Application: gvSIG desktop » gvSIG raster

/* Copyright (C) 2001-2007 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. */

/* $Id: lzw.h 147 2007-04-09 00:44:09Z selinger $ */

#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);