On 6/12/2024 4:15 PM, Rémi Denis-Courmont wrote:
Le keskiviikkona 12. kesäkuuta 2024, 21.39.12 EEST James Almer a écrit :
On 6/12/2024 1:47 AM, Rémi Denis-Courmont wrote:
---
tests/checkasm/h263dsp.c | 47 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 46 insertions(+), 1 deletion(-)
diff --git a/tests/checkasm/h263dsp.c b/tests/checkasm/h263dsp.c
index 2d0957a90b..8a2cdb34df 100644
--- a/tests/checkasm/h263dsp.c
+++ b/tests/checkasm/h263dsp.c
@@ -18,13 +18,55 @@
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
+#include <stdbool.h>
#include <string.h>
#include "checkasm.h"
-#include "libavcodec/h263dsp.h"
+#include "libavutil/avassert.h"
#include "libavutil/mem.h"
#include "libavutil/mem_internal.h"
+#include "libavcodec/h263dsp.h"
+#include "libavcodec/mpegvideodata.h"
+
+static uint_fast8_t mpeg_qscale_rnd(void)
+{
+ int n = rnd(), q = (n >> 1) & 31;
+
+ if (n & 1)
+ return ff_mpeg2_non_linear_qscale[q];
+ else
+ return q << 1;
+}
+
+typedef void (*unquantizer)(int16_t *, size_t, int, int);
+
+static void check_dct_unquantize(unquantizer func, const char *name)
+{
+#define LEN 64
+ LOCAL_ALIGNED_16(int16_t, block0, [LEN]);
+ LOCAL_ALIGNED_16(int16_t, block1, [LEN]);
These are not padded, and unless I'm reading this wrong, an asm
implementation loading say 16 bytes at a time will overread/write in
dct_unquantize_intra (which offsets block by 1).
AFAIU, there is no padding per se, but the block buffer size is always exactly
64 elements, regardless of the number of coeffs, hence this code. The old NEON
intrinsic code seems to assume the block is a multiple of 8 elements, and the
tail can be overwritten safely (hence not checking in memcmp()).
I have a feeling that I am not grasping the implications of you comment here.
An asm function loading 16 bytes at a time from block[1] onwards for
intra may end up reading two bytes more than available at the end of the
128 byte wide buffer.
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