void
nsICODecoder::WriteInternal(const char* aBuffer, uint32_t aCount, DecodeStrategy aStrategy)
{
NS_ABORT_IF_FALSE(!HasError(), "Shouldn't call WriteInternal after error!");
if (!aCount) {
if (mContainedDecoder) {
WriteToContainedDecoder(aBuffer, aCount, aStrategy);
}
return;
}
while (aCount && (mPos < ICONCOUNTOFFSET)) { // Skip to the # of icons.
if (mPos == 2) { // if the third byte is 1: This is an icon, 2: a cursor
if ((*aBuffer != 1) && (*aBuffer != 2)) {
PostDataError();
return;
}
mIsCursor = (*aBuffer == 2);
}
mPos++; aBuffer++; aCount--;
}
if (mPos == ICONCOUNTOFFSET && aCount >= 2) {
mNumIcons = LittleEndian::readUint16(reinterpret_cast<const uint16_t*>(aBuffer));
aBuffer += 2;
mPos += 2;
aCount -= 2;
}
if (mNumIcons == 0)
return; // Nothing to do.
uint16_t colorDepth = 0;
nsIntSize prefSize = mImage.GetRequestedResolution();
if (prefSize.width == 0 && prefSize.height == 0) {
prefSize.SizeTo(PREFICONSIZE, PREFICONSIZE);
}
// A measure of the difference in size between the entry we've found
// and the requested size. We will choose the smallest image that is
// >= requested size (i.e. we assume it's better to downscale a larger
// icon than to upscale a smaller one).
int32_t diff = INT_MIN;
// Loop through each entry's dir entry
while (mCurrIcon < mNumIcons) {
if (mPos >= DIRENTRYOFFSET + (mCurrIcon * sizeof(mDirEntryArray)) &&
mPos < DIRENTRYOFFSET + ((mCurrIcon + 1) * sizeof(mDirEntryArray))) {
uint32_t toCopy = sizeof(mDirEntryArray) -
(mPos - DIRENTRYOFFSET - mCurrIcon * sizeof(mDirEntryArray));
if (toCopy > aCount) {
toCopy = aCount;
}
memcpy(mDirEntryArray + sizeof(mDirEntryArray) - toCopy, aBuffer, toCopy);
mPos += toCopy;
aCount -= toCopy;
aBuffer += toCopy;
}
if (aCount == 0)
return; // Need more data
IconDirEntry e;
if (mPos == (DIRENTRYOFFSET + ICODIRENTRYSIZE) +
(mCurrIcon * sizeof(mDirEntryArray))) {
mCurrIcon++;
ProcessDirEntry(e);
// We can't use GetRealWidth and GetRealHeight here because those operate
// on mDirEntry, here we are going through each item in the directory.
// Calculate the delta between this image's size and the desired size,
// so we can see if it is better than our current-best option.
// In the case of several equally-good images, we use the last one.
int32_t delta = (e.mWidth == 0 ? 256 : e.mWidth) - prefSize.width +
(e.mHeight == 0 ? 256 : e.mHeight) - prefSize.height;
if (e.mBitCount >= colorDepth &&
((diff < 0 && delta >= diff) || (delta >= 0 && delta <= diff))) {
diff = delta;
mImageOffset = e.mImageOffset;
// ensure mImageOffset is >= size of the direntry headers (bug #245631)
uint32_t minImageOffset = DIRENTRYOFFSET +
mNumIcons * sizeof(mDirEntryArray);
if (mImageOffset < minImageOffset) {
PostDataError();
return;
}
colorDepth = e.mBitCount;
memcpy(&mDirEntry, &e, sizeof(IconDirEntry));
}
}
}
if (mPos < mImageOffset) {
// Skip to (or at least towards) the desired image offset
uint32_t toSkip = mImageOffset - mPos;
if (toSkip > aCount)
toSkip = aCount;
mPos += toSkip;
aBuffer += toSkip;
aCount -= toSkip;
}
// If we are within the first PNGSIGNATURESIZE bytes of the image data,
// then we have either a BMP or a PNG. We use the first PNGSIGNATURESIZE
// bytes to determine which one we have.
