[cairo-commit] 4 commits - src/cairoint.h src/cairo-lzw.c
src/cairo-ps-surface.c
Carl Worth
cworth at kemper.freedesktop.org
Thu Mar 23 15:40:41 PST 2006
src/cairo-lzw.c | 747 +++++++++++++++++++++----------------------------
src/cairo-ps-surface.c | 3
src/cairoint.h | 6
3 files changed, 328 insertions(+), 428 deletions(-)
New commits:
diff-tree 3259efed7690670754d7c1e76176ff26464111c3 (from bcfe344608150aa56b1cb37dbc774455bfcf6830)
Author: Carl Worth <cworth at cworth.org>
Date: Thu Mar 23 15:36:41 2006 -0800
_cairo_lzw_compress: Remove unused code which we had for testing
conformance with the LZW compression from libtiff.
diff --git a/src/cairo-lzw.c b/src/cairo-lzw.c
index 1de618c..2a4a8e1 100644
--- a/src/cairo-lzw.c
+++ b/src/cairo-lzw.c
@@ -370,19 +370,6 @@ _cairo_lzw_compress (unsigned char *data
LZW_SYMBOL_SET_CODE (*slot, code_next++, prev, next);
- /* The libtiff code detects a full table and clears it a bit
- * earlier than strictly necessary. Here is the code to do
- * that which might be useful in doing correctness comparisons
- * against the output of libtiff. */
-#if CLEAR_TABLE_EARLY_FOR_IDENTICAL_OUTPUT_COMPAREED_TO_LIBTIFF
- if (code_next == LZW_BITS_BOUNDARY(LZW_BITS_MAX) - 1) {
- _lzw_symbol_table_init (&table);
- _lzw_buf_store_bits (&buf, LZW_CODE_CLEAR_TABLE, code_bits);
- code_bits = LZW_BITS_MIN;
- code_next = LZW_CODE_FIRST;
- }
-#endif
-
if (code_next > LZW_BITS_BOUNDARY(code_bits))
{
code_bits++;
diff-tree bcfe344608150aa56b1cb37dbc774455bfcf6830 (from 639c2fe4df880546d71b2c73ea972fb08b609603)
Author: Carl Worth <cworth at cworth.org>
Date: Thu Mar 23 15:27:00 2006 -0800
Optimize the implementation of _cairo_lzw_compress.
This switches the implementation of _cairo_lzw_compress from using
cairo-hash.c to a custom implementation of the same algorithm that
takes advantage of the specific details of what is needed here.
This final version now has comparable performance to the libtiff code,
but should hopefully be easier to understand.
Add a bunch of comments explaining how the various pieces work.
diff --git a/src/cairo-lzw.c b/src/cairo-lzw.c
index 67a41bd..1de618c 100644
--- a/src/cairo-lzw.c
+++ b/src/cairo-lzw.c
@@ -36,10 +36,9 @@
#include "cairoint.h"
-static unsigned long
-_cairo_hash_bytes (const unsigned char *c, int size);
-
typedef struct _lzw_buf {
+ cairo_status_t status;
+
unsigned char *data;
int data_size;
int num_data;
@@ -52,46 +51,56 @@ typedef struct _lzw_buf {
*
* Initialize an lzw_buf_t to the given size in bytes.
*
- * Returns CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY.
+ * To store objects into the lzw_buf_t, call _lzw_buf_store_bits and
+ * when finished, call _lzw_buf_store_pending, (which flushes out the
+ * last few bits that hadn't yet made a complete byte yet).
+ *
+ * Instead of returning failure from any functions, lzw_buf_t provides
+ * a status value that the caller can query, (and should query at
+ * least once when done with the object). The status value will be
+ * either CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY;
*/
-static cairo_status_t
+static void
_lzw_buf_init (lzw_buf_t *buf, int size)
{
if (size == 0)
size = 16;
+ buf->status = CAIRO_STATUS_SUCCESS;
+
buf->data = malloc (size);
if (buf->data == NULL) {
buf->data_size = 0;
- return CAIRO_STATUS_NO_MEMORY;
+ buf->status = CAIRO_STATUS_NO_MEMORY;
+ return;
}
buf->data_size = size;
buf->num_data = 0;
buf->pending = 0;
buf->pending_bits = 0;
-
- return CAIRO_STATUS_SUCCESS;
-}
-
-static void
-_lzw_buf_fini (lzw_buf_t *buf)
-{
- assert (buf->pending_bits == 0);
-
- free (buf->data);
- buf->data = 0;
}
+/* Increase the buffer size by doubling.
+ *
+ * Returns CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY
+ */
static cairo_status_t
_lzw_buf_grow (lzw_buf_t *buf)
{
int new_size = buf->data_size * 2;
unsigned char *new_data;
+ if (buf->status)
+ return buf->status;
+
new_data = realloc (buf->data, new_size);
- if (new_data == NULL)
- return CAIRO_STATUS_NO_MEMORY;
+ if (new_data == NULL) {
+ free (buf->data);
+ buf->data_size = 0;
+ buf->status = CAIRO_STATUS_NO_MEMORY;
+ return buf->status;
+ }
buf->data = new_data;
buf->data_size = new_size;
@@ -107,17 +116,17 @@ _lzw_buf_grow (lzw_buf_t *buf)
* See also _lzw_buf_store_pending which must be called after the last
* call to _lzw_buf_store_bits.
*
- * Returns CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY.
+ * Sets buf->status to either CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY.
*/
-static cairo_status_t
+static void
_lzw_buf_store_bits (lzw_buf_t *buf, uint16_t value, int num_bits)
{
cairo_status_t status;
assert (value <= (1 << num_bits) - 1);
- if (getenv ("CAIRO_DEBUG_LZW"))
- printf ("%d(%d) ", value, num_bits);
+ if (buf->status)
+ return;
buf->pending = (buf->pending << num_bits) | value;
buf->pending_bits += num_bits;
@@ -126,13 +135,11 @@ _lzw_buf_store_bits (lzw_buf_t *buf, uin
if (buf->num_data >= buf->data_size) {
status = _lzw_buf_grow (buf);
if (status)
- return status;
+ return;
}
buf->data[buf->num_data++] = buf->pending >> (buf->pending_bits - 8);
buf->pending_bits -= 8;
}
-
- return CAIRO_STATUS_SUCCESS;
}
/* Store the last remaining pending bits into the buffer.
