/*
val= 3066839698
val= 0
val= 3799812176 t=14446
*/
public static void testCRC32()
{
CRC32 crc1 = new CRC32();
crc1.Update(new byte[] { 1, 2 });
if (crc1.GetValue() != 3066839698) throw new Exception("Bad CRC32!");
Console.WriteLine("Testing CRC32");
Console.WriteLine("val= " + crc1.GetValue());
crc1.Reset();
Console.WriteLine("val= " + crc1.GetValue());
if (crc1.GetValue() != 0) throw new Exception("Bad CRC32!!");
Random r = new Random();
byte[] all = new byte[2000 * 4];
long t0 = Environment.TickCount;
for (int n = 0; n < 2000; n++) {
byte[] b = createBytes7(n < 50 ? n : n * n - 7);
CRC32 crc = new CRC32();
int offset = 0;
while (offset < b.Length) {
int len = r.Next(b.Length - offset) + 1;
crc.Update(b, offset, len);
offset += len;
}
long x = crc.GetValue();
all[n * 4] = (byte)((x >> 24) & 0xff);
all[n * 4 + 1] = (byte)((x >> 16) & 0xff);
all[n * 4 + 2] = (byte)((x >> 8) & 0xff);
all[n * 4 + 3] = (byte)((x) & 0xff);
}
long t1 = Environment.TickCount;
Adler32 a = new Adler32();
a.Update(all);
long v = a.GetValue();
Console.WriteLine("val= " + v + " t=" + (t1 - t0));
if (v != 3799812176) throw new Exception("Bad cRC32");// tested with Java CRC32
}
private void EndChunkGoForNext()
{
// Called after readging the last byte of chunk
// Checks CRC, and read ID from next CHUNK
// Those values are left in idLastChunk / lenLastChunk
// Skips empty IDATS
do
{
int crc = Hjg.Pngcs.PngHelperInternal.ReadInt4(inputStream); //
offset += 4;
if (checkCrc)
{
int crccalc = (int)crcEngine.GetValue();
if (lenLastChunk > 0 && crc != crccalc)
{
throw new PngjBadCrcException("error reading idat; offset: " + offset);
}
crcEngine.Reset();
}
lenLastChunk = Hjg.Pngcs.PngHelperInternal.ReadInt4(inputStream);
if (lenLastChunk < 0)
{
throw new PngjInputException("invalid len for chunk: " + lenLastChunk);
}
toReadThisChunk = lenLastChunk;
Hjg.Pngcs.PngHelperInternal.ReadBytes(inputStream, idLastChunk, 0, 4);
offset += 8;
ended = !PngCsUtils.arraysEqual4(idLastChunk, Hjg.Pngcs.Chunks.ChunkHelper.b_IDAT);
if (!ended)
{
foundChunksInfo.Add(new PngIDatChunkInputStream.IdatChunkInfo(lenLastChunk, (offset - 8)));
if (checkCrc)
{
crcEngine.Update(idLastChunk, 0, 4);
}
}
// PngHelper.logdebug("IDAT ended. next len= " + lenLastChunk + " idat?" +
// (!ended));
} while (lenLastChunk == 0 && !ended);
// rarely condition is true (empty IDAT ??)
}
public PngIDatChunkInputStream( Stream iStream, int lenFirstChunk, long offset_0 )
{
this.idLastChunk = new byte [ 4 ];
this.toReadThisChunk = 0;
this.ended = false;
this.foundChunksInfo = new List<IdatChunkInfo> ();
this.offset = offset_0;
checkCrc = true;
inputStream = iStream;
crcEngine = new CRC32 ();
this.lenLastChunk = lenFirstChunk;
toReadThisChunk = lenFirstChunk;
System.Array.Copy ( ( Array ) ( Hjg.Pngcs.Chunks.ChunkHelper.b_IDAT ), 0, ( Array ) ( idLastChunk ), 0, 4 );
crcEngine.Update ( idLastChunk, 0, 4 );
foundChunksInfo.Add ( new PngIDatChunkInputStream.IdatChunkInfo ( lenLastChunk, offset_0 - 8 ) );
if ( this.lenLastChunk == 0 )
EndChunkGoForNext ();
}
/// <summary>
/// Constructor must be called just after reading length and id of first IDAT
/// chunk
/// </summary>
///
public PngIDatChunkInputStream(Stream iStream, int lenFirstChunk, long offset_0)
{
this.idLastChunk = new byte[4];
this.toReadThisChunk = 0;
this.ended = false;
this.foundChunksInfo = new List <IdatChunkInfo>();
this.offset = offset_0;
checkCrc = true;
inputStream = iStream;
crcEngine = new CRC32();
this.lenLastChunk = lenFirstChunk;
toReadThisChunk = lenFirstChunk;
// we know it's a IDAT
System.Array.Copy((Array)(Hjg.Pngcs.Chunks.ChunkHelper.b_IDAT), 0, (Array)(idLastChunk), 0, 4);
crcEngine.Update(idLastChunk, 0, 4);
foundChunksInfo.Add(new PngIDatChunkInputStream.IdatChunkInfo(lenLastChunk, offset_0 - 8));
// PngHelper.logdebug("IDAT Initial fragment: len=" + lenLastChunk);
if (this.lenLastChunk == 0)
{
EndChunkGoForNext(); // rare, but...
}
}