if (mCurrIcon == mNumIcons && mPos >= mImageOffset &&
mPos < mImageOffset + PNGSIGNATURESIZE)
{
uint32_t toCopy = PNGSIGNATURESIZE - (mPos - mImageOffset);
if (toCopy > aCount) {
toCopy = aCount;
}
memcpy(mSignature + (mPos - mImageOffset), aBuffer, toCopy);
mPos += toCopy;
aCount -= toCopy;
aBuffer += toCopy;
mIsPNG = !memcmp(mSignature, nsPNGDecoder::pngSignatureBytes,
PNGSIGNATURESIZE);
if (mIsPNG) {
mContainedDecoder = new nsPNGDecoder(mImage);
mContainedDecoder->SetObserver(mObserver);
mContainedDecoder->SetSizeDecode(IsSizeDecode());
mContainedDecoder->InitSharedDecoder(mImageData, mImageDataLength,
mColormap, mColormapSize,
mCurrentFrame);
if (!WriteToContainedDecoder(mSignature, PNGSIGNATURESIZE, aStrategy)) {
return;
}
}
}
// If we have a PNG, let the PNG decoder do all of the rest of the work
if (mIsPNG && mContainedDecoder && mPos >= mImageOffset + PNGSIGNATURESIZE) {
if (!WriteToContainedDecoder(aBuffer, aCount, aStrategy)) {
return;
}
if (!HasSize() && mContainedDecoder->HasSize()) {
PostSize(mContainedDecoder->GetImageMetadata().GetWidth(),
mContainedDecoder->GetImageMetadata().GetHeight());
}
mPos += aCount;
aBuffer += aCount;
aCount = 0;
// Raymond Chen says that 32bpp only are valid PNG ICOs
// http://blogs.msdn.com/b/oldnewthing/archive/2010/10/22/10079192.aspx
if (!IsSizeDecode() &&
!static_cast<nsPNGDecoder*>(mContainedDecoder.get())->IsValidICO()) {
PostDataError();
}
return;
}
// We've processed all of the icon dir entries and are within the
// bitmap info size
if (!mIsPNG && mCurrIcon == mNumIcons && mPos >= mImageOffset &&
mPos >= mImageOffset + PNGSIGNATURESIZE &&
mPos < mImageOffset + BITMAPINFOSIZE) {
// As we were decoding, we did not know if we had a PNG signature or the
// start of a bitmap information header. At this point we know we had
// a bitmap information header and not a PNG signature, so fill the bitmap
// information header with the data it should already have.
memcpy(mBIHraw, mSignature, PNGSIGNATURESIZE);
// We've found the icon.
uint32_t toCopy = sizeof(mBIHraw) - (mPos - mImageOffset);
if (toCopy > aCount)
toCopy = aCount;
memcpy(mBIHraw + (mPos - mImageOffset), aBuffer, toCopy);
mPos += toCopy;
aCount -= toCopy;
aBuffer += toCopy;
}
// If we have a BMP inside the ICO and we have read the BIH header
if (!mIsPNG && mPos == mImageOffset + BITMAPINFOSIZE) {
// Make sure we have a sane value for the bitmap information header
int32_t bihSize = ExtractBIHSizeFromBitmap(reinterpret_cast<int8_t*>(mBIHraw));
if (bihSize != BITMAPINFOSIZE) {
PostDataError();
return;
}
// We are extracting the BPP from the BIH header as it should be trusted
// over the one we have from the icon header
mBPP = ExtractBPPFromBitmap(reinterpret_cast<int8_t*>(mBIHraw));
// Init the bitmap decoder which will do most of the work for us
// It will do everything except the AND mask which isn't present in bitmaps
// bmpDecoder is for local scope ease, it will be freed by mContainedDecoder
nsBMPDecoder *bmpDecoder = new nsBMPDecoder(mImage);
mContainedDecoder = bmpDecoder;
bmpDecoder->SetUseAlphaData(true);
mContainedDecoder->SetObserver(mObserver);
mContainedDecoder->SetSizeDecode(IsSizeDecode());
mContainedDecoder->InitSharedDecoder(mImageData, mImageDataLength,
mColormap, mColormapSize,
mCurrentFrame);
// The ICO format when containing a BMP does not include the 14 byte
// bitmap file header. To use the code of the BMP decoder we need to
// generate this header ourselves and feed it to the BMP decoder.
int8_t bfhBuffer[BMPFILEHEADERSIZE];
if (!FillBitmapFileHeaderBuffer(bfhBuffer)) {
PostDataError();
return;
}
if (!WriteToContainedDecoder((const char*)bfhBuffer, sizeof(bfhBuffer), aStrategy)) {
return;
}
// Setup the cursor hot spot if one is present
SetHotSpotIfCursor();
// Fix the ICO height from the BIH.
