468 lines
16 KiB
C
468 lines
16 KiB
C
/*-----------------------------------------------------------*/
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/* Block Sorting, Lossless Data Compression Library. */
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/* Lempel Ziv Prediction */
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/*-----------------------------------------------------------*/
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/*--
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This file is a part of bsc and/or libbsc, a program and a library for
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lossless, block-sorting data compression.
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Copyright (c) 2009-2012 Ilya Grebnov <ilya.grebnov@gmail.com>
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Copyright (c) 2012 Moinak Ghosh <moinakg@gmail.com>
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See file AUTHORS for a full list of contributors.
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The bsc and libbsc is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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The bsc and libbsc is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the bsc and libbsc. If not, see http://www.gnu.org/licenses/.
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Please see the files COPYING and COPYING.LIB for full copyright information.
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See also the bsc and libbsc web site:
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http://libbsc.com/ for more information.
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--*/
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/*
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* TODO: Port the parallel implementation.
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*/
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#undef LZP_OPENMP
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#include <stdlib.h>
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#include <memory.h>
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#include <string.h>
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#include <allocator.h>
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#include <sys/types.h>
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#include "lzp.h"
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#define LZP_MATCH_FLAG 0xf2
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static
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inline int bsc_lzp_num_blocks(int64_t n)
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{
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int nb;
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if (n < 256 * 1024) return 1;
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if (n < 4 * 1024 * 1024) return 2;
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if (n < 16 * 1024 * 1024) return 4;
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if (n < LZP_MAX_BLOCK) return 8;
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nb = n / LZP_MAX_BLOCK;
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if (n % LZP_MAX_BLOCK) nb++;
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return (nb);
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}
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static
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int bsc_lzp_encode_block(const unsigned char * input, const unsigned char * inputEnd, unsigned char * output, unsigned char * outputEnd, int hashSize, int minLen)
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{
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int *lookup, i;
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if (inputEnd - input < 16)
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{
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return LZP_NOT_COMPRESSIBLE;
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}
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if (lookup = (int *)slab_calloc(NULL, (int)(1 << hashSize), sizeof(int)))
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{
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unsigned int mask = (int)(1 << hashSize) - 1;
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const unsigned char * inputStart = input;
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const unsigned char * outputStart = output;
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const unsigned char * outputEOB = outputEnd - 4;
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unsigned int context = 0;
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for (i = 0; i < 4; ++i)
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{
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context = (context << 8) | (*output++ = *input++);
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}
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const unsigned char * heuristic = input;
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const unsigned char * inputMinLenEnd = inputEnd - minLen - 8;
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while ((input < inputMinLenEnd) && (output < outputEOB))
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{
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unsigned int index = ((context >> 15) ^ context ^ (context >> 3)) & mask;
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int value = lookup[index]; lookup[index] = (int)(input - inputStart);
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if (value > 0)
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{
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const unsigned char * reference = inputStart + value;
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if ((*(unsigned int *)(input + minLen - 4) == *(unsigned int *)(reference + minLen - 4)) && (*(unsigned int *)(input) == *(unsigned int *)(reference)))
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{
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if ((heuristic > input) && (*(unsigned int *)heuristic != *(unsigned int *)(reference + (heuristic - input))))
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{
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goto LZP_MATCH_NOT_FOUND;
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}
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int len = 4;
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for (; input + len < inputMinLenEnd; len += 4)
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{
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if (*(unsigned int *)(input + len) != *(unsigned int *)(reference + len)) break;
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}
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if (len < minLen)
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{
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if (heuristic < input + len) heuristic = input + len;
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goto LZP_MATCH_NOT_FOUND;
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}
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if (input[len] == reference[len]) len++;
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if (input[len] == reference[len]) len++;
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if (input[len] == reference[len]) len++;
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input += len; context = input[-1] | (input[-2] << 8) | (input[-3] << 16) | (input[-4] << 24);
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*output++ = LZP_MATCH_FLAG;
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len -= minLen; while (len >= 254) { len -= 254; *output++ = 254; if (output >= outputEOB) break; }
