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https://github.com/aaru-dps/Aaru.Checksums.Native.git
synced 2025-12-16 11:14:29 +00:00
Use multiple sum algorithm from zlib for Adler and Fletcher checksums.
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165
adler32.c
165
adler32.c
@@ -1,21 +1,29 @@
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/*
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* This file is part of the Aaru Data Preservation Suite.
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* Copyright (c) 2019-2021 Natalia Portillo.
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of the
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* License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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/* adler32.c -- compute the Adler-32 checksum of a data stream
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Copyright (C) 1995-2011 Mark Adler
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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Jean-loup Gailly Mark Adler
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jloup@gzip.org madler@alumni.caltech.edu
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*/
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#include <stdint.h>
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#include <stdlib.h>
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@@ -38,15 +46,138 @@ AARU_EXPORT adler32_ctx* AARU_CALL adler32_init()
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AARU_EXPORT int AARU_CALL adler32_update(adler32_ctx* ctx, const uint8_t* data, uint32_t len)
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{
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uint32_t i;
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if(!ctx || !data) return -1;
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for(i = 0; i < len; i++)
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uint32_t sum1 = ctx->sum1;
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uint32_t sum2 = ctx->sum2;
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unsigned n;
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/* in case user likes doing a byte at a time, keep it fast */
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if(len == 1)
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{
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ctx->sum1 = (ctx->sum1 + data[i]) % ADLER_MODULE;
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ctx->sum2 = (ctx->sum2 + ctx->sum1) % ADLER_MODULE;
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sum1 += data[0];
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if(sum1 >= ADLER_MODULE) sum1 -= ADLER_MODULE;
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sum2 += sum1;
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if(sum2 >= ADLER_MODULE) sum2 -= ADLER_MODULE;
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ctx->sum1 = sum1 & 0xFFFF;
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ctx->sum2 = sum2 & 0xFFFF;
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return 0;
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}
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/* in case short lengths are provided, keep it somewhat fast */
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if(len < 16)
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{
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while(len--)
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{
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sum1 += *data++;
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sum2 += sum1;
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}
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if(sum1 >= ADLER_MODULE) sum1 -= ADLER_MODULE;
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sum2 %= ADLER_MODULE; /* only added so many ADLER_MODULE's */
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ctx->sum1 = sum1 & 0xFFFF;
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ctx->sum2 = sum2 & 0xFFFF;
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return 0;
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}
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/* do length NMAX blocks -- requires just one modulo operation */
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while(len >= NMAX)
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{
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len -= NMAX;
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n = NMAX / 16; /* NMAX is divisible by 16 */
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do {
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sum1 += (data)[0];
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sum2 += sum1;
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sum1 += (data)[0 + 1];
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sum2 += sum1;
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sum1 += (data)[0 + 2];
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sum2 += sum1;
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sum1 += (data)[0 + 2 + 1];
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sum2 += sum1;
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sum1 += (data)[0 + 4];
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sum2 += sum1;
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sum1 += (data)[0 + 4 + 1];
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sum2 += sum1;
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sum1 += (data)[0 + 4 + 2];
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sum2 += sum1;
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sum1 += (data)[0 + 4 + 2 + 1];
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sum2 += sum1;
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sum1 += (data)[8];
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sum2 += sum1;
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sum1 += (data)[8 + 1];
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sum2 += sum1;
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sum1 += (data)[8 + 2];
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sum2 += sum1;
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sum1 += (data)[8 + 2 + 1];
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sum2 += sum1;
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sum1 += (data)[8 + 4];
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sum2 += sum1;
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sum1 += (data)[8 + 4 + 1];
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sum2 += sum1;
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sum1 += (data)[8 + 4 + 2];
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sum2 += sum1;
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sum1 += (data)[8 + 4 + 2 + 1];
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sum2 += sum1;
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/* 16 sums unrolled */
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data += 16;
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} while(--n);
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sum1 %= ADLER_MODULE;
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sum2 %= ADLER_MODULE;
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}
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/* do remaining bytes (less than NMAX, still just one modulo) */
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if(len)
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{ /* avoid modulos if none remaining */
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while(len >= 16)
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{
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len -= 16;
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sum1 += (data)[0];
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sum2 += sum1;
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sum1 += (data)[0 + 1];
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sum2 += sum1;
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sum1 += (data)[0 + 2];
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sum2 += sum1;
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sum1 += (data)[0 + 2 + 1];
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sum2 += sum1;
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sum1 += (data)[0 + 4];
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sum2 += sum1;
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sum1 += (data)[0 + 4 + 1];
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sum2 += sum1;
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sum1 += (data)[0 + 4 + 2];
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sum2 += sum1;
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sum1 += (data)[0 + 4 + 2 + 1];
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sum2 += sum1;
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sum1 += (data)[8];
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sum2 += sum1;
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sum1 += (data)[8 + 1];
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sum2 += sum1;
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sum1 += (data)[8 + 2];
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sum2 += sum1;
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sum1 += (data)[8 + 2 + 1];
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sum2 += sum1;
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sum1 += (data)[8 + 4];
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sum2 += sum1;
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sum1 += (data)[8 + 4 + 1];
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sum2 += sum1;
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sum1 += (data)[8 + 4 + 2];
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sum2 += sum1;
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sum1 += (data)[8 + 4 + 2 + 1];
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sum2 += sum1;
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data += 16;
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}
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while(len--)
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{
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sum1 += *data++;
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sum2 += sum1;
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}
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sum1 %= ADLER_MODULE;
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sum2 %= ADLER_MODULE;
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}
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ctx->sum1 = sum1 & 0xFFFF;
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ctx->sum2 = sum2 & 0xFFFF;
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return 0;
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}
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