On Thu, Dec 21, 2017 at 11:39:02AM +0000, Rostislav Pehlivanov wrote:
> On 20 December 2017 at 19:58, Aurelien Jacobs <au...@gnuage.org> wrote:
>
> > ---
> > libavutil/crc.c | 20 ++++++++++++++++++++
> > libavutil/crc.h | 12 ++++++++++++
> > 2 files changed, 32 insertions(+)
> >
> > diff --git a/libavutil/crc.c b/libavutil/crc.c
> > index 8e44a76ec8..cb26a09a20 100644
> > --- a/libavutil/crc.c
> > +++ b/libavutil/crc.c
> > @@ -413,3 +413,23 @@ uint32_t av_crc(const AVCRC *ctx, uint32_t crc,
> >
> > return crc;
> > }
> > +
> > +uint32_t av_crc_bits(const AVCRC *ctx, uint32_t crc,
> > + const uint8_t *buffer, size_t length)
> > +{
> > + size_t byte_length = length >> 3;
> > + int bit_length = length & 7;
> > +
> > + crc = av_crc(ctx, crc, buffer, byte_length);
> > +
> > + if (bit_length) {
> > + uint8_t bits = buffer[byte_length];
> > + while (bit_length--) {
> > + int8_t mask = (bits ^ crc);
> > + crc = (crc << 1) ^ (ctx[1] & (mask >> 7));
> > + bits <<= 1;
> > + }
> > + }
> > +
> > + return crc;
> > +}
> > diff --git a/libavutil/crc.h b/libavutil/crc.h
> > index e57a1af903..bde31f858a 100644
> > --- a/libavutil/crc.h
> > +++ b/libavutil/crc.h
> > @@ -86,6 +86,7 @@ const AVCRC *av_crc_get_table(AVCRCId crc_id);
> > /**
> > * Calculate the CRC of a block.
> > * @param crc CRC of previous blocks if any or initial value for CRC
> > + * @param length number of bytes in the given block
> > * @return CRC updated with the data from the given block
> > *
> > * @see av_crc_init() "le" parameter
> > @@ -93,6 +94,17 @@ const AVCRC *av_crc_get_table(AVCRCId crc_id);
> > uint32_t av_crc(const AVCRC *ctx, uint32_t crc,
> > const uint8_t *buffer, size_t length) av_pure;
> >
> > +/**
> > + * Calculate the CRC of a block with bits boundary.
> > + * @param crc CRC of previous blocks if any or initial value for CRC
> > + * @param length number of bits in the given block
> > + * @return CRC updated with the data from the given block
> > + *
> > + * @see av_crc_init() "le" parameter
> > + */
> > +uint32_t av_crc_bits(const AVCRC *ctx, uint32_t crc,
> > + const uint8_t *buffer, size_t length) av_pure;
> > +
> > /**
> > * @}
> > */
> >
> > _______________________________________________
> > ffmpeg-devel mailing list
> > ffmpeg-devel@ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >
>
> Sorry, I didn't see that sbc does fucked up crc on 7 bits.
Well, it is not on 7 bits. That actual data length is a multiple of
4 bits.
> In that case could you submit a new version of just the sbc patch which
> adds this back in the decoder?
I moved the function back to sbc, but I keept its usage of av_crc() for
the whole buffer except for the last bits that don't form a full byte.
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