*/
/*
- * Copyright (C) 2012, 2013, 2014, 2015 Eric Biggers
+ * Copyright (C) 2012-2016 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
/* These values are chosen for fast decompression. */
#define LZX_MAINCODE_TABLEBITS 11
-#define LZX_LENCODE_TABLEBITS 10
+#define LZX_LENCODE_TABLEBITS 9
#define LZX_PRECODE_TABLEBITS 6
#define LZX_ALIGNEDCODE_TABLEBITS 7
#define LZX_READ_LENS_MAX_OVERRUN 50
-/* Huffman decoding tables, and arrays that map symbols to codeword lengths. */
-struct lzx_tables {
+struct lzx_decompressor {
- u16 maincode_decode_table[(1 << LZX_MAINCODE_TABLEBITS) +
- (LZX_MAINCODE_MAX_NUM_SYMBOLS * 2)]
- _aligned_attribute(DECODE_TABLE_ALIGNMENT);
+ DECODE_TABLE(maincode_decode_table, LZX_MAINCODE_MAX_NUM_SYMBOLS,
+ LZX_MAINCODE_TABLEBITS, LZX_MAX_MAIN_CODEWORD_LEN);
u8 maincode_lens[LZX_MAINCODE_MAX_NUM_SYMBOLS + LZX_READ_LENS_MAX_OVERRUN];
-
- u16 lencode_decode_table[(1 << LZX_LENCODE_TABLEBITS) +
- (LZX_LENCODE_NUM_SYMBOLS * 2)]
- _aligned_attribute(DECODE_TABLE_ALIGNMENT);
+ DECODE_TABLE(lencode_decode_table, LZX_LENCODE_NUM_SYMBOLS,
+ LZX_LENCODE_TABLEBITS, LZX_MAX_LEN_CODEWORD_LEN);
u8 lencode_lens[LZX_LENCODE_NUM_SYMBOLS + LZX_READ_LENS_MAX_OVERRUN];
+ union {
+ DECODE_TABLE(alignedcode_decode_table, LZX_ALIGNEDCODE_NUM_SYMBOLS,
+ LZX_ALIGNEDCODE_TABLEBITS, LZX_MAX_ALIGNED_CODEWORD_LEN);
+ u8 alignedcode_lens[LZX_ALIGNEDCODE_NUM_SYMBOLS];
+ };
+
+ union {
+ DECODE_TABLE(precode_decode_table, LZX_PRECODE_NUM_SYMBOLS,
+ LZX_PRECODE_TABLEBITS, LZX_MAX_PRE_CODEWORD_LEN);
+ u8 precode_lens[LZX_PRECODE_NUM_SYMBOLS];
+ u8 extra_offset_bits[LZX_MAX_OFFSET_SLOTS];
+ };
+
+ union {
+ DECODE_TABLE_WORKING_SPACE(maincode_working_space,
+ LZX_MAINCODE_MAX_NUM_SYMBOLS,
+ LZX_MAX_MAIN_CODEWORD_LEN);
+ DECODE_TABLE_WORKING_SPACE(lencode_working_space,
+ LZX_LENCODE_NUM_SYMBOLS,
+ LZX_MAX_LEN_CODEWORD_LEN);
+ DECODE_TABLE_WORKING_SPACE(alignedcode_working_space,
+ LZX_ALIGNEDCODE_NUM_SYMBOLS,
+ LZX_MAX_ALIGNED_CODEWORD_LEN);
+ DECODE_TABLE_WORKING_SPACE(precode_working_space,
+ LZX_PRECODE_NUM_SYMBOLS,
+ LZX_MAX_PRE_CODEWORD_LEN);
+ };
- u16 alignedcode_decode_table[(1 << LZX_ALIGNEDCODE_TABLEBITS) +
- (LZX_ALIGNEDCODE_NUM_SYMBOLS * 2)]
- _aligned_attribute(DECODE_TABLE_ALIGNMENT);
- u8 alignedcode_lens[LZX_ALIGNEDCODE_NUM_SYMBOLS];
-} _aligned_attribute(DECODE_TABLE_ALIGNMENT);
-
-/* Least-recently used queue for match offsets. */
-struct lzx_lru_queue {
- u32 R[LZX_NUM_RECENT_OFFSETS];
-};
-
-static inline void
-lzx_lru_queue_init(struct lzx_lru_queue *queue)
-{
- for (unsigned i = 0; i < LZX_NUM_RECENT_OFFSETS; i++)
- queue->R[i] = 1;
-}
-
-/* The main LZX decompressor structure.
