/* vim: set ts=4 sw=4 tw=99 et:

 *

 * 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 "Zone.h"

#include "Spaces.h"

#include "Platform.h"

#include "Spaces-inl.h"

using namespace ke;

HeapStack::HeapStack()

  : chunk_(NULL),

    cursor_(NULL)

{

}

HeapStack::~HeapStack()

{

    if (chunk_)

        HeapChunk::Destroy(chunk_);

}

bool

HeapStack::initialize()

{

    chunk_ = HeapChunk::New(NULL, kStackSize);

    cursor_ = chunk_->first();

    return true;

}

HeapChunk *

HeapChunk::New(HeapChunk *prev, size_t size)

{

    OS::AlignableMapping map = 

        OS::MapAlignedMemory(size, HeapChunk::kAlignment, OS::Map_Commit);

    if (!map.base())

        return NULL;

    HeapChunk *chunk = reinterpret_cast<HeapChunk *>(map.aligned());

    chunk->base_ = map.base();

    chunk->end_ = map.base() + map.size();

    if (prev)

        prev->next_ = chunk;

    return chunk;

}

void

HeapChunk::Destroy(HeapChunk *chunk)

{

    OS::UnmapAlignedMemory(chunk->base(), chunk->size());

}

void

HeapChunk::resetMarkBits()

{

    memset(markBits(), 0, kMarkBytes);

}

FreeList::FreeList()

  : small_objects_(NULL),

    medium_objects_(NULL),

    large_objects_(NULL),

    huge_objects_(NULL)

{

}

void

FreeList::add(FreedObject *obj)

{

    if (obj->size() < kMinObjectSize) 

        return;

    FreedObject **list;

    if (obj->size() < kMaxSmallObject)

        list = &small_objects_;

    else if (obj->size() < kMaxMediumObject)

        list = &medium_objects_;

    else if (obj->size() < kMaxLargeObject)

        list = &large_objects_;

    else

        list = &huge_objects_;

    if (*list)

        (*list)->setNext(obj);

    *list = obj;

}

FreedObject *

FreeList::pick(size_t size)

{

    if (size < kMinObjectSize && small_objects_) {

        FreedObject *obj = small_objects_;

        small_objects_ = small_objects_->next();

        return obj;

    }

    if (size < kMaxSmallObject && medium_objects_) {

        FreedObject *obj = medium_objects_;

        medium_objects_ = medium_objects_->next();

        return obj;

    }

    if (size < kMaxMediumObject && large_objects_) {

        FreedObject *obj = large_objects_;

        large_objects_ = large_objects_->next();

        return obj;

    }

    if (huge_objects_) {

        FreedObject *obj = huge_objects_;

        huge_objects_ = huge_objects_->next();

        return obj;

    }

    return NULL;

}

void

FreeList::reset()

{

    small_objects_ = NULL;

    medium_objects_ = NULL;

    large_objects_ = NULL;

    huge_objects_ = NULL;

}

OldSpace::OldSpace(Zone *zone)

  : zone_(zone),

    first_(NULL),

    last_(NULL)

{

}

bool

OldSpace::initialize()

{

    first_ = HeapChunk::New(first_, HeapChunk::kDefaultSize);

    last_ = first_;

    cursor_ = first_->first();

    return !!first_;

}

OldSpace::~OldSpace()

{

    while (first_) {

        HeapChunk *temp = first_->next();

        HeapChunk::Destroy(first_);

        first_ = temp;

    }

}

Address

OldSpace::allocateSlow(size_t nbytes)

{

    if (FreedObject *obj = freelist_.pick(nbytes)) {

        Address address = reinterpret_cast<Address>(obj);

        size_t actual = obj->size();

        assert(actual >= nbytes);

        if (actual != nbytes)

            markRegionFree(address + nbytes, actual - nbytes);

        return address;

    }

    // Free unused stuff at the end of the current chunk.

    if (cursor_ != last_->end())

        markRegionFree(cursor_, last_->end() - cursor_);

    HeapChunk *chunk;

    if (last_->next()) {

        // The next chunk is guaranteed to be empty.

        chunk = last_->next();

    } else {

        chunk = HeapChunk::New(last_, HeapChunk::kDefaultSize);

        if (!chunk)

            return NULL;

    }

    last_ = chunk;

    cursor_ = chunk->first();

    assert(cursor_ + nbytes <= chunk->end());

    Address address = cursor_;

    cursor_ += nbytes;

    return address;

}

void

OldSpace::markRegionFree(Address start, size_t length)

{

    FreedObject *obj = reinterpret_cast<FreedObject *>(start);

    new (obj) FreedObject(zone_->getMap(MapKind_FreeRegion), length);

    if (length < sizeof(FreedObject)) {

        // Can't encode a list in this object, but it's marked free, so we're done.

        return;

    }

    freelist_.add(obj);

}

void

OldSpace::freeUnusedPages()

{

    HeapChunk **prev = &first_;

    HeapChunk *empty = NULL;

    while (*prev) {

        HeapChunk *chunk = *prev;

        if (chunk->isEmpty()) {

            *prev = chunk->next();

            if (empty) {

                // Remove this chunk.

                HeapChunk::Destroy(chunk);

                continue;

            }

            empty = chunk;                

        }

        prev = chunk->nextp();

    }

    if (empty) {

        *empty->nextp() = NULL;

        *last_->nextp() = empty;

    }

}

void

OldSpace::resetFreeList()

{

    freelist_.reset();

}

LargeObjectSpace::LargeObjectSpace()

  : first_(NULL),

    last_(NULL)

{

}

LargeObjectSpace::~LargeObjectSpace()

{

    while (first_) {

        HeapChunk *temp = first_->next();

        HeapChunk::Destroy(first_);

        first_ = temp;

    }

}

bool

LargeObjectSpace::initialize()

{

    return true;

}

Address

LargeObjectSpace::allocate(size_t nbytes)

{

    assert(IsAligned(nbytes, kObjectAlignment));

    // Always allocate a new chunk for large objects.

    HeapChunk *chunk = HeapChunk::New(last_, nbytes);

    if (!chunk)

        return NULL;

    if (!first_)

        first_ = chunk;

    last_ = chunk;

    return chunk->first();

}

void

LargeObjectSpace::sweep()

{

    if (!first_)

        return;

    HeapChunk **pprev = &first_;

    do {

        HeapChunk *chunk = *pprev;

        Object *obj = reinterpret_cast<Object *>(chunk->first());

        MarkBit bit = HeapChunk::GetMarkBit(obj);

        if (HeapChunk::IsWhite(bit)) {

            *pprev = chunk->next();

            HeapChunk::Destroy(chunk);

        } else {

            assert(HeapChunk::IsBlack(bit));

            HeapChunk::Clear(bit);

            pprev = chunk->nextp();

            last_ = chunk;

        }

    } while (*pprev);

}