问objective-c和C#上的不同adler32校验和

EN

//Get Asset NSData
ALAssetRepresentation *rep = [[p objectForKey:@"assetPath"] defaultRepresentation];
Byte *buffer = (Byte*)malloc(rep.size);
NSUInteger buffered = [rep getBytes:buffer fromOffset:0.0 length:rep.size error:nil];
NSData *data = [NSData dataWithBytesNoCopy:buffer length:buffered freeWhenDone:YES];

//I also need a path to the file so I have to save the NSData to a local file
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *localFilePath = [documentsDirectory stringByAppendingPathComponent:@"png"];
[data writeToFile:localFilePath atomically:YES];
NSString *path = localFilePath;

//Now call the Adler
NSLog(@"checksum_fast:%@", [NSString stringWithFormat:@"%u", adler32_fast([data bytes], [data length])]);
NSLog(@"checksum:%@", [NSString stringWithFormat:@"%u", adler32([data bytes], [data length])]);

//Adler Lib
#define MOD_ADLER 65521
#define BUFFER_SIZE 1000

uint32_t adler32_update(uint32_t ck, const unsigned char data) {
  uint32_t a = ck & 0x0ffff, b = (ck >> 16) & 0x0ffff;
  a = (a + data) % MOD_ADLER;
  b = (b + a) % MOD_ADLER;
  return (b << 16) | a;
}

uint32_t adler32(const unsigned char *data, int data_len) {
  uint64_t ck = 1;
  for(int i=0; i<data_len; i++) {
    ck = adler32_update(ck,data[i]);
  }
  return ck;
}

uint32_t adler32_fast(const unsigned char *data, int data_len) {
  uint32_t a = 1, b = 0;
  for(int i=0; i<data_len; i++) {
    a = (a + data[i]) % MOD_ADLER;
    b = (b + a) % MOD_ADLER;
  }
  return (b << 16) | a;
}

//It use ICSharpCode.SharpZipLib.dll    
byte[] buff = null;
FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read);
BinaryReader br = new BinaryReader(fs);
long numBytes = new FileInfo(path).Length;
buff = br.ReadBytes((int)numBytes);

Adler32 adler = new Adler32();
adler.Reset();
adler.Update(buff, 0, buff.Length);
fs.Close();
fs.Dispose();
br.Close();
buff = null;
return Convert.ToString(adler.Value, 16);