in src/main/java/org/apache/commons/imaging/formats/tiff/datareaders/BitInputStream.java [57:135]
public int readBits(final int count) throws IOException {
if (count < 8) {
if (cacheBitsRemaining == 0) {
// fill cache
cache = in.read();
cacheBitsRemaining = 8;
bytesRead++;
}
if (count > cacheBitsRemaining) {
throw new ImagingException("BitInputStream: can't read bit fields across bytes");
}
// int bits_to_shift = cache_bits_remaining - count;
cacheBitsRemaining -= count;
final int bits = cache >> cacheBitsRemaining;
switch (count) {
case 1:
return bits & 1;
case 2:
return bits & 3;
case 3:
return bits & 7;
case 4:
return bits & 15;
case 5:
return bits & 31;
case 6:
return bits & 63;
case 7:
return bits & 127;
}
}
if (cacheBitsRemaining > 0) {
throw new ImagingException("BitInputStream: incomplete bit read");
}
if (count == 8) {
bytesRead++;
return in.read();
}
/**
* Taking default order of the TIFF to be Little Endian and reversing the bytes in the end if its Big Endian.This is done because majority (may be all)
* of the files will be of Little Endian.
*/
if (byteOrder == ByteOrder.BIG_ENDIAN) {
switch (count) {
case 16:
bytesRead += 2;
return in.read() << 8 | in.read() << 0;
case 24:
bytesRead += 3;
return in.read() << 16 | in.read() << 8 | in.read() << 0;
case 32:
bytesRead += 4;
return in.read() << 24 | in.read() << 16 | in.read() << 8 | in.read() << 0;
default:
break;
}
} else {
switch (count) {
case 16:
bytesRead += 2;
return in.read() << 0 | in.read() << 8;
case 24:
bytesRead += 3;
return in.read() << 0 | in.read() << 8 | in.read() << 16;
case 32:
bytesRead += 4;
return in.read() << 0 | in.read() << 8 | in.read() << 16 | in.read() << 24;
default:
break;
}
}
throw new ImagingException("BitInputStream: unknown error");
}