@@ -140,217 +147,267 @@ _lzw_buf_store_bits (lzw_buf_t *buf, uin
* NOTE: This function must be called after the last call to
* _lzw_buf_store_bits.
*
- * Returns CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY.
+ * Sets buf->status to either CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY.
*/
-static cairo_status_t
+static void
_lzw_buf_store_pending (lzw_buf_t *buf)
{
cairo_status_t status;
+ if (buf->status)
+ return;
+
if (buf->pending_bits == 0)
- return CAIRO_STATUS_SUCCESS;
+ return;
assert (buf->pending_bits < 8);
if (buf->num_data >= buf->data_size) {
status = _lzw_buf_grow (buf);
if (status)
- return status;
+ return;
}
buf->data[buf->num_data++] = buf->pending << (8 - buf->pending_bits);
buf->pending_bits = 0;
-
- return CAIRO_STATUS_SUCCESS;
}
-typedef struct _lzw_symbol {
- cairo_hash_entry_t hash_entry;
+/* LZW defines a few magic code values */
+#define LZW_CODE_CLEAR_TABLE 256
+#define LZW_CODE_EOD 257
+#define LZW_CODE_FIRST 258
- /* "key" is the symbol */
- unsigned char *data;
- int size;
- /* "value" is the code */
- int value;
-} lzw_symbol_t;
+/* We pack three separate values into a symbol as follows:
+ *
+ * 12 bits (31 down to 20): CODE: code value used to represent this symbol
+ * 12 bits (19 down to 8): PREV: previous code value in chain
+ * 8 bits ( 7 down to 0): NEXT: next byte value in chain
+ */
+typedef uint32_t lzw_symbol_t;
+
+#define LZW_SYMBOL_SET(sym, prev, next) ((sym) = ((prev) << 8)|(next))
+#define LZW_SYMBOL_SET_CODE(sym, code, prev, next) ((sym) = ((code << 20)|(prev) << 8)|(next))
+#define LZW_SYMBOL_GET_CODE(sym) (((sym) >> 20))
+#define LZW_SYMBOL_GET_PREV(sym) (((sym) >> 8) & 0x7ff)
+#define LZW_SYMBOL_GET_BYTE(sym) (((sym) >> 0) & 0x0ff)
+/* The PREV+NEXT fields can be seen as the key used to fetch values
+ * from the hash table, while the code is the value fetched.
+ */
+#define LZW_SYMBOL_KEY_MASK 0x000fffff
+
+/* Since code values are only stored starting with 258 we can safely
+ * use a zero value to represent free slots in the hash table. */
+#define LZW_SYMBOL_FREE 0x00000000
+
+/* These really aren't very free for modifying. First, the PostScript
+ * specification sets the 9-12 bit range. Second, the encoding of
+ * lzw_symbol_t above also relies on 2 of LZW_BITS_MAX plus one byte
+ * fitting within 32 bits.
+ *
+ * But other than that, the LZW compression scheme could function with
+ * more bits per code.
+ */
#define LZW_BITS_MIN 9
#define LZW_BITS_MAX 12
#define LZW_BITS_BOUNDARY(bits) ((1<<(bits))-1)
#define LZW_MAX_SYMBOLS (1<<LZW_BITS_MAX)
-typedef struct _lzw_symbols {
- lzw_symbol_t symbols[LZW_MAX_SYMBOLS];
- int num_symbols;
-
- cairo_hash_table_t *table;
-} lzw_symbols_t;
-
-static cairo_bool_t
-_lzw_symbols_equal (const void *key_a, const void *key_b)
-{
- const lzw_symbol_t *symbol_a = key_a;
- const lzw_symbol_t *symbol_b = key_b;
-
- if (symbol_a->size != symbol_b->size)
- return FALSE;
-
- return ! memcmp (symbol_a->data, symbol_b->data, symbol_a->size);
-}
-
-static cairo_status_t
-_lzw_symbols_init (lzw_symbols_t *symbols)
-{
- symbols->num_symbols = 0;
-
- symbols->table = _cairo_hash_table_create (_lzw_symbols_equal);
- if (symbols->table == NULL)
- return CAIRO_STATUS_NO_MEMORY;
-
- return CAIRO_STATUS_SUCCESS;
-}
+#define LZW_SYMBOL_TABLE_SIZE 9013
+#define LZW_SYMBOL_MOD1 LZW_SYMBOL_TABLE_SIZE
+#define LZW_SYMBOL_MOD2 9011
+
+typedef struct _lzw_symbol_table {
+ lzw_symbol_t table[LZW_SYMBOL_TABLE_SIZE];
+} lzw_symbol_table_t;
+/* Initialize the hash table to entirely empty */
static void
-_lzw_symbols_fini (lzw_symbols_t *symbols)
+_lzw_symbol_table_init (lzw_symbol_table_t *table)
{
- int i;
-
- for (i=0; i < symbols->num_symbols; i++)
- _cairo_hash_table_remove (symbols->table, &symbols->symbols[i].hash_entry);
-
- symbols->num_symbols = 0;
-
- _cairo_hash_table_destroy (symbols->table);
+ memset (table->table, 0, LZW_SYMBOL_TABLE_SIZE * sizeof (lzw_symbol_t));
}
+/* Lookup a symbol in the symbol table. The PREV and NEXT fields of
+ * symbol form the key for the lookup.
+ *
+ * If succesful, then this function returns TRUE and slot_ret will be
+ * left pointing at the result that will have the CODE field of
+ * interest.
+ *
+ * If the lookup fails, then this function returns FALSE and slot_ret
+ * will be pointing at the location in the table to which a new CODE
+ * value should be stored along with PREV and NEXT.
+ */
static cairo_bool_t
-_lzw_symbols_has (lzw_symbols_t *symbols,
- lzw_symbol_t *symbol,
- lzw_symbol_t **code)
-{
- symbol->hash_entry.hash = _cairo_hash_bytes (symbol->data, symbol->size);
-
- return _cairo_hash_table_lookup (symbols->table,
- &symbol->hash_entry,
- (cairo_hash_entry_t **) code);
-}
-
-static cairo_status_t
-_lzw_symbols_store (lzw_symbols_t *symbols,
- lzw_symbol_t *symbol)
-{
- cairo_status_t status;
-
- symbol->hash_entry.hash = _cairo_hash_bytes (symbol->data, symbol->size);
-
- symbols->symbols[symbols->num_symbols] = *symbol;
+_lzw_symbol_table_lookup (lzw_symbol_table_t *table,
+ lzw_symbol_t symbol,
+ lzw_symbol_t **slot_ret)
+{
+ /* The algorithm here is identical to that in cairo-hash.c. We
+ * copy it here to allow for a rather more efficient
+ * implementation due to several circumstances that do not apply
+ * to the more general case:
+ *
+ * 1) We have a known bound on the total number of symbols, so we
+ * have a fixed-size table without any copying when growing
+ *
+ * 2) We never delete any entries, so we don't need to
+ * support/check for DEAD entries during lookup.
