lcd: Fix certain drawmode combinations.

Some seldomly used drawmode combinations did not work in conjunction with
alpha bitmaps and backdrops. Now all should work (see comment added) by using
more bits.

Change-Id: I2bc96ecf471fa8c1a608a321a235b9c8527b3dc5

1 files changed, 62 insertions, 34 deletions

diff --git a/firmware/drivers/lcd-16bit-common.c b/firmware/drivers/lcd-16bit-common.c
index dffc1cf..99cbe48 100644
--- a/firmware/drivers/lcd-16bit-common.c
+++ b/firmware/drivers/lcd-16bit-common.c
@@ -623,7 +623,7 @@ void ICODE_ATTR lcd_mono_bitmap_part(const unsigned char *src, int src_x,
 
     /* Use extra bit to avoid if () in the switch-cases below */
     if ((drmode & DRMODE_BG) && lcd_backdrop)
-        drmode |= DRMODE_INT_MOD;
+        drmode |= DRMODE_INT_BD;
 
     /* go through each column and update each pixel  */
     do
@@ -659,7 +659,7 @@ void ICODE_ATTR lcd_mono_bitmap_part(const unsigned char *src, int src_x,
             while (--row);
             break;
 
-          case DRMODE_BG|DRMODE_INT_MOD:
+          case DRMODE_BG|DRMODE_INT_BD:
             bo = lcd_backdrop_offset;
             do
             {
@@ -698,7 +698,7 @@ void ICODE_ATTR lcd_mono_bitmap_part(const unsigned char *src, int src_x,
             while (--row);
             break;
 
-          case DRMODE_SOLID|DRMODE_INT_MOD:
+          case DRMODE_SOLID|DRMODE_INT_BD:
             fg = current_vp->fg_pattern;
             bo = lcd_backdrop_offset;
             do
@@ -817,7 +817,6 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
                                       int stride_image, int stride_src)
 {
     fb_data *dst, *dst_row;
-    const fb_data *image_row;
     unsigned dmask = 0x00000000;
     int drmode = current_vp->drawmode;
     /* nothing to draw? */
@@ -878,21 +877,33 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
         height = LCD_HEIGHT - y;
 #endif
 
+    /* the following drawmode combinations are possible:
+     * 1) COMPLEMENT: just negates the framebuffer contents
+     * 2) BG and BG+backdrop: draws _only_ background pixels with either
+     *    the background color or the backdrop (if any). The backdrop
+     *    is an image in native lcd format
+     * 3) FG and FG+image: draws _only_ foreground pixels with either
+     *    the foreground color or an image buffer. The image is in
+     *    native lcd format
+     * 4) SOLID, SOLID+backdrop, SOLID+image, SOLID+backdrop+image, i.e. all
+     *    possible combinations of 2) and 3). Draws both, fore- and background,
+     *    pixels. The rules of 2) and 3) apply.
+     *
+     * INVERSEVID swaps fore- and background pixels, i.e. background pixels
+     * become foreground ones and vice versa.
+     */
     if (drmode & DRMODE_INVERSEVID)
     {
         dmask = 0xffffffff;
         drmode &= DRMODE_SOLID; /* mask out inversevid */
     }
-    if (drmode == DRMODE_BG)
-        dmask = ~dmask;
-    /* If drawmode is FG use a separate special case that blends the image
-     * onto the current framebuffer contents. Otherwise BG is forced that
-     * blends the image with the backdrop (if any, otherwise background color )*/
+
+    /* Use extra bits to avoid if () in the switch-cases below */
     if (image != NULL)
-        drmode = (drmode == DRMODE_FG) ? DRMODE_FG|DRMODE_INT_MOD : DRMODE_BG;
-    /* Use extra bit to avoid if () in the switch-cases below */
+        drmode |= DRMODE_INT_IMG;
+
     if ((drmode & DRMODE_BG) && lcd_backdrop)
-        drmode |= DRMODE_INT_MOD;
+        drmode |= DRMODE_INT_BD;
 
     dst_row = FBADDR(x, y);
 
@@ -918,10 +929,11 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
 #ifdef ALPHA_BITMAP_READ_WORDS
     pixels = 8 - pixels;
 #endif
-    if (image)
-        image += skip_start_image;
-    image_row = image;
 
