uint32_t impid) {
 
-  uint32_t i;
-  char tmp, cnt;
+  uint32_t i = 0;
+  char tmp = 0, cnt = 0;
 
   if (neorv32_uart0_available() != 0) { // cannot output anything if UART0 is not implemented
     for (i=0; i<4; i++) {
@@ -598,9 +603,9 @@ void neorv32_aux_print_logo(void) {
     {0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0300, 0xc630}
   };
 
-  unsigned int x, y, z;
-  uint16_t tmp;
-  char c;
+  unsigned int x = 0, y = 0, z = 0;
+  uint16_t tmp = 0;
+  char c = 0;
 
   if (neorv32_uart0_available() != 0) { // cannot output anything if UART0 is not implemented
     for (y=0; y<(sizeof(logo_c) / sizeof(logo_c[0])); y++) {

sw/lib/source/neorv32_clint.c

@@ -9,8 +9,6 @@
 /**
  * @file neorv32_clint.c
  * @brief Hardware Local Interruptor (CLINT) HW driver source file.
- *
- * @see https://stnolting.github.io/neorv32/sw/files.html
  */
 
 #include <neorv32.h>
@@ -93,7 +91,7 @@ void neorv32_clint_time_set(uint64_t time) {
  **************************************************************************/
 uint64_t neorv32_clint_time_get(void) {
 
-  uint32_t tmp1, tmp2, tmp3;
+  uint32_t tmp1 = 0, tmp2 = 0, tmp3 = 0;
   while(1) {
     tmp1 = NEORV32_CLINT->MTIME.uint32[1];
     tmp2 = NEORV32_CLINT->MTIME.uint32[0];

sw/lib/source/neorv32_cpu.c

@@ -1,7 +1,7 @@
 // ================================================================================ //
 // The NEORV32 RISC-V Processor - https://github.com/stnolting/neorv32              //
 // Copyright (c) NEORV32 contributors.                                              //
-// Copyright (c) 2020 - 2024 Stephan Nolting. All rights reserved.                  //
+// Copyright (c) 2020 - 2025 Stephan Nolting. All rights reserved.                  //
 // Licensed under the BSD-3-Clause license, see LICENSE for details.                //
 // SPDX-License-Identifier: BSD-3-Clause                                            //
 // ================================================================================ //
@@ -9,8 +9,6 @@
 /**
  * @file neorv32_cpu.c
  * @brief CPU Core Functions HW driver source file.
- *
- * @see https://stnolting.github.io/neorv32/sw/files.html
  */
 
 #include <neorv32.h>
@@ -45,9 +43,7 @@
  **************************************************************************/
 uint64_t neorv32_cpu_get_cycle(void) {
 
-  subwords64_t cycles;
-
-  uint32_t tmp1, tmp2, tmp3;
+  uint32_t tmp1 = 0, tmp2 = 0, tmp3 = 0;
   while(1) {
     tmp1 = neorv32_cpu_csr_read(CSR_CYCLEH);
     tmp2 = neorv32_cpu_csr_read(CSR_CYCLE);
@@ -57,6 +53,7 @@ uint64_t neorv32_cpu_get_cycle(void) {
     }
   }
 
+  subwords64_t cycles;
   cycles.uint32[0] = tmp2;
   cycles.uint32[1] = tmp3;
 
@@ -72,7 +69,6 @@ uint64_t neorv32_cpu_get_cycle(void) {
 void neorv32_cpu_set_mcycle(uint64_t value) {
 
   subwords64_t cycles;
-
   cycles.uint64 = value;
 
   // prevent low-to-high carry while writing
@@ -89,9 +85,7 @@ void neorv32_cpu_set_mcycle(uint64_t value) {
  **************************************************************************/
 uint64_t neorv32_cpu_get_instret(void) {
 
-  subwords64_t cycles;
-
-  uint32_t tmp1, tmp2, tmp3;
+  uint32_t tmp1 = 0, tmp2 = 0, tmp3 = 0;
   while(1) {
     tmp1 = neorv32_cpu_csr_read(CSR_INSTRETH);
     tmp2 = neorv32_cpu_csr_read(CSR_INSTRET);
@@ -101,6 +95,7 @@ uint64_t neorv32_cpu_get_instret(void) {
     }
   }
 
+  subwords64_t cycles;
   cycles.uint32[0] = tmp2;
   cycles.uint32[1] = tmp3;
 
@@ -116,7 +111,6 @@ uint64_t neorv32_cpu_get_instret(void) {
 void neorv32_cpu_set_minstret(uint64_t value) {
 
   subwords64_t cycles;
-
   cycles.uint64 = value;
 
