From 199d9f995da53fe2507821f6d96bbc692574e1a9 Mon Sep 17 00:00:00 2001 From: Vittorio Giovara Date: Wed, 5 Nov 2014 10:29:55 -0500 Subject: mjpegdec: fix undefined shift Add a comment to explain the code. CC: libav-stable@libav.org Bug-Id: CID 1194388 --- libavcodec/mjpegdec.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c index d9a73d8426..01e11bee17 100644 --- a/libavcodec/mjpegdec.c +++ b/libavcodec/mjpegdec.c @@ -964,7 +964,9 @@ static int mjpeg_decode_scan_progressive_ac(MJpegDecodeContext *s, int ss, init_get_bits(&mb_bitmask_gb, mb_bitmask, s->mb_width * s->mb_height); if (!Al) { - s->coefs_finished[c] |= (1LL << (se + 1)) - (1LL << ss); + // s->coefs_finished is a bitmask for coefficients coded + // ss and se are parameters telling start and end coefficients + s->coefs_finished[c] |= (~0ULL >> (63 - (se - ss))) << ss; last_scan = !~s->coefs_finished[c]; } -- cgit v1.2.3