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q3garray.cpp

/****************************************************************************
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**
** This file is part of the Qt3Support module of the Qt Toolkit.
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** included in the packaging of this file.  Alternatively you may (at
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#include "qglobal.h"
#if defined(Q_CC_BOR)
    // needed for qsort() because of a std namespace problem on Borland
#   include "qplatformdefs.h"
#elif defined(Q_WS_WIN)
    // needed for bsearch on some platforms
#   include "qt_windows.h"
#endif

#define      Q3GARRAY_CPP
#include "q3garray.h"
#include <stdlib.h>
#include <string.h>

#ifndef QT_NO_THREAD
#  include "private/qmutexpool_p.h"
#endif

/*
  If USE_MALLOC isn't defined, we use new[] and delete[] to allocate
  memory. The documentation for QMemArray<T>::assign() explicitly
  mentions that the array is freed using free(), so don't mess around
  with USE_MALLOC unless you know what you're doing.
*/
#define USE_MALLOC

#undef NEW
#undef DELETE

#if defined(USE_MALLOC)
#define NEW(type,size)  ((type*)malloc(size*sizeof(type)))
#define DELETE(array)   (free((char*)array))
#else
#define NEW(type,size)  (new type[size])
#define DELETE(array)   (delete[] array)
#define DONT_USE_REALLOC                  // comment to use realloc()
#endif

/*!
  \class Q3GArray
  \reentrant
  \brief The Q3GArray class is an internal class for implementing the QMemArray class.

  \internal

  Q3GArray is a strictly internal class that acts as base class for the
  QMemArray template array.

  It contains an array of bytes and has no notion of an array element.
*/


/*!
  Constructs a null array.
*/

00100 Q3GArray::Q3GArray()
{
    shd = newData();
    Q_CHECK_PTR(shd);
}

/*!
  Dummy constructor; does not allocate any data.

  This constructor does not initialize any array data so subclasses
  must do it. The intention is to make the code more efficient.
*/

00113 Q3GArray::Q3GArray(int, int)
{
}

/*!
  Constructs an array with room for \a size bytes.
*/

00121 Q3GArray::Q3GArray(int size)
{
    if (size < 0) {
#if defined(QT_CHECK_RANGE)
      qWarning("Q3GArray: Cannot allocate array with negative length");
#endif
      size = 0;
    }
    shd = newData();
    Q_CHECK_PTR(shd);
    if (size == 0)                        // zero length
      return;
    shd->data = NEW(char,size);
    Q_CHECK_PTR(shd->data);
    shd->len =
#ifdef QT_Q3GARRAY_SPEED_OPTIM
      shd->maxl =
#endif
      size;
}

/*!
  Constructs a shallow copy of \a a.
*/

00146 Q3GArray::Q3GArray(const Q3GArray &a)
{
    shd = a.shd;
    shd->ref();
}

/*!
  Dereferences the array data and deletes it if this was the last
  reference.
*/

00157 Q3GArray::~Q3GArray()
{
    if (shd && shd->deref()) {            // delete when last reference
      if (shd->data)                // is lost
          DELETE(shd->data);
      deleteData(shd);
      shd = 0;
    }
}


/*!
  \fn Q3GArray &Q3GArray::operator=(const Q3GArray &a)

  Assigns a shallow copy of \a a to this array and returns a reference to
  this array.  Equivalent to assign().
*/

/*!
  \fn void Q3GArray::detach()

  Detaches this array from shared array data.
*/

/*!
  \fn char *Q3GArray::data() const

  Returns a pointer to the actual array data.
*/

/*!
  \fn uint Q3GArray::nrefs() const

  Returns the reference count.
*/

/*!
  \fn uint Q3GArray::size() const

  Returns the size of the array, in bytes.
*/


/*!
  Returns true if this array is equal to \a a, otherwise false.
  The comparison is bitwise, of course.
*/

00205 bool Q3GArray::isEqual(const Q3GArray &a) const
{
    if (size() != a.size())               // different size
      return false;
    if (data() == a.data())               // has same data
      return true;
    return (size() ? memcmp(data(), a.data(), size()) : 0) == 0;
}


