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65 lines
2.1 KiB
C
65 lines
2.1 KiB
C
/*
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Serval rotated buffer primitives
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Copyright (C) 2013 Serval Project Inc.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program 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. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#define __ROTBUF_INLINE
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#include <assert.h>
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#include "rotbuf.h"
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ssize_t rotbuf_delta(const struct rotbuf *origin, const struct rotbuf *dest)
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{
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assert(origin->buf == dest->buf);
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assert(origin->ebuf == dest->ebuf);
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assert(origin->start == dest->start);
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const unsigned char *org = origin->cursor;
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const unsigned char *dst = dest->cursor;
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if (org < origin->start)
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org += origin->ebuf - origin->buf;
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assert(org >= origin->start);
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if (dst < dest->start)
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dst += dest->ebuf - dest->buf;
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assert(dst >= dest->start);
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return dst - org;
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}
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/* Return a pointer/length pair describing the contiguous memory region at the current cursor, and
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* advance the cursor to the next byte after that region (ie, to the start of the next region). If
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* the cursor is already at or past the end of the buffer, returns 0, otherwise sets *buf and *len
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* and returns 1.
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*
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* @author Andrew Bettison <andrew@servalproject.com>
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*/
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int rotbuf_next_chunk(struct rotbuf *rb, unsigned char **bufp, size_t *lenp)
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{
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if (rb->wrap)
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return 0;
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if (rb->cursor >= rb->start) {
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*bufp = rb->cursor;
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*lenp = rb->ebuf - rb->cursor;
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rb->cursor = rb->buf;
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if (rb->cursor == rb->start)
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++rb->wrap;
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return 1;
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}
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*bufp = rb->cursor;
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*lenp = rb->start - rb->cursor;
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rb->cursor = rb->start;
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++rb->wrap;
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return 1;
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}
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