- *
- * Note: we keep track of most of the decompression state outside this
- * structure. This structure only exists so that (1) we can store @window_order
- * and @num_main_syms for multiple calls to lzx_decompress(); and (2) so that we
- * don't have to allocate the large 'struct lzx_tables' on the stack. */
-struct lzx_decompressor {
unsigned window_order;
unsigned num_main_syms;
- struct lzx_tables tables;
-};
-/* Read a Huffman-encoded symbol using the precode. */
-static inline unsigned
-read_huffsym_using_precode(struct input_bitstream *istream,
- const u16 precode_decode_table[])
+ /* Like lzx_extra_offset_bits[], but does not include the entropy-coded
+ * bits of aligned offset blocks */
+ u8 extra_offset_bits_minus_aligned[LZX_MAX_OFFSET_SLOTS];
+
+} _aligned_attribute(DECODE_TABLE_ALIGNMENT);
+
+/* Read a Huffman-encoded symbol using the precode. */
+static forceinline unsigned
+read_presym(const struct lzx_decompressor *d, struct input_bitstream *is)
{
- return read_huffsym(istream, precode_decode_table,
+ return read_huffsym(is, d->precode_decode_table,
LZX_PRECODE_TABLEBITS, LZX_MAX_PRE_CODEWORD_LEN);
}
-/* Read a Huffman-encoded symbol using the main code. */
-static inline unsigned
-read_huffsym_using_maincode(struct input_bitstream *istream,
- const struct lzx_tables *tables)
+/* Read a Huffman-encoded symbol using the main code. */
+static forceinline unsigned
+read_mainsym(const struct lzx_decompressor *d, struct input_bitstream *is)
{
- return read_huffsym(istream, tables->maincode_decode_table,
+ return read_huffsym(is, d->maincode_decode_table,
LZX_MAINCODE_TABLEBITS, LZX_MAX_MAIN_CODEWORD_LEN);
}
-/* Read a Huffman-encoded symbol using the length code. */
-static inline unsigned
-read_huffsym_using_lencode(struct input_bitstream *istream,
- const struct lzx_tables *tables)
+/* Read a Huffman-encoded symbol using the length code. */
+static forceinline unsigned
+read_lensym(const struct lzx_decompressor *d, struct input_bitstream *is)
{
- return read_huffsym(istream, tables->lencode_decode_table,
+ return read_huffsym(is, d->lencode_decode_table,
LZX_LENCODE_TABLEBITS, LZX_MAX_LEN_CODEWORD_LEN);
}
-/* Read a Huffman-encoded symbol using the aligned offset code. */
-static inline unsigned
-read_huffsym_using_alignedcode(struct input_bitstream *istream,
- const struct lzx_tables *tables)
+/* Read a Huffman-encoded symbol using the aligned offset code. */
+static forceinline unsigned
+read_alignedsym(const struct lzx_decompressor *d, struct input_bitstream *is)
{
- return read_huffsym(istream, tables->alignedcode_decode_table,
+ return read_huffsym(is, d->alignedcode_decode_table,
LZX_ALIGNEDCODE_TABLEBITS, LZX_MAX_ALIGNED_CODEWORD_LEN);
}
/*
- * Read the precode from the compressed input bitstream, then use it to decode
- * @num_lens codeword length values.
- *
- * @istream:
- * The input bitstream.
- *
- * @lens:
- * An array that contains the length values from the previous time the
- * codeword lengths for this Huffman code were read, or all 0's if this is
- * the first time. This array must have at least (@num_lens +
- * LZX_READ_LENS_MAX_OVERRUN) entries.
- *
- * @num_lens:
- * Number of length values to decode.
- *
- * Returns 0 on success, or -1 if the data was invalid.
+ * Read a precode from the compressed input bitstream, then use it to decode
+ * @num_lens codeword length values and write them to @lens.