/*!
  Resizes the array to \a newsize bytes. \a optim is either
  MemOptim (the default) or SpeedOptim.
*/
00219 bool Q3GArray::resize(uint newsize, Optimization optim)
{
#ifndef QT_Q3GARRAY_SPEED_OPTIM
    Q_UNUSED(optim);
#endif

    if (newsize == shd->len
#ifdef QT_Q3GARRAY_SPEED_OPTIM
       && newsize == shd->maxl
#endif
      ) // nothing to do
      return true;
    if (newsize == 0) {             // remove array
      if (shd->data)
          DELETE(shd->data);
      shd->data = 0;
      shd->len = 0;
#ifdef QT_Q3GARRAY_SPEED_OPTIM
      shd->maxl = 0;
#endif
      return true;
    }

    uint newmaxl = newsize;
#ifdef QT_Q3GARRAY_SPEED_OPTIM
    if (optim == SpeedOptim) {
      if (newsize <= shd->maxl &&
           (newsize * 4 > shd->maxl || shd->maxl <= 4)) {
          shd->len = newsize;
          return true;
      }
      newmaxl = 4;
      while (newmaxl < newsize)
          newmaxl *= 2;
      // try to spare some memory
      if (newmaxl >= 1024 * 1024 && newsize <= newmaxl - (newmaxl >> 2))
          newmaxl -= newmaxl >> 2;
    }
    shd->maxl = newmaxl;
#endif

    if (shd->data) {                      // existing data
#if defined(DONT_USE_REALLOC)
      char *newdata = NEW(char,newsize);  // manual realloc
      memcpy(newdata, shd->data, QMIN(shd->len,newmaxl));
      DELETE(shd->data);
      shd->data = newdata;
#else
      shd->data = (char *)realloc(shd->data, newmaxl);
#endif
    } else {
      shd->data = NEW(char,newmaxl);
    }
    if (!shd->data)                       // no memory
      return false;
    shd->len = newsize;
    return true;
}

/*!\overload
*/
00280 bool Q3GArray::resize(uint newsize)
{
    return resize(newsize, MemOptim);
}


/*!
  Fills the array with the repeated occurrences of \a d, which is
  \a sz bytes long.
  If \a len is specified as different from -1, then the array will be
  resized to \a len*sz before it is filled.

  Returns true if successful, or false if the memory cannot be allocated
  (only when \a len != -1).

  \sa resize()
*/

00298 bool Q3GArray::fill(const char *d, int len, uint sz)
{
    if (len < 0)
      len = shd->len/sz;                  // default: use array length
    else if (!resize(len*sz))
      return false;
    if (sz == 1)                    // 8 bit elements
      memset(data(), *d, len);
    else if (sz == 4) {             // 32 bit elements
      register Q_INT32 *x = (Q_INT32*)data();
      Q_INT32 v = *((Q_INT32*)d);
      while (len--)
          *x++ = v;
    } else if (sz == 2) {                 // 16 bit elements
      register Q_INT16 *x = (Q_INT16*)data();
      Q_INT16 v = *((Q_INT16*)d);
      while (len--)
          *x++ = v;
    } else {                              // any other size elements
      register char *x = data();
      while (len--) {               // more complicated
          memcpy(x, d, sz);
          x += sz;
      }
    }
    return true;
}

/*!
    \overload
  Shallow copy. Dereference the current array and references the data
  contained in \a a instead. Returns a reference to this array.
  \sa operator=()
*/

00333 Q3GArray &Q3GArray::assign(const Q3GArray &a)
{
    a.shd->ref();                   // avoid 'a = a'
    if (shd->deref()) {             // delete when last reference
      if (shd->data)                // is lost
          DELETE(shd->data);
      deleteData(shd);
    }
    shd = a.shd;
    return *this;
}

/*!
  Shallow copy. Dereference the current array and references the
  array data \a d, which contains \a len bytes.
  Returns a reference to this array.

