[U-Boot] [PATCH] cfb_console: force natural alignment of unzipped bitmap images
Bitmaps contain 32-bit integers aligned at offsets of +2, +6 within the bmp_header structure. This patch forces them to be aligned properly when gzipped bitmaps are used.
Refer to these files for more details: doc/README.displaying-bmps doc/README.arm-unaligned-accesses
Signed-off-by: Eric Nelson eric.nelson@boundarydevices.com --- drivers/video/cfb_console.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/video/cfb_console.c b/drivers/video/cfb_console.c index 6db4073..2209148 100644 --- a/drivers/video/cfb_console.c +++ b/drivers/video/cfb_console.c @@ -1473,7 +1473,10 @@ int video_display_bitmap(ulong bmp_image, int x, int y) printf("Error: malloc in gunzip failed!\n"); return 1; } - if (gunzip(dst, CONFIG_SYS_VIDEO_LOGO_MAX_SIZE, + /* NB: we need to force offset of +2 + * See doc/README.displaying-bmps + */ + if (gunzip(dst+2, CONFIG_SYS_VIDEO_LOGO_MAX_SIZE-2, (uchar *) bmp_image, &len) != 0) { printf("Error: no valid bmp or bmp.gz image at %lx\n", @@ -1489,7 +1492,7 @@ int video_display_bitmap(ulong bmp_image, int x, int y) /* * Set addr to decompressed image */ - bmp = (bmp_image_t *) dst; + bmp = (bmp_image_t *)(dst+2);
if (!((bmp->header.signature[0] == 'B') && (bmp->header.signature[1] == 'M'))) {
Dear Eric Nelson,
In message 1393103071-2788-1-git-send-email-eric.nelson@boundarydevices.com you wrote:
Bitmaps contain 32-bit integers aligned at offsets of +2, +6 within the bmp_header structure. This patch forces them to be aligned properly when gzipped bitmaps are used.
This makes no sense to me. In the Subject: you talk about "unzipped bitmap images", but here you write about "gzipped bitmaps".
I think I understand what you mean, but this needs better wording.
if (gunzip(dst, CONFIG_SYS_VIDEO_LOGO_MAX_SIZE,
/* NB: we need to force offset of +2* See doc/README.displaying-bmps
Incorrect multiline comment style.
Best regards,
Wolfgang Denk
.bmp files contain 32-bit integers aligned at offsets of +2, +6, et cetera within the bmp_header structure (see include/bmp_layout.h).
Support for gzip-compressed .bmp files is present in the cfb_console display subsystem by uncompressing them prior to use.
This patch forces the in-memory header to be aligned properly for these compressed images by extracting them to a 2-byte offset in the memory returned by malloc. Since malloc will always return a 4-byte aligned value, this forces the .bmp header fields to be naturally aligned on 4-byte addresses.
Refer to these files for more details: doc/README.displaying-bmps doc/README.arm-unaligned-accesses
Signed-off-by: Eric Nelson eric.nelson@boundarydevices.com --- Changes in V2: - re-worded the subject line - expanded and re-worded the commit message Changes in V3: - shortened the subject line - fixed multiline comment style - added patch history - sent with "In-Reply-To" header referring to V1 See also: V1: http://patchwork.ozlabs.org/patch/323243/ V2: http://patchwork.ozlabs.org/patch/325348/
drivers/video/cfb_console.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/video/cfb_console.c b/drivers/video/cfb_console.c index 6db4073..b52e9ed 100644 --- a/drivers/video/cfb_console.c +++ b/drivers/video/cfb_console.c @@ -1473,7 +1473,11 @@ int video_display_bitmap(ulong bmp_image, int x, int y) printf("Error: malloc in gunzip failed!\n"); return 1; } - if (gunzip(dst, CONFIG_SYS_VIDEO_LOGO_MAX_SIZE, + /* + * NB: we need to force offset of +2 + * See doc/README.displaying-bmps + */ + if (gunzip(dst+2, CONFIG_SYS_VIDEO_LOGO_MAX_SIZE-2, (uchar *) bmp_image, &len) != 0) { printf("Error: no valid bmp or bmp.gz image at %lx\n", @@ -1489,7 +1493,7 @@ int video_display_bitmap(ulong bmp_image, int x, int y) /* * Set addr to decompressed image */ - bmp = (bmp_image_t *) dst; + bmp = (bmp_image_t *)(dst+2);
if (!((bmp->header.signature[0] == 'B') && (bmp->header.signature[1] == 'M'))) {
On Sat, Mar 08, 2014 at 07:55:52AM -0700, Eric Nelson wrote:
.bmp files contain 32-bit integers aligned at offsets of +2, +6, et cetera within the bmp_header structure (see include/bmp_layout.h).
Support for gzip-compressed .bmp files is present in the cfb_console display subsystem by uncompressing them prior to use.
This patch forces the in-memory header to be aligned properly for these compressed images by extracting them to a 2-byte offset in the memory returned by malloc. Since malloc will always return a 4-byte aligned value, this forces the .bmp header fields to be naturally aligned on 4-byte addresses.
Refer to these files for more details: doc/README.displaying-bmps doc/README.arm-unaligned-accesses
Signed-off-by: Eric Nelson eric.nelson@boundarydevices.com
Applied to u-boot/master, thanks!
participants (3)
-
Eric Nelson -
Tom Rini -
Wolfgang Denk