X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=src%2Flzx-common.c;h=dac43badd9c8d50ea15c2ee877c11e50ea05e3d8;hb=4c73e29d8d74a4e969782d2d40e209337414034c;hp=24bf9974c4ca5783c68c7f0ca0e4479fd23755dc;hpb=a20052d2eaf44eb0466972826f8f9e0c3bcb92d2;p=wimlib diff --git a/src/lzx-common.c b/src/lzx-common.c index 24bf9974..dac43bad 100644 --- a/src/lzx-common.c +++ b/src/lzx-common.c @@ -5,20 +5,18 @@ /* * Copyright (C) 2012, 2013 Eric Biggers * - * This file is part of wimlib, a library for working with WIM files. + * This file 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. * - * wimlib is free software; you can redistribute it and/or modify it under the - * terms of the GNU General Public License as published by the Free - * Software Foundation; either version 3 of the License, or (at your option) - * any later version. - * - * wimlib 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 General Public License for more + * This file 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 General Public License - * along with wimlib; if not, see http://www.gnu.org/licenses/. + * You should have received a copy of the GNU Lesser General Public License + * along with this file; if not, see http://www.gnu.org/licenses/. */ #ifdef HAVE_CONFIG_H @@ -33,15 +31,9 @@ # include #endif -/* LZX uses what it calls 'position slots' to represent match offsets. - * What this means is that a small 'position slot' number and a small - * offset from that slot are encoded instead of one large offset for - * every match. - * - lzx_position_base is an index to the position slot bases - * - lzx_extra_bits states how many bits of offset-from-base data is needed. +/* Mapping: offset slot => first match offset that uses that offset slot. */ - -const u32 lzx_position_base[LZX_MAX_POSITION_SLOTS] = { +const u32 lzx_offset_slot_base[LZX_MAX_OFFSET_SLOTS] = { 0 , 1 , 2 , 3 , 4 , /* 0 --- 4 */ 6 , 8 , 12 , 16 , 24 , /* 5 --- 9 */ 32 , 48 , 64 , 96 , 128 , /* 10 --- 14 */ @@ -55,8 +47,9 @@ const u32 lzx_position_base[LZX_MAX_POSITION_SLOTS] = { 2097152 /* 50 */ }; -#ifdef USE_LZX_EXTRA_BITS_ARRAY -const u8 lzx_extra_bits[LZX_MAX_POSITION_SLOTS] = { +/* Mapping: offset slot => how many extra bits must be read and added to the + * corresponding offset slot base to decode the match offset. */ +const u8 lzx_extra_offset_bits[LZX_MAX_OFFSET_SLOTS] = { 0 , 0 , 0 , 0 , 1 , 1 , 2 , 2 , 3 , 3 , 4 , 4 , 5 , 5 , 6 , @@ -69,57 +62,65 @@ const u8 lzx_extra_bits[LZX_MAX_POSITION_SLOTS] = { 17, 17, 17, 17, 17, 17 }; -#endif -/* LZX window size must be a power of 2 between 2^15 and 2^21, inclusively. */ -bool -lzx_window_size_valid(size_t window_size) +/* Round the specified compression block size (not LZX block size) up to the + * next valid LZX window size, and return its order (log2). Or, if the block + * size is 0 or greater than the largest valid LZX window size, return 0. */ +unsigned +lzx_get_window_order(size_t max_block_size) { - if (window_size == 0 || (u32)window_size != window_size) - return false; - u32 order = bsr32(window_size); - if (window_size != 1U << order) - return false; - return (order >= LZX_MIN_WINDOW_ORDER && order <= LZX_MAX_WINDOW_ORDER); + unsigned order; + + if (max_block_size == 0 || max_block_size > LZX_MAX_WINDOW_SIZE) + return 0; + + order = bsr32(max_block_size); + + if (((u32)1 << order) != max_block_size) + order++; + + return max(order, LZX_MIN_WINDOW_ORDER); } -/* Given a valid LZX window size, return the number of symbols that will exist +/* Given a valid LZX window order, return the number of symbols that will exist * in the main Huffman code. */ unsigned -lzx_get_num_main_syms(u32 window_size) +lzx_get_num_main_syms(unsigned window_order) { + u32 window_size = (u32)1 << window_order; + /* NOTE: the calculation *should* be as