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/*
* Samba compression library - LGPLv3
*
* Copyright © Catalyst IT 2022
*
* ** NOTE! The following LGPL license applies to this file.
* ** It does NOT imply that all of Samba is released under the LGPL
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#ifndef HAVE_LZXPRESS_HUFFMAN_H
#define HAVE_LZXPRESS_HUFFMAN_H
struct huffman_node {
struct huffman_node *left;
struct huffman_node *right;
uint32_t count;
uint16_t symbol;
int8_t depth;
};
/*
* LZX_HUFF_COMP_HASH_BITS is how big to make the hash tables
* (12 means 4096, etc).
*
* A larger number (up to 16) will be faster on long messages (fewer
* collisions), but probably slower on short ones (more prep).
*/
#define LZX_HUFF_COMP_HASH_BITS 14
/*
* This struct just coalesces all the memory you need for LZ77 + Huffman
* compresssion together in one bundle.
*
* There are a few different things you want, you usually want them all, so
* this makes it easy to allocate them all at once.
*/
struct lzxhuff_compressor_mem {
struct huffman_node leaf_nodes[512];
struct huffman_node internal_nodes[512];
uint16_t symbol_values[512];
uint16_t intermediate[65536 + 6];
uint16_t hash_table1[1 << LZX_HUFF_COMP_HASH_BITS];
uint16_t hash_table2[1 << LZX_HUFF_COMP_HASH_BITS];
};
ssize_t lzxpress_huffman_compress(struct lzxhuff_compressor_mem *cmp,
const uint8_t *input_bytes,
size_t input_size,
uint8_t *output,
size_t available_size);
ssize_t lzxpress_huffman_compress_talloc(TALLOC_CTX *mem_ctx,
const uint8_t *input_bytes,
size_t input_size,
uint8_t **output);
ssize_t lzxpress_huffman_decompress(const uint8_t *input,
size_t input_size,
uint8_t *output,
size_t max_output_size);
uint8_t *lzxpress_huffman_decompress_talloc(TALLOC_CTX *mem_ctx,
const uint8_t *input_bytes,
size_t input_size,
size_t output_size);
/*
* lzxpress_huffman_max_compressed_size()
*
* Return the most bytes the compression can take, to allow
* pre-allocation.
*/
size_t lzxpress_huffman_max_compressed_size(size_t input_size);
#endif /* HAVE_LZXPRESS_HUFFMAN_H */
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