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*output++ = (unsigned char)(len);
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}
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else
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{
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unsigned char next;
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LZP_MATCH_NOT_FOUND:
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next = *output++ = *input++; context = (context << 8) | next;
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if (next == LZP_MATCH_FLAG) *output++ = 255;
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}
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}
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else
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{
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context = (context << 8) | (*output++ = *input++);
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}
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}
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while ((input < inputEnd) && (output < outputEOB))
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{
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unsigned int index = ((context >> 15) ^ context ^ (context >> 3)) & mask;
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int value = lookup[index]; lookup[index] = (int)(input - inputStart);
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if (value > 0)
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{
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unsigned char next = *output++ = *input++; context = (context << 8) | next;
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if (next == LZP_MATCH_FLAG) *output++ = 255;
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}
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else
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{
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context = (context << 8) | (*output++ = *input++);
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}
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}
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slab_free(NULL, lookup);
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return (output >= outputEOB) ? LZP_NOT_COMPRESSIBLE : (int)(output - outputStart);
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}
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return LZP_NOT_ENOUGH_MEMORY;
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}
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static
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int bsc_lzp_decode_block(const unsigned char * input, const unsigned char * inputEnd, unsigned char * output, int hashSize, int minLen)
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{
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int *lookup, i;
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if (inputEnd - input < 4)
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{
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return LZP_UNEXPECTED_EOB;
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}
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if (lookup = (int *)slab_calloc(NULL, (int)(1 << hashSize), sizeof(int)))
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{
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unsigned int mask = (int)(1 << hashSize) - 1;
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const unsigned char * outputStart = output;
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unsigned int context = 0;
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for (i = 0; i < 4; ++i)
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{
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context = (context << 8) | (*output++ = *input++);
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}
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while (input < inputEnd)
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{
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unsigned int index = ((context >> 15) ^ context ^ (context >> 3)) & mask;
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int value = lookup[index]; lookup[index] = (int)(output - outputStart);
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if (*input == LZP_MATCH_FLAG && value > 0)
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{
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input++;
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if (*input != 255)
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{
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int len = minLen; while (1) { len += *input; if (*input++ != 254) break; }
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const unsigned char * reference = outputStart + value;
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unsigned char * outputEnd = output + len;
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if (output - reference < 4)
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{
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int offset[4] = {0, 3, 2, 3};
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*output++ = *reference++;
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*output++ = *reference++;
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*output++ = *reference++;
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*output++ = *reference++;
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reference -= offset[output - reference];
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}
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while (output < outputEnd) { *(unsigned int *)output = *(unsigned int*)reference; output += 4; reference += 4; }
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output = outputEnd; context = output[-1] | (output[-2] << 8) | (output[-3] << 16) | (output[-4] << 24);
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}
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else
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{
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input++; context = (context << 8) | (*output++ = LZP_MATCH_FLAG);
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}
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}
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else
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{
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context = (context << 8) | (*output++ = *input++);
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}
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}
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slab_free(NULL, lookup);
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return (int)(output - outputStart);
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}
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return LZP_NOT_ENOUGH_MEMORY;
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}
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static
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int64_t bsc_lzp_compress_serial(const unsigned char * input, unsigned char * output, int64_t n, int hashSize, int minLen)
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{
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if (bsc_lzp_num_blocks(n) == 1)
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{
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int result = bsc_lzp_encode_block(input, input + n, output + 1, output + n - 1, hashSize, minLen);
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if (result >= LZP_NO_ERROR) result = (output[0] = 1, result + 1);
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return result;
