130 lines
2.7 KiB
C
130 lines
2.7 KiB
C
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/*
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* d16align.c
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*
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* Decoding aligned offset block
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*/
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#include "decoder.h"
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int NEAR decode_aligned_offset_block(
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t_decoder_context * context,
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long bufpos,
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int amount_to_decode /* yes, it will equal 32768 */
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)
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{
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ulong match_pos;
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ulong temp_pos;
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ulong dec_bitbuf;
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byte *dec_input_curpos;
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byte *dec_end_input_pos;
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MATCH match_info;
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int match_length;
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int c;
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char m;
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char dec_bitcount;
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/*
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* Store commonly used variables locally
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*/
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dec_bitcount = context->dec_bitcount;
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dec_bitbuf = context->dec_bitbuf;
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dec_input_curpos = context->dec_input_curpos;
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dec_end_input_pos = context->dec_end_input_pos;
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/*
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* see comment in d16verb.c about why this is a DO loop,
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* and why we allow a signed int to hold the value 32768.
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*/
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do
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{
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/*
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* Decode an item
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*/
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DECODE_MAIN_TREE(c);
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if ((c -= NUM_CHARS) < 0)
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{
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context->DComp_Token_Literal(context, (byte) c);
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amount_to_decode--;
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}
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else
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{
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/*
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* Get match length slot
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*/
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if ((match_length = c & NUM_PRIMARY_LENGTHS) == NUM_PRIMARY_LENGTHS)
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{
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DECODE_LEN_TREE_NOEOFCHECK(match_length);
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}
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/*
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* Get match position slot
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*/
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m = c >> NL_SHIFT;
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if (m > 2)
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{
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if (dec_extra_bits[ m ] >= 3)
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{
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if (dec_extra_bits[m]-3)
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{
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/* no need to getbits17 */
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GET_BITS_NOEOFCHECK(dec_extra_bits[ m ] - 3, temp_pos);
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}
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else
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{
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temp_pos = 0;
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}
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match_pos = MP_POS_minus2[m] + (temp_pos << 3);
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DECODE_ALIGNED_NOEOFCHECK(temp_pos);
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match_pos += temp_pos;
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}
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else
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{
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if (dec_extra_bits[m])
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{
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GET_BITS_NOEOFCHECK(dec_extra_bits[ m ], match_pos);
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match_pos += MP_POS_minus2[m];
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}
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else
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{
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match_pos = MP_POS_minus2[m];
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}
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}
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context->dec_last_matchpos_offset[2] = context->dec_last_matchpos_offset[1];
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context->dec_last_matchpos_offset[1] = context->dec_last_matchpos_offset[0];
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context->dec_last_matchpos_offset[0] = match_pos;
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}
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else
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{
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match_pos = context->dec_last_matchpos_offset[m];
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if (m)
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{
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context->dec_last_matchpos_offset[m] = context->dec_last_matchpos_offset[0];
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context->dec_last_matchpos_offset[0] = match_pos;
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}
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}
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match_length += MIN_MATCH;
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match_info.Len = match_length;
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match_info.Dist = match_pos;
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context->DComp_Token_Match(context, match_info);
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amount_to_decode -= match_length;
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}
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} while (amount_to_decode > 0);
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context->dec_bitcount = dec_bitcount;
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context->dec_bitbuf = dec_bitbuf;
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context->dec_input_curpos = dec_input_curpos;
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return 0;
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}
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