*/
static int
-lzx_read_codeword_lens(struct input_bitstream *istream, u8 *lens, unsigned num_lens)
+lzx_read_codeword_lens(struct lzx_decompressor *d, struct input_bitstream *is,
+ u8 *lens, unsigned num_lens)
{
- u16 precode_decode_table[(1 << LZX_PRECODE_TABLEBITS) +
- (LZX_PRECODE_NUM_SYMBOLS * 2)]
- _aligned_attribute(DECODE_TABLE_ALIGNMENT);
- u8 precode_lens[LZX_PRECODE_NUM_SYMBOLS];
u8 *len_ptr = lens;
u8 *lens_end = lens + num_lens;
- int ret;
- /* Read the lengths of the precode codewords. These are given
- * explicitly. */
+ /* Read the lengths of the precode codewords. These are stored
+ * explicitly. */
for (int i = 0; i < LZX_PRECODE_NUM_SYMBOLS; i++) {
- precode_lens[i] = bitstream_read_bits(istream,
- LZX_PRECODE_ELEMENT_SIZE);
+ d->precode_lens[i] =
+ bitstream_read_bits(is, LZX_PRECODE_ELEMENT_SIZE);
}
- /* Make the decoding table for the precode. */
- ret = make_huffman_decode_table(precode_decode_table,
- LZX_PRECODE_NUM_SYMBOLS,
- LZX_PRECODE_TABLEBITS,
- precode_lens,
- LZX_MAX_PRE_CODEWORD_LEN);
- if (ret)
- return ret;
+ /* Build the decoding table for the precode. */
+ if (make_huffman_decode_table(d->precode_decode_table,
+ LZX_PRECODE_NUM_SYMBOLS,
+ LZX_PRECODE_TABLEBITS,
+ d->precode_lens,
+ LZX_MAX_PRE_CODEWORD_LEN,
+ d->precode_working_space))
+ return -1;
/* Decode the codeword lengths. */
do {
u8 len;
/* Read the next precode symbol. */
- presym = read_huffsym_using_precode(istream,
- precode_decode_table);
+ presym = read_presym(d, is);
if (presym < 17) {
/* Difference from old length */
len = *len_ptr - presym;
if (presym == 17) {
/* Run of 0's */
- run_len = 4 + bitstream_read_bits(istream, 4);
+ run_len = 4 + bitstream_read_bits(is, 4);
len = 0;
} else if (presym == 18) {
/* Longer run of 0's */
- run_len = 20 + bitstream_read_bits(istream, 5);
+ run_len = 20 + bitstream_read_bits(is, 5);
len = 0;
} else {
/* Run of identical lengths */
- run_len = 4 + bitstream_read_bits(istream, 1);
- presym = read_huffsym_using_precode(istream,
- precode_decode_table);
+ run_len = 4 + bitstream_read_bits(is, 1);
+ presym = read_presym(d, is);
if (unlikely(presym > 17))
return -1;
len = *len_ptr - presym;
do {
*len_ptr++ = len;
} while (--run_len);
- /* Worst case overrun is when presym == 18,
+ /*
+ * The worst case overrun is when presym == 18,
* run_len == 20 + 31, and only 1 length was remaining.
* So LZX_READ_LENS_MAX_OVERRUN == 50.
*
* can corrupt the previous values in the second half.
* This doesn't really matter because the resulting
* lengths will still be in range, and data that
- * generates overruns is invalid anyway. */
+ * generates overruns is invalid anyway.
+ */
}
} while (len_ptr < lens_end);
+
return 0;
}
/*
- * Read the header of an LZX block and save the block type and size in
- * *block_type_ret and *block_size_ret, respectively.
- *
- * If the block is compressed, also update the Huffman decode @tables with the
- * new Huffman codes.
- *
- * If the block is uncompressed, also update the match offset @queue with the
- * new match offsets.
- *
- * Return 0 on success, or -1 if the data was invalid.
+ * Read the header of an LZX block. For all block types, the block type and
+ * size is saved in *block_type_ret and *block_size_ret, respectively. For
+ * compressed blocks, the codeword lengths are also saved. For uncompressed
+ * blocks, the recent offsets queue is also updated.