+ *
+ * 3) The object fits in 32 bits so we store each object in its
+ * entirety within the table rather than storing objects
+ * externally and putting pointers in the table, (which here
+ * would just double the storage requirements and have negative
+ * impacts on memory locality).
+ */
+ int i, idx, step, hash = symbol & LZW_SYMBOL_KEY_MASK;
+ lzw_symbol_t candidate;
+
+ idx = hash % LZW_SYMBOL_MOD1;
+ step = 0;
+
+ *slot_ret = NULL;
+ for (i = 0; i < LZW_SYMBOL_TABLE_SIZE; i++)
+ {
+ candidate = table->table[idx];
+ if (candidate == LZW_SYMBOL_FREE)
+ {
+ *slot_ret = &table->table[idx];
+ return FALSE;
+ }
+ else /* candidate is LIVE */
+ {
+ if ((candidate & LZW_SYMBOL_KEY_MASK) ==
+ (symbol & LZW_SYMBOL_KEY_MASK))
+ {
+ *slot_ret = &table->table[idx];
+ return TRUE;
+ }
+ }
- status = _cairo_hash_table_insert (symbols->table, &symbols->symbols[symbols->num_symbols].hash_entry);
- if (status)
- return status;
+ if (step == 0) {
+ step = hash % LZW_SYMBOL_MOD2;
+ if (step == 0)
+ step = 1;
+ }
- symbols->num_symbols++;
+ idx += step;
+ if (idx >= LZW_SYMBOL_TABLE_SIZE)
+ idx -= LZW_SYMBOL_TABLE_SIZE;
+ }
- return CAIRO_STATUS_SUCCESS;
+ return FALSE;
}
-#define LZW_CODE_CLEAR_TABLE 256
-#define LZW_CODE_EOD 257
-#define LZW_CODE_FIRST 258
-
-unsigned char *
+/* Compress a bytestream using the LZW algorithm.
+ *
+ * This is an original implementation based on reading the
+ * specification of the LZWDecode filter in the PostScript Language
+ * Reference. The free parameters in the LZW algorithm are set to the
+ * values mandated by PostScript, (symbols encoded with widths from 9
+ * to 12 bits).
+ *
+ * This function returns a pointer to a newly allocated buffer holding
+ * the compressed data, or NULL if an out-of-memory situation
+ * occurs.
+ *
+ * Notice that any one of the _lzw_buf functions called here could
+ * trigger an out-of-memory condition. But lzw_buf_t uses cairo's
+ * shutdown-on-error idiom, so it's safe to continue to call into
+ * lzw_buf without having to check for errors, (until a final check at
+ * the end).
+ */
+cairo_public unsigned char *
_cairo_lzw_compress (unsigned char *data, unsigned long *size_in_out)
{
- cairo_status_t status;
int bytes_remaining = *size_in_out;
- lzw_symbols_t symbols;
- lzw_symbol_t symbol, *tmp, *code;
lzw_buf_t buf;
+ lzw_symbol_table_t table;
+ lzw_symbol_t symbol, *slot;
int code_next = LZW_CODE_FIRST;
int code_bits = LZW_BITS_MIN;
+ int prev, next;
- status = _lzw_buf_init (&buf, *size_in_out / 4);
- if (status)
+ if (*size_in_out == 0)
return NULL;
- status = _lzw_symbols_init (&symbols);
- if (status) {
- _lzw_buf_fini (&buf);
- return NULL;
- }
+ _lzw_buf_init (&buf, *size_in_out);
- _lzw_buf_store_bits (&buf, LZW_CODE_CLEAR_TABLE, code_bits);
+ _lzw_symbol_table_init (&table);
- symbol.data = data;
- symbol.size = 2;
+ /* The LZW header is a clear table code. */
+ _lzw_buf_store_bits (&buf, LZW_CODE_CLEAR_TABLE, code_bits);
- while (bytes_remaining) {
- code = NULL;
- while (symbol.size <= bytes_remaining &&
- _lzw_symbols_has (&symbols, &symbol, &tmp))
- {
- code = tmp;
- symbol.size++;
+ while (1) {
+
+ /* Find the longest existing code in the symbol table that
+ * matches the current input, if any. */
+ prev = *data++;
+ bytes_remaining--;
+ if (bytes_remaining) {
+ do
+ {
+ next = *data++;
+ bytes_remaining--;
+ LZW_SYMBOL_SET (symbol, prev, next);
+ if (_lzw_symbol_table_lookup (&table, symbol, &slot))
+ prev = LZW_SYMBOL_GET_CODE (*slot);
+ } while (bytes_remaining && *slot != LZW_SYMBOL_FREE);
+ if (*slot == LZW_SYMBOL_FREE) {
+ data--;
+ bytes_remaining++;
+ }
}
- if (code)
- _lzw_buf_store_bits (&buf, code->value, code_bits);
- else
- _lzw_buf_store_bits (&buf, symbol.data[0], code_bits);
+ /* Write the code into the output. This is either a byte read
+ * directly from the input, or a code from the last successful
+ * lookup. */
+ _lzw_buf_store_bits (&buf, prev, code_bits);
- if (symbol.size == bytes_remaining + 1)
+ if (bytes_remaining == 0)
break;
- symbol.value = code_next++;
- _lzw_symbols_store (&symbols, &symbol);
+ LZW_SYMBOL_SET_CODE (*slot, code_next++, prev, next);
- /* XXX: This is just for compatibility testing against libtiff. */
+ /* The libtiff code detects a full table and clears it a bit
+ * earlier than strictly necessary. Here is the code to do
+ * that which might be useful in doing correctness comparisons
+ * against the output of libtiff. */
+#if CLEAR_TABLE_EARLY_FOR_IDENTICAL_OUTPUT_COMPAREED_TO_LIBTIFF
if (code_next == LZW_BITS_BOUNDARY(LZW_BITS_MAX) - 1) {
- _lzw_symbols_fini (&symbols);
- _lzw_symbols_init (&symbols);
+ _lzw_symbol_table_init (&table);
_lzw_buf_store_bits (&buf, LZW_CODE_CLEAR_TABLE, code_bits);
code_bits = LZW_BITS_MIN;
code_next = LZW_CODE_FIRST;
}
+#endif
if (code_next > LZW_BITS_BOUNDARY(code_bits))
{
code_bits++;
if (code_bits > LZW_BITS_MAX) {
- _lzw_symbols_fini (&symbols);
- _lzw_symbols_init (&symbols);
- _lzw_buf_store_bits (&buf, LZW_CODE_CLEAR_TABLE, code_bits);
+ _lzw_symbol_table_init (&table);
+ _lzw_buf_store_bits (&buf, LZW_CODE_CLEAR_TABLE, code_bits - 1);
code_bits = LZW_BITS_MIN;
code_next = LZW_CODE_FIRST;
}
}
-
- if (code) {
- symbol.data += (symbol.size - 1);
