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/*************************************************
* Adler32 Source File *
* (C) 1999-2006 The Botan Project *
*************************************************/
#include <botan/adler32.h>
#include <botan/bit_ops.h>
namespace Botan {
/*************************************************
* Adler32 Checksum *
*************************************************/
void Adler32::hash(const byte input[], u32bit length)
{
u32bit S1x = S1, 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(u32bit j = 0; j != length; ++j)
{
S1x += input[j]; S2x += S1x;
}
S1x %= 65521;
S2x %= 65521;
S1 = S1x;
S2 = S2x;
}
/*************************************************
* Update an Adler32 Checksum *
*************************************************/
void Adler32::add_data(const byte input[], u32bit length)
{
const u32bit PROCESS_AMOUNT = 5552;
while(length >= PROCESS_AMOUNT)
{
hash(input, PROCESS_AMOUNT);
input += PROCESS_AMOUNT;
length -= PROCESS_AMOUNT;
}
hash(input, length);
}
/*************************************************
* Finalize an Adler32 Checksum *
*************************************************/
void Adler32::final_result(byte output[])
{
output[0] = get_byte(2, S2);
output[1] = get_byte(3, S2);
output[2] = get_byte(2, S1);
output[3] = get_byte(3, S1);
clear();
}
}
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