follows: * * u32 max_offset = window_size - LZX_MIN_MATCH_LEN; - * u32 max_formatted_offset = max_offset + LZX_OFFSET_OFFSET; - * u32 num_position_slots = 1 + lzx_get_position_slot_raw(max_formatted_offset); + * u32 max_adjusted_offset = max_offset + LZX_OFFSET_OFFSET; + * u32 num_offset_slots = 1 + lzx_get_offset_slot_raw(max_adjusted_offset); * * However since LZX_MIN_MATCH_LEN == LZX_OFFSET_OFFSET, we would get - * max_formatted_offset == window_size, which would bump the number of - * position slots up by 1 since every valid LZX window size is equal to - * a position base value. The format doesn't do this, and instead + * max_adjusted_offset == window_size, which would bump the number of + * offset slots up by 1 since every valid LZX window size is equal to a + * offset slot base value. The format doesn't do this, and instead * disallows matches with minimum length and maximum offset. This sets - * max_formatted_offset = window_size - 1, so instead we must calculate: + * max_adjusted_offset = window_size - 1, so instead we must calculate: * - * num_position_slots = 1 + lzx_get_position_slot_raw(window_size - 1); + * num_offset_slots = 1 + lzx_get_offset_slot_raw(window_size - 1); * * ... which is the same as * - * num_position_slots = lzx_get_position_slot_raw(window_size); + * num_offset_slots = lzx_get_offset_slot_raw(window_size); * - * ... since every valid window size is equal to a position base value. + * ... since every valid window size is equal to an offset base value. */ - unsigned num_position_slots = lzx_get_position_slot_raw(window_size); + unsigned num_offset_slots = lzx_get_offset_slot_raw(window_size); /* Now calculate the number of main symbols as LZX_NUM_CHARS literal - * symbols, plus 8 symbols per position slot (since there are 8 possible - * length headers, and we need all (position slot, length header) + * symbols, plus 8 symbols per offset slot (since there are 8 possible + * length headers, and we need all (offset slot, length header) * combinations). */ - return LZX_NUM_CHARS + (num_position_slots << 3); + return LZX_NUM_CHARS + (num_offset_slots << 3); } static void -do_translate_target(s32 *target, s32 input_pos) +do_translate_target(sle32 *target, s32 input_pos) { s32 abs_offset, rel_offset; @@ -138,7 +139,7 @@ do_translate_target(s32 *target, s32 input_pos) } static void -undo_translate_target(s32 *target, s32 input_pos) +undo_translate_target(sle32 *target, s32 input_pos) { s32 abs_offset, rel_offset; @@ -193,7 +194,7 @@ inline /* Although inlining the 'process_target' function still speeds up the SSE2 case, it bloats the binary more. */ #endif void -lzx_e8_filter(u8 *data, s32 size, void (*process_target)(s32 *, s32)) +lzx_e8_filter(u8 *data, u32 size, void (*process_target)(sle32 *, s32)) { #ifdef __SSE2__ /* SSE2 vectorized implementation for x86_64. This speeds up LZX @@ -248,7 +249,7 @@ lzx_e8_filter(u8 *data, s32 size, void (*process_target)(s32 *, s32)) /* Do (or undo) the e8 translation. */ u8 *p8 = (u8 *)p128 + bit; - (*process_target)((s32 *)(p8 + 1), + (*process_target)((sle32 *)(p8 + 1), p8 - data); /* Don't start an e8 translation in the @@ -278,7 +279,7 @@ lzx_e8_filter(u8 *data, s32 size, void (*process_target)(s32 *, s32)) u8 *p8_end = data + size - 10; do { if (*p8 == 0xe8) { - (*process_target)((s32 *)(p8 + 1), p8 - data); + (*process_target)((sle32 *)(p8 + 1), p8 - data); p8 += 5; } else { p8++; @@ -288,13 +289,13 @@ lzx_e8_filter(u8 *data, s32 size, void (*process_target)(s32 *, s32)) } void -lzx_do_e8_preprocessing(u8 *data, s32 size) +lzx_do_e8_preprocessing(u8 *data, u32 size) { lzx_e8_filter(data, size, do_translate_target); } void -lzx_undo_e8_preprocessing(u8 *data, s32 size) +lzx_undo_e8_preprocessing(u8 *data, u32 size) { lzx_e8_filter(data, size, undo_translate_target); }