Initial revision

1 files changed, 77 insertions, 0 deletions

diff --git a/adler32.cpp b/adler32.cpp
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+++ b/adler32.cpp
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+// adler32.cpp - written and placed in the public domain by Wei Dai
+
+#include "pch.h"
+#include "adler32.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+void Adler32::Update(const byte *input, unsigned int length)
+{
+	const unsigned long BASE = 65521;
+
+	unsigned long s1 = m_s1;
+	unsigned long s2 = m_s2;
+
+	if (length % 8 != 0)
+	{
+		do
+		{
+			s1 += *input++;
+			s2 += s1;
+			length--;
+		} while (length % 8 != 0);
+
+		if (s1 >= BASE)
+			s1 -= BASE;
+		s2 %= BASE;
+	}
+
+	while (length > 0)
+	{
+		s1 += input[0]; s2 += s1;
+		s1 += input[1]; s2 += s1;
+		s1 += input[2]; s2 += s1;
+		s1 += input[3]; s2 += s1;
+		s1 += input[4]; s2 += s1;
+		s1 += input[5]; s2 += s1;
+		s1 += input[6]; s2 += s1;
+		s1 += input[7]; s2 += s1;
+
+		length -= 8;
+		input += 8;
+
+		if (s1 >= BASE)
+			s1 -= BASE;
+		if (length % 0x8000 == 0)
+			s2 %= BASE;
+	}
+
+	assert(s1 < BASE);
+	assert(s2 < BASE);
+
+	m_s1 = (word16)s1;
+	m_s2 = (word16)s2;
+}
+
+void Adler32::TruncatedFinal(byte *hash, unsigned int size)
+{
+	ThrowIfInvalidTruncatedSize(size);
+
+	switch (size)
+	{
+	default:
+		hash[3] = byte(m_s1);
+	case 3:
+		hash[2] = byte(m_s1 >> 8);
+	case 2:
+		hash[1] = byte(m_s2);
+	case 1:
+		hash[0] = byte(m_s2 >> 8);
+	case 0:
+		;
+	}
+
+	Reset();
+}
+
+NAMESPACE_END