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47 lines
1.5 KiB
47 lines
1.5 KiB
/* |
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* jchuff.h |
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* |
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* Copyright (C) 1991-1997, Thomas G. Lane. |
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* This file is part of the Independent JPEG Group's software. |
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* For conditions of distribution and use, see the accompanying README file. |
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* |
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* This file contains declarations for Huffman entropy encoding routines |
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* that are shared between the sequential encoder (jchuff.c) and the |
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* progressive encoder (jcphuff.c). No other modules need to see these. |
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*/ |
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/* The legal range of a DCT coefficient is |
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* -1024 .. +1023 for 8-bit data; |
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* -16384 .. +16383 for 12-bit data. |
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* Hence the magnitude should always fit in 10 or 14 bits respectively. |
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*/ |
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#if BITS_IN_JSAMPLE == 8 |
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#define MAX_COEF_BITS 10 |
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#else |
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#define MAX_COEF_BITS 14 |
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#endif |
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/* Derived data constructed for each Huffman table */ |
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typedef struct { |
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unsigned int ehufco[256]; /* code for each symbol */ |
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char ehufsi[256]; /* length of code for each symbol */ |
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/* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */ |
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} c_derived_tbl; |
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/* Short forms of external names for systems with brain-damaged linkers. */ |
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#ifdef NEED_SHORT_EXTERNAL_NAMES |
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#define jpeg_make_c_derived_tbl jMkCDerived |
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#define jpeg_gen_optimal_table jGenOptTbl |
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#endif /* NEED_SHORT_EXTERNAL_NAMES */ |
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/* Expand a Huffman table definition into the derived format */ |
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EXTERN(void) jpeg_make_c_derived_tbl |
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JPP((j_compress_ptr cinfo, boolean isDC, int tblno, |
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c_derived_tbl ** pdtbl)); |
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/* Generate an optimal table definition given the specified counts */ |
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EXTERN(void) jpeg_gen_optimal_table |
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JPP((j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[]));
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