*/
static int
-lzx_read_block_header(struct input_bitstream *istream,
- unsigned num_main_syms,
- unsigned window_order,
- int *block_type_ret,
- u32 *block_size_ret,
- struct lzx_tables *tables,
- struct lzx_lru_queue *queue)
+lzx_read_block_header(struct lzx_decompressor *d, struct input_bitstream *is,
+ u32 recent_offsets[], int *block_type_ret,
+ u32 *block_size_ret)
{
int block_type;
u32 block_size;
- int ret;
- bitstream_ensure_bits(istream, 4);
+ bitstream_ensure_bits(is, 4);
- /* The first three bits tell us what kind of block it is, and should be
- * one of the LZX_BLOCKTYPE_* values. */
- block_type = bitstream_pop_bits(istream, 3);
+ /* Read the block type. */
+ block_type = bitstream_pop_bits(is, 3);
- /* Read the block size. This mirrors the behavior of
- * lzx_write_compressed_block() in lzx_compress.c; see that for more
- * details. */
- if (bitstream_pop_bits(istream, 1)) {
+ /* Read the block size. */
+ if (bitstream_pop_bits(is, 1)) {
block_size = LZX_DEFAULT_BLOCK_SIZE;
} else {
- u32 tmp;
- block_size = 0;
-
- tmp = bitstream_read_bits(istream, 8);
- block_size |= tmp;
- tmp = bitstream_read_bits(istream, 8);
- block_size <<= 8;
- block_size |= tmp;
-
- if (window_order >= 16) {
- tmp = bitstream_read_bits(istream, 8);
+ block_size = bitstream_read_bits(is, 16);
+ if (d->window_order >= 16) {
block_size <<= 8;
- block_size |= tmp;
+ block_size |= bitstream_read_bits(is, 8);
}
}
case LZX_BLOCKTYPE_ALIGNED:
- /* Read the aligned offset code and prepare its decode table.
- */
+ /* Read the aligned offset codeword lengths. */
for (int i = 0; i < LZX_ALIGNEDCODE_NUM_SYMBOLS; i++) {
- tables->alignedcode_lens[i] =
- bitstream_read_bits(istream,
+ d->alignedcode_lens[i] =
+ bitstream_read_bits(is,
LZX_ALIGNEDCODE_ELEMENT_SIZE);
}
- ret = make_huffman_decode_table(tables->alignedcode_decode_table,
- LZX_ALIGNEDCODE_NUM_SYMBOLS,
- LZX_ALIGNEDCODE_TABLEBITS,
- tables->alignedcode_lens,
- LZX_MAX_ALIGNED_CODEWORD_LEN);
- if (ret)
- return ret;
-
/* Fall though, since the rest of the header for aligned offset
* blocks is the same as that for verbatim blocks. */
case LZX_BLOCKTYPE_VERBATIM:
- /* Read the main code and prepare its decode table.
- *
- * Note that the codeword lengths in the main code are encoded
- * in two parts: one part for literal symbols, and one part for
- * match symbols. */
-
- ret = lzx_read_codeword_lens(istream, tables->maincode_lens,
- LZX_NUM_CHARS);
- if (ret)
- return ret;
-
- ret = lzx_read_codeword_lens(istream,
- tables->maincode_lens + LZX_NUM_CHARS,
- num_main_syms - LZX_NUM_CHARS);
- if (ret)
- return ret;
-
- ret = make_huffman_decode_table(tables->maincode_decode_table,
- num_main_syms,
- LZX_MAINCODE_TABLEBITS,
- tables->maincode_lens,
- LZX_MAX_MAIN_CODEWORD_LEN);
- if (ret)
- return ret;
-
- /* Read the length code and prepare its decode table. */
-
- ret = lzx_read_codeword_lens(istream, tables->lencode_lens,
- LZX_LENCODE_NUM_SYMBOLS);
- if (ret)
- return ret;
-
- ret = make_huffman_decode_table(tables->lencode_decode_table,
- LZX_LENCODE_NUM_SYMBOLS,
- LZX_LENCODE_TABLEBITS,
- tables->lencode_lens,
- LZX_MAX_LEN_CODEWORD_LEN);
- if (ret)
- return ret;
+ /* Read the main codeword lengths, which are divided into two
+ * parts: literal symbols and match headers. */
+
+ if (lzx_read_codeword_lens(d, is, d->maincode_lens,
+ LZX_NUM_CHARS))
+ return -1;
+
+ if (lzx_read_codeword_lens(d, is, d->maincode_lens + LZX_NUM_CHARS,
+ d->num_main_syms - LZX_NUM_CHARS))
+ return -1;
+
+
+ /* Read the length codeword lengths. */
+
+ if (lzx_read_codeword_lens(d, is, d->lencode_lens,
+ LZX_LENCODE_NUM_SYMBOLS))
+ return -1;
break;
case LZX_BLOCKTYPE_UNCOMPRESSED:
-
- /* Before reading the three LRU match offsets from the
- * uncompressed block header, the stream must be aligned on a
- * 16-bit boundary. But, unexpectedly, if the stream is
+ /*
+ * The header of an uncompressed block contains new values for
+ * the recent offsets queue, starting on the next 16-bit
+ * boundary in the bitstream. Careful: if the stream is
* *already* aligned, the correct thing to do is to throw away
- * the next 16 bits. */
-
- bitstream_ensure_bits(istream, 1);
- bitstream_align(istream);
- queue->R[0] = bitstream_read_u32(istream);
- queue->R[1] = bitstream_read_u32(istream);
- queue->R[2] = bitstream_read_u32(istream);
+ * the next 16 bits (this is probably a mistake in the format).