// Fix the height on the BIH to be /2 so our BMP decoder will understand.
if (!FixBitmapHeight(reinterpret_cast<int8_t*>(mBIHraw))) {
PostDataError();
return;
}
// Fix the ICO width from the BIH.
if (!FixBitmapWidth(reinterpret_cast<int8_t*>(mBIHraw))) {
PostDataError();
return;
}
// Write out the BMP's bitmap info header
if (!WriteToContainedDecoder(mBIHraw, sizeof(mBIHraw), aStrategy)) {
return;
}
PostSize(mContainedDecoder->GetImageMetadata().GetWidth(),
mContainedDecoder->GetImageMetadata().GetHeight());
// We have the size. If we're doing a size decode, we got what
// we came for.
if (IsSizeDecode())
return;
// Sometimes the ICO BPP header field is not filled out
// so we should trust the contained resource over our own
// information.
mBPP = bmpDecoder->GetBitsPerPixel();
// Check to make sure we have valid color settings
uint16_t numColors = GetNumColors();
if (numColors == (uint16_t)-1) {
PostDataError();
return;
}
}
// If we have a BMP
if (!mIsPNG && mContainedDecoder && mPos >= mImageOffset + BITMAPINFOSIZE) {
uint16_t numColors = GetNumColors();
if (numColors == (uint16_t)-1) {
PostDataError();
return;
}
// Feed the actual image data (not including headers) into the BMP decoder
uint32_t bmpDataOffset = mDirEntry.mImageOffset + BITMAPINFOSIZE;
uint32_t bmpDataEnd = mDirEntry.mImageOffset + BITMAPINFOSIZE +
static_cast<nsBMPDecoder*>(mContainedDecoder.get())->GetCompressedImageSize() +
4 * numColors;
// If we are feeding in the core image data, but we have not yet
// reached the ICO's 'AND buffer mask'
if (mPos >= bmpDataOffset && mPos < bmpDataEnd) {
// Figure out how much data the BMP decoder wants
uint32_t toFeed = bmpDataEnd - mPos;
if (toFeed > aCount) {
toFeed = aCount;
}
if (!WriteToContainedDecoder(aBuffer, toFeed, aStrategy)) {
return;
}
mPos += toFeed;
aCount -= toFeed;
aBuffer += toFeed;
}
// If the bitmap is fully processed, treat any left over data as the ICO's
// 'AND buffer mask' which appears after the bitmap resource.
if (!mIsPNG && mPos >= bmpDataEnd) {
// There may be an optional AND bit mask after the data. This is
// only used if the alpha data is not already set. The alpha data
// is used for 32bpp bitmaps as per the comment in ICODecoder.h
// The alpha mask should be checked in all other cases.
if (static_cast<nsBMPDecoder*>(mContainedDecoder.get())->GetBitsPerPixel() != 32 ||
!static_cast<nsBMPDecoder*>(mContainedDecoder.get())->HasAlphaData()) {
uint32_t rowSize = ((GetRealWidth() + 31) / 32) * 4; // + 31 to round up
if (mPos == bmpDataEnd) {
mPos++;
mRowBytes = 0;
mCurLine = GetRealHeight();
mRow = (uint8_t*)moz_realloc(mRow, rowSize);
if (!mRow) {
PostDecoderError(NS_ERROR_OUT_OF_MEMORY);
return;
}
}
// Ensure memory has been allocated before decoding.
