* along with wimlib; if not, see http://www.gnu.org/licenses/.
*/
-#include "xpress.h"
-#include "compress.h"
-#include <stdlib.h>
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include "wimlib.h"
+#include "wimlib/assert.h"
+#include "wimlib/compress.h"
+#include "wimlib/error.h"
+#include "wimlib/util.h"
+#include "wimlib/xpress.h"
+
+#ifdef HAVE_ALLOCA_H
+# include <alloca.h>
+#endif
+
#include <string.h>
+/* Intermediate XPRESS match/literal representation. */
+struct xpress_match {
+ u16 adjusted_len; /* Match length minus XPRESS_MIN_MATCH_LEN */
+ u16 offset; /* Match offset */
+ /* For literals, offset == 0 and adjusted_len is the literal. */
+};
+
/*
* Writes @match, which is a match given in the intermediate representation for
* XPRESS matches, to the output stream @ostream.
*
* @codewords and @lens provide the Huffman code that is being used.
*/
-static int
-xpress_write_match(struct output_bitstream *ostream, u32 match,
- const u16 codewords[], const u8 lens[])
+static void
+xpress_write_match(struct xpress_match match,
+ struct output_bitstream *restrict ostream,
+ const u16 codewords[restrict],
+ const u8 lens[restrict])
{
- u32 adjusted_match_len = match & 0xffff;
- u32 match_offset = match >> 16;
- u32 len_hdr = min(adjusted_match_len, 0xf);
- u32 offset_bsr = bsr32(match_offset);
- u32 sym = len_hdr | (offset_bsr << 4) | XPRESS_NUM_CHARS;
- int ret;
-
- ret = bitstream_put_bits(ostream, codewords[sym], lens[sym]);
- if (ret != 0)
- return ret;
-
- if (adjusted_match_len >= 0xf) {
- u8 byte1 = min(adjusted_match_len - 0xf, 0xff);
- ret = bitstream_put_byte(ostream, byte1);
- if (ret != 0)
- return ret;
+ u8 len_hdr = min(match.adjusted_len, 0xf);
+ u8 offset_bsr = bsr32(match.offset);
+ unsigned sym = XPRESS_NUM_CHARS + ((offset_bsr << 4) | len_hdr);
+
+ bitstream_put_bits(ostream, codewords[sym], lens[sym]);
+
+ if (match.adjusted_len >= 0xf) {
+ u8 byte1 = min(match.adjusted_len - 0xf, 0xff);
+ bitstream_put_byte(ostream, byte1);
if (byte1 == 0xff) {
- ret = bitstream_put_two_bytes(ostream, adjusted_match_len);
- if (ret != 0)
- return ret;
+ bitstream_put_byte(ostream, match.adjusted_len & 0xff);
+ bitstream_put_byte(ostream, match.adjusted_len >> 8);
}
}
- return bitstream_put_bits(ostream,
- match_offset ^ (1 << offset_bsr), offset_bsr);
+ bitstream_put_bits(ostream, match.offset ^ (1U << offset_bsr), offset_bsr);
}
-static int
-xpress_write_compressed_literals(struct output_bitstream *ostream,
- const u32 match_tab[],
- unsigned num_matches,
- const u16 codewords[],
- const u8 lens[])
+static void
+xpress_write_matches_and_literals(struct output_bitstream *ostream,
+ const struct xpress_match matches[restrict],
+ input_idx_t num_matches,
+ const u16 codewords[restrict],
+ const u8 lens[restrict])
{
- for (unsigned i = 0; i < num_matches; i++) {
- int ret;
- u32 match = match_tab[i];
-
- if (match >= XPRESS_NUM_CHARS) /* match */
- ret = xpress_write_match(ostream, match, codewords,
- lens);
- else /* literal byte */
- ret = bitstream_put_bits(ostream, codewords[match],
- lens[match]);
- if (ret != 0)
- return ret;
+ for (input_idx_t i = 0; i < num_matches; i++) {
