78 lines
2.0 KiB
C
78 lines
2.0 KiB
C
/* ****************************************************************************
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* utils/checksum.c -- Checksum-ing techniques.
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* Copyright (C) 2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
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*
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* This file is part of libcasio.
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* libcasio is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 3.0 of the License,
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* or (at your option) any later version.
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*
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* libcasio is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU 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 License
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* along with libcasio; if not, see <http://www.gnu.org/licenses/>.
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* ************************************************************************* */
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#include "../internals.h"
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/**
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* casio_checksum_cas:
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* Make checksums great again.
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*
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* @arg mem the memory zone.
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* @arg size the memory zone size.
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* @arg cs the current checksum.
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* @return the new checksum.
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*/
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int casio_checksum_cas(void *mem, size_t size, int cs)
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{
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unsigned char *m = mem;
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while (size--)
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cs = (cs - *m++) & 255;
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return (cs);
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}
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/**
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* casio_checksum_sub:
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* Make the CASIOWIN type of checksums.
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*
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* @arg mem the memory zone.
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* @arg size the memory zone size.
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* @arg cs the current checksum.
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* @return the new checksum.
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*/
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int casio_checksum_sub(void *mem, size_t size, int cs)
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{
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unsigned char *m = mem;
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while (size--)
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cs = (cs - *m++) & 255;
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return (cs);
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}
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/**
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* casio_checksum32:
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* Make checksums great again.
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*
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* @arg mem the memory zone.
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* @arg size the memory zone size.
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* @arg cs the current checksum.
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* @return the new checksum.
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*/
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casio_uint32_t casio_checksum32(void *mem, size_t size,
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casio_uint32_t cs)
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{
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casio_uint8_t *m = mem;
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while (size--)
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cs += *m++;
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return (cs);
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}
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