Enable RGB565 input color format

This change enables compression of RGB565 input to YCbCr (default) output format.
Main intention for this change is to enable the emulator to directly compress
RGB565 framebuffer without converting it into RGB888 prior to passing it to the
compression routine.

Change-Id: I86240a2481fd1904eb9b9140b18b372200a71093

2 files changed, 69 insertions, 3 deletions

diff --git a/distrib/jpeg-6b/jccolor.c b/distrib/jpeg-6b/jccolor.c
index 57a76c3..67078ab 100644
--- a/distrib/jpeg-6b/jccolor.c
+++ b/distrib/jpeg-6b/jccolor.c
@@ -173,6 +173,53 @@ rgb_ycc_convert (j_compress_ptr cinfo,
   }
 }
 
+#ifdef ANDROID_RGB
+/* Converts RGB565 row into YCbCr */
+METHODDEF(void)
+rgb565_ycc_convert (j_compress_ptr cinfo,
+		 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
+		 JDIMENSION output_row, int num_rows)
+{
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  register int r, g, b;
+  register INT32 * ctab = cconvert->rgb_ycc_tab;
+  register unsigned short* inptr;
+  register JSAMPROW outptr0, outptr1, outptr2;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->image_width;
+
+  while (--num_rows >= 0) {
+    inptr = (unsigned short*)(*input_buf++);
+    outptr0 = output_buf[0][output_row];
+    outptr1 = output_buf[1][output_row];
+    outptr2 = output_buf[2][output_row];
+    output_row++;
+    for (col = 0; col < num_cols; col++) {
+      register const unsigned short color = inptr[col];
+      r = ((color & 0xf800) >> 8) | ((color & 0xf800) >> 14);
+      g = ((color & 0x7e0) >> 3) | ((color & 0x7e0) >> 9);
+      b = ((color & 0x1f) << 3) | ((color & 0x1f) >> 2);
+      /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
+       * must be too; we do not need an explicit range-limiting operation.
+       * Hence the value being shifted is never negative, and we don't
+       * need the general RIGHT_SHIFT macro.
+       */
+      /* Y */
+      outptr0[col] = (JSAMPLE)
+		((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
+		 >> SCALEBITS);
+      /* Cb */
+      outptr1[col] = (JSAMPLE)
+		((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
+		 >> SCALEBITS);
+      /* Cr */
+      outptr2[col] = (JSAMPLE)
+		((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
+		 >> SCALEBITS);
+    }
+  }
+}
+#endif  /* ANDROID_RGB */
 
 /**************** Cases other than RGB -> YCbCr **************/
 
@@ -355,12 +402,12 @@ null_convert (j_compress_ptr cinfo,
         JSAMPROW outptr0 = output_buf[0][output_row];
         JSAMPROW outptr1 = output_buf[1][output_row];
         JSAMPROW outptr2 = output_buf[2][output_row];
-        
+
         int col = num_cols;
         int col4 = col >> 2;
         if (col4 > 0 && ptr_is_quad(inptr) && ptr_is_quad(outptr0) &&
                         ptr_is_quad(outptr1) && ptr_is_quad(outptr2)) {
-            
+
             const UINT32* in = (const UINT32*)inptr;
             UINT32* out0 = (UINT32*)outptr0;
             UINT32* out1 = (UINT32*)outptr1;
@@ -453,6 +500,13 @@ jinit_color_converter (j_compress_ptr cinfo)
       ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
     break;
 
+#ifdef ANDROID_RGB
+  case JCS_RGB_565:
+    if (cinfo->input_components != 2)
+      ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
+    break;
+#endif  /* ANDROID_RGB */
+
   default:			/* JCS_UNKNOWN can be anything */
     if (cinfo->input_components < 1)
       ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
@@ -490,8 +544,15 @@ jinit_color_converter (j_compress_ptr cinfo)
     if (cinfo->in_color_space == JCS_RGB) {
       cconvert->pub.start_pass = rgb_ycc_start;
       cconvert->pub.color_convert = rgb_ycc_convert;
-    } else if (cinfo->in_color_space == JCS_YCbCr)
+    } else if (cinfo->in_color_space == JCS_YCbCr) {
       cconvert->pub.color_convert = null_convert;
+    }
+#ifdef ANDROID_RGB
+    else if (cinfo->in_color_space == JCS_RGB_565) {
+      cconvert->pub.start_pass = rgb_ycc_start;
+      cconvert->pub.color_convert = rgb565_ycc_convert;
+    }
+#endif  /* ANDROID_RGB */
     else
       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
     break;
diff --git a/distrib/jpeg-6b/jcparam.c b/distrib/jpeg-6b/jcparam.c
index 6fc48f5..b305179 100644
--- a/distrib/jpeg-6b/jcparam.c
+++ b/distrib/jpeg-6b/jcparam.c
@@ -377,6 +377,11 @@ jpeg_default_colorspace (j_compress_ptr cinfo)
   case JCS_UNKNOWN:
     jpeg_set_colorspace(cinfo, JCS_UNKNOWN);
     break;
+#ifdef ANDROID_RGB
+  case JCS_RGB_565:
+    jpeg_set_colorspace(cinfo, JCS_YCbCr);
+    break;
+#endif  /* ANDROID_RGB */
   default:
     ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
   }