On Sat, Jul 08, 2017 at 11:12:06AM +0200, Paul B Mahol wrote:
> [...]
> static inline void skip_bits(GetBitContext *s, int n)
> {
> +#ifdef CACHED_BITSTREAM_READER
> + if (n <= s->bits_left)
> + skip_remaining(s, n);
> + else {
> + n -= s->bits_left;
> + skip_remaining(s, s->bits_left);
This causes undefined behavior if s->bits_left == 64.
> + if (n >= 64) {
> + unsigned skip = n;
> +
> + n -= skip;
> + s->index += skip;
> + }
This block looks strange.
> + refill_32(s);
> + if (n)
> + skip_remaining(s, n);
> + }
> +#else
> OPEN_READER(re, s);
> LAST_SKIP_BITS(re, s, n);
> CLOSE_READER(re, s);
> +#endif
> +}
> +
> +static inline void skip_bits_long(GetBitContext *s, int n)
> +{
> +#ifdef CACHED_BITSTREAM_READER
> + skip_bits(s, n);
> +#else
> +#if UNCHECKED_BITSTREAM_READER
> + s->index += n;
> +#else
> + s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index);
Uncached bitstream reader allows seeking back by passing negative n
here. If cached bitstream reader disallows this, there should be a
comment saying so (and possibly an assert).
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