[FFmpeg-devel] [RFC]Do not alias data pointer in kega decoder

[Paul B Mahol]

On 2/28/13, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> Hi!
>
> Attached patch fixes the kega fate failure with icc 13.1.0 on intel64 -
> http://fate.ffmpeg.org/report.cgi?time=20130228212822&slot=x86_64-archlinux-icc-2013
> -
> a regression since 33cd32b. Since it does not help for ia32, it is probably
>
> not the correct solution;-(
>
> Other ideas welcome, Carl Eugen
>
> diff --git a/libavcodec/kgv1dec.c b/libavcodec/kgv1dec.c
> index 008843c..8efd238 100644
> --- a/libavcodec/kgv1dec.c
> +++ b/libavcodec/kgv1dec.c
> @@ -50,7 +50,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
>      const uint8_t *buf_end = buf + avpkt->size;
>      KgvContext * const c = avctx->priv_data;
>      int offsets[8];
> -    uint16_t *out, *prev;
> +    uint8_t *out, *prev;
>      int outcnt = 0, maxcnt;
>      int w, h, i, res;
>
> @@ -75,9 +75,9 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
>      c->cur.reference = 3;
>      if ((res = ff_get_buffer(avctx, &c->cur)) < 0)
>          return res;
> -    out  = (uint16_t *) c->cur.data[0];
> +    out  = c->cur.data[0];
>      if (c->prev.data[0]) {
> -        prev = (uint16_t *) c->prev.data[0];
> +        prev = c->prev.data[0];
>      } else {
>          prev = NULL;
>      }
> @@ -90,11 +90,12 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
>          buf += 2;
>
>          if (!(code & 0x8000)) {
> -            out[outcnt++] = code; // rgb555 pixel coded directly
> +            AV_WL16(&out[2 * outcnt], code); // rgb555 pixel coded directly

AV_WN16 ?

> +            outcnt++;
>          } else {
>              int count;
>              int inp_off;
> -            uint16_t *inp;
> +            uint8_t *inp;
>
>              if ((code & 0x6000) == 0x6000) {
>                  // copy from previous frame
> @@ -148,7 +149,8 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
>                  break;
>
>              for (i = inp_off; i < count + inp_off; i++) {
> -                out[outcnt++] = inp[i];
> +                AV_WN16(&out[2 * outcnt], AV_RN16(&inp[2 * i]));
> +                outcnt++;
>              }
>          }
>      }