+ if (matches[i].offset) {
+ /* Real match */
+ xpress_write_match(matches[i], ostream, codewords, lens);
+ } else {
+ /* Literal byte */
+ u8 lit = matches[i].adjusted_len;
+ bitstream_put_bits(ostream, codewords[lit], lens[lit]);
+ }
}
- return bitstream_put_bits(ostream, codewords[XPRESS_END_OF_DATA],
- lens[XPRESS_END_OF_DATA]);
+ bitstream_put_bits(ostream, codewords[XPRESS_END_OF_DATA], lens[XPRESS_END_OF_DATA]);
}
-static u32
-xpress_record_literal(u8 literal, void *__freq_tab)
+struct xpress_record_ctx {
+ input_idx_t freqs[XPRESS_NUM_SYMBOLS];
+ struct xpress_match *matches;
+};
+
+static void
+xpress_record_literal(u8 lit, void *_ctx)
{
- freq_t *freq_tab = __freq_tab;
- freq_tab[literal]++;
- return literal;
+ struct xpress_record_ctx *ctx = _ctx;
+ ctx->freqs[lit]++;
+ *(ctx->matches++) = (struct xpress_match) { .offset = 0, .adjusted_len = lit };
}
-static u32
-xpress_record_match(unsigned match_offset, unsigned match_len,
- void *freq_tab, void *ignore)
+static void
+xpress_record_match(unsigned len, unsigned offset, void *_ctx)
{
- wimlib_assert(match_len >= XPRESS_MIN_MATCH &&
- match_len <= XPRESS_MAX_MATCH);
- wimlib_assert(match_offset >= XPRESS_MIN_OFFSET &&
- match_offset <= XPRESS_MAX_OFFSET);
+ struct xpress_record_ctx *ctx = _ctx;
- /*
- * The intermediate representation of XPRESS matches is as follows:
- *
- * bits description
- * ---- -----------------------------------------------------------
- *
- * 16-31 match offset (XPRESS_MIN_OFFSET < x < XPRESS_MAX_OFFSET)
- *
- * 0-15 adjusted match length (0 <= x <= XPRESS_MAX_MATCH - XPRESS_MIN_MATCH)
- *
- * Literals are simply represented as themselves and can be
- * distinguished from matches by the fact that only literals will have
- * the upper three bytes completely clear. */
-
- u32 adjusted_match_len = match_len - XPRESS_MIN_MATCH;
- u32 len_hdr = min(adjusted_match_len, 0xf);
- u32 offset_bsr = bsr32(match_offset);
- u32 sym = len_hdr | (offset_bsr << 4) | XPRESS_NUM_CHARS;
- ((freq_t*)freq_tab)[sym]++;
- return adjusted_match_len | (match_offset << 16);
+ XPRESS_ASSERT(len >= XPRESS_MIN_MATCH_LEN);
+ XPRESS_ASSERT(len <= XPRESS_MAX_MATCH_LEN);
+ XPRESS_ASSERT(offset >= XPRESS_MIN_OFFSET);
+ XPRESS_ASSERT(offset <= XPRESS_MAX_OFFSET);
+
+ unsigned adjusted_len = len - XPRESS_MIN_MATCH_LEN;
+ unsigned len_hdr = min(adjusted_len, 0xf);
+ unsigned sym = XPRESS_NUM_CHARS + ((bsr32(offset) << 4) | len_hdr);
+
+ XPRESS_ASSERT(sym >= XPRESS_NUM_CHARS);
+ XPRESS_ASSERT(sym < XPRESS_NUM_SYMBOLS);
+
+ ctx->freqs[sym]++;
+ *(ctx->matches++) = (struct xpress_match) { .offset = offset,
+ .adjusted_len = adjusted_len };
}
static const struct lz_params xpress_lz_params = {
- .min_match = XPRESS_MIN_MATCH,
- .max_match = XPRESS_MAX_MATCH,
+ .min_match = XPRESS_MIN_MATCH_LEN,
+ .max_match = XPRESS_MAX_MATCH_LEN,
+ .max_offset = XPRESS_MAX_OFFSET,
.good_match = 16,
.nice_match = 32,
.max_chain_len = 16,
.too_far = 4096,
};
-/*
- * Performs XPRESS compression on a block of data.
- *
- * Please see the documentation for the 'compress_func_t' type in write.c for
- * the exact behavior of this function and how to call it.