NS_ABORT_IF_FALSE(mRow, "mRow is null");
if (!mRow) {
PostDataError();
return;
}
while (mCurLine > 0 && aCount > 0) {
uint32_t toCopy = std::min(rowSize - mRowBytes, aCount);
if (toCopy) {
memcpy(mRow + mRowBytes, aBuffer, toCopy);
aCount -= toCopy;
aBuffer += toCopy;
mRowBytes += toCopy;
}
if (rowSize == mRowBytes) {
mCurLine--;
mRowBytes = 0;
uint32_t* imageData =
static_cast<nsBMPDecoder*>(mContainedDecoder.get())->GetImageData();
if (!imageData) {
PostDataError();
return;
}
uint32_t* decoded = imageData + mCurLine * GetRealWidth();
uint32_t* decoded_end = decoded + GetRealWidth();
uint8_t* p = mRow, *p_end = mRow + rowSize;
while (p < p_end) {
uint8_t idx = *p++;
for (uint8_t bit = 0x80; bit && decoded<decoded_end; bit >>= 1) {
// Clear pixel completely for transparency.
if (idx & bit) {
*decoded = 0;
}
decoded++;
}
}
}
}
}
void
nsICODecoder::WriteInternal(const char* aBuffer, PRUint32 aCount)
{
NS_ABORT_IF_FALSE(!HasError(), "Shouldn't call WriteInternal after error!");
if (!aCount) // aCount=0 means EOF
return;
while (aCount && (mPos < ICONCOUNTOFFSET)) { // Skip to the # of icons.
if (mPos == 2) { // if the third byte is 1: This is an icon, 2: a cursor
if ((*aBuffer != 1) && (*aBuffer != 2)) {
PostDataError();
return;
}
mIsCursor = (*aBuffer == 2);
}
mPos++; aBuffer++; aCount--;
}
if (mPos == ICONCOUNTOFFSET && aCount >= 2) {
mNumIcons = LITTLE_TO_NATIVE16(((PRUint16*)aBuffer)[0]);
aBuffer += 2;
mPos += 2;
aCount -= 2;
}
if (mNumIcons == 0)
return; // Nothing to do.
PRUint16 colorDepth = 0;
// Loop through each entry's dir entry
while (mCurrIcon < mNumIcons) {
if (mPos >= DIRENTRYOFFSET + (mCurrIcon * sizeof(mDirEntryArray)) &&
mPos < DIRENTRYOFFSET + ((mCurrIcon + 1) * sizeof(mDirEntryArray))) {
PRUint32 toCopy = sizeof(mDirEntryArray) -
(mPos - DIRENTRYOFFSET - mCurrIcon * sizeof(mDirEntryArray));
if (toCopy > aCount) {
toCopy = aCount;
}
memcpy(mDirEntryArray + sizeof(mDirEntryArray) - toCopy, aBuffer, toCopy);
mPos += toCopy;
aCount -= toCopy;
aBuffer += toCopy;
}
if (aCount == 0)
return; // Need more data
IconDirEntry e;
if (mPos == (DIRENTRYOFFSET + ICODIRENTRYSIZE) +
(mCurrIcon * sizeof(mDirEntryArray))) {
mCurrIcon++;
ProcessDirEntry(e);
// We can't use GetRealWidth and GetRealHeight here because those operate
// on mDirEntry, here we are going through each item in the directory
if (((e.mWidth == 0 ? 256 : e.mWidth) == PREFICONSIZE &&
(e.mHeight == 0 ? 256 : e.mHeight) == PREFICONSIZE &&
(e.mBitCount >= colorDepth)) ||
(mCurrIcon == mNumIcons && mImageOffset == 0)) {
mImageOffset = e.mImageOffset;
// ensure mImageOffset is >= size of the direntry headers (bug #245631)
PRUint32 minImageOffset = DIRENTRYOFFSET +
mNumIcons * sizeof(mDirEntryArray);
if (mImageOffset < minImageOffset) {
PostDataError();
return;
}
colorDepth = e.mBitCount;
memcpy(&mDirEntry, &e, sizeof(IconDirEntry));
}
}
}
if (mPos < mImageOffset) {
// Skip to (or at least towards) the desired image offset
PRUint32 toSkip = mImageOffset - mPos;
if (toSkip > aCount)
toSkip = aCount;
mPos += toSkip;
aBuffer += toSkip;
aCount -= toSkip;
}
// If we are within the first PNGSIGNATURESIZE bytes of the image data,
// then we have either a BMP or a PNG. We use the first PNGSIGNATURESIZE
// bytes to determine which one we have.