- bytes_remaining -= (symbol.size - 1);
- } else {
- symbol.data += 1;
- bytes_remaining -= 1;
- }
- symbol.size = 2;
}
+ /* The LZW footer is an end-of-data code. */
_lzw_buf_store_bits (&buf, LZW_CODE_EOD, code_bits);
_lzw_buf_store_pending (&buf);
- _lzw_symbols_fini (&symbols);
+ /* See if we ever ran out of memory while writing to buf. */
+ if (buf.status == CAIRO_STATUS_NO_MEMORY) {
+ *size_in_out = 0;
+ return NULL;
+ }
+
+ assert (buf.status == CAIRO_STATUS_SUCCESS);
*size_in_out = buf.num_data;
return buf.data;
}
-
-static unsigned long
-_cairo_hash_bytes (const unsigned char *c, int size)
-{
- /* This is the djb2 hash. */
- unsigned long hash = 5381;
- while (size--)
- hash = ((hash << 5) + hash) + *c++;
- return hash;
-}
diff-tree 639c2fe4df880546d71b2c73ea972fb08b609603 (from ec60bb0a606cadf3120d1cebc88e248a3e056c19)
Author: Carl Worth <cworth at cworth.org>
Date: Thu Mar 23 15:23:29 2006 -0800
cairo-lzw: Replace LZW code from libtiff with an original implementation.
This new implementation is an entirely original work directly from the
description of the LZWDecode filter in the PostScript Language
Reference, (and in spite of the bugs in the examples provided in that
reference).
This implementation uses the existing cairo-hash.c for the symbol
table. This implementation is somewhat easier to read than the libtiff
code, and avoids any code that may have an advertising clause
attached. This new implementation is the simplest thing I could
implement. It is not as efficient as the libtiff code, (though I did
expect better things from cairo-hash.c).
diff --git a/src/cairo-lzw.c b/src/cairo-lzw.c
index a0d737e..67a41bd 100644
--- a/src/cairo-lzw.c
+++ b/src/cairo-lzw.c
@@ -1,6 +1,6 @@
/* cairo - a vector graphics library with display and print output
*
- * Copyright © 2006 Red Hat, Inc
+ * Copyright © 2006 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
@@ -27,473 +27,330 @@
*
* The Original Code is the cairo graphics library.
*
- * Contributor(s):
- * Alexander Larsson <alexl at redhat.com>
+ * The Initial Developer of the Original Code is University of Southern
+ * California.
*
- * This code is derived from tif_lzw.c in libtiff 3.8.0.
- * The original copyright notice appears below in its entirety.
+ * Contributor(s):
+ * Carl D. Worth <cworth at cworth.org>
*/
#include "cairoint.h"
-#include <stdlib.h>
-#include <stdio.h>
-#include <stdint.h>
-#include <stdarg.h>
-#include <assert.h>
-#include <string.h>
-
-/*
- * Copyright (c) 1988-1997 Sam Leffler
- * Copyright (c) 1991-1997 Silicon Graphics, Inc.
- *
- * Permission to use, copy, modify, distribute, and sell this software and
- * its documentation for any purpose is hereby granted without fee, provided
- * that (i) the above copyright notices and this permission notice appear in
- * all copies of the software and related documentation, and (ii) the names of
- * Sam Leffler and Silicon Graphics may not be used in any advertising or
- * publicity relating to the software without the specific, prior written
- * permission of Sam Leffler and Silicon Graphics.
- *
- * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
- * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
- *
- * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
- * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
- * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
- * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
- * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
- * OF THIS SOFTWARE.
- */
+static unsigned long
+_cairo_hash_bytes (const unsigned char *c, int size);
+
+typedef struct _lzw_buf {
+ unsigned char *data;
+ int data_size;
+ int num_data;
+ uint32_t pending;
+ int pending_bits;
+} lzw_buf_t;
-/*
- * TIFF Library.
- * Rev 5.0 Lempel-Ziv & Welch Compression Support
- *
- * This code is derived from the compress program whose code is
- * derived from software contributed to Berkeley by James A. Woods,
- * derived from original work by Spencer Thomas and Joseph Orost.
+/* An lzw_buf_t is a simple, growable chunk of memory for holding
+ * variable-size objects of up to 16 bits each.
*
- * The original Berkeley copyright notice appears below in its entirety.
+ * Initialize an lzw_buf_t to the given size in bytes.
+ *
+ * Returns CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY.
*/
+static cairo_status_t
+_lzw_buf_init (lzw_buf_t *buf, int size)
+{
+ if (size == 0)
+ size = 16;
+
+ buf->data = malloc (size);
+ if (buf->data == NULL) {
+ buf->data_size = 0;
+ return CAIRO_STATUS_NO_MEMORY;
+ }
+
+ buf->data_size = size;
+ buf->num_data = 0;
+ buf->pending = 0;
+ buf->pending_bits = 0;
+
+ return CAIRO_STATUS_SUCCESS;
+}
+
+static void
+_lzw_buf_fini (lzw_buf_t *buf)
+{
+ assert (buf->pending_bits == 0);
+
+ free (buf->data);
+ buf->data = 0;
+}
+
+static cairo_status_t
+_lzw_buf_grow (lzw_buf_t *buf)
+{
+ int new_size = buf->data_size * 2;
+ unsigned char *new_data;
+
+ new_data = realloc (buf->data, new_size);
+ if (new_data == NULL)
+ return CAIRO_STATUS_NO_MEMORY;
+
+ buf->data = new_data;
+ buf->data_size = new_size;
-#define MAXCODE(n) ((1L<<(n))-1)
-/*
- * The TIFF spec specifies that encoded bit
- * strings range from 9 to 12 bits.
