D:/work/code_by/IOStream/ByteArrayOutputStream.cpp

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#include <mem.h>
#include "ByteArrayOutputStream.h"

TByteArrayOutputStream::TByteArrayOutputStream()
{
  List = new TMyList();
  bufferSize = 1024;
  totalSize = writeSize = 0;
}

TByteArrayOutputStream::TByteArrayOutputStream(int size)
{
  List = new TMyList();
  bufferSize = size;
  totalSize = writeSize = 0;
}

TByteArrayOutputStream::~TByteArrayOutputStream()
{
  Reset();
  delete List;
}

void TByteArrayOutputStream::Reset(void)
{
  int i;

  for (i = List->count - 1; i >= 0; i--)
    delete[] (unsigned char *)List->Items(i);
  List->Clear();
  totalSize = writeSize = 0;
}

int TByteArrayOutputStream::Size(void)
{
  return totalSize;
}

int TByteArrayOutputStream::ToByteArray(void *dst)
{
  return ToByteArray(dst, 0, totalSize);
}

int TByteArrayOutputStream::ToByteArray(void *dst, int from, int size)
{
  unsigned char *p;
  int i, n, result;

  if (from >= totalSize)
    return 0;

  p = (unsigned char *)dst;
  result = from + size > totalSize? totalSize - from : size;  //複製的byte數

  i = from / bufferSize;  //從此buffer開始
  n = bufferSize - from % bufferSize;  //頭一個buffer要複製的byte數
  if (n >= result)
    n = result;
  memcpy(p, (unsigned char *)List->Items(i) + from % bufferSize, n);  //複製此buffer的後面n個byte

  if (n == result)  //複製完畢
    return result;
  p += n;
  size = result - n;

  while (size > bufferSize)
  {
    memcpy(p, List->Items(++i), bufferSize);
    p += bufferSize;
    size -= bufferSize;
  }
  memcpy(p, List->Items(i + 1), size);  //複製此buffer的前面size個byte

  return result;
}

void TByteArrayOutputStream::Write(int n)
{
  static unsigned char *buffer = NULL;

  if (writeSize < bufferSize)
  {
    if (totalSize == 0)
      List->Add(buffer = new unsigned char[bufferSize]);
    buffer[writeSize++] = n;
  }
  else
  {
    List->Add(buffer = new unsigned char[bufferSize]);
    buffer[0] = n;
    writeSize = 1;
  }
  ++totalSize;
}

void TByteArrayOutputStream::WriteTo(TOutputStream *Stream)
{
  int i;

  if (totalSize == 0)
    return;
    
  for (i = 0; i < List->count - 1; i++)
    Stream->Writes(List->Items(i), bufferSize);
  Stream->Writes(List->Items(i), totalSize - bufferSize * (List->count - 1));
}

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