manes/runtime.cpp

   1 /* Quarn OS
   2  *
   3  * Runtime functions for C++
   4  *
   5  * Copyright (C) 2008 Pawel Dziepak
   6  *
   7  * This is set of functions that are needed to correctly execute code written
   8  * in the C++ programming language. Main part of this file is runtime_start()
   9  * function, which calls all constructors of global and static objects.
  10  */
  11
  12 #include "manes/error.h"
  13
  14 /* Calls constructors of all global and static objects */
  15 void runtime_start() {
  16         extern int _bss_end;
  17         extern int _bss;
  18         int bss_size = (int)&_bss_end - (int)&_bss;
  19         char *bss = (char*)&_bss;
  20
  21         /* Clear bss section */
  22         for (int i = 0; i < (int)bss_size; i++) bss[i] = 0;
  23
  24         /* Threre is a constructors list: __CTOR_LIST__
  25          * First entry of the list is the number of constructors.
  26          * Other entries are pointers to the constructors.
  27          * Everyting is set in the linker script
  28          */
  29         extern void (*__CTOR_LIST__)();
  30         void (**constr)() = &__CTOR_LIST__;
  31         int number = *(int*)constr;
  32
  33         for (int i = 1; i <= number; i++) (constr[i])();
  34 }
  35
  36 /* Code that should be executed when program exit, which won't ever
  37  * happen to Manes
  38  */
  39 void *__dso_handle __attribute__((weak));
  40 extern "C" void __cxa_atexit(void (*)(void *), void *, void *) {
  41         /* manes::error er("runtime: attempt to terminate kernel process");
  42         er.critical(); */
  43 }
  44
  45 namespace __cxxabiv1 {
  46         /* Function shows error message when a call to pure virtual function
  47          * has happened */
  48         extern "C" void __cxa_pure_virtual(void) {
  49                 manes::error er("runtime: call to pure virtual function");
  50                 er.critical();
  51         }
  52 }
  53