- */
-unsigned
-xpress_compress(const void *__uncompressed_data, unsigned uncompressed_len,
- void *__compressed_data)
+/* API function documented in wimlib.h */
+WIMLIBAPI unsigned
+wimlib_xpress_compress(const void * restrict uncompressed_data,
+ unsigned uncompressed_len,
+ void * restrict compressed_data)
{
- const u8 *uncompressed_data = __uncompressed_data;
- u8 *compressed_data = __compressed_data;
+ u8 *cptr = compressed_data;
struct output_bitstream ostream;
- u32 match_tab[uncompressed_len];
- freq_t freq_tab[XPRESS_NUM_SYMBOLS];
+
+ struct xpress_record_ctx record_ctx;
+
+ struct xpress_match *matches;
+ input_idx_t *prev_tab;
+ u8 *udata;
+
u16 codewords[XPRESS_NUM_SYMBOLS];
u8 lens[XPRESS_NUM_SYMBOLS];
- unsigned num_matches;
- unsigned compressed_len;
- unsigned i;
- int ret;
+ input_idx_t num_matches;
+ input_idx_t compressed_len;
+ input_idx_t i;
- wimlib_assert(uncompressed_len <= 32768);
-
- /* XPRESS requires 256 bytes of overhead for the Huffman tables, so it's
- * impossible cannot compress 256 bytes or less of data to less than the
+ /* XPRESS requires 256 bytes of overhead for the Huffman code, so it's
+ * impossible to compress 256 bytes or less of data to less than the
* input size.
*
* +1 to take into account that the buffer for compressed data is 1 byte
* smaller than the buffer for uncompressed data.
*
* +4 to take into account that init_output_bitstream() requires at
- * least 4 bytes of data. */
+ * least 4 bytes of data. */
if (uncompressed_len < XPRESS_NUM_SYMBOLS / 2 + 1 + 4)
return 0;
- ZERO_ARRAY(freq_tab);
- num_matches = lz_analyze_block(uncompressed_data, uncompressed_len,
- match_tab, xpress_record_match,
- xpress_record_literal, freq_tab,
- NULL, freq_tab,
- &xpress_lz_params);
+ if (uncompressed_len <= STACK_MAX) {
+ matches = alloca(uncompressed_len * sizeof(matches[0]));
+ udata = alloca(uncompressed_len + 8);
+ prev_tab = alloca(uncompressed_len * sizeof(prev_tab[0]));
+ } else {
+ matches = MALLOC(uncompressed_len * sizeof(matches[0]));
+ udata = MALLOC(uncompressed_len + 8);
+ prev_tab = MALLOC(uncompressed_len * sizeof(prev_tab[0]));
+ if (matches == NULL || udata == NULL || prev_tab == NULL) {
+ WARNING("Failed to allocate memory for compression...");
+ compressed_len = 0;
+ goto out_free;
+ }
+ }
- freq_tab[XPRESS_END_OF_DATA]++;
+ /* Copy the data to a temporary buffer, but only to avoid
+ * inconsequential accesses of uninitialized memory in
+ * lz_analyze_block(). */
+ memcpy(udata, uncompressed_data, uncompressed_len);
+ memset(udata + uncompressed_len, 0, 8);
+ /* Determine match/literal sequence to divide the data into. */
+ ZERO_ARRAY(record_ctx.freqs);
+ record_ctx.matches = matches;
+ lz_analyze_block(udata,
+ uncompressed_len,
+ xpress_record_match,
+ xpress_record_literal,
+ &record_ctx,
+ &xpress_lz_params,
+ prev_tab);
+
+ num_matches = (record_ctx.matches - matches);
+
+ /* Account for end of data symbol. */
+ record_ctx.freqs[XPRESS_END_OF_DATA]++;
+
+ /* Build the Huffman code. */
make_canonical_huffman_code(XPRESS_NUM_SYMBOLS, XPRESS_MAX_CODEWORD_LEN,
- freq_tab, lens, codewords);
+ record_ctx.freqs, lens, codewords);
- /* IMPORTANT NOTE:
- *
- * It's tempting to output the 512 Huffman codeword lengths using the
- * bitstream_put_bits() function. However, this is NOT correct because
- * bitstream_put_bits() will output 2 bytes at a time in little-endian
- * order, which is the order that is needed for the compressed literals.
- * However, the bytes in the lengths table are in order, so they need to
- * be written one at a time without using bitstream_put_bits().
