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jdarith.c
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C/C++ Source or Header
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1992-11-10
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1KB
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43 lines
/*
* jdarith.c
*
* Copyright (C) 1991, 1992, Thomas G. Lane.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
* This file contains arithmetic entropy decoding routines.
* These routines are invoked via the methods entropy_decode
* and entropy_decode_init/term.
*/
#include "jinclude.h"
#ifdef D_ARITH_CODING_SUPPORTED
/*
* The arithmetic coding option of the JPEG standard specifies Q-coding,
* which is covered by patents held by IBM (and possibly AT&T and Mitsubishi).
* At this time it does not appear to be legal for the Independent JPEG
* Group to distribute software that implements arithmetic coding.
* We have therefore removed arithmetic coding support from the
* distributed source code.
*
* We're not happy about it either.
*/
/*
* The method selection routine for arithmetic entropy decoding.
*/
GLOBAL void
jseldarithmetic (decompress_info_ptr cinfo)
{
if (cinfo->arith_code) {
ERREXIT(cinfo->emethods, "Sorry, there are legal restrictions on arithmetic coding");
}
}
#endif /* D_ARITH_CODING_SUPPORTED */