+ return CAIRO_STATUS_SUCCESS;
+}
+
+/* Store the lowest num_bits bits of values into buf.
+ *
+ * NOTE: The bits of value above size_in_bits must be 0, (so don't lie
+ * about the size).
+ *
+ * See also _lzw_buf_store_pending which must be called after the last
+ * call to _lzw_buf_store_bits.
+ *
+ * Returns CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY.
*/
-#define BITS_MIN 9 /* start with 9 bits */
-#define BITS_MAX 12 /* max of 12 bit strings */
-/* predefined codes */
-#define CODE_CLEAR 256 /* code to clear string table */
-#define CODE_EOI 257 /* end-of-information code */
-#define CODE_FIRST 258 /* first free code entry */
-#define CODE_MAX MAXCODE(BITS_MAX)
-#define HSIZE 9001L /* 91% occupancy */
-#define HSHIFT (13-8)
-#ifdef LZW_COMPAT
-/* NB: +1024 is for compatibility with old files */
-#define CSIZE (MAXCODE(BITS_MAX)+1024L)
-#else
-#define CSIZE (MAXCODE(BITS_MAX)+1L)
-#endif
-
-typedef uint16_t hcode_t; /* codes fit in 16 bits */
-typedef struct {
- long hash;
- hcode_t code;
-} hash_t;
-
-typedef struct {
- /* Out buffer */
- unsigned char *out_buffer; /* compressed out buffer */
- size_t out_buffer_size; /* # of allocated bytes in out buffer */
- unsigned char *out_buffer_pos; /* current spot in out buffer */
- size_t out_buffer_bytes; /* # of data bytes in out buffer */
- unsigned char *out_buffer_end; /* bound on out_buffer */
-
- unsigned short nbits; /* # of bits/code */
- unsigned short maxcode; /* maximum code for lzw_nbits */
- unsigned short free_ent; /* next free entry in hash table */
- long nextdata; /* next bits of i/o */
- long nextbits; /* # of valid bits in lzw_nextdata */
-
- int enc_oldcode; /* last code encountered */
- long enc_checkpoint; /* point at which to clear table */
-#define CHECK_GAP 10000 /* enc_ratio check interval */
- long enc_ratio; /* current compression ratio */
- long enc_incount; /* (input) data bytes encoded */
- long enc_outcount; /* encoded (output) bytes */
- hash_t* enc_hashtab; /* kept separate for small machines */
-} LZWCodecState;
+static cairo_status_t
+_lzw_buf_store_bits (lzw_buf_t *buf, uint16_t value, int num_bits)
+{
+ cairo_status_t status;
-static void cl_hash(LZWCodecState*);
+ assert (value <= (1 << num_bits) - 1);
-/*
- * LZW Encoding.
+ if (getenv ("CAIRO_DEBUG_LZW"))
+ printf ("%d(%d) ", value, num_bits);
+
+ buf->pending = (buf->pending << num_bits) | value;
+ buf->pending_bits += num_bits;
+
+ while (buf->pending_bits >= 8) {
+ if (buf->num_data >= buf->data_size) {
+ status = _lzw_buf_grow (buf);
+ if (status)
+ return status;
+ }
+ buf->data[buf->num_data++] = buf->pending >> (buf->pending_bits - 8);
+ buf->pending_bits -= 8;
+ }
+
+ return CAIRO_STATUS_SUCCESS;
+}
+
+/* Store the last remaining pending bits into the buffer.
+ *
+ * NOTE: This function must be called after the last call to
+ * _lzw_buf_store_bits.
+ *
+ * Returns CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY.
*/
+static cairo_status_t
+_lzw_buf_store_pending (lzw_buf_t *buf)
+{
+ cairo_status_t status;
+
+ if (buf->pending_bits == 0)
+ return CAIRO_STATUS_SUCCESS;
+
+ assert (buf->pending_bits < 8);
+
+ if (buf->num_data >= buf->data_size) {
+ status = _lzw_buf_grow (buf);
+ if (status)
+ return status;
+ }
+
+ buf->data[buf->num_data++] = buf->pending << (8 - buf->pending_bits);
+ buf->pending_bits = 0;
+
+ return CAIRO_STATUS_SUCCESS;
+}
+
+typedef struct _lzw_symbol {
+ cairo_hash_entry_t hash_entry;
+
+ /* "key" is the symbol */
+ unsigned char *data;
+ int size;
+ /* "value" is the code */
+ int value;
+} lzw_symbol_t;
+
+#define LZW_BITS_MIN 9
+#define LZW_BITS_MAX 12
+#define LZW_BITS_BOUNDARY(bits) ((1<<(bits))-1)
+#define LZW_MAX_SYMBOLS (1<<LZW_BITS_MAX)
+
+typedef struct _lzw_symbols {
+ lzw_symbol_t symbols[LZW_MAX_SYMBOLS];
+ int num_symbols;
+
+ cairo_hash_table_t *table;
+} lzw_symbols_t;
-static unsigned char *
-grow_out_buffer (LZWCodecState *sp, unsigned char *op)
+static cairo_bool_t
+_lzw_symbols_equal (const void *key_a, const void *key_b)
{
- size_t cc;
-
- cc = (size_t)(op - sp->out_buffer);
-
- sp->out_buffer_size = sp->out_buffer_size * 2;
- sp->out_buffer = realloc (sp->out_buffer, sp->out_buffer_size);
- /*
- * The 4 here insures there is space for 2 max-sized
- * codes in LZWEncode and LZWPostDecode.