+ */
+ bitstream_ensure_bits(is, 1);
+ bitstream_align(is);
+ recent_offsets[0] = bitstream_read_u32(is);
+ recent_offsets[1] = bitstream_read_u32(is);
+ recent_offsets[2] = bitstream_read_u32(is);
/* Offsets of 0 are invalid. */
- if (queue->R[0] == 0 || queue->R[1] == 0 || queue->R[2] == 0)
+ if (recent_offsets[0] == 0 || recent_offsets[1] == 0 ||
+ recent_offsets[2] == 0)
return -1;
break;
return 0;
}
-/*
- * Decompress a block of LZX-compressed data.
- *
- * @block_type:
- * The type of the block (LZX_BLOCKTYPE_VERBATIM or LZX_BLOCKTYPE_ALIGNED).
- * @out_begin
- * The beginning of the (uncompressed) output buffer.
- * @out_next
- * Pointer to the location in the (uncompressed) output buffer at which
- * this block will start.
- * @out_block_end
- * Pointer to the location in the (uncompressed) output buffer at which
- * this block will end.
- * @tables:
- * The Huffman decoding tables for this block.
- * @queue:
- * The least-recently-used queue for match offsets.
- * @istream:
- * The input bitstream, positioned at the start of the block data.
- *
- * Returns 0 on success, or -1 if the data was invalid.
- */
+/* Decompress a block of LZX-compressed data. */
static int
-lzx_decompress_block(int block_type, u8 * const out_begin,
- u8 * out_next, u8 * const out_block_end,
- const struct lzx_tables *tables,
- struct lzx_lru_queue *queue,
- struct input_bitstream *istream)
+lzx_decompress_block(struct lzx_decompressor *d, struct input_bitstream *is,
+ int block_type, u32 block_size,
+ u8 * const out_begin, u8 *out_next, u32 recent_offsets[])
{
- unsigned mainsym;
- u32 match_len;
- unsigned offset_slot;
- u32 match_offset;
- unsigned num_extra_bits;
- unsigned ones_if_aligned = 0U - (block_type == LZX_BLOCKTYPE_ALIGNED);
+ u8 * const block_end = out_next + block_size;
+ unsigned min_aligned_offset_slot;
- while (out_next != out_block_end) {
+ /*
+ * Build the Huffman decode tables. We always need to build the main
+ * and length decode tables. For aligned blocks we additionally need to
+ * build the aligned offset decode table.