  Do not delete \a d later, because Q3GArray takes care of that.
*/

00353 Q3GArray &Q3GArray::assign(const char *d, uint len)
{
    if (shd->count > 1) {                 // disconnect this
      shd->count--;
      shd = newData();
      Q_CHECK_PTR(shd);
    } else {
      if (shd->data)
          DELETE(shd->data);
    }
    shd->data = (char *)d;
    shd->len =
#ifdef QT_Q3GARRAY_SPEED_OPTIM
      shd->maxl =
#endif
      len;
    return *this;
}

/*!
  Deep copy. Dereference the current array and obtains a copy of the data
  contained in \a a instead. Returns a reference to this array.
  \sa assign(), operator=()
*/

00378 Q3GArray &Q3GArray::duplicate(const Q3GArray &a)
{
    if (a.shd == shd) {             // a.duplicate(a) !
      if (shd->count > 1) {
          shd->count--;
          register array_data *n = newData();
          Q_CHECK_PTR(n);
          if ((n->len=shd->len)) {
            n->data = NEW(char,n->len);
            Q_CHECK_PTR(n->data);
            if (n->data)
                memcpy(n->data, shd->data, n->len);
          } else {
            n->data = 0;
          }
          shd = n;
      }
      return *this;
    }
    char *oldptr = 0;
    if (shd->count > 1) {                 // disconnect this
      shd->count--;
      shd = newData();
      Q_CHECK_PTR(shd);
    } else {                              // delete after copy was made
      oldptr = shd->data;
    }
    if (a.shd->len) {                     // duplicate data
      shd->data = NEW(char,a.shd->len);
      Q_CHECK_PTR(shd->data);
      if (shd->data)
          memcpy(shd->data, a.shd->data, a.shd->len);
    } else {
      shd->data = 0;
    }
    shd->len =
#ifdef QT_Q3GARRAY_SPEED_OPTIM
      shd->maxl =
#endif
      a.shd->len;
    if (oldptr)
      DELETE(oldptr);
    return *this;
}

/*!
    \overload
  Deep copy. Dereferences the current array and obtains a copy of
  \a len characters from array data \a d instead.  Returns a reference
  to this array.
  \sa assign(), operator=()
*/

00431 Q3GArray &Q3GArray::duplicate(const char *d, uint len)
{
    char *data;
    if (d == 0 || len == 0) {
      data = 0;
      len  = 0;
    } else {
      if (shd->count == 1 && shd->len == len) {
          if (shd->data != d)       // avoid self-assignment
            memcpy(shd->data, d, len);    // use same buffer
          return *this;
      }
      data = NEW(char,len);
      Q_CHECK_PTR(data);
      memcpy(data, d, len);
    }
    if (shd->count > 1) {                 // detach
      shd->count--;
      shd = newData();
      Q_CHECK_PTR(shd);
    } else {                              // just a single reference
      if (shd->data)
          DELETE(shd->data);
    }
    shd->data = data;
    shd->len =
#ifdef QT_Q3GARRAY_SPEED_OPTIM
      shd->maxl =
#endif
      len;
    return *this;
}

/*!
  Resizes this array to \a len bytes and copies the \a len bytes at
  address \a d into it.

  \warning This function disregards the reference count mechanism.  If
  other Q3GArrays reference the same data as this, all will be updated.
*/

00472 void Q3GArray::store(const char *d, uint len)
{                                   // store, but not deref
    resize(len);
    memcpy(shd->data, d, len);
}


/*!
  \fn array_data *Q3GArray::sharedBlock() const

  Returns a pointer to the shared array block.

  \warning

  Do not use this function.  Using it is begging for trouble.  We dare
  not remove it, for fear of breaking code, but we \e strongly
  discourage new use of it.
*/

/*!
  \fn void Q3GArray::setSharedBlock(array_data *p)

  Sets the shared array block to \a p.