+    /* image is only accessed in DRMODE_INT_IMG cases, i.e. when non-NULL.
+     * Therefore NULL accesses are impossible and we can increment
+     * unconditionally (applies for stride at the end of the loop as well) */
+    image += skip_start_image;
     /* go through the rows and update each pixel */
     do
     {
@@ -929,16 +941,10 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
          * temp vars just before the loop helps gcc to opimize the loop better
          * (testing showed ~15% speedup) */
         unsigned fg, bg;
-        uintptr_t bo;
+        ptrdiff_t bo, img_offset;
         col = width;
         dst = dst_row;
         dst_row += ROW_INC;
-        if (image_row) {
-            image = image_row;
-            image_row += STRIDE_MAIN(stride_image,1);
-        }
-        else
-            image = dst;
 #ifdef ALPHA_BITMAP_READ_WORDS
 #define UPDATE_SRC_ALPHA    do { \
             if (--pixels) \
@@ -964,8 +970,7 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
                 data = *(++src) ^ dmask; \
         } while (0)
 #endif
-        /* we don't want to have this in our inner
-         * loop and the codesize increase is minimal */
+
         switch (drmode)
         {
             case DRMODE_COMPLEMENT:
@@ -978,12 +983,12 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
                 }
                 while (--col);
                 break;
-            case DRMODE_BG|DRMODE_INT_MOD:
+            case DRMODE_BG|DRMODE_INT_BD:
                 bo = lcd_backdrop_offset;
                 do
                 {
                     fb_data c = *(fb_data *)((uintptr_t)dst +  bo);
-                    *dst = blend_two_colors(c, *image, data & ALPHA_COLOR_LOOKUP_SIZE );
+                    *dst = blend_two_colors(c, *dst, data & ALPHA_COLOR_LOOKUP_SIZE );
                     dst += COL_INC;
                     image += STRIDE_MAIN(1, stride_image);
                     UPDATE_SRC_ALPHA;
@@ -994,19 +999,18 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
                 bg = current_vp->bg_pattern;
                 do
                 {
-                    *dst = blend_two_colors(bg, *image, data & ALPHA_COLOR_LOOKUP_SIZE );
+                    *dst = blend_two_colors(bg, *dst, data & ALPHA_COLOR_LOOKUP_SIZE );
                     dst += COL_INC;
-                    image += STRIDE_MAIN(1, stride_image);
                     UPDATE_SRC_ALPHA;
                 }
                 while (--col);
                 break;
-            case DRMODE_FG|DRMODE_INT_MOD:
+            case DRMODE_FG|DRMODE_INT_IMG:
+                img_offset = image - dst;
                 do
                 {
-                    *dst = blend_two_colors(*dst, *image, data & ALPHA_COLOR_LOOKUP_SIZE );
+                    *dst = blend_two_colors(*dst, *(dst + img_offset), data & ALPHA_COLOR_LOOKUP_SIZE );
                     dst += COL_INC;
-                    image += STRIDE_MAIN(1, stride_image);
                     UPDATE_SRC_ALPHA;
                 }
                 while (--col);
@@ -1021,7 +1025,7 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
                 }
                 while (--col);
                 break;
-            case DRMODE_SOLID|DRMODE_INT_MOD:
+            case DRMODE_SOLID|DRMODE_INT_BD:
                 bo = lcd_backdrop_offset;
                 fg = current_vp->fg_pattern;
                 do
@@ -1033,13 +1037,35 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
                 }
                 while (--col);
                 break;
+            case DRMODE_SOLID|DRMODE_INT_IMG:
+                bg = current_vp->bg_pattern;
+                img_offset = image - dst;
+                do
+                {
+                    *dst = blend_two_colors(bg, *(dst + img_offset), data & ALPHA_COLOR_LOOKUP_SIZE );
+                    dst += COL_INC;
+                    UPDATE_SRC_ALPHA;
+                }
+                while (--col);
+                break;
+            case DRMODE_SOLID|DRMODE_INT_BD|DRMODE_INT_IMG:
+                bo = lcd_backdrop_offset;
+                img_offset = image - dst;
+                do
+                {
+                    fb_data *c = (fb_data *)((uintptr_t)dst +  bo);
+                    *dst = blend_two_colors(*c, *(dst + img_offset), data & ALPHA_COLOR_LOOKUP_SIZE );
+                    dst += COL_INC;
+                    UPDATE_SRC_ALPHA;
+                }
+                while (--col);
+                break;
             case DRMODE_SOLID:
                 bg = current_vp->bg_pattern;
                 fg = current_vp->fg_pattern;
                 do
                 {
-                    *dst = blend_two_colors(bg, fg,
-                                    data & ALPHA_COLOR_LOOKUP_SIZE );
+                    *dst = blend_two_colors(bg, fg, data & ALPHA_COLOR_LOOKUP_SIZE );
                     dst += COL_INC;
                     UPDATE_SRC_ALPHA;
                 }
@@ -1073,6 +1099,8 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
                 data >>= skip_end * ALPHA_COLOR_LOOKUP_SHIFT;
         }
 #endif
+
+        image += STRIDE_MAIN(stride_image,1);
     } while (--row);
 
     BLEND_FINISH;