- */
- sp->out_buffer_end = sp->out_buffer + sp->out_buffer_size-1 - 4;
-
- return sp->out_buffer + cc;
+ const lzw_symbol_t *symbol_a = key_a;
+ const lzw_symbol_t *symbol_b = key_b;
+
+ if (symbol_a->size != symbol_b->size)
+ return FALSE;
+
+ return ! memcmp (symbol_a->data, symbol_b->data, symbol_a->size);
}
-static int
-LZWSetupEncode (LZWCodecState* sp)
+static cairo_status_t
+_lzw_symbols_init (lzw_symbols_t *symbols)
{
- memset (sp, 0, sizeof (LZWCodecState));
- sp->enc_hashtab = (hash_t*) malloc (HSIZE * sizeof (hash_t));
- if (sp->enc_hashtab == NULL)
- return 0;
- return 1;
+ symbols->num_symbols = 0;
+
+ symbols->table = _cairo_hash_table_create (_lzw_symbols_equal);
+ if (symbols->table == NULL)
+ return CAIRO_STATUS_NO_MEMORY;
+
+ return CAIRO_STATUS_SUCCESS;
}
static void
-LZWFreeEncode (LZWCodecState* sp)
+_lzw_symbols_fini (lzw_symbols_t *symbols)
{
- if (sp->enc_hashtab)
- free (sp->enc_hashtab);
+ int i;
+
+ for (i=0; i < symbols->num_symbols; i++)
+ _cairo_hash_table_remove (symbols->table, &symbols->symbols[i].hash_entry);
+
+ symbols->num_symbols = 0;
+
+ _cairo_hash_table_destroy (symbols->table);
}
+static cairo_bool_t
+_lzw_symbols_has (lzw_symbols_t *symbols,
+ lzw_symbol_t *symbol,
+ lzw_symbol_t **code)
+{
+ symbol->hash_entry.hash = _cairo_hash_bytes (symbol->data, symbol->size);
-/*
- * Reset encoding state at the start of a strip.
- */
-static void
-LZWPreEncode (LZWCodecState *sp)
+ return _cairo_hash_table_lookup (symbols->table,
+ &symbol->hash_entry,
+ (cairo_hash_entry_t **) code);
+}
+
+static cairo_status_t
+_lzw_symbols_store (lzw_symbols_t *symbols,
+ lzw_symbol_t *symbol)
{
- sp->nbits = BITS_MIN;
- sp->maxcode = MAXCODE(BITS_MIN);
- sp->free_ent = CODE_FIRST;
- sp->nextbits = 0;
- sp->nextdata = 0;
- sp->enc_checkpoint = CHECK_GAP;
- sp->enc_ratio = 0;
- sp->enc_incount = 0;
- sp->enc_outcount = 0;
- /*
- * The 4 here insures there is space for 2 max-sized
- * codes in LZWEncode and LZWPostDecode.
- */
- sp->out_buffer_end = sp->out_buffer + sp->out_buffer_size-1 - 4;
- cl_hash(sp); /* clear hash table */
- sp->enc_oldcode = (hcode_t) -1; /* generates CODE_CLEAR in LZWEncode */
-}
-
-#define CALCRATIO(sp, rat) { \
- if (incount > 0x007fffff) { /* NB: shift will overflow */ \
- rat = outcount >> 8; \
- rat = (rat == 0 ? 0x7fffffff : incount/rat); \
- } else \
- rat = (incount << 8) / outcount; \
-}
-#define PutNextCode(op, c) { \
- nextdata = (nextdata << nbits) | c; \
- nextbits += nbits; \
- *op++ = (unsigned char)(nextdata >> (nextbits-8)); \
- nextbits -= 8; \
- if (nextbits >= 8) { \
- *op++ = (unsigned char)(nextdata >> (nextbits-8)); \
- nextbits -= 8; \
- } \
- outcount += nbits; \
-}
-
-/*
- * Encode a chunk of pixels.
- *
- * Uses an open addressing double hashing (no chaining) on the
- * prefix code/next character combination. We do a variant of
- * Knuth's algorithm D (vol. 3, sec. 6.4) along with G. Knott's
- * relatively-prime secondary probe. Here, the modular division
- * first probe is gives way to a faster exclusive-or manipulation.
- * Also do block compression with an adaptive reset, whereby the
- * code table is cleared when the compression ratio decreases,
- * but after the table fills. The variable-length output codes
- * are re-sized at this point, and a CODE_CLEAR is generated
- * for the decoder.
- */
-static int
-LZWEncode (LZWCodecState *sp,
- unsigned char *bp,
- size_t cc)
-{
- register long fcode;
- register hash_t *hp;
- register int h, c;
- hcode_t ent;
- long disp;
- long incount, outcount, checkpoint;
- long nextdata, nextbits;
- int free_ent, maxcode, nbits;
- unsigned char *op;
-
- /*
- * Load local state.
- */
- incount = sp->enc_incount;
- outcount = sp->enc_outcount;
- checkpoint = sp->enc_checkpoint;
- nextdata = sp->nextdata;
- nextbits = sp->nextbits;
- free_ent = sp->free_ent;
- maxcode = sp->maxcode;
- nbits = sp->nbits;
- op = sp->out_buffer_pos;
- ent = sp->enc_oldcode;
-
- if (ent == (hcode_t) -1 && cc > 0) {
- /*
- * NB: This is safe because it can only happen
- * at the start of a strip where we know there
- * is space in the data buffer.
- */
- PutNextCode(op, CODE_CLEAR);
- ent = *bp++; cc--; incount++;
+ cairo_status_t status;
+
+ symbol->hash_entry.hash = _cairo_hash_bytes (symbol->data, symbol->size);
+
+ symbols->symbols[symbols->num_symbols] = *symbol;
+
+ status = _cairo_hash_table_insert (symbols->table, &symbols->symbols[symbols->num_symbols].hash_entry);
+ if (status)
+ return status;
+
+ symbols->num_symbols++;
+
+ return CAIRO_STATUS_SUCCESS;
+}
+
+#define LZW_CODE_CLEAR_TABLE 256
+#define LZW_CODE_EOD 257
+#define LZW_CODE_FIRST 258
+
+unsigned char *
+_cairo_lzw_compress (unsigned char *data, unsigned long *size_in_out)
+{
+ cairo_status_t status;
+ int bytes_remaining = *size_in_out;
+ lzw_symbols_t symbols;
+ lzw_symbol_t symbol, *tmp, *code;
+ lzw_buf_t buf;
+ int code_next = LZW_CODE_FIRST;
+ int code_bits = LZW_BITS_MIN;
+
+ status = _lzw_buf_init (&buf, *size_in_out / 4);
+ if (status)
+ return NULL;
+
+ status = _lzw_symbols_init (&symbols);
+ if (status) {
+ _lzw_buf_fini (&buf);
+ return NULL;
}
- while (cc > 0) {
- c = *bp++; cc--; incount++;
- fcode = ((long)c << BITS_MAX) + ent;
- h = (c << HSHIFT) ^ ent; /* xor hashing */
-#ifdef _WINDOWS
- /*
- * Check hash index for an overflow.
