/*

  * Copyright (C) 2012 David Anderson

  *

  * This file is part of JITCraft.

  *

  * JITCraft is free software: you can redistribute it and/or modify it under

  * the terms of the GNU General Public License as published by the Free

  * Software Foundation, either version 3 of the License, or (at your option)

  * any later version.

  * 

  * Foobar is distributed in the hope that it will be useful, but WITHOUT ANY

  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

  * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License along with

  * JITCraft. If not, see http://www.gnu.org/licenses/.

  */

 #include <new>

 #include <stdlib.h>

 #include "Stack.h"

 #include "Zone.h"

 #include "Heap-inl.h"

 using namespace jc;

 Stack::Stack()

   : buffer_(NULL),

     top_(NULL),

     end_(NULL)

 {

 }

 Stack::~Stack()

 {

     free(buffer_);

 }

 bool

 Stack::initialize()

 {

     buffer_ = (char *)malloc(STACK_SIZE);

     if (!buffer_)

         return false;

     top_ = NULL;

     end_ = buffer_ + STACK_SIZE;

     return true;

 }

 static inline size_t

 SizeForCodeFrame(Code *code)

 {

     return sizeof(Frame) + sizeof(LocalSlot) * (code->nlocals() + code->maxStackDepth());

 }

 Frame *

 Stack::pushFrame(Frame *prev, Code *code)

 {

     size_t nbytes = SizeForCodeFrame(code);

     if (reinterpret_cast<char *>(top_->sp) + nbytes >= end_)

         return NULL;

     Frame *frame = reinterpret_cast<Frame *>(top_->sp);

     new (frame) Frame(prev, top_->pc, code, ZONE()->heap().lifoPosition());

     memset(frame->locals(), 0, sizeof(LocalSlot) * code->nlocals());

     top_->pc = frame->code()->start();

     top_->sp = frame->stackBase();

     return frame;

 }

 Frame *

 Stack::popFrame(Frame *frame)

 {

     Frame *prev = frame->prev();

     Code *code = frame->code();

     size_t nbytes = sizeof(LocalSlot) * code->nlocals() +

                     sizeof(Frame) +

                     sizeof(LocalSlot) * code->nargs();

     top_->pc = frame->prevpc();

     top_->sp = reinterpret_cast<LocalSlot *>(reinterpret_cast<char *>(top_->sp) - nbytes);

     ZONE()->heap().unwindLifo(frame->lifoPosition());

     return prev;

 }