Add support for decoding to 565 to libjpeg_turbo

jdmaster.c

 /*
  * jdmaster.c
  *
  * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1991-1997, Thomas G. Lane.
  * Modified 2002-2009 by Guido Vollbeding.
  * libjpeg-turbo Modifications:
  * Copyright (C) 2009-2011, D. R. Commander.
+ * Copyright (C) 2013, Linaro Limited.
+
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file contains master control logic for the JPEG decompressor.
  * These routines are concerned with selecting the modules to be executed
  * and with determining the number of passes and the work to be done in each
  * pass.
  */
 
 #define JPEG_INTERNALS
 #include "jinclude.h"
@@ skipping 25 matching lines @@
  * CRUCIAL: this must match the actual capabilities of jdmerge.c!
  */
 
 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)
     return FALSE;
-  /* jdmerge.c only supports YCC=>RGB color conversion */
+  /* jdmerge.c only supports YCC=>RGB and YCC=>RGB565 color conversion */
   if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
       (cinfo->out_color_space != JCS_RGB &&
+      cinfo->out_color_space != JCS_RGB565 &&
       cinfo->out_color_space != JCS_EXT_RGB &&
       cinfo->out_color_space != JCS_EXT_RGBX &&
       cinfo->out_color_space != JCS_EXT_BGR &&
       cinfo->out_color_space != JCS_EXT_BGRX &&
       cinfo->out_color_space != JCS_EXT_XBGR &&
       cinfo->out_color_space != JCS_EXT_XRGB &&
       cinfo->out_color_space != JCS_EXT_RGBA &&
       cinfo->out_color_space != JCS_EXT_BGRA &&
       cinfo->out_color_space != JCS_EXT_ABGR &&
-      cinfo->out_color_space != JCS_EXT_ARGB) ||
-      cinfo->out_color_components != rgb_pixelsize[cinfo->out_color_space])
+      cinfo->out_color_space != JCS_EXT_ARGB))
+    return FALSE;
+  if ((cinfo->out_color_space == JCS_RGB565 &&
+      cinfo->out_color_components != 3) ||
+      (cinfo->out_color_space != JCS_RGB565 &&
+      cinfo->out_color_components != rgb_pixelsize[cinfo->out_color_space]))
     return FALSE;
   /* and it only handles 2h1v or 2h2v sampling ratios */
   if (cinfo->comp_info[0].h_samp_factor != 2 ||
       cinfo->comp_info[1].h_samp_factor != 1 ||
       cinfo->comp_info[2].h_samp_factor != 1 ||
       cinfo->comp_info[0].v_samp_factor >  2 ||
       cinfo->comp_info[1].v_samp_factor != 1 ||
       cinfo->comp_info[2].v_samp_factor != 1)
     return FALSE;
   /* furthermore, it doesn't work if we've scaled the IDCTs differently */
@@ skipping 267 matching lines @@
   case JCS_EXT_BGRX:
   case JCS_EXT_XBGR:
   case JCS_EXT_XRGB:
   case JCS_EXT_RGBA:
   case JCS_EXT_BGRA:
   case JCS_EXT_ABGR:
   case JCS_EXT_ARGB:
     cinfo->out_color_components = rgb_pixelsize[cinfo->out_color_space];
     break;
   case JCS_YCbCr:
+  case JCS_RGB565:
     cinfo->out_color_components = 3;
     break;
   case JCS_CMYK:
   case JCS_YCCK:
     cinfo->out_color_components = 4;
     break;
   default:                      /* else must be same colorspace as in file */
     cinfo->out_color_components = cinfo->num_components;
     break;
   }
@@ skipping 359 matching lines @@
       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                                   SIZEOF(my_decomp_master));
   cinfo->master = (struct jpeg_decomp_master *) master;
   master->pub.prepare_for_output_pass = prepare_for_output_pass;
   master->pub.finish_output_pass = finish_output_pass;
 
   master->pub.is_dummy_pass = FALSE;
 
   master_selection(cinfo);
 }