VMFrame *VMFrameStack::PopFrame()
{
if (Blocks == NULL)
{
return NULL;
}
VMFrame *frame = Blocks->LastFrame;
if (frame == NULL)
{
return NULL;
}
// Free any string registers this frame had.
FString *regs = frame->GetRegS();
for (int i = frame->NumRegS; i != 0; --i)
{
(regs++)->~FString();
}
// Free any parameters this frame left behind.
VMValue *param = frame->GetParam();
for (int i = frame->NumParam; i != 0; --i)
{
(param++)->~VMValue();
}
VMFrame *parent = frame->ParentFrame;
if (parent == NULL)
{
// Popping the last frame off the stack.
if (Blocks != NULL)
{
assert(Blocks->NextBlock == NULL);
Blocks->LastFrame = NULL;
Blocks->InitFreeSpace();
}
return NULL;
}
if ((VM_UBYTE *)parent < (VM_UBYTE *)Blocks || (VM_UBYTE *)parent >= (VM_UBYTE *)Blocks + Blocks->BlockSize)
{ // Parent frame is in a different block, so move this one to the unused list.
BlockHeader *next = Blocks->NextBlock;
assert(next != NULL);
assert((VM_UBYTE *)parent >= (VM_UBYTE *)next && (VM_UBYTE *)parent < (VM_UBYTE *)next + next->BlockSize);
Blocks->NextBlock = UnusedBlocks;
UnusedBlocks = Blocks;
Blocks = next;
}
else
{
Blocks->LastFrame = parent;
Blocks->FreeSpace = (VM_UBYTE *)frame;
}
return parent;
}