  \warning

  Do not use this function.  Using it is begging for trouble.  We dare
  not remove it, for fear of breaking code, but we \e strongly
  discourage new use of it.
*/


/*!
  Sets raw data and returns a reference to the array.

  Dereferences the current array and sets the new array data to \a d and
  the new array size to \a len.      Do not attempt to resize or re-assign the
  array data when raw data has been set.
  Call resetRawData(d,len) to reset the array.

  Setting raw data is useful because it sets QMemArray data without
  allocating memory or copying data.

  Example of intended use:
  \code
    static uchar bindata[] = { 231, 1, 44, ... };
    QByteArray    a;
    a.setRawData(bindata, sizeof(bindata));     // a points to bindata
    QDataStream s(a, IO_ReadOnly);        // open on a's data
    s >> <something>;                     // read raw bindata
    s.close();
    a.resetRawData(bindata, sizeof(bindata)); // finished
  \endcode

  Example of misuse (do not do this):
  \code
    static uchar bindata[] = { 231, 1, 44, ... };
    QByteArray    a, b;
    a.setRawData(bindata, sizeof(bindata));     // a points to bindata
    a.resize(8);                    // will crash
    b = a;                          // will crash
    a[2] = 123;                           // might crash
      // forget to resetRawData - will crash
  \endcode

  \warning If you do not call resetRawData(), Q3GArray will attempt to
  deallocate or reallocate the raw data, which might not be too good.
  Be careful.
*/

00542 Q3GArray &Q3GArray::setRawData(const char *d, uint len)
{
    duplicate(0, 0);                      // set null data
    shd->data = (char *)d;
    shd->len  = len;
    return *this;
}

/*!
  Resets raw data.

  The arguments must be the data, \a d, and length \a len, that were
  passed to setRawData().  This is for consistency checking.
*/

00557 void Q3GArray::resetRawData(const char *d, uint len)
{
    if (d != shd->data || len != shd->len) {
#if defined(QT_CHECK_STATE)
      qWarning("Q3GArray::resetRawData: Inconsistent arguments");
#endif
      return;
    }
    shd->data = 0;
    shd->len  = 0;
}


/*!
  Finds the first occurrence of \a d in the array from position \a index,
  where \a sz is the size of the \a d element.

  Note that \a index is given in units of \a sz, not bytes.

  This function only compares whole cells, not bytes.
*/

00579 int Q3GArray::find(const char *d, uint index, uint sz) const
{
    index *= sz;
    if (index >= shd->len) {
#if defined(QT_CHECK_RANGE)
      qWarning("Q3GArray::find: Index %d out of range", index/sz);
#endif
      return -1;
    }
    register uint i;
    uint ii;
    switch (sz) {
      case 1: {                     // 8 bit elements
          register char *x = data() + index;
          char v = *d;
          for (i=index; i<shd->len; i++) {
            if (*x++ == v)
                break;
          }
          ii = i;
          }
          break;
      case 2: {                     // 16 bit elements
          register Q_INT16 *x = (Q_INT16*)(data() + index);
          Q_INT16 v = *((Q_INT16*)d);
          for (i=index; i<shd->len; i+=2) {
            if (*x++ == v)
                break;
          }
          ii = i/2;
          }
          break;
      case 4: {                     // 32 bit elements
          register Q_INT32 *x = (Q_INT32*)(data() + index);
          Q_INT32 v = *((Q_INT32*)d);
          for (i=index; i<shd->len; i+=4) {
            if (*x++ == v)
                break;
          }
          ii = i/4;
          }
          break;
      default: {                    // any size elements
          for (i=index; i<shd->len; i+=sz) {
            if (memcmp(d, &shd->data[i], sz) == 0)
                break;
          }
          ii = i/sz;
          }
          break;
    }
    return i<shd->len ? (int)ii : -1;
}

/*!
  Returns the number of occurrences of \a d in the array, where \a sz is
  the size of the \a d element.

