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This PR aims to fix some issues relating to tasks and Sming. Using an esp32-s2, here's the task list as it looks presently: ``` # | Core | Prio | Run Time | % Time | Name 9 | 0 | 23 | 40591 | 2% | wifi 2 | 0 | 22 | 28009 | 1% | esp_timer 1 | 0 | 20 | 0 | 0% | sys_evt 8 | 0 | 18 | 3003 | 0% | tiT 5 | 0 | 1 | 0 | 0% | Tmr Svc 6 | 0 | 1 | 1928397 | 96% | Sming 4 | 0 | 0 | 0 | 0% | IDLE ``` *tiT == TCP/IP (LWIP) *Tmr Svc == FreeRTOS software timers (low resolution, runs at tick rate 1kHz) And for this PR: ``` # | Core | Prio | Run Time | % Time | Name 7 | 0 | 23 | 0 | 0% | wifi 1 | 0 | 22 | 46 | 0% | esp_timer 5 | 0 | 20 | 21243 | 1% | Sming 6 | 0 | 18 | 375 | 0% | tiT 4 | 0 | 1 | 0 | 0% | Tmr Svc 3 | 0 | 0 | 1978336 | 98% | IDLE ``` This is for a dual-core ESP32: ``` # | Core | Prio | Run Time | % Time | Name 1 | 0 | 24 | 0 | 0% | ipc0 14 | 0 | 23 | 25717 | 0% | wifi 3 | 0 | 22 | 2537 | 0% | esp_timer 8 | 0 | 1 | 0 | 0% | Tmr Svc 6 | 0 | 0 | 1971743 | 49% | IDLE 2 | 1 | 24 | 0 | 0% | ipc1 12 | 1 | 20 | 31857 | 0% | Sming 13 | 1 | 18 | 2088 | 0% | tiT 7 | 1 | 0 | 1966055 | 49% | IDLE ``` *ipcN == InterProcess Communication allows IDF to run code in the context of a specific CPU. The FreeRTOS scheduler will run the highest-priority thread which is ready to do work. It reverts to 'round-robin' if two ready threads have the same priority. Sming is now a high priority task, so is now capable of blocking other tasks. Sming takes priority over the tcpip thread. The Sming task implements the standard event loop. This ensures events are handled in the correct context. When there are no events to process it will idle correctly and allow lower priority tasks to run. The task watchdog is configured to fire if an event takes more than about 7 seconds. Sming code makes good use of stack for performance reasons and needs a reasonably-sized stack (currently 16KBytes). This applies to any tasks which run Sming code, currently the tcpip and Sming tasks. We now have one less task to deal with. **Default event queue** Once the default event queue is running we could just use the existing code as-is. However, to get the task watchdog to work correctly we need a custom event handling loop. That involves replacing all the default event loop functions. Another benefit of this approach is that where there are no events to process the CPU is allowed to idle. This is more consistent with how the IDF is supposed to work and may be important for power saving. **Software timers** Sming uses its `Timer2` definition for this which now no longer uses the 'legacy' FRC timer implementation. The IDF provides a queue for software timers managed by the `esp_timer` task. As this is a higher priority than Sming it behaves like an interrupt, pre-empting Sming when it has work to do. Instead of handling the timer event directly, we post it to the event queue so it is handled in the main Sming task. **Hardware timers** Sming uses its `Timer1` definition for this, which has now been implemented so the HardwareTimer class works as expected. It uses Timer Group 0, Index 0 for this. **Other changes** Wait for UART FIFOs to empty at startup to avoid truncated debug messages. Found `cache2phys` SDK call which implements `flashmem_get_address`. SDK config only needs to specify `CONFIG_BOOTLOADER_LOG_LEVEL` setting, others are handled automatically. Add `Wrap` build function to replace multiple uses of `-Wl,-wrap,XXXX` in makefiles. WifiEventsImpl attempts to register handlers in static constructor, so provide `wifi_set_event_handler_cb` to defer this (as for ESP8266). Add `TaskStat` class to allow simple monitoring of task usage. Add example use to Basic_IFS sample.
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