RexxActivationStack.cpp

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/* Copyright (c) 2005-2009 Rexx Language Association. All rights reserved.    */
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/******************************************************************************/
/* REXX Kernel                                       RexxActivationStack.c    */
/*                                                                            */
/* Primitive Activation Frame Stack support classes                           */
/*                                                                            */
/* NOTE:  activations are an execution time only object.  They are never      */
/*        flattened or saved in the image, and hence will never be in old     */
/*        space.  Because of this, activations "cheat" and do not use         */
/*        OrefSet to assign values to get better performance.  Care must be   */
/*        used to maintain this situation.                                    */
/*                                                                            */
/******************************************************************************/
#include <ctype.h>
#include <string.h>
#include "RexxCore.h"
#include "RexxActivationStack.hpp"
 
 
void RexxActivationFrameBuffer::live(size_t liveMark)
/******************************************************************************/
/* Function:  Normal garbage collection live marking                          */
/******************************************************************************/
{
  /* we only mark housekeeping type fields.  The main buffer */
  /* entries are marked by the owning activations. */
  memory_mark(this->previous);
}
 
void RexxActivationFrameBuffer::liveGeneral(int reason)
/******************************************************************************/
/* Function:  Normal garbage collection live marking                          */
/******************************************************************************/
{
  memory_mark_general(this->previous);
}
 
void RexxActivationFrameBuffer::flatten(RexxEnvelope *envelope)
/******************************************************************************/
/* Function:  Flatten an object                                               */
/******************************************************************************/
{
  setUpFlatten(RexxActivationFrameBuffer)
  /* we only mark housekeeping type fields.  The main buffer */
  /* entries are marked by the owning activations. */
 
   flatten_reference(newThis->previous, envelope);
 
  cleanUpFlatten
}
 
 
void RexxActivationStack::live(size_t liveMark)
/******************************************************************************/
/* Function:  Normal garbage collection live marking                          */
/******************************************************************************/
{
  memory_mark(this->current);
  memory_mark(this->unused);
}
 
void RexxActivationStack::liveGeneral(int reason)
/******************************************************************************/
/* Function:  Normal garbage collection live marking                          */
/******************************************************************************/
{
  memory_mark_general(this->current);
  memory_mark_general(this->unused);
}
 
void RexxActivationStack::init()
/******************************************************************************/
/* Function:  Initialize a frame stack for a new activity.                    */
/******************************************************************************/
{
    /* create a new frame buffer with the default size. */
    current = new_activationFrameBuffer(DefaultFrameBufferSize);
    unused = OREF_NULL;
}
 
void RexxActivationStack::expandCapacity(size_t entries)
/******************************************************************************/
/* Function:  Expand the capacity of the stack to add at least entries        */
/*            additional values on the stack.                                 */
/******************************************************************************/
{
    RexxActivationFrameBuffer *next;
    entries = Numerics::maxVal(entries, (stringsize_t)DefaultFrameBufferSize);
    /* do we have an unused one we're holding ready that has enough */
    /* room? */
    if (unused != OREF_NULL && unused->hasCapacity(entries))
    {
        /* just activate this one for use */
        next = unused;
        unused = OREF_NULL;
    }
    else
    {
        /* create a new frame buffer */
        next = new_activationFrameBuffer(entries);
    }
    /* chain the existing buffer off of the new one */
    next->push(current);
    /* set this up as the new current stack */
    current = next;
}
 
 
RexxActivationFrameBuffer *RexxActivationFrameBuffer::newInstance(
    size_t entries)                   /* space for entries in the fame     */
/******************************************************************************/
/* Function:  Create a new expression stack                                   */
/******************************************************************************/
{
  RexxActivationFrameBuffer *newObj;   /* newly created buffer              */
 
                                       /* Get new object                    */
  newObj = (RexxActivationFrameBuffer *)new_object(sizeof(RexxActivationFrameBuffer) + (entries * sizeof(RexxObject *)), T_ActivationFrameBuffer);
  newObj->size = entries;              /* set the size                      */
  newObj->next = 0;                    /* set the top element               */
  newObj->previous = OREF_NULL;        /* no previous element yet           */
  return newObj;                       /* return the new stack item         */
}