Nicolas George:
> gautamr...@gmail.com (12020-07-03):
>> From: Gautam Ramakrishnan <gautamr...@gmail.com>
>>
>> This patch adds a pgx decoder.
>
> Reviewing even after push, because there are problems to fix.
>
>> ---
>> Changelog | 1 +
>> doc/general.texi | 2 +
>> libavcodec/Makefile | 1 +
>> libavcodec/allcodecs.c | 1 +
>> libavcodec/codec_desc.c | 7 ++
>> libavcodec/codec_id.h | 1 +
>> libavcodec/pgxdec.c | 169 ++++++++++++++++++++++++++++++++++++++++
>> libavcodec/version.h | 4 +-
>> 8 files changed, 184 insertions(+), 2 deletions(-)
>> create mode 100644 libavcodec/pgxdec.c
>>
[...]
>> +#define WRITE_FRAME(D, PIXEL, suffix)
>> \
>> + static inline void write_frame_ ##D(AVPacket *avpkt, AVFrame *frame,
>> GetByteContext *g, \
>> + int width, int height, int sign,
>> int depth) \
>> + {
>> \
>> + int i, j;
>> \
>> + for (i = 0; i < height; i++) {
>> \
>
>> + PIXEL *line = (PIXEL*)frame->data[0] +
>> i*frame->linesize[0]/sizeof(PIXEL); \
>
> It would have been more elegant and more efficient to keep the
> incrementation of line at the end of the loop than to keep its
> initialization here.
>
>> + for (j = 0; j < width; j++) {
>> \
>> + int val;
>> \
>> + if (sign)
>> \
>
>> + val = (PIXEL)bytestream2_get_ ##suffix(g) + (1 <<
>> (depth - 1)); \
>
> Casting unsigned to negative signed is not portable.
>
It's not completely portable, but FFmpeg does not aim for complete
portability: "Implementation defined behavior for signed integers is
assumed to match the expected behavior for two’s complement". (see
https://ffmpeg.org/developer.html#C-language-features)
>> + else
>> \
>> + val = bytestream2_get_ ##suffix(g);
>> \
>> + val <<= (D - depth);
>> \
>
>> + *(line + j) = val;
>> \
>
> *(line + j) is almost always better written line[j]
>
>> + }
>> \
>> + }
>> \
>> + }
>> \
>> +
>> +WRITE_FRAME(8, int8_t, byte)
>> +WRITE_FRAME(16, int16_t, be16)
>> +
- Andreas
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