fb: add pitch to fb_fragment_t

The put_pixel helpers really needed reworking to properly handle
subframe fragments modules like montage will utilize.  I had the
stride present as it's convenient for a number of modules that
maintain a buf pointer as they progress down a row, but the pitch
is more applicable to put_pixel for scaling the y coordinate.

Now there's both pitch and stride so everyone's happy with what's
most convenient for their needs.

4 files changed, 14 insertions, 9 deletions

diff --git a/src/drm_fb.c b/src/drm_fb.c
index 3d0f6ba..cfaae29 100644
--- a/src/drm_fb.c
+++ b/src/drm_fb.c
@@ -455,6 +455,7 @@ static void * drm_fb_page_alloc(void *context, fb_page_t *res_page)
 	res_page->fragment.height = c->mode->vdisplay;
 	res_page->fragment.frame_height = c->mode->vdisplay;
 	res_page->fragment.stride = create_dumb.pitch - (c->mode->hdisplay * 4);
+	res_page->fragment.pitch = create_dumb.pitch;
 
 	return p;
 }
diff --git a/src/fb.c b/src/fb.c
index 7485800..a20fdd3 100644
--- a/src/fb.c
+++ b/src/fb.c
@@ -319,9 +319,7 @@ int fb_fragment_slice_single(const fb_fragment_t *fragment, unsigned n_fragments
 	if (yoff >= fragment->height)
 		return 0;
 
-	pitch = (fragment->width * 4) + fragment->stride;
-
-	res_fragment->buf = ((void *)fragment->buf) + yoff * pitch;
+	res_fragment->buf = ((void *)fragment->buf) + yoff * fragment->pitch;
 	res_fragment->x = fragment->x;
 	res_fragment->y = yoff;
 	res_fragment->width = fragment->width;
@@ -329,6 +327,7 @@ int fb_fragment_slice_single(const fb_fragment_t *fragment, unsigned n_fragments
 	res_fragment->frame_width = fragment->frame_width;
 	res_fragment->frame_height = fragment->frame_height;
 	res_fragment->stride = fragment->stride;
+	res_fragment->pitch = fragment->pitch;
 
 	return 1;
 }
@@ -337,7 +336,6 @@ int fb_fragment_slice_single(const fb_fragment_t *fragment, unsigned n_fragments
 int fb_fragment_tile_single(const fb_fragment_t *fragment, unsigned tile_size, unsigned num, fb_fragment_t *res_fragment)
 {
 	unsigned	w = fragment->width / tile_size, h = fragment->height / tile_size;
-	unsigned	pitch = (fragment->width * 4) + fragment->stride;
 	unsigned	x, y, xoff, yoff;
 
 	if (w * tile_size < fragment->width)
@@ -355,7 +353,7 @@ int fb_fragment_tile_single(const fb_fragment_t *fragment, unsigned tile_size, u
 	xoff = x * tile_size;
 	yoff = y * tile_size;
 
-	res_fragment->buf = (void *)fragment->buf + (yoff * pitch) + (xoff * 4);
+	res_fragment->buf = (void *)fragment->buf + (yoff * fragment->pitch) + (xoff * 4);
 	res_fragment->x = fragment->x + xoff;
 	res_fragment->y = fragment->y + yoff;
 	res_fragment->width = MIN(fragment->width - xoff, tile_size);
@@ -363,6 +361,7 @@ int fb_fragment_tile_single(const fb_fragment_t *fragment, unsigned tile_size, u
 	res_fragment->frame_width = fragment->frame_width;
 	res_fragment->frame_height = fragment->frame_height;
 	res_fragment->stride = fragment->stride + ((fragment->width - res_fragment->width) * 4);
+	res_fragment->pitch = fragment->pitch;
 
 	return 1;
 }
diff --git a/src/fb.h b/src/fb.h
index f9d0b77..dfd4550 100644
--- a/src/fb.h
+++ b/src/fb.h
@@ -17,6 +17,7 @@ typedef struct fb_fragment_t {
 	unsigned	frame_width;	/* width of the frame this fragment is part of */
 	unsigned	frame_height;	/* height of the frame this fragment is part of */
 	unsigned	stride;		/* number of bytes from the end of one row to the start of the next */
+	unsigned	pitch;		/* number of bytes separating y from y + 1, including any padding */
 } fb_fragment_t;
 
 /* This is a page handle object for page flip submission/life-cycle.
@@ -67,10 +68,9 @@ static inline int fb_fragment_contains(fb_fragment_t *fragment, int x, int y)
 /* puts a pixel into the fragment, no bounds checking is performed. */
 static inline void fb_fragment_put_pixel_unchecked(fb_fragment_t *fragment, int x, int y, uint32_t pixel)
 {
-	uint32_t	*pixels = fragment->buf;
+	uint32_t	*pixels = ((void *)fragment->buf) + (y - fragment->y) * fragment->pitch;
 
-	/* FIXME this assumes stride is aligned to 4 */
-	pixels[((y - fragment->y) * (fragment->width + (fragment->stride >> 2))) + (x - fragment->x)] = pixel;
+	pixels[x - fragment->x] = pixel;
 }
 
 
@@ -89,7 +89,11 @@ static inline int fb_fragment_put_pixel_checked(fb_fragment_t *fragment, int x,
 /* zero a fragment */
 static inline void fb_fragment_zero(fb_fragment_t *fragment)
 {
-	memset(fragment->buf, 0, ((fragment->width << 2) + fragment->stride) * fragment->height);
+	void	*buf = fragment->buf;
+
+	/* TODO: there should be a fast-path for non-divided fragments where there's no stride to skip */
+	for (int y = 0; y < fragment->height; y++, buf += fragment->pitch)
+		memset(buf, 0, fragment->pitch - fragment->stride);
 }
 
 #endif
diff --git a/src/sdl_fb.c b/src/sdl_fb.c
index 8d0241b..a3eb0d1 100644
--- a/src/sdl_fb.c
+++ b/src/sdl_fb.c
@@ -195,6 +195,7 @@ static void * sdl_fb_page_alloc(void *context, fb_page_t *res_page)
 	res_page->fragment.height = c->height;
 	res_page->fragment.frame_height = c->height;
 	res_page->fragment.stride = p->surface->pitch - (c->width * 4);
+	res_page->fragment.pitch = p->surface->pitch;
 
 	return p;
 }