initial

system/src/cortexm/_initialize_hardware.c

@@ -0,0 +1,87 @@
+//
+// This file is part of the µOS++ III distribution.
+// Copyright (c) 2014 Liviu Ionescu.
+//
+
+// ----------------------------------------------------------------------------
+
+#include "cmsis_device.h"
+
+// ----------------------------------------------------------------------------
+
+extern unsigned int __vectors_start;
+
+// Forward declarations.
+
+void
+__initialize_hardware_early(void);
+
+void
+__initialize_hardware(void);
+
+// ----------------------------------------------------------------------------
+
+// This is the early hardware initialisation routine, it can be
+// redefined in the application for more complex cases that
+// require early inits (before BSS init).
+//
+// Called early from _start(), right before data & bss init.
+//
+// After Reset the Cortex-M processor is in Thread mode,
+// priority is Privileged, and the Stack is set to Main.
+
+void
+__attribute__((weak))
+__initialize_hardware_early(void)
+{
+  // Call the CSMSIS system initialisation routine.
+  SystemInit();
+
+#if defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)
+  // Set VTOR to the actual address, provided by the linker script.
+  // Override the manual, possibly wrong, SystemInit() setting.
+  SCB->VTOR = (uint32_t)(&__vectors_start);
+#endif
+
+  // The current version of SystemInit() leaves the value of the clock
+  // in a RAM variable (SystemCoreClock), which will be cleared shortly,
+  // so it needs to be recomputed after the RAM initialisations
+  // are completed.
+
+#if defined(OS_INCLUDE_STARTUP_INIT_FP) || (defined (__VFP_FP__) && !defined (__SOFTFP__))
+
+  // Normally FP init is done by SystemInit(). In case this is not done
+  // there, it is possible to force its inclusion by defining
+  // OS_INCLUDE_STARTUP_INIT_FP.
+
+  // Enable the Cortex-M4 FPU only when -mfloat-abi=hard.
+  // Code taken from Section 7.1, Cortex-M4 TRM (DDI0439C)
+
+  // Set bits 20-23 to enable CP10 and CP11 coprocessor
+  SCB->CPACR |= (0xF << 20);
+
+#endif // (__VFP_FP__) && !(__SOFTFP__)
+
+#if defined(OS_DEBUG_SEMIHOSTING_FAULTS)
+  SCB->SHCSR |= SCB_SHCSR_USGFAULTENA_Msk;
+#endif
+}
+
+// This is the second hardware initialisation routine, it can be
+// redefined in the application for more complex cases that
+// require custom inits (before constructors), otherwise these can
+// be done in main().
+//
+// Called from _start(), right after data & bss init, before
+// constructors.
+
+void
+__attribute__((weak))
+__initialize_hardware(void)
+{
+  // Call the CSMSIS system clock routine to store the clock frequency
+  // in the SystemCoreClock global RAM location.
+  SystemCoreClockUpdate();
+}
+
+// ----------------------------------------------------------------------------