[LIBJPEG]

[reactos.git] / reactos / dll / 3rdparty / libjpeg / jdmaster.c

diff --git a/reactos/dll/3rdparty/libjpeg/jdmaster.c b/reactos/dll/3rdparty/libjpeg/jdmaster.c
index 6f42d3c..ab95090 100644 (file)
--- a/reactos/dll/3rdparty/libjpeg/jdmaster.c
+++ b/reactos/dll/3rdparty/libjpeg/jdmaster.c
@@ -2,7 +2,7 @@
  * jdmaster.c
  *
  * Copyright (C) 1991-1997, Thomas G. Lane.
- * Modified 2002-2013 by Guido Vollbeding.
+ * Modified 2002-2015 by Guido Vollbeding.
  * This file is part of the Independent JPEG Group's software.
  * For conditions of distribution and use, see the accompanying README file.
  *
@@ -45,11 +45,23 @@ LOCAL(boolean)
 use_merged_upsample (j_decompress_ptr cinfo)
 {
 #ifdef UPSAMPLE_MERGING_SUPPORTED
-  /* Merging is the equivalent of plain box-filter upsampling */
-  if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
+  /* Merging is the equivalent of plain box-filter upsampling. */
+  /* The following condition is only needed if fancy shall select
+   * a different upsampling method.  In our current implementation
+   * fancy only affects the DCT scaling, thus we can use fancy
+   * upsampling and merged upsample simultaneously, in particular
+   * with scaled DCT sizes larger than the default DCTSIZE.
+   */
+#if 0
+  if (cinfo->do_fancy_upsampling)
+    return FALSE;
+#endif
+  if (cinfo->CCIR601_sampling)
     return FALSE;
   /* jdmerge.c only supports YCC=>RGB color conversion */
-  if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
+  if ((cinfo->jpeg_color_space != JCS_YCbCr &&
+       cinfo->jpeg_color_space != JCS_BG_YCC) ||
+      cinfo->num_components != 3 ||
       cinfo->out_color_space != JCS_RGB ||
       cinfo->out_color_components != RGB_PIXELSIZE ||
       cinfo->color_transform)
@@ -199,30 +211,20 @@ jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
  * These processes all use a common table prepared by the routine below.
  *
  * For most steps we can mathematically guarantee that the initial value
- * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
- * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
- * limiting step (just after the IDCT), a wildly out-of-range value is 
- * possible if the input data is corrupt.  To avoid any chance of indexing
+ * of x is within 2*(MAXJSAMPLE+1) of the legal range, so a table running
+ * from -2*(MAXJSAMPLE+1) to 3*MAXJSAMPLE+2 is sufficient.  But for the
+ * initial limiting step (just after the IDCT), a wildly out-of-range value
+ * is possible if the input data is corrupt.  To avoid any chance of indexing
  * off the end of memory and getting a bad-pointer trap, we perform the
  * post-IDCT limiting thus:
- *             x = range_limit[x & MASK];
+ *             x = (sample_range_limit - SUBSET)[(x + CENTER) & MASK];
  * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
  * samples.  Under normal circumstances this is more than enough range and
  * a correct output will be generated; with bogus input data the mask will
  * cause wraparound, and we will safely generate a bogus-but-in-range output.
  * For the post-IDCT step, we want to convert the data from signed to unsigned
  * representation by adding CENTERJSAMPLE at the same time that we limit it.
- * So the post-IDCT limiting table ends up looking like this:
- *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
- *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
- *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
- *   0,1,...,CENTERJSAMPLE-1
- * Negative inputs select values from the upper half of the table after
- * masking.
- *
- * We can save some space by overlapping the start of the post-IDCT table
- * with the simpler range limiting table.  The post-IDCT table begins at
- * sample_range_limit + CENTERJSAMPLE.
+ * This is accomplished with SUBSET = CENTER - CENTERJSAMPLE.
  *
  * Note that the table is allocated in near data space on PCs; it's small
  * enough and used often enough to justify this.
@@ -237,23 +239,17 @@ prepare_range_limit_table (j_decompress_ptr cinfo)
 
   table = (JSAMPLE *)
     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
-               (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
-  table += (MAXJSAMPLE+1);     /* allow negative subscripts of simple table */
+                               5 * (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
+  /* First segment of range limit table: limit[x] = 0 for x < 0 */
+  MEMZERO(table, 2 * (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
+  table += 2 * (MAXJSAMPLE+1); /* allow negative subscripts of table */
   cinfo->sample_range_limit = table;
-  /* First segment of "simple" table: limit[x] = 0 for x < 0 */
-  MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
-  /* Main part of "simple" table: limit[x] = x */
+  /* Main part of range limit table: limit[x] = x */
   for (i = 0; i <= MAXJSAMPLE; i++)
     table[i] = (JSAMPLE) i;
-  table += CENTERJSAMPLE;      /* Point to where post-IDCT table starts */
-  /* End of simple table, rest of first half of post-IDCT table */
-  for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
+  /* End of range limit table: limit[x] = MAXJSAMPLE for x > MAXJSAMPLE */
+  for (; i < 3 * (MAXJSAMPLE+1); i++)
     table[i] = MAXJSAMPLE;
-  /* Second half of post-IDCT table */
-  MEMZERO(table + (2 * (MAXJSAMPLE+1)),
-         (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
-  MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
-         cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
 }