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82 lines
2 KiB
C
82 lines
2 KiB
C
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///////////////////////////////////////////////////////////////////////////////
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//
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/// \file vli_encoder.c
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/// \brief Encodes 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_encode(lzma_vli vli, size_t *restrict vli_pos, size_t vli_size,
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uint8_t *restrict out, size_t *restrict out_pos,
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size_t out_size)
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{
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if (vli > LZMA_VLI_VALUE_MAX || *vli_pos >= 9 || vli_size > 9
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|| (vli != 0 && (vli >> (7 * *vli_pos)) == 0))
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return LZMA_PROG_ERROR;
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if (*out_pos >= out_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 (vli <= 0x7F && *vli_pos >= vli_size) {
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// Single-byte integer
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out[(*out_pos)++] = vli;
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return LZMA_STREAM_END;
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}
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// First byte of a multibyte integer
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out[(*out_pos)++] = (vli & 0x7F) | 0x80;
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}
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while (*out_pos < out_size) {
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const lzma_vli b = vli >> (7 * *vli_pos);
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++*vli_pos;
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if (b <= 0x7F && *vli_pos >= vli_size) {
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// Last byte of a multibyte integer
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out[(*out_pos)++] = (b & 0xFF) | 0x80;
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return LZMA_STREAM_END;
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}
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// Middle byte of a multibyte integer
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out[(*out_pos)++] = b & 0x7F;
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}
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// vli is not yet completely written out.
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return LZMA_OK;
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}
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extern LZMA_API size_t
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lzma_vli_size(lzma_vli vli)
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{
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if (vli > LZMA_VLI_VALUE_MAX)
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return 0;
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size_t i = 0;
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do {
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vli >>= 7;
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++i;
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} while (vli != 0);
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assert(i <= 9);
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return i;
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}
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