- */
- if (h >= HSIZE)
- h -= HSIZE;
-#endif
- hp = &sp->enc_hashtab[h];
- if (hp->hash == fcode) {
- ent = hp->code;
- continue;
+
+ _lzw_buf_store_bits (&buf, LZW_CODE_CLEAR_TABLE, code_bits);
+
+ symbol.data = data;
+ symbol.size = 2;
+
+ while (bytes_remaining) {
+ code = NULL;
+ while (symbol.size <= bytes_remaining &&
+ _lzw_symbols_has (&symbols, &symbol, &tmp))
+ {
+ code = tmp;
+ symbol.size++;
}
- if (hp->hash >= 0) {
- /*
- * Primary hash failed, check secondary hash.
- */
- disp = HSIZE - h;
- if (h == 0)
- disp = 1;
- do {
- /*
- * Avoid pointer arithmetic 'cuz of
- * wraparound problems with segments.
- */
- if ((h -= disp) < 0)
- h += HSIZE;
- hp = &sp->enc_hashtab[h];
- if (hp->hash == fcode) {
- ent = hp->code;
- goto hit;
- }
- } while (hp->hash >= 0);
+
+ if (code)
+ _lzw_buf_store_bits (&buf, code->value, code_bits);
+ else
+ _lzw_buf_store_bits (&buf, symbol.data[0], code_bits);
+
+ if (symbol.size == bytes_remaining + 1)
+ break;
+
+ symbol.value = code_next++;
+ _lzw_symbols_store (&symbols, &symbol);
+
+ /* XXX: This is just for compatibility testing against libtiff. */
+ if (code_next == LZW_BITS_BOUNDARY(LZW_BITS_MAX) - 1) {
+ _lzw_symbols_fini (&symbols);
+ _lzw_symbols_init (&symbols);
+ _lzw_buf_store_bits (&buf, LZW_CODE_CLEAR_TABLE, code_bits);
+ code_bits = LZW_BITS_MIN;
+ code_next = LZW_CODE_FIRST;
}
- /*
- * New entry, emit code and add to table.
- */
- /*
- * Verify there is space in the buffer for the code
- * and any potential Clear code that might be emitted
- * below. The value of limit is setup so that there
- * are at least 4 bytes free--room for 2 codes.
- */
- if (op > sp->out_buffer_end) {
- op = grow_out_buffer (sp, op);
- if (sp->out_buffer == NULL) {
- return 0;
+
+ if (code_next > LZW_BITS_BOUNDARY(code_bits))
+ {
+ code_bits++;
+ if (code_bits > LZW_BITS_MAX) {
+ _lzw_symbols_fini (&symbols);
+ _lzw_symbols_init (&symbols);
+ _lzw_buf_store_bits (&buf, LZW_CODE_CLEAR_TABLE, code_bits);
+ code_bits = LZW_BITS_MIN;
+ code_next = LZW_CODE_FIRST;
}
}
- PutNextCode(op, ent);
- ent = c;
- hp->code = free_ent++;
- hp->hash = fcode;
- if (free_ent == CODE_MAX-1) {
- /* table is full, emit clear code and reset */
- cl_hash(sp);
- sp->enc_ratio = 0;
- incount = 0;
- outcount = 0;
- free_ent = CODE_FIRST;
- PutNextCode(op, CODE_CLEAR);
- nbits = BITS_MIN;
- maxcode = MAXCODE(BITS_MIN);
+
+ if (code) {
+ symbol.data += (symbol.size - 1);
+ bytes_remaining -= (symbol.size - 1);
} else {
- /*
- * If the next entry is going to be too big for
- * the code size, then increase it, if possible.
- */
- if (free_ent > maxcode) {
- nbits++;
- assert(nbits <= BITS_MAX);
- maxcode = (int) MAXCODE(nbits);
- } else if (incount >= checkpoint) {
- long rat;
- /*
- * Check compression ratio and, if things seem
- * to be slipping, clear the hash table and
- * reset state. The compression ratio is a
- * 24+8-bit fractional number.
- */
- checkpoint = incount+CHECK_GAP;
- CALCRATIO(sp, rat);
- if (rat <= sp->enc_ratio) {
- cl_hash(sp);
- sp->enc_ratio = 0;
- incount = 0;
- outcount = 0;
- free_ent = CODE_FIRST;
- PutNextCode(op, CODE_CLEAR);
- nbits = BITS_MIN;
- maxcode = MAXCODE(BITS_MIN);
- } else
- sp->enc_ratio = rat;
- }
+ symbol.data += 1;
+ bytes_remaining -= 1;
}
- hit:
- ;
+ symbol.size = 2;
}
-
- /*
- * Restore global state.
- */
- sp->enc_incount = incount;
- sp->enc_outcount = outcount;
- sp->enc_checkpoint = checkpoint;
- sp->enc_oldcode = ent;
- sp->nextdata = nextdata;
- sp->nextbits = nextbits;
- sp->free_ent = free_ent;
- sp->maxcode = maxcode;
- sp->nbits = nbits;
- sp->out_buffer_pos = op;
- return 1;
-}
-
-/*
- * Finish off an encoded strip by flushing the last
- * string and tacking on an End Of Information code.
- */
-static int
-LZWPostEncode (LZWCodecState *sp)
-{
- unsigned char *op = sp->out_buffer_pos;
- long nextbits = sp->nextbits;
- long nextdata = sp->nextdata;
- long outcount = sp->enc_outcount;
- int nbits = sp->nbits;
-
- if (op > sp->out_buffer_end) {
- op = grow_out_buffer (sp, op);
- if (sp->out_buffer == NULL) {
- return 0;
- }
- }
- if (sp->enc_oldcode != (hcode_t) -1) {
- PutNextCode(op, sp->enc_oldcode);
- sp->enc_oldcode = (hcode_t) -1;
- }
- PutNextCode(op, CODE_EOI);
- if (nextbits > 0)
- *op++ = (unsigned char)(nextdata << (8-nextbits));
- sp->out_buffer_bytes = (size_t)(op - sp->out_buffer);
- return 1;
-}
-/*
- * Reset encoding hash table.
