UA1ZBE Custom Firmware v1.0

Features:
- VFO mode with direct frequency input
- POCSAG decoder (512/1200 baud) with BCH(31,21) correction
- Full-screen Spectrum analyzer
- FM Radio receiver
- RSSI signal indicator overlay
- Custom boot splash (UA1ZBE / POCSAG pager / build date)

Architecture:
- app/mode.c — mode dispatcher (VFO/POCSAG/Spectrum/FM)
- app/boot_splash.c — 2-second boot splash
- app/pocsag/ — POCSAG decoder + BCH correction
- app/display_rssi.c — RSSI indicator
- main.c — entry point with custom init
- syscalls.c — bare-metal _sbrk stub

Build: arm-none-eabi-gcc -Os -flto -Wall -Werror -Wextra
Size: 57.9KB Flash / 3.6KB RAM

Controls:
- 0-9: Direct frequency input (VFO)
- SK2: POCSAG mode
- SK1: Spectrum analyzer
- 0: FM Radio
- EXIT: Return to VFO
- F/*: Toggle 512/1200 baud (in POCSAG)

external/CMSIS_5/CMSIS/RTOS/Template/CPP/Mutex.cpp

@@ -0,0 +1,31 @@
+#include "Mutex.h"
+
+#include <string.h>
+//#include "error.h"
+
+namespace rtos {
+
+Mutex::Mutex() {
+#ifdef CMSIS_OS_RTX
+    memset(_mutex_data, 0, sizeof(_mutex_data));
+    _osMutexDef.mutex = _mutex_data;
+#endif
+    _osMutexId = osMutexCreate(&_osMutexDef);
+    if (_osMutexId == NULL) {
+//        error("Error initializing the mutex object\n");
+    }
+}
+
+osStatus Mutex::lock(uint32_t millisec) {
+    return osMutexWait(_osMutexId, millisec);
+}
+
+bool Mutex::trylock() {
+    return (osMutexWait(_osMutexId, 0) == osOK);
+}
+
+osStatus Mutex::unlock() {
+    return osMutexRelease(_osMutexId);
+}
+
+}