diff options
Diffstat (limited to 'converter/other/fiasco/lib/arith.c')
| -rw-r--r-- | converter/other/fiasco/lib/arith.c | 130 |
1 files changed, 65 insertions, 65 deletions
diff --git a/converter/other/fiasco/lib/arith.c b/converter/other/fiasco/lib/arith.c index 825d4757..e61e753e 100644 --- a/converter/other/fiasco/lib/arith.c +++ b/converter/other/fiasco/lib/arith.c @@ -2,7 +2,7 @@ * arith.c: Adaptive arithmetic coding and decoding * * Written by: Ullrich Hafner - * + * * This file is part of FIASCO (Fractal Image And Sequence COdec) * Copyright (C) 1994-2000 Ullrich Hafner */ @@ -27,7 +27,7 @@ /****************************************************************************** public code - + ******************************************************************************/ arith_t * @@ -35,7 +35,7 @@ alloc_encoder (bitfile_t *output) /* * Arithmetic coder constructor: * Initialize the arithmetic coder. - * + * * Return value: * A pointer to the new coder structure */ @@ -43,7 +43,7 @@ alloc_encoder (bitfile_t *output) arith_t *arith = Calloc (1, sizeof (arith_t)); assert (output); - + arith->low = LOW; arith->high = HIGH; arith->underflow = 0; @@ -58,7 +58,7 @@ free_encoder (arith_t *arith) * Arithmetic encoder destructor. * Flush the arithmetic coder. Append all remaining bits to the * output stream. Append zero bits to get the output file byte aligned. - * + * * No return value. */ { @@ -66,14 +66,14 @@ free_encoder (arith_t *arith) u_word_t high; /* end of the current code range */ u_word_t underflow; /* number of underflow bits pending */ bitfile_t *output; - + assert (arith); low = arith->low; high = arith->high; underflow = arith->underflow; output = arith->file; - + low = high; RESCALE_OUTPUT_INTERVAL; @@ -92,7 +92,7 @@ encode_symbol (unsigned symbol, arith_t *arith, model_t *model) * * The model is updated after encoding the symbol (if necessary the * symbol counts are rescaled). - * + * * Return value: * information content of the encoded symbol. * @@ -110,7 +110,7 @@ encode_symbol (unsigned symbol, arith_t *arith, model_t *model) u_word_t high; /* end of the current code range */ u_word_t underflow; /* number of underflow bits pending */ bitfile_t *output; /* output file */ - + assert (model && arith); /* @@ -122,7 +122,7 @@ encode_symbol (unsigned symbol, arith_t *arith, model_t *model) output = arith->file; assert (high > low); - + if (model->order > 0) /* order-'n' model*/ { unsigned power; /* multiplicator */ @@ -134,10 +134,10 @@ encode_symbol (unsigned symbol, arith_t *arith, model_t *model) */ power = 1; /* multiplicator */ index = 0; /* address of prob. model */ - - for (i = 0; i < model->order; i++) /* genarate a M-nary number */ + + for (i = 0; i < model->order; i++) /* generate a M-nary number */ { - index += model->context [i] * power; + index += model->context [i] * power; power *= model->symbols; } @@ -160,9 +160,9 @@ encode_symbol (unsigned symbol, arith_t *arith, model_t *model) range = (high - low) + 1; high = low + (u_word_t) ((range * high_count) / scale - 1); low = low + (u_word_t) ((range * low_count) / scale); - + RESCALE_OUTPUT_INTERVAL; - + if (model->scale > 0) /* adaptive model */ { unsigned i; @@ -189,7 +189,7 @@ encode_symbol (unsigned symbol, arith_t *arith, model_t *model) arith->low = low; arith->high = high; arith->underflow = underflow; - + return - log2 ((high_count - low_count) / (real_t) scale); } @@ -214,21 +214,21 @@ encode_array (bitfile_t *output, const unsigned *data, const unsigned *context, assert (output && c_symbols && data); assert (n_context == 1 || context); - + /* * Allocate probability models, start with uniform distribution */ totals = Calloc (n_context, sizeof (u_word_t *)); { unsigned c; - + for (c = 0; c < n_context; c++) { unsigned i; - + totals [c] = Calloc (c_symbols [c] + 1, sizeof (u_word_t)); totals [c][0] = 0; - + for (i = 0; i < c_symbols [c]; i++) totals [c][i + 1] = totals [c][i] + 1; } @@ -242,7 +242,7 @@ encode_array (bitfile_t *output, const unsigned *data, const unsigned *context, u_word_t high = 0xffff; /* End of the current code range */ u_word_t underflow = 0; /* Number of underflow bits pending */ unsigned n; - + for (n = 0; n < n_data; n++) { u_word_t low_count; /* lower bound of 'symbol' interval */ @@ -253,8 +253,8 @@ encode_array (bitfile_t *output, const unsigned *data, const unsigned *context, int c; /* context of current data symbol */ d = data [n]; - c = n_context > 1 ? context [n] : 0; - + c = n_context > 1 ? context [n] : 0; + scale = totals [c][c_symbols [c]]; low_count = totals [c][d]; high_count = totals [c][d + 1]; @@ -266,7 +266,7 @@ encode_array (bitfile_t *output, const unsigned *data, const unsigned *context, high = low + (u_word_t) ((range * high_count) / scale - 1); low = low + (u_word_t) ((range * low_count) / scale); RESCALE_OUTPUT_INTERVAL; - + /* * Update probability models */ @@ -275,7 +275,7 @@ encode_array (bitfile_t *output, const unsigned *data, const unsigned *context, for (i = d + 1; i < c_symbols [c] + 1; i++) totals [c][i]++; - + if (totals [c][c_symbols [c]] > scaling) /* scaling */ for (i = 1; i < c_symbols [c] + 1; i++) { @@ -292,7 +292,7 @@ encode_array (bitfile_t *output, const unsigned *data, const unsigned *context, RESCALE_OUTPUT_INTERVAL; OUTPUT_BYTE_ALIGN (output); } - + /* * Cleanup ... */ @@ -310,16 +310,16 @@ alloc_decoder (bitfile_t *input) * Arithmetic decoder constructor: * Initialize the arithmetic decoder with the first * 16 input bits from the stream 'input'. - * + * * Return value: * A pointer to the new decoder structure */ { arith_t *arith = Calloc (1, sizeof (arith_t)); - + assert (input); - + arith->low = LOW; arith->high = HIGH; arith->code = get_bits (input, 16); @@ -333,8 +333,8 @@ free_decoder (arith_t *arith) /* * Arithmetic decoder destructor: * Flush the arithmetic decoder, i.e., read bits to get the input - * file byte aligned. - * + * file byte aligned. + * * No return value. * * Side effects: @@ -354,8 +354,8 @@ decode_symbol (arith_t *arith, model_t *model) * Decode the next symbol - the state of the arithmetic decoder * is given in 'arith'. Read refinement bits from the stream 'input' * and use the given probability 'model'. Update the probability model after - * deconding the symbol (if necessary also rescale the symbol counts). - * + * decoding the symbol (if necessary also rescale the symbol counts). + * * Return value: * decoded symbol * @@ -375,7 +375,7 @@ decode_symbol (arith_t *arith, model_t *model) bitfile_t *input; /* input file */ assert (arith && model); - + /* * Get interval values */ @@ -385,22 +385,22 @@ decode_symbol (arith_t *arith, model_t *model) input = arith->file; assert (high > low); - + if (model->order > 0) /* order-'n' model */ { unsigned power; /* multiplicator */ unsigned i; - + /* * Compute index of the probability model to use. * See init_model() for more details. */ power = 1; /* multiplicator */ index = 0; /* address of prob. model */ - - for (i = 0; i < model->order; i++) /* genarate a m-nary number */ + + for (i = 0; i < model->order; i++) /* generate a m-nary number */ { - index += model->context[i] * power; + index += model->context[i] * power; power *= model->symbols; } @@ -420,7 +420,7 @@ decode_symbol (arith_t *arith, model_t *model) if (model->order > 0) /* order-'n' model */ { unsigned i; - + for (i = 0; i < model->order - 1; i++) model->context [i] = model->context [i + 1]; model->context [i] = symbol; @@ -432,15 +432,15 @@ decode_symbol (arith_t *arith, model_t *model) { u_word_t low_count; /* lower bound of 'symbol' interval */ u_word_t high_count; /* upper bound of 'symbol' interval */ - + low_count = model->totals [index + symbol]; high_count = model->totals [index + symbol + 1]; high = low + (u_word_t) ((range * high_count) / scale - 1 ); low = low + (u_word_t) ((range * low_count) / scale ); } - + RESCALE_INPUT_INTERVAL; - + if (model->scale > 0) /* adaptive model */ { unsigned i; @@ -460,7 +460,7 @@ decode_symbol (arith_t *arith, model_t *model) } } } - + /* * Store interval values */ @@ -488,28 +488,28 @@ decode_array (bitfile_t *input, const unsigned *context, { unsigned *data; /* array to store decoded symbols */ u_word_t **totals; /* probability model */ - + if (n_context < 1) n_context = 1; /* always use one context */ assert (input && c_symbols); assert (n_context == 1 || context); data = Calloc (n_data, sizeof (unsigned)); - + /* * Allocate probability models, start with uniform distribution */ totals = Calloc (n_context, sizeof (u_word_t *)); { unsigned c; - + for (c = 0; c < n_context; c++) { unsigned i; - + totals [c] = Calloc (c_symbols [c] + 1, sizeof (u_word_t)); totals [c][0] = 0; - + for (i = 0; i < c_symbols [c]; i++) totals [c][i + 1] = totals [c][i] + 1; } @@ -523,8 +523,8 @@ decode_array (bitfile_t *input, const unsigned *context, u_word_t low = 0; /* Start of the current code range */ u_word_t high = 0xffff; /* End of the current code range */ unsigned n; - - for (n = 0; n < n_data; n++) + + for (n = 0; n < n_data; n++) { u_word_t scale; /* range of all 'm' symbol intervals */ u_word_t low_count; /* lower bound of 'symbol' interval */ @@ -534,13 +534,13 @@ decode_array (bitfile_t *input, const unsigned *context, unsigned d; /* current data symbol */ unsigned c; /* context of current data symbol */ - c = n_context > 1 ? context [n] : 0; + c = n_context > 1 ? context [n] : 0; assert (high > low); scale = totals [c][c_symbols [c]]; range = (high - low) + 1; count = (((code - low) + 1 ) * scale - 1) / range; - + for (d = c_symbols [c]; count < totals [c][d]; d--) /* next symbol */ ; low_count = totals [c][d]; @@ -558,7 +558,7 @@ decode_array (bitfile_t *input, const unsigned *context, for (i = d + 1; i < c_symbols [c] + 1; i++) totals [c][i]++; - + if (totals [c][c_symbols [c]] > scaling) /* scaling */ for (i = 1; i < c_symbols [c] + 1; i++) { @@ -577,12 +577,12 @@ decode_array (bitfile_t *input, const unsigned *context, */ { unsigned c; - + for (c = 0; c < n_context; c++) Free (totals [c]); Free (totals); } - + return data; } @@ -600,10 +600,10 @@ alloc_model (unsigned m, unsigned scale, unsigned n, unsigned *totals) * * Return value: * a pointer to the new probability model structure. - * + * * Note: We recommend a small size of the alphabet because no escape codes * are used to encode/decode previously unseen symbols. - * + * */ { model_t *model; /* new probability model */ @@ -621,7 +621,7 @@ alloc_model (unsigned m, unsigned scale, unsigned n, unsigned *totals) model->order = n; model->context = n > 0 ? Calloc (n, sizeof (unsigned)) : NULL; /* - * Allocate memory for the probabilty model. + * Allocate memory for the probability model. * Each of the m^n different contexts requires its own probability model. */ for (num = 1, i = 0; i < model->order; i++) @@ -644,17 +644,17 @@ alloc_model (unsigned m, unsigned scale, unsigned n, unsigned *totals) */ power = 1; /* multiplicator */ index = 0; /* address of prob. model */ - - for (i = 0; i < model->order; i++) /* genarate a m-nary number */ + + for (i = 0; i < model->order; i++) /* generate a m-nary number */ { - index += model->context[i] * power; + index += model->context[i] * power; power *= model->symbols; } index *= model->symbols + 1; /* size of each model is m + 1 */ model->totals [index + 0] = 0; /* always zero */ - + for (i = 1; i <= model->symbols; i++) /* prob of each symbol is 1/m or as given in totals */ model->totals[index + i] = model->totals [index + i - 1] @@ -667,14 +667,14 @@ alloc_model (unsigned m, unsigned scale, unsigned n, unsigned *totals) { dec = NO; model->context[i]++; - if (model->context[i] >= model->symbols) + if (model->context[i] >= model->symbols) { /* change previous context */ model->context[i] = 0; if (i > 0) /* there's still a context remaining */ dec = YES; else - cont = NO; /* all context models initilized */ + cont = NO; /* all context models initialized */ } } } |