another bitwise operator question
Author
Hello, i have a binary pattern written to a file, it is written backwards . .
so 11000101 is written to the file, 1 then 0 then 1 then 0 etc.
I want to read this binary back from the file into an unsigned char, however i need to read it back into a varibale backwards too, so i need to read it in
1 then 0 then 1 then 0 and store the result as an unsigned char, i think i might need to use bitwise operations but im not too sure any help would be lovely. Thank you
[Edited by - LordFallout on March 23, 2007 2:30:24 PM]
This page proposes a simple way of reversing the bits in an integer, but it could be easily adapted to a char.
Author
buffer[n] |= BinNumber << i;
i got what i wanted like this, i do recieve some irratic behaviour though :S
i got what i wanted like this, i do recieve some irratic behaviour though :S
So, did you get what you wanted, or not? If not, please post the input, the expected result, and the actual result.
Author
Ok, well i have two text files and an image, i hide one text file in an image by changing random pixels, i change the LSB of each pixel too match a single bit of text byte, for a file with 1 byte of text, i.e one character of type unsigned char i store 8 bits within the picture i tried to hide this text
This is a Hidden text message, it is not hidden anymore.
and recieved this text
This is a Hidden text message, it ) J Rp6>hÊF
it is the right size just somwhere the text gets muddled up. I input the binary like so
and output like so
I cant really understand how only some of the text gets messed up, i can provide more of an explanation if needed. It confuses me a little typing it haha
edit: the filesize is set depending on the size of the input file.
This is a Hidden text message, it is not hidden anymore.
and recieved this text
This is a Hidden text message, it ) J Rp6>hÊF
it is the right size just somwhere the text gets muddled up. I input the binary like so
RandX = new int[FileSize * 8]; RandY = new int[FileSize * 8]; RandomGenerator->GetPairs( RandX, RandY, FileSize * 8, Dest->Picture->Bitmap->Width, Dest->Picture->Bitmap->Height ); for (int y=0; y < Dest->Picture->Bitmap->Height; y++) { for (int x=0; x < Dest->Picture->Bitmap->Width; x++) { if( x == RandX[PixelIndex] && y == RandY[PixelIndex] ) { int shiftedNumber = buffer[n]; BinNumber = (shiftedNumber >> i) & 1; Pixel.Colours = Dest->Canvas->Pixels[x][y]; ColorToRGB(Pixel.Colours); CurrentColour = GetRValue(Pixel.Channel.Red); CurrentColour = CurrentColour & ~1 | BinNumber; Pixel.Channel.Red = CurrentColour; Dest->Canvas->Pixels[x][y] = Pixel.Colours; Pixel.Colours = Dest->Canvas->Pixels[x][y]; ColorToRGB(Pixel.Colours); CurrentColour = GetRValue(Pixel.Channel.Red); PixelIndex++; x = 0; y = 0; i++; if( i > 7 ) { n++; i = 0; } } } }and output like so
RandX = new int[FileSize * 8]; RandY = new int[FileSize * 8]; RandomGenerator->GetPairs( RandX, RandY, FileSize * 8, Dest->Picture->Bitmap->Width, Dest->Picture->Bitmap->Height ); for (int y=0; y < Dest->Picture->Bitmap->Height; y++) { for (int x=0; x < Dest->Picture->Bitmap->Width; x++) { if( x == RandX[PixelIndex] && y == RandY[PixelIndex] ) { Pixel.Colours = Dest->Canvas->Pixels[x][y]; ColorToRGB(Pixel.Colours); CurrentColour = GetRValue(Pixel.Channel.Red); BinNumber = (CurrentColour >> 0) & 1; buffer[n] |= BinNumber << i; PixelIndex++; x = 0; y = 0; i++; if( i > 7 ) { buffer[n + 1] = 0; n++; i = 0; } } } }I cant really understand how only some of the text gets messed up, i can provide more of an explanation if needed. It confuses me a little typing it haha
edit: the filesize is set depending on the size of the input file.
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