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libg1m/src/utils/skip.c

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C

/* *****************************************************************************
* utils/skip.c -- skip some bytes (useful for debugging).
* Copyright (C) 2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
*
* This file is part of libg1m.
* libg1m is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 3.0 of the License,
* or (at your option) any later version.
*
* libg1m is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with libg1m; if not, see <http://www.gnu.org/licenses/>.
* ************************************************************************** */
#include <libg1m/internals.h>
/**
* g1m_skip:
* Skip some bytes.
*
* @arg buffer the buffer from which to read.
* @arg size the size to skip.
* @arg checksum pointer to the checksum variable if there is one.
*/
int g1m_skip(g1m_buffer_t *buffer, size_t size, uint32_t *checksum)
{
uint8_t buf[1024]; int err;
uint32_t add = 0;
#if LOGLEVEL <= ll_error
size_t orig = size;
#endif
while (size) {
/* read that much */
size_t curlen = min(size, 1024);
size -= curlen;
buffer->g1m_buffer_offset += curlen;
if ((err = (*buffer->g1m_buffer_read)(buffer->g1m_buffer_cookie, buf,
curlen))) {
log_error("Skipping has failed after %" PRIuSIZE " bytes",
orig - size);
return (err);
}
/* feed the checksum */
add = g1m_checksum32(buf, curlen, add);
}
/* add to checksum */
if (checksum) *checksum += add;
/* no error */
return (0);
}