- *
- * Because of this, init_output_bitstream() is not called until after
- * the lengths table is output.
- */
+ /* Output the Huffman code as a series of 512 4-bit lengths. */
for (i = 0; i < XPRESS_NUM_SYMBOLS; i += 2)
- *compressed_data++ = (lens[i] & 0xf) | (lens[i + 1] << 4);
+ *cptr++ = (lens[i] & 0xf) | (lens[i + 1] << 4);
- init_output_bitstream(&ostream, compressed_data,
+ /* Output the encoded matches/literals. */
+ init_output_bitstream(&ostream, cptr,
uncompressed_len - XPRESS_NUM_SYMBOLS / 2 - 1);
+ xpress_write_matches_and_literals(&ostream, matches,
+ num_matches, codewords, lens);
- ret = xpress_write_compressed_literals(&ostream, match_tab,
- num_matches, codewords, lens);
- if (ret)
- return 0;
-
- /* Flush any bits that are buffered. */
- ret = flush_output_bitstream(&ostream);
- if (ret)
- return 0;
+ /* Flush any pending data and get the length of the compressed data. */
+ compressed_len = flush_output_bitstream(&ostream);
+ if (compressed_len == ~(input_idx_t)0) {
+ compressed_len = 0;
+ goto out_free;
+ }
+ compressed_len += XPRESS_NUM_SYMBOLS / 2;
- /* Assert that there are no output bytes between the ostream.output
- * pointer and the ostream.next_bit_output pointer. This can only
- * happen if bytes had been written at the ostream.output pointer before
- * the last bit word was written to the stream. But, this does not
- * occur since xpress_write_match() always finishes by writing some bits
- * (a Huffman symbol), and the bitstream was just flushed. */
- wimlib_assert(ostream.output - ostream.next_bit_output == 2);
-
- /* The length of the compressed data is supposed to be the value of the
- * ostream.output pointer before flushing, which is now the
- * output.next_bit_output pointer after flushing.
- *
- * There will be an extra 2 bytes at the ostream.bit_output pointer,
- * which is zeroed out. (These 2 bytes may be either the last bytes in
- * the compressed data, in which case they are actually unnecessary, or
- * they may precede a number of bytes embedded into the bitstream.) */
- if (ostream.bit_output >
- (const u8*)__compressed_data + uncompressed_len - 3)
- return 0;
- *(u16*)ostream.bit_output = cpu_to_le16(0);
- compressed_len = ostream.next_bit_output - (const u8*)__compressed_data;
-
- wimlib_assert(compressed_len <= uncompressed_len - 1);
-
-#ifdef ENABLE_VERIFY_COMPRESSION
- /* Verify that we really get the same thing back when decompressing. */
- u8 buf[uncompressed_len];
- ret = xpress_decompress(__compressed_data, compressed_len, buf,
- uncompressed_len);
- if (ret) {
- ERROR("xpress_compress(): Failed to decompress data we "
- "compressed");
- abort();
+#if defined(ENABLE_XPRESS_DEBUG) || defined(ENABLE_VERIFY_COMPRESSION)
+ /* Verify that we really get the same thing back when decompressing. */
+ if (wimlib_xpress_decompress(compressed_data, compressed_len,
+ udata, uncompressed_len))
+ {
+ ERROR("Failed to decompress data we "
+ "compressed using XPRESS algorithm");
+ wimlib_assert(0);
+ compressed_len = 0;
+ goto out_free;
}
- for (i = 0; i < uncompressed_len; i++) {
- if (buf[i] != uncompressed_data[i]) {
- ERROR("xpress_compress(): Data we compressed didn't "
- "decompress to the original data (difference at "
- "byte %u of %u)", i + 1, uncompressed_len);
- abort();
- }
+
+ if (memcmp(uncompressed_data, udata, uncompressed_len)) {
+ ERROR("Data we compressed using XPRESS algorithm "
+ "didn't decompress to original");
+ wimlib_assert(0);
+ compressed_len = 0;
+ goto out_free;
}
#endif
+
+out_free:
+ if (uncompressed_len > STACK_MAX) {
+ FREE(matches);
+ FREE(udata);
+ FREE(prev_tab);
+ }
return compressed_len;
}
git://wimlib.net / wimlib / blobdiff