+ */
+
+ if (make_huffman_decode_table(d->maincode_decode_table,
+ d->num_main_syms,
+ LZX_MAINCODE_TABLEBITS,
+ d->maincode_lens,
+ LZX_MAX_MAIN_CODEWORD_LEN,
+ d->maincode_working_space))
+ return -1;
- mainsym = read_huffsym_using_maincode(istream, tables);
+ if (make_huffman_decode_table(d->lencode_decode_table,
+ LZX_LENCODE_NUM_SYMBOLS,
+ LZX_LENCODE_TABLEBITS,
+ d->lencode_lens,
+ LZX_MAX_LEN_CODEWORD_LEN,
+ d->lencode_working_space))
+ return -1;
+
+ if (block_type == LZX_BLOCKTYPE_ALIGNED) {
+ if (make_huffman_decode_table(d->alignedcode_decode_table,
+ LZX_ALIGNEDCODE_NUM_SYMBOLS,
+ LZX_ALIGNEDCODE_TABLEBITS,
+ d->alignedcode_lens,
+ LZX_MAX_ALIGNED_CODEWORD_LEN,
+ d->alignedcode_working_space))
+ return -1;
+ min_aligned_offset_slot = LZX_MIN_ALIGNED_OFFSET_SLOT;
+ memcpy(d->extra_offset_bits, d->extra_offset_bits_minus_aligned,
+ sizeof(lzx_extra_offset_bits));
+ } else {
+ min_aligned_offset_slot = LZX_MAX_OFFSET_SLOTS;
+ memcpy(d->extra_offset_bits, lzx_extra_offset_bits,
+ sizeof(lzx_extra_offset_bits));
+ }
+
+ /* Decode the literals and matches. */
+
+ do {
+ unsigned mainsym;
+ unsigned length;
+ u32 offset;
+ unsigned offset_slot;
+
+ mainsym = read_mainsym(d, is);
if (mainsym < LZX_NUM_CHARS) {
- /* Literal */
+ /* Literal */
*out_next++ = mainsym;
continue;
}
- /* Match */
+ /* Match */
/* Decode the length header and offset slot. */
- mainsym -= LZX_NUM_CHARS;
- match_len = mainsym % LZX_NUM_LEN_HEADERS;
- offset_slot = mainsym / LZX_NUM_LEN_HEADERS;
+ STATIC_ASSERT(LZX_NUM_CHARS % LZX_NUM_LEN_HEADERS == 0);
+ length = mainsym % LZX_NUM_LEN_HEADERS;
+ offset_slot = (mainsym - LZX_NUM_CHARS) / LZX_NUM_LEN_HEADERS;
/* If needed, read a length symbol to decode the full length. */
- if (match_len == LZX_NUM_PRIMARY_LENS)
- match_len += read_huffsym_using_lencode(istream, tables);
- match_len += LZX_MIN_MATCH_LEN;
+ if (length == LZX_NUM_PRIMARY_LENS)
+ length += read_lensym(d, is);
+ length += LZX_MIN_MATCH_LEN;
if (offset_slot < LZX_NUM_RECENT_OFFSETS) {
/* Repeat offset */
/* Note: This isn't a real LRU queue, since using the R2
- * offset doesn't bump the R1 offset down to R2. This
- * quirk allows all 3 recent offsets to be handled by
- * the same code. (For R0, the swap is a no-op.) */
- match_offset = queue->R[offset_slot];
- queue->R[offset_slot] = queue->R[0];
- queue->R[0] = match_offset;
+ * offset doesn't bump the R1 offset down to R2. */
+ offset = recent_offsets[offset_slot];
+ recent_offsets[offset_slot] = recent_offsets[0];
} else {
/* Explicit offset */
-
- /* Look up the number of extra bits that need to be read
- * to decode offsets with this offset slot. */
- num_extra_bits = lzx_extra_offset_bits[offset_slot];
-
- /* Start with the offset slot base value. */
- match_offset = lzx_offset_slot_base[offset_slot];
-
- /* In aligned offset blocks, the low-order 3 bits of
- * each offset are encoded using the aligned offset
- * code. Otherwise, all the extra bits are literal. */
-
