X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=src%2Flzx-common.c;h=566161c3585abf4130ed265a270aa7e09c8cba8d;hb=3d8ef754a66f76c8f7121b65a4e466bce6a75f0f;hp=24bf9974c4ca5783c68c7f0ca0e4479fd23755dc;hpb=a20052d2eaf44eb0466972826f8f9e0c3bcb92d2;p=wimlib diff --git a/src/lzx-common.c b/src/lzx-common.c index 24bf9974..566161c3 100644 --- a/src/lzx-common.c +++ b/src/lzx-common.c @@ -33,14 +33,8 @@ # 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: position slot => first match offset that uses that position slot. */ - const u32 lzx_position_base[LZX_MAX_POSITION_SLOTS] = { 0 , 1 , 2 , 3 , 4 , /* 0 --- 4 */ 6 , 8 , 12 , 16 , 24 , /* 5 --- 9 */ @@ -55,6 +49,8 @@ const u32 lzx_position_base[LZX_MAX_POSITION_SLOTS] = { 2097152 /* 50 */ }; +/* Mapping: position slot => how many extra bits must be read and added to the + * corresponding position base to decode the match offset. */ #ifdef USE_LZX_EXTRA_BITS_ARRAY const u8 lzx_extra_bits[LZX_MAX_POSITION_SLOTS] = { 0 , 0 , 0 , 0 , 1 , @@ -71,23 +67,32 @@ const u8 lzx_extra_bits[LZX_MAX_POSITION_SLOTS] = { }; #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 > (1 << LZX_MAX_WINDOW_ORDER)) + return 0; + + order = bsr32(max_block_size); + + if ((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 = 1 << window_order; + /* NOTE: the calculation *should* be as follows: * * u32 max_offset = window_size - LZX_MIN_MATCH_LEN; @@ -119,7 +124,7 @@ lzx_get_num_main_syms(u32 window_size) } 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 +143,7 @@ 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 +198,7 @@ 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 +253,7 @@ 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 +283,7 @@ 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 +293,13 @@ 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); }