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}
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int nBlocks = bsc_lzp_num_blocks(n);
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int chunkSize;
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int blockId;
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int64_t outputPtr = 1 + 8 * nBlocks;
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if (n > LZP_MAX_BLOCK)
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chunkSize = LZP_MAX_BLOCK;
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else
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chunkSize = n / nBlocks;
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output[0] = nBlocks;
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for (blockId = 0; blockId < nBlocks; ++blockId)
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{
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int64_t inputStart = blockId * chunkSize;
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int inputSize = blockId != nBlocks - 1 ? chunkSize : n - inputStart;
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int outputSize = inputSize; if (outputSize > n - outputPtr) outputSize = n - outputPtr;
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int result = bsc_lzp_encode_block(input + inputStart, input + inputStart + inputSize, output + outputPtr, output + outputPtr + outputSize, hashSize, minLen);
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if (result < LZP_NO_ERROR)
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{
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if (outputPtr + inputSize >= n) return LZP_NOT_COMPRESSIBLE;
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result = inputSize; memcpy(output + outputPtr, input + inputStart, inputSize);
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}
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*(int *)(output + 1 + 8 * blockId + 0) = inputSize;
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*(int *)(output + 1 + 8 * blockId + 4) = result;
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outputPtr += result;
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}
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return outputPtr;
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}
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#ifdef LZP_OPENMP
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static
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int bsc_lzp_compress_parallel(const unsigned char * input, unsigned char * output, int64_t n, int hashSize, int minLen)
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{
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if (unsigned char * buffer = (unsigned char *)bsc_malloc(n * sizeof(unsigned char)))
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{
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int compressionResult[ALPHABET_SIZE];
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int nBlocks = bsc_lzp_num_blocks(n);
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int result = LZP_NO_ERROR;
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int chunkSize = n / nBlocks;
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int numThreads = omp_get_max_threads();
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if (numThreads > nBlocks) numThreads = nBlocks;
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output[0] = nBlocks;
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#pragma omp parallel num_threads(numThreads) if(numThreads > 1)
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{
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if (omp_get_num_threads() == 1)
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{
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result = bsc_lzp_compress_serial(input, output, n, hashSize, minLen);
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}
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else
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{
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#pragma omp for schedule(dynamic)
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for (int blockId = 0; blockId < nBlocks; ++blockId)
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{
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int blockStart = blockId * chunkSize;
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int blockSize = blockId != nBlocks - 1 ? chunkSize : n - blockStart;
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compressionResult[blockId] = bsc_lzp_encode_block(input + blockStart, input + blockStart + blockSize, buffer + blockStart, buffer + blockStart + blockSize, hashSize, minLen);
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if (compressionResult[blockId] < LZP_NO_ERROR) compressionResult[blockId] = blockSize;
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*(int *)(output + 1 + 8 * blockId + 0) = blockSize;
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*(int *)(output + 1 + 8 * blockId + 4) = compressionResult[blockId];
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}
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#pragma omp single
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{
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result = 1 + 8 * nBlocks;
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for (int blockId = 0; blockId < nBlocks; ++blockId)
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{
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result += compressionResult[blockId];
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}
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if (result >= n) result = LZP_NOT_COMPRESSIBLE;
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}
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if (result >= LZP_NO_ERROR)
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{
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#pragma omp for schedule(dynamic)
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for (int blockId = 0; blockId < nBlocks; ++blockId)
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{
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int blockStart = blockId * chunkSize;
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int blockSize = blockId != nBlocks - 1 ? chunkSize : n - blockStart;
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int outputPtr = 1 + 8 * nBlocks;
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for (int p = 0; p < blockId; ++p) outputPtr += compressionResult[p];
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if (compressionResult[blockId] != blockSize)
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{
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memcpy(output + outputPtr, buffer + blockStart, compressionResult[blockId]);
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}
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else
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{
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memcpy(output + outputPtr, input + blockStart, compressionResult[blockId]);
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}
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}
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}
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}
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}
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bsc_free(buffer);
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return result;
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}
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return LZP_NOT_ENOUGH_MEMORY;
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}