- if ((num_extra_bits & ones_if_aligned) >= LZX_NUM_ALIGNED_OFFSET_BITS) {
- match_offset +=
- bitstream_read_bits(istream,
- num_extra_bits -
- LZX_NUM_ALIGNED_OFFSET_BITS)
- << LZX_NUM_ALIGNED_OFFSET_BITS;
- match_offset += read_huffsym_using_alignedcode(istream, tables);
- } else {
- match_offset += bitstream_read_bits(istream, num_extra_bits);
+ offset = bitstream_read_bits(is, d->extra_offset_bits[offset_slot]);
+ if (offset_slot >= min_aligned_offset_slot) {
+ offset = (offset << LZX_NUM_ALIGNED_OFFSET_BITS) |
+ read_alignedsym(d, is);
}
-
- /* Adjust the offset. */
- match_offset -= LZX_OFFSET_ADJUSTMENT;
+ offset += lzx_offset_slot_base[offset_slot];
/* Update the match offset LRU queue. */
- BUILD_BUG_ON(LZX_NUM_RECENT_OFFSETS != 3);
- queue->R[2] = queue->R[1];
- queue->R[1] = queue->R[0];
- queue->R[0] = match_offset;
+ STATIC_ASSERT(LZX_NUM_RECENT_OFFSETS == 3);
+ recent_offsets[2] = recent_offsets[1];
+ recent_offsets[1] = recent_offsets[0];
}
+ recent_offsets[0] = offset;
- /* Validate the match, then copy it to the current position. */
-
- if (unlikely(match_len > out_block_end - out_next))
- return -1;
-
- if (unlikely(match_offset > out_next - out_begin))
+ /* Validate the match and copy it to the current position. */
+ if (unlikely(lz_copy(length, offset, out_begin,
+ out_next, block_end, LZX_MIN_MATCH_LEN)))
return -1;
+ out_next += length;
+ } while (out_next != block_end);
- lz_copy(out_next, match_len, match_offset, out_block_end,
- LZX_MIN_MATCH_LEN);
-
- out_next += match_len;
- }
return 0;
}
static int
-lzx_decompress(const void *compressed_data, size_t compressed_size,
- void *uncompressed_data, size_t uncompressed_size,
- void *_dec)
+lzx_decompress(const void *restrict compressed_data, size_t compressed_size,
+ void *restrict uncompressed_data, size_t uncompressed_size,
+ void *restrict _d)
{
- struct lzx_decompressor *dec = _dec;
- struct input_bitstream istream;
- struct lzx_lru_queue queue;
+ struct lzx_decompressor *d = _d;
u8 * const out_begin = uncompressed_data;
u8 *out_next = out_begin;
u8 * const out_end = out_begin + uncompressed_size;
- int block_type;
- u32 block_size;
- bool may_have_e8_byte;
- int ret;
-
- init_input_bitstream(&istream, compressed_data, compressed_size);
+ struct input_bitstream is;
+ STATIC_ASSERT(LZX_NUM_RECENT_OFFSETS == 3);
+ u32 recent_offsets[LZX_NUM_RECENT_OFFSETS] = {1, 1, 1};
+ unsigned may_have_e8_byte = 0;
- /* Initialize the recent offsets queue. */
- lzx_lru_queue_init(&queue);
+ init_input_bitstream(&is, compressed_data, compressed_size);
- /* Codeword lengths begin as all 0's for delta encoding purposes. */
- memset(dec->tables.maincode_lens, 0, dec->num_main_syms);
- memset(dec->tables.lencode_lens, 0, LZX_LENCODE_NUM_SYMBOLS);
+ /* Codeword lengths begin as all 0's for delta encoding purposes. */
+ memset(d->maincode_lens, 0, d->num_main_syms);
+ memset(d->lencode_lens, 0, LZX_LENCODE_NUM_SYMBOLS);
- /* Set this to true if there may be 0xe8 bytes in the uncompressed data.
