95 lines
2 KiB
C
95 lines
2 KiB
C
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/*
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* decinit.c
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*
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* Initialisation routines for LZX decoder
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*/
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#include "decoder.h"
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/*
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* Allocate memory for decompression
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*/
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bool NEAR allocate_decompression_memory(t_decoder_context *context)
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{
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ulong pos_start;
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context->dec_num_position_slots = 4;
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pos_start = 4;
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while (1)
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{
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pos_start += 1L << dec_extra_bits[context->dec_num_position_slots];
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context->dec_num_position_slots++;
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if (pos_start >= context->dec_window_size)
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break;
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}
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#ifdef BIT16
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if (DComp_Init(context))
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return false;
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#else
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if (!(context->dec_mem_window = (byte *) context->dec_malloc(context->dec_window_size+(MAX_MATCH+4))))
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return false;
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#endif
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return true;
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}
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/*
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* Free decompression memory
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*/
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void NEAR free_decompression_memory(t_decoder_context *context)
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{
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#ifdef BIT16
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DComp_Close(context);
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#else
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if (context->dec_mem_window)
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{
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context->dec_free(context->dec_mem_window);
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context->dec_mem_window = NULL;
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}
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#endif
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}
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/*
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* Set/reset decoder trees to initial state
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*/
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void NEAR reset_decoder_trees(t_decoder_context *context)
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{
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memset(context->dec_main_tree_len, 0, MAIN_TREE_ELEMENTS);
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memset(context->dec_main_tree_prev_len, 0, MAIN_TREE_ELEMENTS);
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memset(context->dec_secondary_length_tree_len, 0, NUM_SECONDARY_LENGTHS);
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memset(context->dec_secondary_length_tree_prev_len, 0, NUM_SECONDARY_LENGTHS);
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}
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/*
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* Miscellaneous state initialisations
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*/
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void NEAR decoder_misc_init(t_decoder_context *context)
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{
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context->dec_last_matchpos_offset[0] = 1;
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context->dec_last_matchpos_offset[1] = 1;
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context->dec_last_matchpos_offset[2] = 1;
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context->dec_bufpos = 0;
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context->dec_position_at_start = 0;
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context->dec_decoder_state = DEC_STATE_START_NEW_BLOCK;
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context->dec_block_size = 0;
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/* so that initialise_decoder_bitbuf() will succeed */
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context->dec_block_type = BLOCKTYPE_INVALID;
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context->dec_first_time_this_group = true;
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context->dec_current_file_size = 0;
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context->dec_error_condition = false;
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}
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