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#endif
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int64_t lzp_compress(const unsigned char * input, unsigned char * output, int64_t n, int hashSize, int minLen, int features)
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{
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#ifdef LZP_OPENMP
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if ((bsc_lzp_num_blocks(n) != 1) && (features & LZP_FEATURE_MULTITHREADING))
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{
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return bsc_lzp_compress_parallel(input, output, n, hashSize, minLen);
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}
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#endif
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return bsc_lzp_compress_serial(input, output, n, hashSize, minLen);
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}
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int64_t lzp_decompress(const unsigned char * input, unsigned char * output, int64_t n, int hashSize, int minLen, int features)
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{
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int nBlocks = input[0];
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if (nBlocks == 1)
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{
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return bsc_lzp_decode_block(input + 1, input + n, output, hashSize, minLen);
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}
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int decompressionResult[ALPHABET_SIZE];
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#ifdef LZP_OPENMP
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if (features & LZP_FEATURE_MULTITHREADING)
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{
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#pragma omp parallel for schedule(dynamic)
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for (int blockId = 0; blockId < nBlocks; ++blockId)
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{
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int inputPtr = 0; for (int p = 0; p < blockId; ++p) inputPtr += *(int *)(input + 1 + 8 * p + 4);
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int outputPtr = 0; for (int p = 0; p < blockId; ++p) outputPtr += *(int *)(input + 1 + 8 * p + 0);
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inputPtr += 1 + 8 * nBlocks;
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int inputSize = *(int *)(input + 1 + 8 * blockId + 4);
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int outputSize = *(int *)(input + 1 + 8 * blockId + 0);
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if (inputSize != outputSize)
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{
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decompressionResult[blockId] = bsc_lzp_decode_block(input + inputPtr, input + inputPtr + inputSize, output + outputPtr, hashSize, minLen);
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}
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else
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{
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decompressionResult[blockId] = inputSize; memcpy(output + outputPtr, input + inputPtr, inputSize);
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}
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}
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}
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else
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#endif
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{
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int blockId, p;
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for (blockId = 0; blockId < nBlocks; ++blockId)
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{
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int64_t inputPtr = 0; for (p = 0; p < blockId; ++p) inputPtr += *(int *)(input + 1 + 8 * p + 4);
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int64_t outputPtr = 0; for (p = 0; p < blockId; ++p) outputPtr += *(int *)(input + 1 + 8 * p + 0);
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inputPtr += 1 + 8 * nBlocks;
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int inputSize = *(int *)(input + 1 + 8 * blockId + 4);
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int outputSize = *(int *)(input + 1 + 8 * blockId + 0);
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if (inputSize != outputSize)
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{
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decompressionResult[blockId] = bsc_lzp_decode_block(input + inputPtr, input + inputPtr + inputSize, output + outputPtr, hashSize, minLen);
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}
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else
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{
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decompressionResult[blockId] = inputSize; memcpy(output + outputPtr, input + inputPtr, inputSize);
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}
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}
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}
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int64_t dataSize = 0;
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int result = LZP_NO_ERROR;
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int blockId;
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for (blockId = 0; blockId < nBlocks; ++blockId)
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{
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if (decompressionResult[blockId] < LZP_NO_ERROR) result = decompressionResult[blockId];
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dataSize += decompressionResult[blockId];
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}
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return (result == LZP_NO_ERROR) ? dataSize : result;
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}
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/*
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* Counter-intuitively we use a larger hash (with better LZP compression) for lower global
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* compression levels. So that LZP preprocessing plays along nicely with the primary
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* compression algorithm being used and actually provides a benefit.
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*/
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int lzp_hash_size(int level) {
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if (level > 7) {
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return (LZP_DEFAULT_LZPHASHSIZE + 2);
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} else if (level > 5) {
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return (LZP_DEFAULT_LZPHASHSIZE + 3);
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} else if (level > 3) {
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return (LZP_DEFAULT_LZPHASHSIZE + 4);
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} else {
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return (LZP_DEFAULT_LZPHASHSIZE + 5);
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}
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}
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/*-----------------------------------------------------------*/
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/* End lzp.cpp */
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/*-----------------------------------------------------------*/
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