   // prevent low-to-high carry while writing
@@ -144,9 +138,8 @@ void neorv32_cpu_delay_ms(uint32_t time_ms) {
 
   // use CYCLE CSRs
   // -------------------------------------------
-  if ( (neorv32_cpu_csr_read(CSR_MXISA) & (1<<CSR_MXISA_ZICNTR)) && // cycle counter available?
-       ((neorv32_cpu_csr_read(CSR_MCOUNTINHIBIT) & (1<<CSR_MCOUNTINHIBIT_CY)) == 0) ) { // counter is running?
-
+  if ((neorv32_cpu_csr_read(CSR_MXISA) & (1<<CSR_MXISA_ZICNTR)) && // cycle counter available?
+      ((neorv32_cpu_csr_read(CSR_MCOUNTINHIBIT) & (1<<CSR_MCOUNTINHIBIT_CY)) == 0)) { // counter is running?
     tmp = neorv32_cpu_get_cycle() + wait_cycles;
     while (neorv32_cpu_get_cycle() < tmp);
   }
@@ -154,7 +147,6 @@ void neorv32_cpu_delay_ms(uint32_t time_ms) {
   // use MTIME machine timer
   // -------------------------------------------
   else if (NEORV32_SYSINFO->SOC & (1 << SYSINFO_SOC_IO_CLINT)) { // MTIMER available?
-
     tmp = neorv32_clint_time_get() + wait_cycles;
     while (neorv32_clint_time_get() < tmp);
   }
@@ -162,10 +154,8 @@ void neorv32_cpu_delay_ms(uint32_t time_ms) {
   // simple loop as fall-back (imprecise!)
   // -------------------------------------------
   else {
-
     const uint32_t loop_cycles_c = 16; // clock cycles per iteration of the ASM loop
     uint32_t iterations = (uint32_t)(wait_cycles / loop_cycles_c);
-
     asm volatile (" .balign 4                                        \n" // make sure this is 32-bit aligned
                   " __neorv32_cpu_delay_ms_start:                    \n"
                   " beq  %[cnt_r], zero, __neorv32_cpu_delay_ms_end  \n" // 3 cycles (not taken)
@@ -408,7 +398,7 @@ uint32_t neorv32_cpu_hpm_get_num_counters(void) {
  **************************************************************************/
 uint32_t neorv32_cpu_hpm_get_size(void) {
 
-  uint32_t tmp, cnt;
+  uint32_t tmp = 0, cnt = 0;
 
   // HPMs implemented at all?
   if ((neorv32_cpu_csr_read(CSR_MXISA) & (1<<CSR_MXISA_ZIHPM)) == 0) {

sw/lib/source/neorv32_rte.c

@@ -9,8 +9,6 @@
 /**
  * @file neorv32_rte.c
  * @brief NEORV32 Runtime Environment.
- *
- * @see https://stnolting.github.io/neorv32/sw/files.html
  */
 
 #include <neorv32.h>
@@ -155,7 +153,7 @@ void __attribute__((__naked__,aligned(4))) neorv32_rte_core(void) {
   asm volatile ("fence");
 
   // find according trap handler base address
-  uint32_t handler_base;
+  uint32_t handler_base = 0;
   switch (neorv32_cpu_csr_read(CSR_MCAUSE)) {
     case TRAP_CODE_I_ACCESS:     handler_base = __neorv32_rte_vector_lut[RTE_TRAP_I_ACCESS];     break;
     case TRAP_CODE_I_ILLEGAL:    handler_base = __neorv32_rte_vector_lut[RTE_TRAP_I_ILLEGAL];    break;
@@ -419,8 +417,8 @@ void neorv32_rte_debug_handler(void) {
  **************************************************************************/
 void __neorv32_rte_print_hex(uint32_t num, int digits) {
 
-  int i;
-  static const char hex_symbols[] = "0123456789ABCDEF";
+  int i = 0;
+  const char hex_symbols[] = "0123456789ABCDEF";
 
   if (neorv32_uart0_available() != 0) { // cannot output anything if UART0 is not implemented
     neorv32_uart0_putc('0');

sw/lib/source/neorv32_trng.c

@@ -1,7 +1,7 @@
 // ================================================================================ //
 // The NEORV32 RISC-V Processor - https://github.com/stnolting/neorv32              //
 // Copyright (c) NEORV32 contributors.                                              //
-// Copyright (c) 2020 - 2024 Stephan Nolting. All rights reserved.                  //
+// Copyright (c) 2020 - 2025 Stephan Nolting. All rights reserved.                  //
 // Licensed under the BSD-3-Clause license, see LICENSE for details.                //
 // SPDX-License-Identifier: BSD-3-Clause                                            //
 // ================================================================================ //
@@ -9,10 +9,6 @@
 /**
  * @file neorv32_trng.c
  * @brief True Random Number Generator (TRNG) HW driver source file.
- *
- * @note These functions should only be used if the TRNG unit was synthesized (IO_TRNG_EN = true).
- *
- * @see https://stnolting.github.io/neorv32/sw/files.html
  */
 
