Re: [Qemu-devel] [PATCH] target-m68k: Implement bfffo

[Laurent Vivier]

Le 15/11/2016 à 21:44, Richard Henderson a écrit :
> Signed-off-by: Richard Henderson <address@hidden>

> diff --git a/target-m68k/translate.c b/target-m68k/translate.c
> index bc6ec39..ed40ade 100644
> --- a/target-m68k/translate.c
> +++ b/target-m68k/translate.c
> @@ -3913,7 +3913,14 @@ DISAS_INSN(bfop_reg)
>      TCGv src = DREG(insn, 0);
>      int len = ((extract32(ext, 0, 5) - 1) & 31) + 1;
>      int ofs = extract32(ext, 6, 5);  /* big bit-endian */
> -    TCGv mask;
> +    TCGv mask, tofs, tlen;
> +
> +    TCGV_UNUSED(tofs);
> +    TCGV_UNUSED(tlen);
> +    if ((insn & 0x0f00) == 0x0d00) { /* bfffo */
> +        tofs = tcg_temp_new();
> +        tlen = tcg_temp_new();
> +    }
>  
>      if ((ext & 0x820) == 0) {
>          /* Immediate width and offset.  */
> @@ -3925,6 +3932,10 @@ DISAS_INSN(bfop_reg)
>          }
>          tcg_gen_andi_i32(QREG_CC_N, QREG_CC_N, ~maski);
>          mask = tcg_const_i32(ror32(maski, ofs));
> +        if (!TCGV_IS_UNUSED(tofs)) {
> +            tcg_gen_movi_i32(tofs, ofs);
> +            tcg_gen_movi_i32(tlen, len);
> +        }
>      } else {
>          TCGv tmp = tcg_temp_new();
>          if (ext & 0x20) {
> @@ -3933,9 +3944,15 @@ DISAS_INSN(bfop_reg)
>              tcg_gen_andi_i32(tmp, tmp, 31);
>              mask = tcg_const_i32(0x7fffffffu);
>              tcg_gen_shr_i32(mask, mask, tmp);
> +            if (!TCGV_IS_UNUSED(tlen)) {
> +                tcg_gen_mov_i32(tlen, tmp);

We must add 1 here, otherwise the value stays between 0 and 31, not 1
and 32:

+                tcg_gen_addi_i32(tlen, tmp, 1);

> +            }
>          } else {
>              /* Immediate width */
>              mask = tcg_const_i32(0x7fffffffu >> (len - 1));
> +            if (!TCGV_IS_UNUSED(tlen)) {
> +                tcg_gen_movi_i32(tlen, len);
> +            }
>          }

In the case of the immediate value, it is added at beginning of the
function:

>      int len = ((extract32(ext, 0, 5) - 1) & 31) + 1;

Laurent