/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsSegmentedBuffer.h"

#include "nsMemory.h"

nsresult

nsSegmentedBuffer::Init(uint32_t aSegmentSize, uint32_t aMaxSize)

{

  if (mSegmentArrayCount != 0) {

    return NS_ERROR_FAILURE;  // initialized more than once

  }

  mSegmentSize = aSegmentSize;

  mMaxSize = aMaxSize;

#if 0 // testing...

  mSegmentArrayCount = 2;

#else

  mSegmentArrayCount = NS_SEGMENTARRAY_INITIAL_COUNT;

#endif

  return NS_OK;

}

char*

nsSegmentedBuffer::AppendNewSegment()

{

  if (GetSize() >= mMaxSize) {

    return nullptr;

  }

  if (!mSegmentArray) {

    uint32_t bytes = mSegmentArrayCount * sizeof(char*);

    mSegmentArray = (char**)moz_xmalloc(bytes);

    memset(mSegmentArray, 0, bytes);

  }

  if (IsFull()) {

    uint32_t newArraySize = mSegmentArrayCount * 2;

    uint32_t bytes = newArraySize * sizeof(char*);

    mSegmentArray = (char**)moz_xrealloc(mSegmentArray, bytes);

    // copy wrapped content to new extension

    if (mFirstSegmentIndex > mLastSegmentIndex) {

      // deal with wrap around case

      memcpy(&mSegmentArray[mSegmentArrayCount],

             mSegmentArray,

             mLastSegmentIndex * sizeof(char*));

      memset(mSegmentArray, 0, mLastSegmentIndex * sizeof(char*));

      mLastSegmentIndex += mSegmentArrayCount;

      memset(&mSegmentArray[mLastSegmentIndex], 0,

             (newArraySize - mLastSegmentIndex) * sizeof(char*));

    } else {

      memset(&mSegmentArray[mLastSegmentIndex], 0,

             (newArraySize - mLastSegmentIndex) * sizeof(char*));

    }

    mSegmentArrayCount = newArraySize;

  }

  char* seg = (char*)malloc(mSegmentSize);

  if (!seg) {

    return nullptr;

  }

  mSegmentArray[mLastSegmentIndex] = seg;

  mLastSegmentIndex = ModSegArraySize(mLastSegmentIndex + 1);

  return seg;

}

bool

nsSegmentedBuffer::DeleteFirstSegment()

{

  NS_ASSERTION(mSegmentArray[mFirstSegmentIndex] != nullptr, "deleting bad segment");

  free(mSegmentArray[mFirstSegmentIndex]);

  mSegmentArray[mFirstSegmentIndex] = nullptr;

  int32_t last = ModSegArraySize(mLastSegmentIndex - 1);

  if (mFirstSegmentIndex == last) {

    mLastSegmentIndex = last;

    return true;

  } else {

    mFirstSegmentIndex = ModSegArraySize(mFirstSegmentIndex + 1);

    return false;

  }

}

bool

nsSegmentedBuffer::DeleteLastSegment()

{

  int32_t last = ModSegArraySize(mLastSegmentIndex - 1);

  NS_ASSERTION(mSegmentArray[last] != nullptr, "deleting bad segment");

  free(mSegmentArray[last]);

  mSegmentArray[last] = nullptr;

  mLastSegmentIndex = last;

  return (bool)(mLastSegmentIndex == mFirstSegmentIndex);

}

bool

nsSegmentedBuffer::ReallocLastSegment(size_t aNewSize)

{

  int32_t last = ModSegArraySize(mLastSegmentIndex - 1);

  NS_ASSERTION(mSegmentArray[last] != nullptr, "realloc'ing bad segment");

  char* newSegment = (char*)realloc(mSegmentArray[last], aNewSize);

  if (newSegment) {

    mSegmentArray[last] = newSegment;

    return true;

  }

  return false;

}

void

nsSegmentedBuffer::Empty()

{

  if (mSegmentArray) {

    for (uint32_t i = 0; i < mSegmentArrayCount; i++) {

      if (mSegmentArray[i]) {

        free(mSegmentArray[i]);

      }

    }

    free(mSegmentArray);

    mSegmentArray = nullptr;

  }

  mSegmentArrayCount = NS_SEGMENTARRAY_INITIAL_COUNT;

  mFirstSegmentIndex = mLastSegmentIndex = 0;

}

#if 0

void

TestSegmentedBuffer()

{

  nsSegmentedBuffer* buf = new nsSegmentedBuffer();

  NS_ASSERTION(buf, "out of memory");

  buf->Init(4, 16);

  char* seg;

  bool empty;

  seg = buf->AppendNewSegment();

  NS_ASSERTION(seg, "AppendNewSegment failed");

  seg = buf->AppendNewSegment();

  NS_ASSERTION(seg, "AppendNewSegment failed");

  seg = buf->AppendNewSegment();

  NS_ASSERTION(seg, "AppendNewSegment failed");

  empty = buf->DeleteFirstSegment();

  NS_ASSERTION(!empty, "DeleteFirstSegment failed");

  empty = buf->DeleteFirstSegment();

  NS_ASSERTION(!empty, "DeleteFirstSegment failed");

  seg = buf->AppendNewSegment();

  NS_ASSERTION(seg, "AppendNewSegment failed");

  seg = buf->AppendNewSegment();

  NS_ASSERTION(seg, "AppendNewSegment failed");

  seg = buf->AppendNewSegment();

  NS_ASSERTION(seg, "AppendNewSegment failed");

  empty = buf->DeleteFirstSegment();

  NS_ASSERTION(!empty, "DeleteFirstSegment failed");

  empty = buf->DeleteFirstSegment();

  NS_ASSERTION(!empty, "DeleteFirstSegment failed");

  empty = buf->DeleteFirstSegment();

  NS_ASSERTION(!empty, "DeleteFirstSegment failed");

  empty = buf->DeleteFirstSegment();

  NS_ASSERTION(empty, "DeleteFirstSegment failed");

  delete buf;

}

#endif

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