  This function only compares whole cells, not bytes.
*/

00640 int Q3GArray::contains(const char *d, uint sz) const
{
    register uint i = shd->len;
    int count = 0;
    switch (sz) {
      case 1: {                     // 8 bit elements
          register char *x = data();
          char v = *d;
          while (i--) {
            if (*x++ == v)
                count++;
          }
          }
          break;
      case 2: {                     // 16 bit elements
          register Q_INT16 *x = (Q_INT16*)data();
          Q_INT16 v = *((Q_INT16*)d);
          i /= 2;
          while (i--) {
            if (*x++ == v)
                count++;
          }
          }
          break;
      case 4: {                     // 32 bit elements
          register Q_INT32 *x = (Q_INT32*)data();
          Q_INT32 v = *((Q_INT32*)d);
          i /= 4;
          while (i--) {
            if (*x++ == v)
                count++;
          }
          }
          break;
      default: {                    // any size elements
          for (i=0; i<shd->len; i+=sz) {
            if (memcmp(d, &shd->data[i], sz) == 0)
                count++;
          }
          }
          break;
    }
    return count;
}

static int cmp_item_size = 0;

#if defined(Q_C_CALLBACKS)
extern "C" {
#endif

#ifdef Q_OS_TEMP
static int __cdecl cmp_arr(const void *n1, const void *n2)
#else
static int cmp_arr(const void *n1, const void *n2)
#endif
{
    return (n1 && n2) ? memcmp(n1, n2, cmp_item_size)
                  : (n1 ? 1 : (n2 ? -1 : 0));
    // ### Qt 3.0: Add a virtual compareItems() method and call that instead
}

#if defined(Q_C_CALLBACKS)
}
#endif

/*!
  Sorts the first \a sz items of the array.
*/

00710 void Q3GArray::sort(uint sz)
{
    int numItems = size() / sz;
    if (numItems < 2)
      return;

#ifndef QT_NO_THREAD
    QMutexLocker locker(QMutexPool::globalInstanceGet(&cmp_item_size));
#endif

    cmp_item_size = sz;
    qsort(shd->data, numItems, sz, cmp_arr);
}

/*!
  Binary search; assumes that \a d is a sorted array of size \a sz.
*/

00728 int Q3GArray::bsearch(const char *d, uint sz) const
{
    int numItems = size() / sz;
    if (!numItems)
      return -1;

#ifndef QT_NO_THREAD
    QMutexLocker locker(QMutexPool::globalInstanceGet(&cmp_item_size));
#endif

    cmp_item_size = sz;
    char* r = (char*)::bsearch(d, shd->data, numItems, sz, cmp_arr);
    if (!r)
      return -1;
    while((r >= shd->data + sz) && (cmp_arr(r - sz, d) == 0))
      r -= sz;    // search to first of equal elements; bsearch is undef
    return (int)((r - shd->data) / sz);
}


/*!
  \fn char *Q3GArray::at(uint index) const

  Returns a pointer to the byte at offset \a index in the array.
*/

/*!
  Expand the array if necessary, and copies (the first part of) its
  contents from the \a index * \a sz bytes at \a d.

  Returns true if the operation succeeds, false if it runs out of
  memory.

  \warning This function disregards the reference count mechanism.  If
  other Q3GArrays reference the same data as this, all will be changed.
*/

00765 bool Q3GArray::setExpand(uint index, const char *d, uint sz)
{
    index *= sz;
    if (index >= shd->len) {
      if (!resize(index+sz))        // no memory
          return false;
    }
    memcpy(data() + index, d, sz);
    return true;
}


/*!
  Prints a warning message if at() or [] is given a bad index.
*/

00781 void Q3GArray::msg_index(uint index)
{
#if defined(QT_CHECK_RANGE)
    qWarning("Q3GArray::at: Absolute index %d out of range", index);
#else
    Q_UNUSED(index)
#endif
}


/*!
  Returns a new shared array block.
*/

00795 Q3GArray::array_data * Q3GArray::newData()
{
    return new array_data;
}


/*!
  Deletes the shared array block \a p.
*/

00805 void Q3GArray::deleteData(array_data *p)
{
    delete p;
}

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