[FFmpeg-devel] [PATCH 2/2] avcodec/anm: Don't unnecessarily use context variables

[Peter Ross]

On Sat, May 30, 2020 at 06:33:00AM +0200, Andreas Rheinhardt wrote:
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
>  libavcodec/anm.c | 39 +++++++++++++++++++--------------------
>  1 file changed, 19 insertions(+), 20 deletions(-)
> 
> diff --git a/libavcodec/anm.c b/libavcodec/anm.c
> index e9b19d880d..134640ee36 100644
> --- a/libavcodec/anm.c
> +++ b/libavcodec/anm.c
> @@ -31,13 +31,12 @@
>  typedef struct AnmContext {
>      AVFrame *frame;
>      int palette[AVPALETTE_COUNT];
> -    GetByteContext gb;
> -    int x;  ///< x coordinate position
>  } AnmContext;
>  
>  static av_cold int decode_init(AVCodecContext *avctx)
>  {
>      AnmContext *s = avctx->priv_data;
> +    GetByteContext gb;
>      int i;
>  
>      if (avctx->extradata_size < 16 * 8 + 4 * 256)
> @@ -49,10 +48,10 @@ static av_cold int decode_init(AVCodecContext *avctx)
>      if (!s->frame)
>          return AVERROR(ENOMEM);
>  
> -    bytestream2_init(&s->gb, avctx->extradata, avctx->extradata_size);
> -    bytestream2_skipu(&s->gb, 16 * 8);
> +    bytestream2_init(&gb, avctx->extradata, avctx->extradata_size);
> +    bytestream2_skipu(&gb, 16 * 8);
>      for (i = 0; i < 256; i++)
> -        s->palette[i] = (0xFFU << 24) | bytestream2_get_le32u(&s->gb);
> +        s->palette[i] = (0xFFU << 24) | bytestream2_get_le32u(&gb);
>  
>      return 0;
>  }
> @@ -115,7 +114,8 @@ static int decode_frame(AVCodecContext *avctx,
>      AnmContext *s = avctx->priv_data;
>      const int buf_size = avpkt->size;
>      uint8_t *dst, *dst_end;
> -    int count, ret;
> +    GetByteContext gb;
> +    int count, ret, x = 0;
>  
>      if (buf_size < 7)
>          return AVERROR_INVALIDDATA;
> @@ -125,37 +125,36 @@ static int decode_frame(AVCodecContext *avctx,
>      dst     = s->frame->data[0];
>      dst_end = s->frame->data[0] + s->frame->linesize[0]*avctx->height;
>  
> -    bytestream2_init(&s->gb, avpkt->data, buf_size);
> +    bytestream2_init(&gb, avpkt->data, buf_size);
>  
> -    if (bytestream2_get_byte(&s->gb) != 0x42) {
> +    if (bytestream2_get_byte(&gb) != 0x42) {
>          avpriv_request_sample(avctx, "Unknown record type");
>          return AVERROR_INVALIDDATA;
>      }
> -    if (bytestream2_get_byte(&s->gb)) {
> +    if (bytestream2_get_byte(&gb)) {
>          avpriv_request_sample(avctx, "Padding bytes");
>          return AVERROR_PATCHWELCOME;
>      }
> -    bytestream2_skip(&s->gb, 2);
> +    bytestream2_skip(&gb, 2);
>  
> -    s->x = 0;
>      do {
>          /* if statements are ordered by probability */
>  #define OP(gb, pixel, count) \
> -    op(&dst, dst_end, (gb), (pixel), (count), &s->x, avctx->width, s->frame->linesize[0])
> +    op(&dst, dst_end, (gb), (pixel), (count), &x, avctx->width, s->frame->linesize[0])
>  
> -        int type = bytestream2_get_byte(&s->gb);
> +        int type = bytestream2_get_byte(&gb);
>          count = type & 0x7F;
>          type >>= 7;
>          if (count) {
> -            if (OP(type ? NULL : &s->gb, -1, count)) break;
> +            if (OP(type ? NULL : &gb, -1, count)) break;
>          } else if (!type) {
>              int pixel;
> -            count = bytestream2_get_byte(&s->gb);  /* count==0 gives nop */
> -            pixel = bytestream2_get_byte(&s->gb);
> +            count = bytestream2_get_byte(&gb);  /* count==0 gives nop */
> +            pixel = bytestream2_get_byte(&gb);
>              if (OP(NULL, pixel, count)) break;
>          } else {
>              int pixel;
> -            type = bytestream2_get_le16(&s->gb);
> +            type = bytestream2_get_le16(&gb);
>              count = type & 0x3FFF;
>              type >>= 14;
>              if (!count) {
> @@ -167,11 +166,11 @@ static int decode_frame(AVCodecContext *avctx,
>                  }
>                  continue;
>              }
> -            pixel = type == 3 ? bytestream2_get_byte(&s->gb) : -1;
> +            pixel = type == 3 ? bytestream2_get_byte(&gb) : -1;
>              if (type == 1) count += 0x4000;
> -            if (OP(type == 2 ? &s->gb : NULL, pixel, count)) break;
> +            if (OP(type == 2 ? &gb : NULL, pixel, count)) break;
>          }
> -    } while (bytestream2_get_bytes_left(&s->gb) > 0);
> +    } while (bytestream2_get_bytes_left(&gb) > 0);
>  
>      memcpy(s->frame->data[1], s->palette, AVPALETTE_SIZE);
>  
> -- 
> 2.20.1

ok.

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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