Re: [FFmpeg-devel] [PATCH 12/35] avcodec/proresenc_anatoliy: shuffle encode_codeword() code to match Kostya encoder

[Stefano Sabatini <stefasab@gmail.com>]

On date Monday 2023-12-11 02:35:13 +0100, Clément Bœsch wrote:
> Code is functionally identical, it's just rename of variables, cosmetics
> and branch logic shuffling.
> ---
>  libavcodec/proresenc_anatoliy.c | 45 +++++++++++++++++----------------
>  1 file changed, 23 insertions(+), 22 deletions(-)
> 
> diff --git a/libavcodec/proresenc_anatoliy.c b/libavcodec/proresenc_anatoliy.c
> index 804ff6ddf7..c7e43fc88c 100644
> --- a/libavcodec/proresenc_anatoliy.c
> +++ b/libavcodec/proresenc_anatoliy.c
> @@ -226,31 +226,32 @@ static int int_from_list_or_default(void *ctx, const char *val_name, int val,
>      return default_value;
>  }
>  
> -static void encode_codeword(PutBitContext *pb, int val, int codebook)
> +static void encode_codeword(PutBitContext *pb, int val, unsigned codebook)
>  {
> -    unsigned int rice_order, exp_order, switch_bits, first_exp, exp, zeros;
> -
> -    /* number of bits to switch between rice and exp golomb */
> -    switch_bits = codebook & 3;
> -    rice_order  = codebook >> 5;
> -    exp_order   = (codebook >> 2) & 7;
> -
> -    first_exp = ((switch_bits + 1) << rice_order);
> -
> -    if (val >= first_exp) { /* exp golomb */
> -        val -= first_exp;
> -        val += (1 << exp_order);
> -        exp = av_log2(val);
> -        zeros = exp - exp_order + switch_bits + 1;
> -        put_bits(pb, zeros, 0);
> -        put_bits(pb, exp + 1, val);
> -    } else if (rice_order) {
> -        put_bits(pb, (val >> rice_order), 0);
> -        put_bits(pb, 1, 1);
> -        put_sbits(pb, rice_order, val);
> +    unsigned int rice_order, exp_order, switch_bits, switch_val;
> +    int exponent;
> +
> +    /* number of prefix bits to switch between Rice and expGolomb */
> +    switch_bits = (codebook & 3) + 1;
> +    rice_order  =  codebook >> 5;       /* rice code order */
> +    exp_order   = (codebook >> 2) & 7;  /* exp golomb code order */
> +
> +    switch_val  = switch_bits << rice_order;
> +
> +    if (val >= switch_val) {
> +        val -= switch_val - (1 << exp_order);
> +        exponent = av_log2(val);
> +
> +        put_bits(pb, exponent - exp_order + switch_bits, 0);
> +        put_bits(pb, exponent + 1, val);
>      } else {
> -        put_bits(pb, val, 0);
> +        exponent = val >> rice_order;
> +
> +        if (exponent)
> +            put_bits(pb, exponent, 0);
>          put_bits(pb, 1, 1);
> +        if (rice_order)
> +            put_sbits(pb, rice_order, val);
>      }
>  }
>  
> -- 
> 2.43.0

Should be equivalent to the original code (and with some small
optimizations), so it should be fine.
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