if (mCurrIcon == mNumIcons && mPos >= mImageOffset &&
mPos < mImageOffset + PNGSIGNATURESIZE)
{
PRUint32 toCopy = PNGSIGNATURESIZE - (mPos - mImageOffset);
if (toCopy > aCount) {
toCopy = aCount;
}
memcpy(mSignature + (mPos - mImageOffset), aBuffer, toCopy);
mPos += toCopy;
aCount -= toCopy;
aBuffer += toCopy;
mIsPNG = !memcmp(mSignature, nsPNGDecoder::pngSignatureBytes,
PNGSIGNATURESIZE);
if (mIsPNG) {
mContainedDecoder = new nsPNGDecoder();
mContainedDecoder->InitSharedDecoder(mImage, mObserver);
mContainedDecoder->Write(mSignature, PNGSIGNATURESIZE);
mDataError = mContainedDecoder->HasDataError();
if (mContainedDecoder->HasDataError()) {
return;
}
}
}
// If we have a PNG, let the PNG decoder do all of the rest of the work
if (mIsPNG && mContainedDecoder && mPos >= mImageOffset + PNGSIGNATURESIZE) {
mContainedDecoder->Write(aBuffer, aCount);
mDataError = mContainedDecoder->HasDataError();
if (mContainedDecoder->HasDataError()) {
return;
}
mPos += aCount;
aBuffer += aCount;
aCount = 0;
// Raymond Chen says that 32bpp only are valid PNG ICOs
// http://blogs.msdn.com/b/oldnewthing/archive/2010/10/22/10079192.aspx
if (static_cast<nsPNGDecoder*>(mContainedDecoder.get())->HasValidInfo() &&
static_cast<nsPNGDecoder*>(mContainedDecoder.get())->GetPixelDepth() != 32) {
PostDataError();
}
return;
}
// We've processed all of the icon dir entries and are within the
// bitmap info size
if (!mIsPNG && mCurrIcon == mNumIcons && mPos >= mImageOffset &&
mPos >= mImageOffset + PNGSIGNATURESIZE &&
mPos < mImageOffset + BITMAPINFOSIZE) {
// As we were decoding, we did not know if we had a PNG signature or the
// start of a bitmap information header. At this point we know we had
// a bitmap information header and not a PNG signature, so fill the bitmap
// information header with the data it should already have.
memcpy(mBIHraw, mSignature, PNGSIGNATURESIZE);
// We've found the icon.
PRUint32 toCopy = sizeof(mBIHraw) - (mPos - mImageOffset);
if (toCopy > aCount)
toCopy = aCount;
memcpy(mBIHraw + (mPos - mImageOffset), aBuffer, toCopy);
mPos += toCopy;
aCount -= toCopy;
aBuffer += toCopy;
}
// If we have a BMP inside the ICO and we have read the BIH header
if (!mIsPNG && mPos == mImageOffset + BITMAPINFOSIZE) {
// Make sure we have a sane value for the bitmap information header
PRInt32 bihSize = ExtractBIHSizeFromBitmap(reinterpret_cast<PRInt8*>(mBIHraw));
if (bihSize != BITMAPINFOSIZE) {
PostDataError();
return;
}
// We are extracting the BPP from the BIH header as it should be trusted
// over the one we have from the icon header
mBPP = ExtractBPPFromBitmap(reinterpret_cast<PRInt8*>(mBIHraw));
// Init the bitmap decoder which will do most of the work for us
// It will do everything except the AND mask which isn't present in bitmaps
// bmpDecoder is for local scope ease, it will be freed by mContainedDecoder
nsBMPDecoder *bmpDecoder = new nsBMPDecoder();
mContainedDecoder = bmpDecoder;
bmpDecoder->SetUseAlphaData(PR_TRUE);
mContainedDecoder->SetSizeDecode(IsSizeDecode());
mContainedDecoder->InitSharedDecoder(mImage, mObserver);
// The ICO format when containing a BMP does not include the 14 byte
// bitmap file header. To use the code of the BMP decoder we need to
// generate this header ourselves and feed it to the BMP decoder.
