/*
- * lzx-common.c - Common code for LZX compression and decompression.
+ * lzx_common.c - Common code for LZX compression and decompression.
*/
/*
- * Copyright (C) 2012, 2013, 2014 Eric Biggers
+ * Copyright (C) 2012, 2013, 2014, 2015 Eric Biggers
*
* 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
#include <string.h>
+#ifdef __SSE2__
+# include <emmintrin.h>
+#endif
+
+#ifdef __AVX2__
+# include <immintrin.h>
+#endif
+
#include "wimlib/bitops.h"
#include "wimlib/endianness.h"
#include "wimlib/lzx_common.h"
#include "wimlib/unaligned.h"
#include "wimlib/util.h"
-#ifdef __SSE2__
-# include <emmintrin.h>
-#endif
-
/* Mapping: offset slot => first match offset that uses that offset slot.
*/
-const u32 lzx_offset_slot_base[LZX_MAX_OFFSET_SLOTS] = {
+const u32 lzx_offset_slot_base[LZX_MAX_OFFSET_SLOTS + 1] = {
0 , 1 , 2 , 3 , 4 , /* 0 --- 4 */
6 , 8 , 12 , 16 , 24 , /* 5 --- 9 */
32 , 48 , 64 , 96 , 128 , /* 10 --- 14 */
196608 , 262144 , 393216 , 524288 , 655360 , /* 35 --- 39 */
786432 , 917504 , 1048576, 1179648, 1310720, /* 40 --- 44 */
1441792, 1572864, 1703936, 1835008, 1966080, /* 45 --- 49 */
- 2097152 /* 50 */
+ 2097152 /* extra */
};
/* Mapping: offset slot => how many extra bits must be read and added to the
16, 17, 17, 17, 17,
17, 17, 17, 17, 17,
17, 17, 17, 17, 17,
- 17
};
-/* 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. */
+/* Round the specified buffer size up to the next valid LZX window size, and
+ * return its order (log2). Or, if the buffer size is 0 or greater than the
+ * largest valid LZX window size, return 0. */
unsigned
-lzx_get_window_order(size_t max_block_size)
+lzx_get_window_order(size_t max_bufsize)
{
unsigned order;
- if (max_block_size == 0 || max_block_size > LZX_MAX_WINDOW_SIZE)
+ if (max_bufsize == 0 || max_bufsize > LZX_MAX_WINDOW_SIZE)
return 0;
- order = fls32(max_block_size);
+ order = fls32(max_bufsize);
- if (((u32)1 << order) != max_block_size)
+ if (((u32)1 << order) != max_bufsize)
order++;
return max(order, LZX_MIN_WINDOW_ORDER);
}
+unsigned
+lzx_get_num_offset_slots(unsigned window_order)
+{
+ /* Note: one would expect that the maximum match offset would be
+ * 'window_size - LZX_MIN_MATCH_LEN', which would occur if the first two
+ * bytes were to match the last two bytes. However, the format
+ * disallows this case. This reduces the number of needed offset slots
+ * by 1. */
+ u32 window_size = (u32)1 << window_order;
+ u32 max_offset = window_size - LZX_MIN_MATCH_LEN - 1;
+ return 1 + lzx_get_offset_slot(max_offset);
+}
+
/* 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(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_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_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_adjusted_offset = window_size - 1, so instead we must calculate:
- *
- * num_offset_slots = 1 + lzx_get_offset_slot_raw(window_size - 1);
- *
- * ... which is the same as
- *
- * num_offset_slots = lzx_get_offset_slot_raw(window_size);
- *
- * ... since every valid window size is equal to an offset base value.
- */
- 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 offset slot (since there are 8 possible
- * length headers, and we need all (offset slot, length header)
- * combinations). */
- return LZX_NUM_CHARS + (num_offset_slots << 3);
+ return LZX_NUM_CHARS + (lzx_get_num_offset_slots(window_order) *
+ LZX_NUM_LEN_HEADERS);
}
static void
for (;;) {
u32 e8_mask;
u8 *orig_p = p;
- #ifdef __SSE2__
+ #ifdef __AVX2__
+ const __m256i e8_bytes = _mm256_set1_epi8(0xE8);
+ for (;;) {
+ __m256i bytes = *(const __m256i *)p;
+ __m256i cmpresult = _mm256_cmpeq_epi8(bytes, e8_bytes);
+ e8_mask = _mm256_movemask_epi8(cmpresult);
+ if (e8_mask)
+ break;
+ p += 32;
+ }
+ #else
const __m128i e8_bytes = _mm_set1_epi8(0xE8);
for (;;) {
/* Read the next 32 bytes of data and test them
}
p += 32;
}
- #else
- /* AVX-2 */
- const __m256i e8_bytes = _mm256_set1_epi8(0xE8);
- for (;;) {
- __m256i bytes = *(const __m256i *)p;
- __m256i cmpresult = _mm256_cmpeq_epi8(bytes, e8_bytes);
- e8_mask = _mm256_movemask_epi8(cmpresult);
- if (e8_mask)
- break;
- p += 32;
- }
#endif
/* Did we pass over data with no E8 bytes? */
git://wimlib.net / wimlib / blobdiff