// Copyright (c) 1994 James Clark

// See the file COPYING for copying permission.

#include "splib.h"

#include "Allocator.h"

#include "macros.h"

#ifdef SP_NAMESPACE

namespace SP_NAMESPACE {

#endif

Allocator::Allocator(size_t maxSize, unsigned blocksPerSegment)

: objectSize_(maxSize),

  blocksPerSegment_(blocksPerSegment),

  freeList_(0),

  segments_(0)

{

}

Allocator::~Allocator()

{

  SegmentHeader *p = segments_;

  while (p) {

    SegmentHeader *tem = p->next;

    if (p->liveCount == 0)

      ::operator delete(p);

    else

      p->freeList = 0;

    p = tem;

  }

}

void *Allocator::alloc(size_t sz)

{

  if (sz > objectSize_)

    tooBig(sz);

  Block *tem = freeList_;

  if (tem) {

    tem->header.seg->liveCount += 1;

    freeList_ = tem->next;

    return &(tem->next);

  }

  else

    return alloc1();

}

void *Allocator::allocSimple(size_t sz)

{

  BlockHeader *p = (BlockHeader *)::operator new(sz + sizeof(BlockHeader));

  p->seg = 0;

  return p + 1;

}

void Allocator::free(void *p)

{

  BlockHeader *b = ((BlockHeader *)p) - 1;

  SegmentHeader *seg = b->seg;

  if (seg == 0)

    ::operator delete(b);

  else {

    Block **freeList = seg->freeList;

    if (freeList == 0) {

      seg->liveCount -= 1;

      if (seg->liveCount == 0)

	::operator delete(seg);

    }

    else {

      ((Block *)b)->next = *freeList;

      *freeList = (Block *)b;

      seg->liveCount -= 1;

    }

  }

}

void *Allocator::alloc1()

{

  SegmentHeader *seg

    = (SegmentHeader *)::operator new(sizeof(SegmentHeader)

				      + ((objectSize_ + sizeof(BlockHeader))

					 * blocksPerSegment_));

  seg->next = segments_;

  segments_ = seg;

  seg->liveCount = 1;

  seg->freeList = &freeList_;

  char *p = (char *)(seg + 1);

  Block *head = 0;

  for (size_t n = blocksPerSegment_; n > 0; n--) {

    ((Block *)p)->next = head;

    ((Block *)p)->header.seg = seg;

    head = (Block *)p;

    p += sizeof(BlockHeader) + objectSize_;

  }

  freeList_ = head->next;

  return &(head->next);

}

void Allocator::tooBig(size_t sz)

{

  ASSERT(sz <= objectSize_);

}

#ifdef SP_NAMESPACE

}

#endif