hi,the implemention of Context::regs() is like this:
return reinterpret_cast<Entry_frame*>(Cpu::stack_align(reinterpret_cast<Mword>(this + Size)) -1;
how this algorithm came out?i think the memory of the object is allocated by c++ compiler, but why '(this + Size)' could get Entry_frame of a thread?
On Wed Apr 29, 2015 at 14:20:11 +0800, watermirror wrote:
hi,the implemention of Context::regs() is like this:
return reinterpret_cast<Entry_frame*>(Cpu::stack_align(reinterpret_cast<Mword>(this + Size)) -1;
how this algorithm came out?i think the memory of the object is allocated by c++ compiler, but why '(this + Size)' could get Entry_frame of a thread?
The stacks of the threads have a 2^n size and are size-aligned which makes such calculations possible. Threads also have their own new operator which handles this.
Adam
l4-hackers@os.inf.tu-dresden.de