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///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Industrial Light & Magic nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
///////////////////////////////////////////////////////////////////////////
#include <string.h>
#include "ImfRle.h"
#include "ImfNamespace.h"
OPENEXR_IMF_INTERNAL_NAMESPACE_SOURCE_ENTER
namespace {
const int MIN_RUN_LENGTH = 3;
const int MAX_RUN_LENGTH = 127;
}
//
// Compress an array of bytes, using run-length encoding,
// and return the length of the compressed data.
//
int
rleCompress (int inLength, const char in[], signed char out[])
{
const char *inEnd = in + inLength;
const char *runStart = in;
const char *runEnd = in + 1;
signed char *outWrite = out;
while (runStart < inEnd)
{
while (runEnd < inEnd &&
*runStart == *runEnd &&
runEnd - runStart - 1 < MAX_RUN_LENGTH)
{
++runEnd;
}
if (runEnd - runStart >= MIN_RUN_LENGTH)
{
//
// Compressable run
//
*outWrite++ = (runEnd - runStart) - 1;
*outWrite++ = *(signed char *) runStart;
runStart = runEnd;
}
else
{
//
// Uncompressable run
//
while (runEnd < inEnd &&
((runEnd + 1 >= inEnd ||
*runEnd != *(runEnd + 1)) ||
(runEnd + 2 >= inEnd ||
*(runEnd + 1) != *(runEnd + 2))) &&
runEnd - runStart < MAX_RUN_LENGTH)
{
++runEnd;
}
*outWrite++ = runStart - runEnd;
while (runStart < runEnd)
{
*outWrite++ = *(signed char *) (runStart++);
}
}
++runEnd;
}
return outWrite - out;
}
//
// Uncompress an array of bytes compressed with rleCompress().
// Returns the length of the oncompressed data, or 0 if the
// length of the uncompressed data would be more than maxLength.
//
int
rleUncompress (int inLength, int maxLength, const signed char in[], char out[])
{
char *outStart = out;
while (inLength > 0)
{
if (*in < 0)
{
int count = -((int)*in++);
inLength -= count + 1;
if (0 > (maxLength -= count))
return 0;
// check the input buffer is big enough to contain
// 'count' bytes of remaining data
if (inLength < 0)
return 0;
memcpy(out, in, count);
out += count;
in += count;
}
else
{
int count = *in++;
inLength -= 2;
if (0 > (maxLength -= count + 1))
return 0;
// check the input buffer is big enough to contain
// byte to be duplicated
if (inLength < 0)
return 0;
memset(out, *(char*)in, count+1);
out += count+1;
in++;
}
}
return out - outStart;
}
OPENEXR_IMF_INTERNAL_NAMESPACE_SOURCE_EXIT
|
