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74 lines
1.8 KiB
74 lines
1.8 KiB
namespace com.hitrust.util.Checksums
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{
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using System;
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public sealed class Adler32 : IChecksum
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{
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private static readonly uint BASE = 0xfff1;
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private uint checksum;
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public Adler32()
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{
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this.Reset();
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}
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public void Reset()
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{
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this.checksum = 1;
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}
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public void Update(int bval)
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{
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uint s1 = this.checksum & 0xffff;
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uint s2 = this.checksum >> 0x10;
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s1 = (uint) ((s1 + (bval & 0xff)) % BASE);
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s2 = (s1 + s2) % BASE;
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this.checksum = (s2 << 0x10) + s1;
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}
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public void Update(byte[] buffer)
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{
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this.Update(buffer, 0, buffer.Length);
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}
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public void Update(byte[] buf, int off, int len)
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{
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if (buf == null)
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{
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throw new ArgumentNullException("buf");
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}
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if (((off < 0) || (len < 0)) || ((off + len) > buf.Length))
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{
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throw new ArgumentOutOfRangeException();
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}
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uint s1 = this.checksum & 0xffff;
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uint s2 = this.checksum >> 0x10;
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while (len > 0)
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{
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int n = 0xed8;
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if (n > len)
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{
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n = len;
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}
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len -= n;
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while (--n >= 0)
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{
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s1 += (uint) (buf[off++] & 0xff);
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s2 += s1;
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}
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s1 = s1 % BASE;
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s2 = s2 % BASE;
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}
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this.checksum = (s2 << 0x10) | s1;
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}
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public long Value
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{
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get
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{
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return (long) this.checksum;
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}
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}
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}
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}
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