PRInt8 bfhBuffer[BMPFILEHEADERSIZE];
if (!FillBitmapFileHeaderBuffer(bfhBuffer)) {
PostDataError();
return;
}
mContainedDecoder->Write((const char*)bfhBuffer, sizeof(bfhBuffer));
mDataError = mContainedDecoder->HasDataError();
if (mContainedDecoder->HasDataError()) {
return;
}
// Setup the cursor hot spot if one is present
SetHotSpotIfCursor();
// Fix the height on the BMP resource
FillBitmapInformationBufferHeight((PRInt8*)mBIHraw);
// Write out the BMP's bitmap info header
mContainedDecoder->Write(mBIHraw, sizeof(mBIHraw));
mDataError = mContainedDecoder->HasDataError();
if (mContainedDecoder->HasDataError()) {
return;
}
// We have the size. If we're doing a size decode, we got what
// we came for.
if (IsSizeDecode())
return;
// Sometimes the ICO BPP header field is not filled out
// so we should trust the contained resource over our own
// information.
mBPP = bmpDecoder->GetBitsPerPixel();
// Check to make sure we have valid color settings
PRUint16 numColors = GetNumColors();
if (numColors == (PRUint16)-1) {
PostDataError();
return;
}
}
// If we have a BMP
if (!mIsPNG && mContainedDecoder && mPos >= mImageOffset + BITMAPINFOSIZE) {
PRUint16 numColors = GetNumColors();
if (numColors == (PRUint16)-1) {
PostDataError();
return;
}
// Feed the actual image data (not including headers) into the BMP decoder
PRInt32 bmpDataOffset = mDirEntry.mImageOffset + BITMAPINFOSIZE;
PRInt32 bmpDataEnd = mDirEntry.mImageOffset + BITMAPINFOSIZE +
static_cast<nsBMPDecoder*>(mContainedDecoder.get())->GetCompressedImageSize() +
4 * numColors;
// If we are feeding in the core image data, but we have not yet
// reached the ICO's 'AND buffer mask'
if (mPos >= bmpDataOffset && mPos < bmpDataEnd) {
// Figure out how much data the BMP decoder wants
PRUint32 toFeed = bmpDataEnd - mPos;
if (toFeed > aCount) {
toFeed = aCount;
}
mContainedDecoder->Write(aBuffer, toFeed);
mDataError = mContainedDecoder->HasDataError();
if (mContainedDecoder->HasDataError()) {
return;
}
mPos += toFeed;
aCount -= toFeed;
aBuffer += toFeed;
}
// If the bitmap is fully processed, treat any left over data as the ICO's
// 'AND buffer mask' which appears after the bitmap resource.
if (!mIsPNG && mPos >= bmpDataEnd) {
// There may be an optional AND bit mask after the data. This is
// only used if the alpha data is not already set. The alpha data
// is used for 32bpp bitmaps as per the comment in ICODecoder.h
// The alpha mask should be checked in all other cases.
if (static_cast<nsBMPDecoder*>(mContainedDecoder.get())->GetBitsPerPixel() != 32 ||
!static_cast<nsBMPDecoder*>(mContainedDecoder.get())->HasAlphaData()) {
PRUint32 rowSize = ((GetRealWidth() + 31) / 32) * 4; // + 31 to round up
if (mPos == bmpDataEnd) {
mPos++;
mRowBytes = 0;
mCurLine = GetRealHeight();
mRow = (PRUint8*)moz_realloc(mRow, rowSize);
if (!mRow) {
PostDecoderError(NS_ERROR_OUT_OF_MEMORY);
return;
}
}
// Ensure memory has been allocated before decoding.
NS_ABORT_IF_FALSE(mRow, "mRow is null");
NS_ABORT_IF_FALSE(mImage, "mImage is null");
if (!mRow || !mImage) {
PostDataError();
return;
}
while (mCurLine > 0 && aCount > 0) {
PRUint32 toCopy = NS_MIN(rowSize - mRowBytes, aCount);
if (toCopy) {
memcpy(mRow + mRowBytes, aBuffer, toCopy);
aCount -= toCopy;
aBuffer += toCopy;
mRowBytes += toCopy;
}
if (rowSize == mRowBytes) {
mCurLine--;
mRowBytes = 0;
PRUint32* imageData =
static_cast<nsBMPDecoder*>(mContainedDecoder.get())->GetImageData();
if (!imageData) {
PostDataError();
return;
}
PRUint32* decoded = imageData + mCurLine * GetRealWidth();
PRUint32* decoded_end = decoded + GetRealWidth();
PRUint8* p = mRow, *p_end = mRow + rowSize;
while (p < p_end) {
PRUint8 idx = *p++;
for (PRUint8 bit = 0x80; bit && decoded<decoded_end; bit >>= 1) {
// Clear pixel completely for transparency.
if (idx & bit) {
*decoded = 0;
}
decoded++;
}
}
}
}
}