- */
-static void
-cl_hash (LZWCodecState* sp)
-{
- register hash_t *hp = &sp->enc_hashtab[HSIZE-1];
- register long i = HSIZE-8;
-
- do {
- i -= 8;
- hp[-7].hash = -1;
- hp[-6].hash = -1;
- hp[-5].hash = -1;
- hp[-4].hash = -1;
- hp[-3].hash = -1;
- hp[-2].hash = -1;
- hp[-1].hash = -1;
- hp[ 0].hash = -1;
- hp -= 8;
- } while (i >= 0);
- for (i += 8; i > 0; i--, hp--)
- hp->hash = -1;
-}
-
-/*
- * Copyright (c) 1985, 1986 The Regents of the University of California.
- * All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * James A. Woods, derived from original work by Spencer Thomas
- * and Joseph Orost.
- *
- * Redistribution and use in source and binary forms are permitted
- * provided that the above copyright notice and this paragraph are
- * duplicated in all such forms and that any documentation,
- * advertising materials, and other materials related to such
- * distribution and use acknowledge that the software was developed
- * by the University of California, Berkeley. The name of the
- * University may not be used to endorse or promote products derived
- * from this software without specific prior written permission.
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
- * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
- */
+ _lzw_buf_store_bits (&buf, LZW_CODE_EOD, code_bits);
-void *
-_cairo_lzw_compress (void *data, unsigned long *data_size_in_out)
-{
- LZWCodecState state;
-
- if (!LZWSetupEncode (&state))
- goto bail0;
-
- state.out_buffer_size = *data_size_in_out/4;
- /* We need *some* space at least */
- if (state.out_buffer_size < 256)
- state.out_buffer_size = 256;
- state.out_buffer = malloc (state.out_buffer_size);
- if (state.out_buffer == NULL)
- goto bail1;
-
- state.out_buffer_pos = state.out_buffer;
- state.out_buffer_bytes = 0;
-
- LZWPreEncode (&state);
- if (!LZWEncode (&state, data, *data_size_in_out))
- goto bail2;
- if (!LZWPostEncode(&state))
- goto bail2;
-
- LZWFreeEncode(&state);
+ _lzw_buf_store_pending (&buf);
- *data_size_in_out = state.out_buffer_bytes;
- return state.out_buffer;
-
- bail2:
- if (state.out_buffer)
- free (state.out_buffer);
- bail1:
- LZWFreeEncode(&state);
- bail0:
- return NULL;
+ _lzw_symbols_fini (&symbols);
+
+ *size_in_out = buf.num_data;
+ return buf.data;
+}
+
+static unsigned long
+_cairo_hash_bytes (const unsigned char *c, int size)
+{
+ /* This is the djb2 hash. */
+ unsigned long hash = 5381;
+ while (size--)
+ hash = ((hash << 5) + hash) + *c++;
+ return hash;
}
diff --git a/src/cairoint.h b/src/cairoint.h
index fdb8fc5..3dc0f7e 100644
--- a/src/cairoint.h
+++ b/src/cairoint.h
@@ -2145,8 +2145,8 @@ _cairo_output_stream_write_base85_string
const char *data,
size_t length);
-cairo_private void *
-_cairo_lzw_compress (void *data, unsigned long *data_size_in_out);
+unsigned char *
+_cairo_lzw_compress (unsigned char *data, unsigned long *data_size_in_out);
cairo_private cairo_status_t
_cairo_output_stream_vprintf (cairo_output_stream_t *stream,
diff-tree ec60bb0a606cadf3120d1cebc88e248a3e056c19 (from cabe94a15c277bb8a5f0c71f25cc8bc9e22ecb41)
Author: Carl Worth <cworth at cworth.org>
Date: Thu Mar 23 15:00:40 2006 -0800
Rename _cairo_compress_lzw to _cairo_lzw_compress and tighten the parameter list.
diff --git a/src/cairo-lzw.c b/src/cairo-lzw.c
index bb764f3..a0d737e 100644
--- a/src/cairo-lzw.c
+++ b/src/cairo-lzw.c
@@ -460,14 +460,14 @@ cl_hash (LZWCodecState* sp)
*/
void *
-_cairo_compress_lzw (void *data, unsigned long data_size, unsigned long *compressed_size)
+_cairo_lzw_compress (void *data, unsigned long *data_size_in_out)
{
LZWCodecState state;
if (!LZWSetupEncode (&state))
goto bail0;
- state.out_buffer_size = data_size/4;
+ state.out_buffer_size = *data_size_in_out/4;
/* We need *some* space at least */
if (state.out_buffer_size < 256)
state.out_buffer_size = 256;
@@ -479,14 +479,14 @@ _cairo_compress_lzw (void *data, unsigne
state.out_buffer_bytes = 0;
LZWPreEncode (&state);
- if (!LZWEncode (&state, data, data_size))
+ if (!LZWEncode (&state, data, *data_size_in_out))
goto bail2;
if (!LZWPostEncode(&state))
goto bail2;
LZWFreeEncode(&state);
- *compressed_size = state.out_buffer_bytes;
+ *data_size_in_out = state.out_buffer_bytes;
return state.out_buffer;
bail2:
diff --git a/src/cairo-ps-surface.c b/src/cairo-ps-surface.c
index ff4f0e8..a646d45 100644
--- a/src/cairo-ps-surface.c
+++ b/src/cairo-ps-surface.c
@@ -724,7 +724,8 @@ emit_image (cairo_ps_surface_t *surfa
}
}
- compressed = _cairo_compress_lzw (rgb, rgb_size, &compressed_size);
+ compressed_size = rgb_size;
+ compressed = _cairo_lzw_compress (rgb, &compressed_size);
if (compressed == NULL) {
status = CAIRO_STATUS_NO_MEMORY;
goto bail2;
diff --git a/src/cairoint.h b/src/cairoint.h
index d5abfc7..fdb8fc5 100644
--- a/src/cairoint.h
+++ b/src/cairoint.h
@@ -2146,9 +2146,7 @@ _cairo_output_stream_write_base85_string
size_t length);
cairo_private void *
-_cairo_compress_lzw (void *data,
- unsigned long data_size,
- unsigned long *compressed_size);
+_cairo_lzw_compress (void *data, unsigned long *data_size_in_out);
cairo_private cairo_status_t
_cairo_output_stream_vprintf (cairo_output_stream_t *stream,
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