bopti: add support for r5g6b5 and r5g6b5a on fxcg50

This commit introduces bopti for fxcg50 with the first basic 16-bit
formats. The performance is rather slow, especially for large images,
and will need refinements and/or overclock to be really efficient in
full-screen real-time applications.

include/gint/display-fx.h

@@ -81,37 +81,6 @@ typedef struct
 
 } GPACKED(4) image_t;
 
-/* dimage() - render a full image
-   This function blits an image on the VRAM using gint's special format. It is
-   a special case of dsubimage() where the full image is drawn with clipping.
-
-   @x @y   Coordinates of the top-left corner of the image
-   @image  Pointer to image encoded with [fxconv] */
-void dimage(int x, int y, image_t const *image);
-
-/* Option values for dsubimage() */
-enum {
-	/* No option */
-	DIMAGE_NONE = 0x00,
-
-	/* Disable clipping, ie. adjustments to the specified subrectangle and
-	   screen location such that any part that overflows from the image or
-	   the screen is ignored. Slightly faster. */
-	DIMAGE_NOCLIP = 0x01,
-};
-
-/* dsubimage() - render a section of an image
-   This function blits a subrectangle [left, top, width, height] of an image on
-   the VRAM. It is more general than dimage() and also provides a few options.
-
-   @x @y           Coordinates on screen of the rendered subrectangle
-   @image          Pointer to image encoded with [fxconv]
-   @left @top      Top-left coordinates of the subrectangle within [image]
-   @width @height  Subrectangle dimensions
-   @flags          OR-combination of DIMAGE_* flags */
-void dsubimage(int x, int y, image_t const *image, int left, int top,
-	int width, int height, int flags);
-
 #endif /* FX9860G */
 
 #endif /* GINT_DISPLAY_FX */

include/gint/display.h

@@ -199,6 +199,43 @@ void dsize(const char *str, font_t const * font, int *w, int *h);
            fxcg50:  Any R5G6B5 color, or C_NONE */
 void dtext(int x, int y, const char *str, int fg, int bg);
 
+//---
+//	Image rendering (bopti)
+//---
+
+/* The image_t structure is platform-dependent. */
+
+/* dimage() - render a full image
+   This function blits an image on the VRAM using gint's special format. It is
+   a special case of dsubimage() where the full image is drawn with clipping.
+
+   @x @y   Coordinates of the top-left corner of the image
+   @image  Pointer to image encoded with [fxconv] */
+void dimage(int x, int y, image_t const *image);
+
+/* Option values for dsubimage() */
+enum {
+	/* No option */
+	DIMAGE_NONE = 0x00,
+
+	/* Disable clipping, ie. adjustments to the specified subrectangle and
+	   screen location such that any part that overflows from the image or
+	   the screen is ignored. Slightly faster. */
+	DIMAGE_NOCLIP = 0x01,
+};
+
+/* dsubimage() - render a section of an image
+   This function blits a subrectangle [left, top, width, height] of an image on
+   the VRAM. It is more general than dimage() and also provides a few options.
+
+   @x @y           Coordinates on screen of the rendered subrectangle
+   @image          Pointer to image encoded with [fxconv]
+   @left @top      Top-left coordinates of the subrectangle within [image]
+   @width @height  Subrectangle dimensions
+   @flags          OR-combination of DIMAGE_* flags */
+void dsubimage(int x, int y, image_t const *image, int left, int top,
+	int width, int height, int flags);
+
 //---
 //	Advanced functions
 //---

src/render-cg/bopti-asm.h

@@ -22,4 +22,16 @@ void bopti_r5g6b5(uint16_t const *data, uint16_t *target, int width,
 void bopti_r5g6b5a(uint16_t const *data, uint16_t *target, int width,
 	int height, int in_stride, int out_stride, uint16_t alpha);
 
+/* bopti_render_clip(): Render with clipping
+   Same parameters as dsubimage(), except for flags. */
+void bopti_render_clip(int x, int y, image_t const *img, int left, int top,
+	int width, int height);
+
+/* bopti_render_clip(): Render without clipping
+   Behaviour is not defined if (left,top)+(width,height) is not included in the
+   source image or (x,y)+(width,height) is not included in the VRAM area.
+   Same parameters as dsubimage(), except for flags. */
+void bopti_render_noclip(int x, int y, image_t const *img, int left, int top,
+	int width, int height);
+
 #endif /* GINT_RENDERCG_BOPTIASM */

src/render-cg/dimage.c

@@ -0,0 +1,23 @@
+#define GINT_NEED_VRAM
+#include <gint/display.h>
+#include "bopti-asm.h"
+
+/* dimage() - render a full image */
+void dimage(int x, int y, image_t const *img)
+{
+	bopti_render_clip(x, y, img, 0, 0, img->width, img->height);
+}
+
+/* dsubimage() - render a section of an image */
+void dsubimage(int x, int y, image_t const *img, int left, int top,
+	int width, int height, int flags)
+{
+	if(flags & DIMAGE_NOCLIP)
+	{
+		bopti_render_noclip(x, y, img, left, top, width, height);
+	}
+	else
+	{
+		bopti_render_clip(x, y, img, left, top, width, height);
+	}
+}