1 files changed, 81 insertions, 0 deletions
diff --git a/src/lib/checksum/adler32/adler32.cpp b/src/lib/checksum/adler32/adler32.cpp
new file mode 100644
index 000000000..62589733f
--- /dev/null
+++ b/src/lib/checksum/adler32/adler32.cpp
@@ -0,0 +1,81 @@
+/*
+* Adler32
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/adler32.h>
+#include <botan/loadstor.h>
+
+namespace Botan {
+
+namespace {
+
+void adler32_update(const byte input[], size_t length,
+                    u16bit& S1, u16bit& S2)
+   {
+   u32bit S1x = S1;
+   u32bit S2x = S2;
+
+   while(length >= 16)
+      {
+      S1x += input[ 0]; S2x += S1x;
+      S1x += input[ 1]; S2x += S1x;
+      S1x += input[ 2]; S2x += S1x;
+      S1x += input[ 3]; S2x += S1x;
+      S1x += input[ 4]; S2x += S1x;
+      S1x += input[ 5]; S2x += S1x;
+      S1x += input[ 6]; S2x += S1x;
+      S1x += input[ 7]; S2x += S1x;
+      S1x += input[ 8]; S2x += S1x;
+      S1x += input[ 9]; S2x += S1x;
+      S1x += input[10]; S2x += S1x;
+      S1x += input[11]; S2x += S1x;
+      S1x += input[12]; S2x += S1x;
+      S1x += input[13]; S2x += S1x;
+      S1x += input[14]; S2x += S1x;
+      S1x += input[15]; S2x += S1x;
+      input += 16;
+      length -= 16;
+      }
+
+   for(size_t j = 0; j != length; ++j)
+      {
+      S1x += input[j];
+      S2x += S1x;
+      }
+
+   S1 = S1x % 65521;
+   S2 = S2x % 65521;
+   }
+
+}
+
+/*
+* Update an Adler32 Checksum
+*/
+void Adler32::add_data(const byte input[], size_t length)
+   {
+   const size_t PROCESS_AMOUNT = 5552;
+
+   while(length >= PROCESS_AMOUNT)
+      {
+      adler32_update(input, PROCESS_AMOUNT, S1, S2);
+      input += PROCESS_AMOUNT;
+      length -= PROCESS_AMOUNT;
+      }
+
+   adler32_update(input, length, S1, S2);
+   }
+
+/*
+* Finalize an Adler32 Checksum
+*/
+void Adler32::final_result(byte output[])
+   {
+   store_be(output, S2, S1);
+   clear();
+   }
+
+}