 #include <neorv32.h>
@@ -42,7 +38,7 @@ void neorv32_trng_enable(void) {
   NEORV32_TRNG->CTRL = 0; // disable and reset
 
   // wait for all internal components to reset
-  int i;
+  int i = 0;
   for (i=0; i<256; i++) {
     asm volatile ("nop");
   }

sw/lib/source/neorv32_twi.c

@@ -1,7 +1,7 @@
 // ================================================================================ //
 // The NEORV32 RISC-V Processor - https://github.com/stnolting/neorv32              //
 // Copyright (c) NEORV32 contributors.                                              //
-// Copyright (c) 2020 - 2024 Stephan Nolting. All rights reserved.                  //
+// Copyright (c) 2020 - 2025 Stephan Nolting. All rights reserved.                  //
 // Licensed under the BSD-3-Clause license, see LICENSE for details.                //
 // SPDX-License-Identifier: BSD-3-Clause                                            //
 // ================================================================================ //
@@ -9,10 +9,6 @@
 /**
  * @file neorv32_twi.c
  * @brief Two-Wire Interface Controller (TWI) HW driver source file.
- *
- * @note These functions should only be used if the TWI unit was synthesized (IO_TWI_EN = true).
- *
- * @see https://stnolting.github.io/neorv32/sw/files.html
  */
 
 #include <neorv32.h>
@@ -161,8 +157,8 @@ int neorv32_twi_get(uint8_t *data) {
  **************************************************************************/
 int neorv32_twi_trans(uint8_t *data, int mack) {
 
-  uint8_t rx_data;
-  int device_ack;
+  uint8_t rx_data = 0;
+  int device_ack = 0;
 
   while (NEORV32_TWI->CTRL & (1<<TWI_CTRL_TX_FULL)); // wait for free TX entry
 

sw/lib/source/neorv32_uart.c

@@ -48,10 +48,10 @@ int  neorv32_uart_scan(neorv32_uart_t *UARTx, char *buffer, int max_size, int ec
  **************************************************************************/
 int neorv32_uart_available(neorv32_uart_t *UARTx) {
 
-  if ( ((uint32_t)UARTx == NEORV32_UART0_BASE) && (NEORV32_SYSINFO->SOC & (1 << SYSINFO_SOC_IO_UART0)) ) {
+  if (((uint32_t)UARTx == NEORV32_UART0_BASE) && (NEORV32_SYSINFO->SOC & (1 << SYSINFO_SOC_IO_UART0))) {
     return 1;
   }
-  else if ( ((uint32_t)UARTx == NEORV32_UART1_BASE) && (NEORV32_SYSINFO->SOC & (1 << SYSINFO_SOC_IO_UART1)) ) {
+  else if (((uint32_t)UARTx == NEORV32_UART1_BASE) && (NEORV32_SYSINFO->SOC & (1 << SYSINFO_SOC_IO_UART1))) {
     return 1;
   }
   else {
@@ -329,10 +329,15 @@ void neorv32_uart_puts(neorv32_uart_t *UARTx, const char *s) {
  **************************************************************************/
 void neorv32_uart_vprintf(neorv32_uart_t *UARTx, const char *format, va_list args) {
 
-  char c;
-  char string_buf[33];
-  int32_t n;
-  unsigned int tmp;
+  char c = 0;
+  char __attribute__((aligned(4))) string_buf[36]; // optimize stack layout
+  int32_t n = 0;
+  unsigned int tmp = 0;
+
+  // prevent uninitialized stack bytes
+  for (n=0; n<sizeof(string_buf); n++) {
+    string_buf[n] = 0;
+  }
 
   while ((c = *format++)) {
     if (c == '%') {
@@ -377,7 +382,7 @@ void neorv32_uart_vprintf(neorv32_uart_t *UARTx, const char *format, va_list arg
           neorv32_uart_putc(UARTx, c);
           break;
 
-        default: // unsupported formating character
+        default: // unsupported formatting character
           neorv32_uart_putc(UARTx, '%');
           neorv32_uart_putc(UARTx, c);
           break;