- */
- may_have_e8_byte = false;
-
- /* The compressed data will consist of one or more blocks. The
- * following loop decompresses one block, and it runs until there all
- * the compressed data has been decompressed, so there are no more
- * blocks. */
+ /* Decompress blocks until we have all the uncompressed data. */
while (out_next != out_end) {
+ int block_type;
+ u32 block_size;
- ret = lzx_read_block_header(&istream, dec->num_main_syms,
- dec->window_order, &block_type,
- &block_size, &dec->tables, &queue);
- if (ret)
- return ret;
-
- if (block_size > out_end - out_next)
+ if (lzx_read_block_header(d, &is, recent_offsets,
+ &block_type, &block_size))
return -1;
- if (block_type != LZX_BLOCKTYPE_UNCOMPRESSED) {
-
- /* Compressed block. */
+ if (block_size < 1 || block_size > out_end - out_next)
+ return -1;
- ret = lzx_decompress_block(block_type,
- out_begin,
- out_next,
- out_next + block_size,
- &dec->tables,
- &queue,
- &istream);
- if (ret)
- return ret;
+ if (likely(block_type != LZX_BLOCKTYPE_UNCOMPRESSED)) {
- /* If the first 0xe8 byte was in this block, it must
- * have been encoded as a literal using mainsym 0xe8. */
- if (dec->tables.maincode_lens[0xe8] != 0)
- may_have_e8_byte = true;
+ /* Compressed block */
+ if (lzx_decompress_block(d, &is, block_type, block_size,
+ out_begin, out_next,
+ recent_offsets))
+ return -1;
- out_next += block_size;
+ /* If the first E8 byte was in this block, then it must
+ * have been encoded as a literal using mainsym E8. */
+ may_have_e8_byte |= d->maincode_lens[0xE8];
} else {
- /* Uncompressed block. */
- out_next = bitstream_read_bytes(&istream, out_next, block_size);
- if (!out_next)
+ /* Uncompressed block */
+ if (bitstream_read_bytes(&is, out_next, block_size))
return -1;
- /* Re-align the bitstream if an odd number of bytes was
- * read. */
+ /* Re-align the bitstream if needed. */
if (block_size & 1)
- bitstream_read_byte(&istream);
+ bitstream_read_byte(&is);
- may_have_e8_byte = true;
+ /* There may have been an E8 byte in the block. */
+ may_have_e8_byte = 1;
}
+ out_next += block_size;
}
- /* Postprocess the data unless it cannot possibly contain 0xe8 bytes */
+ /* Postprocess the data unless it cannot possibly contain E8 bytes. */
if (may_have_e8_byte)
- lzx_undo_e8_preprocessing(uncompressed_data, uncompressed_size);
+ lzx_postprocess(uncompressed_data, uncompressed_size);
return 0;
}
-static void
-lzx_free_decompressor(void *_dec)
-{
- struct lzx_decompressor *dec = _dec;
-
- ALIGNED_FREE(dec);
-}
-
static int
-lzx_create_decompressor(size_t max_block_size, void **dec_ret)
+lzx_create_decompressor(size_t max_block_size, void **d_ret)
{
- struct lzx_decompressor *dec;
unsigned window_order;
+ struct lzx_decompressor *d;
window_order = lzx_get_window_order(max_block_size);
if (window_order == 0)
return WIMLIB_ERR_INVALID_PARAM;
- /* The aligned allocation is needed to ensure that the lzx_tables are
- * aligned properly. */
- dec = ALIGNED_MALLOC(sizeof(struct lzx_decompressor),
- DECODE_TABLE_ALIGNMENT);
- if (!dec)
+ d = ALIGNED_MALLOC(sizeof(*d), DECODE_TABLE_ALIGNMENT);
+ if (!d)
return WIMLIB_ERR_NOMEM;
- dec->window_order = window_order;
- dec->num_main_syms = lzx_get_num_main_syms(window_order);
+ d->window_order = window_order;
+ d->num_main_syms = lzx_get_num_main_syms(window_order);
+
+ /* Initialize 'd->extra_offset_bits_minus_aligned'. */
+ STATIC_ASSERT(sizeof(d->extra_offset_bits_minus_aligned) ==
+ sizeof(lzx_extra_offset_bits));
+ STATIC_ASSERT(sizeof(d->extra_offset_bits) ==
+ sizeof(lzx_extra_offset_bits));
+ memcpy(d->extra_offset_bits_minus_aligned, lzx_extra_offset_bits,
+ sizeof(lzx_extra_offset_bits));
+ for (unsigned offset_slot = LZX_MIN_ALIGNED_OFFSET_SLOT;
+ offset_slot < LZX_MAX_OFFSET_SLOTS; offset_slot++)
+ {
+ d->extra_offset_bits_minus_aligned[offset_slot] -=
+ LZX_NUM_ALIGNED_OFFSET_BITS;
+ }
- *dec_ret = dec;
+ *d_ret = d;
return 0;
}
+static void
+lzx_free_decompressor(void *_d)
+{
+ ALIGNED_FREE(_d);
+}
+
const struct decompressor_ops lzx_decompressor_ops = {
.create_decompressor = lzx_create_decompressor,
.decompress = lzx_decompress,
git://wimlib.net / wimlib / blobdiff