SDL_blit_slow: remove one nested 'if()' because of ARGB2101010 handling

src/video/SDL_blit_slow.c

@@ -24,6 +24,21 @@
 #include "SDL_blit.h"
 #include "SDL_blit_slow.h"
 
+#define FORMAT_ALPHA      0
+#define FORMAT_NO_ALPHA  -1
+#define FORMAT_2101010    1
+#define FORMAT_HAS_ALPHA(format)        format == 0
+#define FORMAT_HAS_NO_ALPHA(format)     format < 0
+static int SDL_INLINE detect_format(SDL_PixelFormat *pf) {
+    if (pf->format == SDL_PIXELFORMAT_ARGB2101010) {
+        return FORMAT_2101010;
+    } else if (pf->Amask) {
+        return FORMAT_ALPHA;
+    } else {
+        return FORMAT_NO_ALPHA;
+    }
+}
+
 /* The ONE TRUE BLITTER
  * This puppy has to handle all the unoptimized cases - yes, it's slow.
  */
@@ -46,11 +61,14 @@ SDL_Blit_Slow(SDL_BlitInfo * info)
     SDL_PixelFormat *dst_fmt = info->dst_fmt;
     int srcbpp = src_fmt->BytesPerPixel;
     int dstbpp = dst_fmt->BytesPerPixel;
-    int srcfmt_isnot_2101010 = (src_fmt->format != SDL_PIXELFORMAT_ARGB2101010);
-    int dstfmt_isnot_2101010 = (dst_fmt->format != SDL_PIXELFORMAT_ARGB2101010);
+    int srcfmt_val;
+    int dstfmt_val;
     Uint32 rgbmask = ~src_fmt->Amask;
     Uint32 ckey = info->colorkey & rgbmask;
 
+    srcfmt_val = detect_format(src_fmt);
+    dstfmt_val = detect_format(dst_fmt);
+
     incy = (info->src_h << 16) / info->dst_h;
     incx = (info->src_w << 16) / info->dst_w;
     posy = incy / 2; /* start at the middle of pixel */
@@ -64,13 +82,12 @@ SDL_Blit_Slow(SDL_BlitInfo * info)
         while (n--) {
             srcx = posx >> 16;
             src = (info->src + (srcy * info->src_pitch) + (srcx * srcbpp));
-            if (srcfmt_isnot_2101010) {
-                if (src_fmt->Amask) {
-                    DISEMBLE_RGBA(src, srcbpp, src_fmt, srcpixel, srcR, srcG, srcB, srcA);
-                } else {
-                    DISEMBLE_RGB(src, srcbpp, src_fmt, srcpixel, srcR, srcG, srcB);
-                    srcA = 0xFF;
-                }
+
+            if (FORMAT_HAS_ALPHA(srcfmt_val)) {
+                DISEMBLE_RGBA(src, srcbpp, src_fmt, srcpixel, srcR, srcG, srcB, srcA);
+            } else if (FORMAT_HAS_NO_ALPHA(srcfmt_val)) {
+                DISEMBLE_RGB(src, srcbpp, src_fmt, srcpixel, srcR, srcG, srcB);
+                srcA = 0xFF;
             } else {
                 /* SDL_PIXELFORMAT_ARGB2101010 */
                 srcpixel = *((Uint32 *)(src));
@@ -89,13 +106,11 @@ SDL_Blit_Slow(SDL_BlitInfo * info)
                     continue;
                 }
             }
-            if (dstfmt_isnot_2101010) {
-                if (dst_fmt->Amask) {
-                    DISEMBLE_RGBA(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG, dstB, dstA);
-                } else {
-                    DISEMBLE_RGB(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG, dstB);
-                    dstA = 0xFF;
-                }
+            if (FORMAT_HAS_ALPHA(dstfmt_val)) {
+                DISEMBLE_RGBA(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG, dstB, dstA);
+            } else if (FORMAT_HAS_NO_ALPHA(dstfmt_val)) {
+                DISEMBLE_RGB(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG, dstB);
+                dstA = 0xFF;
             } else {
                 /* SDL_PIXELFORMAT_ARGB2101010 */
                 dstpixel = *((Uint32 *)(dst));
@@ -162,16 +177,15 @@ SDL_Blit_Slow(SDL_BlitInfo * info)
                     dstA = 255;
                 break;
             }
-            if (dstfmt_isnot_2101010) {
-                if (dst_fmt->Amask) {
-                    ASSEMBLE_RGBA(dst, dstbpp, dst_fmt, dstR, dstG, dstB, dstA);
-                } else {
-                    ASSEMBLE_RGB(dst, dstbpp, dst_fmt, dstR, dstG, dstB);
-                }
+            if (FORMAT_HAS_ALPHA(dstfmt_val)) {
+                ASSEMBLE_RGBA(dst, dstbpp, dst_fmt, dstR, dstG, dstB, dstA);
+            } else if (FORMAT_HAS_NO_ALPHA(dstfmt_val)) {
+                ASSEMBLE_RGB(dst, dstbpp, dst_fmt, dstR, dstG, dstB);
             } else {
-                Uint32 Pixel;
-                ARGB2101010_FROM_RGBA(Pixel, dstR, dstG, dstB, dstA);
-                *(Uint32 *)dst = Pixel;
+                /* SDL_PIXELFORMAT_ARGB2101010 */
+                Uint32 pixel;
+                ARGB2101010_FROM_RGBA(pixel, dstR, dstG, dstB, dstA);
+                *(Uint32 *)dst = pixel;
             }
             posx += incx;
             dst += dstbpp;