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/* Copyright (C) 2001-2015 Peter Selinger.
This file is part of Potrace. It is free software and it is covered
by the GNU General Public License. See the file COPYING for details. */
#define LZW_NORMAL 0
#define LZW_EOD 1
/* user visible state */
struct lzw_stream_s {
char *next_in; /* pointer to next input character */
int avail_in; /* number of input chars available */
char *next_out; /* pointer to next free byte in output buffer */
int avail_out; /* remaining size of output buffer */
void *internal; /* internal state, not user accessible */
};
typedef struct lzw_stream_s lzw_stream_t;
/* user visible functions */
/* The interface for compression and decompression is the same. The
application must first call lzw_init to create and initialize a
compression object. Then it calls lzw_compress on this object
repeatedly, as follows: next_in and next_out must point to valid,
non-overlapping regions of memory of size at least avail_in and
avail_out, respectively. The lzw_compress function will read and
process as many input bytes as possible as long as there is room in
the output buffer. It will update next_in, avail_in, next_out, and
avail_out accordingly. Some input may be consumed without producing
any output, or some output may be produced without consuming any
input. However, the lzw_compress function makes progress in the
sense that, after calling this function, at least one of avail_in
or avail_out is guaranteed to be 0. The mode flag is normally set
to LZW_NORMAL. It can be set to LZW_EOD (end of data) to indicate
that the current input buffer represents the entire remaining input
data stream. When called with mode=LZW_EOD, and avail_out is
non-zero after the call, then the application may conclude that the
end of output has been reached. (However, if avail_out==0 after the
call, then lzw_compress should be called again with the remaining
input, if any). Finally, lzw_free should be called to deallocate
the lzw_stream. Lzw_init returns NULL on error, with errno
set. Lzw_compress returns 0 on success, and 1 on error with errno
set. EINVAL is used to indicate an internal error, which should not
happen. */
lzw_stream_t *lzw_init(void);
int lzw_compress(lzw_stream_t *s, int mode);
void lzw_free(lzw_stream_t *s);
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