Add RGB5A1 support, used by some VC games

include/jpeg/jpegint.h

@@ -77,6 +77,9 @@ typedef size_t JUINTPTR;
 #define IsExtRGB(cs) \
   (cs == JCS_RGB || (cs >= JCS_EXT_RGB && cs <= JCS_EXT_ARGB))
 
+#define IsExtRGB2(cs) \
+  (cs >= JCS_EXT_RGB565 && cs <= JCS_EXT_RGB4)
+
 /*
  * Left shift macro that handles a negative operand without causing any
  * sanitizer warnings

include/jpeg/jpeglib.h

@@ -275,6 +275,9 @@ typedef enum {
   JCS_EXT_BGRA,           /* blue/green/red/alpha */
   JCS_EXT_ABGR,           /* alpha/blue/green/red */
   JCS_EXT_ARGB,           /* alpha/red/green/blue */
+  JCS_EXT_RGB565,
+  JCS_EXT_RGB5A1,
+  JCS_EXT_RGB4,
   JCS_RGB565              /* 5-bit red/6-bit green/5-bit blue */
 } J_COLOR_SPACE;
 

source/jpeg/jccolor.c

@@ -277,8 +277,8 @@ rgb565_ycc_convert(j_compress_ptr cinfo, _JSAMPARRAY input_buf,
     output_row++;
     for (col = 0; col < num_cols; col++) {
       short in = *(short *)inptr;
-      r = cconvert->rb_5_tab[((in >> 11) & 0x1f)];
-      g = cconvert->g_6_tab[((in >> 5) & 0x3f)];
+      r = cconvert->rb_5_tab[(in >> 11) & 0x1f];
+      g = cconvert->g_6_tab[(in >> 5) & 0x3f];
       b = cconvert->rb_5_tab[in & 0x1f];
       inptr += 2;
       /* If the inputs are 0.._MAXJSAMPLE, the outputs of these equations
@@ -302,6 +302,54 @@ rgb565_ycc_convert(j_compress_ptr cinfo, _JSAMPARRAY input_buf,
 #endif
 }
 
+INLINE
+LOCAL(void)
+rgb5a1_ycc_convert(j_compress_ptr cinfo, _JSAMPARRAY input_buf,
+                   _JSAMPIMAGE output_buf, JDIMENSION output_row,
+                   int num_rows)
+{
+#if BITS_IN_JSAMPLE != 16
+  my_cconvert_ptr cconvert = (my_cconvert_ptr)cinfo->cconvert;
+  register int r, g, b;
+  register JLONG *ctab = cconvert->rgb_ycc_tab;
+  register _JSAMPROW inptr;
+  register _JSAMPROW outptr0, outptr1, outptr2;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->image_width;
+
+  while (--num_rows >= 0) {
+    inptr = *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++) {
+      short in = *(short *)inptr;
+      r = cconvert->rb_5_tab[(in >> 11) & 0x1f];
+      g = cconvert->rb_5_tab[(in >> 6) & 0x1f];
+      b = cconvert->rb_5_tab[(in >> 1) & 0x1f];
+      inptr += 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);
+    }
+  }
+#else
+  ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+#endif
+}
+
 /*
  * Convert some rows of samples to the JPEG colorspace.
  */
@@ -339,10 +387,14 @@ rgb_ycc_convert(j_compress_ptr cinfo, _JSAMPARRAY input_buf,
     extxrgb_ycc_convert_internal(cinfo, input_buf, output_buf, output_row,
                                  num_rows);
     break;
-  case JCS_RGB565:
+  case JCS_EXT_RGB565:
     rgb565_ycc_convert(cinfo, input_buf, output_buf, output_row,
                        num_rows);
     break;
+  case JCS_EXT_RGB5A1:
+    rgb5a1_ycc_convert(cinfo, input_buf, output_buf, output_row,
+                       num_rows);
+    break;
   default:
     rgb_ycc_convert_internal(cinfo, input_buf, output_buf, output_row,
                              num_rows);
@@ -644,7 +696,9 @@ _jinit_color_converter(j_compress_ptr cinfo)
       ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
     break;
 
-  case JCS_RGB565:
+  case JCS_EXT_RGB565:
+  case JCS_EXT_RGB5A1:
+  case JCS_EXT_RGB4:
   case JCS_YCbCr:
     if (cinfo->input_components != 3)
       ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
@@ -718,9 +772,9 @@ _jinit_color_converter(j_compress_ptr cinfo)
       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
     if (cinfo->num_components != 3)
       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
-    if (IsExtRGB(cinfo->in_color_space) || cinfo->in_color_space == JCS_RGB565) {
+    if (IsExtRGB(cinfo->in_color_space) || IsExtRGB2(cinfo->in_color_space)) {
 #ifdef WITH_SIMD
-      if (jsimd_can_rgb_ycc() && cinfo->in_color_space != JCS_RGB565)
+      if (jsimd_can_rgb_ycc() && !IsExtRGB2(cinfo->in_color_space))
         cconvert->pub._color_convert = jsimd_rgb_ycc_convert;
       else
 #endif

source/jpeg/jcparam.c

@@ -301,7 +301,9 @@ jpeg_default_colorspace(j_compress_ptr cinfo)
   case JCS_EXT_BGRA:
   case JCS_EXT_ABGR:
   case JCS_EXT_ARGB:
-  case JCS_RGB565:
+  case JCS_EXT_RGB565:
+  case JCS_EXT_RGB5A1:
+  case JCS_EXT_RGB4:
     if (cinfo->master->lossless)
       jpeg_set_colorspace(cinfo, JCS_RGB);
     else

source/nwm/rp_nwm.c

@@ -587,7 +587,11 @@ static void rpReadyWork(BLIT_CONTEXT *ctx, u32 work_next) {
 		cinfo->image_width = ctx->height;
 		cinfo->image_height = ctx->width;
 		cinfo->input_components = ctx->format == 0 ? 4 : 3;
-		cinfo->in_color_space = ctx->format == 0 ? JCS_EXT_XBGR : ctx->format == 1 ? JCS_EXT_BGR : JCS_RGB565;
+		cinfo->in_color_space =
+			ctx->format == 0 ? JCS_EXT_XBGR :
+			ctx->format == 1 ? JCS_EXT_BGR :
+			ctx->format == 2 ? JCS_EXT_RGB565 :
+			ctx->format == 3 ? JCS_EXT_RGB5A1 : JCS_EXT_RGB4;
 
 		cinfo->restart_in_rows = jpeg_adjusted_rows[work_next];
 		cinfo->restart_interval = cinfo->restart_in_rows * mcus_per_row;
@@ -972,7 +976,7 @@ static int rpCaptureScreen(u32 work_next, int isTop) {
 
 	u32 format = (isTop ? tl_format : bl_format) & 0x0f;
 
-	if (format >= 3)
+	if (format > 3) // TODO add RGB4 support (in modified libjpeg-turbo)
 		goto final;
 
 	u32 bpp; /* bytes per pixel */