mbed sdk boot: default nvic implementation

Latest cmsis files provide virtual nvic implementation, therefore all nvic
set/get vectors were removed. As the result, we did not reallocate vectors
for mbed SDK. This should fix it for most of the platforms (cortex m0 and
cortex a9 need to provide own if they need it).

Author: 0xc0170

platform/mbed_sdk_boot.c

@@ -17,6 +17,7 @@
 #include "mbed_toolchain.h"
 #include <stdlib.h>
 #include <stdint.h>
+#include "cmsis.h"
 
 /* This startup is for mbed 2 baremetal. There is no config for RTOS for mbed 2,
  * therefore we protect this file with MBED_CONF_RTOS_PRESENT
@@ -46,6 +47,24 @@ MBED_WEAK void software_init_hook_rtos()
     // Nothing by default
 }
 
+void mbed_copy_nvic(void)
+{
+    /* If vector address in RAM is defined, copy and switch to dynamic vectors. Exceptions for M0 which doesn't have
+    VTOR register and for A9 for which CMSIS doesn't define NVIC_SetVector; in both cases target code is
+    responsible for correctly handling the vectors.
+    */
+#if !defined(__CORTEX_M0) && !defined(__CORTEX_A9)
+#ifdef NVIC_RAM_VECTOR_ADDRESS
+    uint32_t *old_vectors = (uint32_t *)SCB->VTOR;
+    uint32_t *vectors = (uint32_t*)NVIC_RAM_VECTOR_ADDRESS;
+    for (int i = 0; i < NVIC_NUM_VECTORS; i++) {
+        vectors[i] = old_vectors[i];
+    }
+    SCB->VTOR = (uint32_t)NVIC_RAM_VECTOR_ADDRESS;
+#endif /* NVIC_RAM_VECTOR_ADDRESS */
+#endif /* !defined(__CORTEX_M0) && !defined(__CORTEX_A9) */
+}
+
 /* Toolchain specific main code */
 
 #if defined (__CC_ARM)
@@ -60,6 +79,7 @@ int $Sub$$main(void)
 
 void _platform_post_stackheap_init(void) 
 {
+    mbed_copy_nvic();
     mbed_sdk_init();
 }
 
@@ -69,6 +89,7 @@ extern int __real_main(void);
 
 void software_init_hook(void)
 {
+    mbed_copy_nvic();
     mbed_sdk_init();
     software_init_hook_rtos();
 }
@@ -82,7 +103,11 @@ int __wrap_main(void)
 
 #elif defined (__ICCARM__)
 
-// cmsis.S file implements the mbed SDK boot for IAR
+int __low_level_init(void)
+{
+  mbed_copy_nvic();
+  return 1;
+}
 
 #endif