From c881616cfbbd8c20d67f469d363254b2c56a12b7 Mon Sep 17 00:00:00 2001 From: Vito Caputo Date: Wed, 27 Apr 2022 13:46:04 -0700 Subject: til_fb: til_fb_fragment_t.{pitch,stride} uint32_t units Originally it seemed sensible to make these units of bytes, for flexibility reasons. But it's advantageous for everything to be able to assume pixels are always 4-byte/32-bit aligned. Having the stride/pitch be in bytes of units made it theoretically possible to produce unaligned rows of pixels, which would break that assumption. I don't think anything was ever actually producing such things, and I've added some asserts to the {sdl,drm}_fb.c page acquisition code to go fatal on such pages. This change required going through all the modules and get rid of their uint32_t vs. void* dances and other such 1-byte vs. 4-byte scaling arithmetic. Code is simpler now, and probably faster in some cases. And now allows future work to just assume things cna always occur 4-bytes at a time without concern for unaligned accesses. --- src/drm_fb.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'src/drm_fb.c') diff --git a/src/drm_fb.c b/src/drm_fb.c index 328c92c..927f46c 100644 --- a/src/drm_fb.c +++ b/src/drm_fb.c @@ -476,6 +476,12 @@ static void * drm_fb_page_alloc(til_fb_t *fb, void *context, til_fb_page_t *res_ pexit_if(drmModeAddFB(c->drm_fd, c->mode->hdisplay, c->mode->vdisplay, 24, 32, create_dumb.pitch, create_dumb.handle, &fb_id) < 0, "unable to add dumb buffer"); + /* prevent unaligned pitches, we're just simplifying everything in rototiller that wants + * to do word-at-a-time operations without concern for arches that get angry when that happens + * on unaligned addresses. + */ + assert(!(create_dumb.pitch & 0x3)); + p->mmap = map; p->mmap_size = create_dumb.size; p->drm_dumb_handle = map_dumb.handle; @@ -486,8 +492,8 @@ static void * drm_fb_page_alloc(til_fb_t *fb, void *context, til_fb_page_t *res_ res_page->fragment.frame_width = c->mode->hdisplay; 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; + res_page->fragment.pitch = create_dumb.pitch >> 2; + res_page->fragment.stride = res_page->fragment.pitch - (c->mode->hdisplay); return p; } -- cgit v1.2.1