135 lines
4.2 KiB
C
135 lines
4.2 KiB
C
/*
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* Copyright (C) Matthieu Suiche 2008
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the author nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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#include "lzxpress.h"
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#define __BUF_POS_CONST(buf,ofs)(((const guint8 *)buf)+(ofs))
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#define __PULL_BYTE(buf,ofs) \
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((guint8)((*__BUF_POS_CONST(buf,ofs)) & 0xFF))
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#ifndef PULL_LE_UINT16
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#define PULL_LE_UINT16(buf,ofs) ((guint16)( \
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((guint16)(((guint16)(__PULL_BYTE(buf,(ofs)+0))) << 0)) | \
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((guint16)(((guint16)(__PULL_BYTE(buf,(ofs)+1))) << 8)) \
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))
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#endif
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#ifndef PULL_LE_UINT32
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#define PULL_LE_UINT32(buf,ofs) ((guint32)( \
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((guint32)(((guint32)(__PULL_BYTE(buf,(ofs)+0))) << 0)) | \
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((guint32)(((guint32)(__PULL_BYTE(buf,(ofs)+1))) << 8)) | \
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((guint32)(((guint32)(__PULL_BYTE(buf,(ofs)+2))) << 16)) | \
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((guint32)(((guint32)(__PULL_BYTE(buf,(ofs)+3))) << 24)) \
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))
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#endif
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gssize lzxpress_decompress(const guint8 *input,
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guint32 input_size,
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guint8 *output,
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guint32 max_output_size)
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{
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guint32 output_index, input_index;
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guint32 indicator, indicator_bit;
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guint32 length;
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guint32 offset;
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guint32 nibble_index;
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output_index = 0;
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input_index = 0;
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indicator = 0;
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indicator_bit = 0;
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nibble_index = 0;
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do {
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if (indicator_bit == 0) {
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indicator = PULL_LE_UINT32(input, input_index);
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input_index += (guint32)sizeof(guint32);
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indicator_bit = 32;
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}
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indicator_bit--;
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/*
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* check whether the bit specified by indicator_bit is set or not
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* set in indicator. For example, if indicator_bit has value 4
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* check whether the 4th bit of the value in indicator is set
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*/
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if (((indicator >> indicator_bit) & 1) == 0) {
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output[output_index] = input[input_index];
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input_index += (guint32)sizeof(guint8);
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output_index += (guint32)sizeof(guint8);
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} else {
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length = PULL_LE_UINT16(input, input_index);
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input_index += (guint32)sizeof(guint16);
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offset = length / 8;
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length = length % 8;
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if (length == 7) {
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if (nibble_index == 0) {
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nibble_index = input_index;
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length = input[input_index] % 16;
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input_index += (guint32)sizeof(guint8);
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} else {
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length = input[nibble_index] / 16;
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nibble_index = 0;
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}
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if (length == 15) {
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length = input[input_index];
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input_index += (guint32)sizeof(guint8);
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if (length == 255) {
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length = PULL_LE_UINT16(input, input_index);
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input_index += (guint32)sizeof(guint16);
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length -= (15 + 7);
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}
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length += 15;
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}
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length += 7;
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}
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length += 3;
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do {
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if ((output_index >= max_output_size) || ((offset + 1) > output_index)) break;
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output[output_index] = output[output_index - offset - 1];
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output_index += (guint32)sizeof(guint8);
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length -= (guint32)sizeof(guint8);
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} while (length != 0);
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}
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} while ((output_index < max_output_size) && (input_index < (input_size)));
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return output_index;
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}
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