Enable optional GPROF profiling of apps

Apps can now use gprof to analyze performance and runtimes.  This requires
significant RAM and really only makes sense on devices with PSRAM to store
the state.

When the menu item is selected, allocates RAM and tracks function calls and
periodically samples the PC to generate a histogram of application usage.
Data written out to a gmon.out file, which can then be transferred to
a PC using gdb or a SD card.

Author: earlephilhower

boards.txt

@@ -181,7 +181,7 @@ class RP2040 {
     void begin() {
         _epoch = 0;
 #if !defined(__riscv)
-        if (!__isFreeRTOS) {
+        if (0 && !__isFreeRTOS) {
             // Enable SYSTICK exception
             exception_set_exclusive_handler(SYSTICK_EXCEPTION, _SystickHandler);
             systick_hw->csr = 0x7;
@@ -218,7 +218,7 @@ class RP2040 {
     volatile uint64_t _epoch = 0;
     inline uint32_t getCycleCount() {
 #if !defined(__riscv)
-        if (!__isFreeRTOS) {
+        if (0 && !__isFreeRTOS) {
             uint32_t epoch;
             uint32_t ctr;
             do {
@@ -236,7 +236,7 @@ class RP2040 {
 
     inline uint64_t getCycleCount64() {
 #if !defined(__riscv)
-        if (!__isFreeRTOS) {
+        if (0 && !__isFreeRTOS) {
             uint64_t epoch;
             uint64_t ctr;
             do {

cores/rp2040/RP2040Support.h

@@ -30,7 +30,9 @@ extern bool __isFreeRTOS;
 // FreeRTOS has been set up
 extern volatile bool __freeRTOSinitted;
 
+#ifdef __cplusplus
 extern "C" {
+#endif // __cplusplus
     struct QueueDefinition; /* Using old naming convention so as not to break kernel aware debuggers. */
     typedef struct QueueDefinition   * QueueHandle_t;
     typedef QueueHandle_t SemaphoreHandle_t;
@@ -57,5 +59,7 @@ extern "C" {
 
     extern void __freertos_task_exit_critical() __attribute__((weak));
     extern void __freertos_task_enter_critical() __attribute__((weak));
+#ifdef __cplusplus
 }
 extern SemaphoreHandle_t __get_freertos_mutex_for_ptr(mutex_t *m, bool recursive = false);
+#endif // __cplusplus