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Diffstat (limited to 'base/compression/lzss_compression.cc')
| -rw-r--r-- | base/compression/lzss_compression.cc | 171 |
1 files changed, 0 insertions, 171 deletions
diff --git a/base/compression/lzss_compression.cc b/base/compression/lzss_compression.cc deleted file mode 100644 index 3ffdf7e95..000000000 --- a/base/compression/lzss_compression.cc +++ /dev/null @@ -1,171 +0,0 @@ -/* - * Copyright (c) 2003-2005 The Regents of The University of Michigan - * All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions are - * met: redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer; - * redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution; - * neither the name of the copyright holders nor the names of its - * contributors may be used to endorse or promote products derived from - * this software without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS - * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT - * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR - * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT - * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, - * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT - * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, - * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY - * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT - * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE - * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. - */ - -/** @file - * LZSSCompression definitions. - */ - -#include <assert.h> - -#include "base/compression/lzss_compression.hh" - -#include "base/misc.hh" //for fatal - -void -LZSSCompression::findSubString(uint8_t *src, int back, int size, uint16_t &L, - uint16_t &P) -{ - int front = 0; - int max_length = size - back; - L = 0; - P = back - 1; - while (front < back) { - while (src[front] != src[back] && front < back) ++front; - if (front >= back) { - return; - } - int i = 1; - while (src[front+i] == src[back+i] && i < max_length) ++i; - if (i >= L) { - L = i; - P = front; - } - if (src[front+i] != src[back+i-1]) { - // can't find a longer substring until past this point. - front += i; - } else { - ++front; - } - } -} - -int -LZSSCompression::emitByte(uint8_t *dest, uint8_t byte) -{ - if ((byte >> 5 & 0x7) == 0 || (byte >> 5 & 0x7) == 7) { - // If the top 3 bits are the same, emit 00<6bits> - dest[0] = byte & 0x3f; - return 1; - } else { - // emit 01XXXXXX <8 bits> - dest[0] = 0x40; - dest[1] = byte; - return 2; - } -} - -void -LZSSCompression::emitString(uint8_t *dest, uint16_t P, uint16_t L) -{ - // Emit 1<7P> <5P><3L> <8L> - dest[0] = 1<<7 | (P >> 5 & 0x7f); - dest[1] = ((P & 0x1f) << 3) | (L>>8 & 0x3); - dest[2] = L & 0xFF; -} - -int -LZSSCompression::compress(uint8_t *dest, uint8_t *src, int size) -{ - if (size > 4096) { - fatal("Compression can only handle block sizes of 4096 bytes or less"); - } - - // Encode the first byte. - int dest_index = emitByte(dest, src[0]); - int i = 1; - // A 11 bit field - uint16_t L; - // A 12 bit field - uint16_t P = 0; - - while (i < size && dest_index < size) { - L = 0; - - if (dest_index+3 >= size) { - dest_index = size; - continue; - } - - if (i == size - 1) { - // Output the character - dest_index += emitByte(&dest[dest_index], src[i]); - ++i; - continue; - } - findSubString(src, i, size, L, P); - if (L > 1) { - // Output the string reference - emitString(&dest[dest_index], P, L); - dest_index += 3; - i = i+L; - } else { - // Output the character - dest_index += emitByte(&dest[dest_index], src[i]); - ++i; - } - } - - if (dest_index >= size) { - // Have expansion instead of compression, just copy. - memcpy(dest,src,size); - return size; - } - return dest_index; -} - -int -LZSSCompression::uncompress(uint8_t *dest, uint8_t *src, int size) -{ - int index = 0; - int i = 0; - while (i < size) { - if (src[i] & 1<<7 ) { - // We have a string - // Extract P - int start = (src[i] & 0x3f)<<5 | ((src[i+1] >> 3) & 0x1f); - // Extract L - int len = (src[i+1] & 0x07)<<8 | src[i+2]; - i += 3; - for (int j = start; j < start+len; ++j) { - dest[index++] = dest[j]; - } - } else { - // We have a character - if (src[i] & 1<<6) { - // Value is in the next byte - dest[index++] = src[i+1]; - i += 2; - } else { - // just extend the lower 6 bits - dest[index++] = (src[i] & 0x3f) | ((src[i] & 1<<5) ? 0xC0 : 0); - ++i; - } - } - } - return index; -} |