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70 lines
1.8 KiB
C
70 lines
1.8 KiB
C
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///////////////////////////////////////////////////////////////////////////////
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//
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/// \file vli_decoder.c
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/// \brief Decodes variable-length integers
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//
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// Copyright (C) 2007 Lasse Collin
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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///////////////////////////////////////////////////////////////////////////////
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#include "common.h"
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extern LZMA_API lzma_ret
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lzma_vli_decode(lzma_vli *restrict vli, size_t *restrict vli_pos,
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const uint8_t *restrict in, size_t *restrict in_pos,
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size_t in_size)
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{
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if (*vli > LZMA_VLI_VALUE_MAX || *vli_pos >= 9
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|| (*vli >> (7 * *vli_pos)) != 0)
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return LZMA_PROG_ERROR;
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if (*in_pos >= in_size)
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return LZMA_BUF_ERROR;
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if (*vli_pos == 0) {
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*vli_pos = 1;
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if (in[*in_pos] <= 0x7F) {
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// Single-byte integer
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*vli = in[*in_pos];
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++*in_pos;
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return LZMA_STREAM_END;
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}
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*vli = in[*in_pos] & 0x7F;
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++*in_pos;
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}
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while (*in_pos < in_size) {
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// Read in the next byte.
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*vli |= (lzma_vli)(in[*in_pos] & 0x7F) << (*vli_pos * 7);
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++*vli_pos;
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// Check if this is the last byte of a multibyte integer.
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if (in[*in_pos] & 0x80) {
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++*in_pos;
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return LZMA_STREAM_END;
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}
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// Limit variable-length representation to nine bytes.
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if (*vli_pos == 9)
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return LZMA_DATA_ERROR;
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// Increment input position only when the byte was accepted.
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++*in_pos;
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}
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return LZMA_OK;
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}
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