wip: linked build

Author: facchinm

cores/arduino/main.cpp

@@ -5,6 +5,7 @@
  */
 
 #include "Arduino.h"
+#include <cstdint>
 #ifdef CONFIG_LLEXT
 #include <zephyr/llext/symbol.h>
 #endif
@@ -45,4 +46,40 @@ int main(void) {
 
 #ifdef CONFIG_LLEXT
 LL_EXTENSION_SYMBOL(main);
-#endif
+#endif
+
+/* These magic symbols are provided by the linker.  */
+extern void (*__preinit_array_start []) (void) __attribute__((weak));
+extern void (*__preinit_array_end []) (void) __attribute__((weak));
+extern void (*__init_array_start []) (void) __attribute__((weak));
+extern void (*__init_array_end []) (void) __attribute__((weak));
+
+static void __libc_init_array (void)
+{
+  size_t count;
+  size_t i;
+
+  count = __preinit_array_end - __preinit_array_start;
+  for (i = 0; i < count; i++)
+    __preinit_array_start[i] ();
+
+  count = __init_array_end - __init_array_start;
+  for (i = 0; i < count; i++)
+    __init_array_start[i] ();
+}
+
+extern "C" __attribute__((section(".entry_point"), used)) void entry_point(k_thread_stack_t* stack, size_t stack_size) {
+  // copy .data in the right place
+  // .bss should already be in the right place
+  // call constructors
+  extern uintptr_t _sidata;
+  extern uintptr_t _sdata;
+  extern uintptr_t _edata;
+  extern uintptr_t _sbss;
+  extern uintptr_t _ebss;
+  //__asm volatile ("cpsie i");
+  memcpy(&_sdata, &_sidata, &_edata - &_sdata);
+  memset(&_sbss, 0, &_ebss - &_sbss);
+  __libc_init_array();
+  main();
+}