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// ByteSwap.cpp
#include "StdAfx.h"
#include "../../Common/MyCom.h"
#include "../ICoder.h"
#include "../Common/RegisterCodec.h"
namespace NCompress {
namespace NByteSwap {
class CByteSwap2:
public ICompressFilter,
public CMyUnknownImp
{
public:
MY_UNKNOWN_IMP1(ICompressFilter);
INTERFACE_ICompressFilter(;)
};
class CByteSwap4:
public ICompressFilter,
public CMyUnknownImp
{
public:
MY_UNKNOWN_IMP1(ICompressFilter);
INTERFACE_ICompressFilter(;)
};
STDMETHODIMP CByteSwap2::Init() { return S_OK; }
STDMETHODIMP_(UInt32) CByteSwap2::Filter(Byte *data, UInt32 size)
{
const UInt32 kStep = 2;
if (size < kStep)
return 0;
size &= ~(kStep - 1);
const Byte *end = data + (size_t)size;
do
{
Byte b0 = data[0];
data[0] = data[1];
data[1] = b0;
data += kStep;
}
while (data != end);
return size;
}
STDMETHODIMP CByteSwap4::Init() { return S_OK; }
STDMETHODIMP_(UInt32) CByteSwap4::Filter(Byte *data, UInt32 size)
{
const UInt32 kStep = 4;
if (size < kStep)
return 0;
size &= ~(kStep - 1);
const Byte *end = data + (size_t)size;
do
{
Byte b0 = data[0];
Byte b1 = data[1];
data[0] = data[3];
data[1] = data[2];
data[2] = b1;
data[3] = b0;
data += kStep;
}
while (data != end);
return size;
}
REGISTER_FILTER_CREATE(CreateFilter2, CByteSwap2())
REGISTER_FILTER_CREATE(CreateFilter4, CByteSwap4())
REGISTER_CODECS_VAR
{
REGISTER_FILTER_ITEM(CreateFilter2, CreateFilter2, 0x20302, "Swap2"),
REGISTER_FILTER_ITEM(CreateFilter4, CreateFilter4, 0x20304, "Swap4")
};
REGISTER_CODECS(ByteSwap)
}}
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