Re: [PATCH qemu v2 1/2] ppc: Define SETFIELD for the ppc target

[Peter Maydell <peter.maydell@linaro.org>]

On Fri, 17 Jun 2022 at 07:20, Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
>
> It keeps repeating, move it to the header. This uses __builtin_ctzl() to
> allow using the macros in #define.
>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>  include/hw/pci-host/pnv_phb3_regs.h | 16 ----------------
>  target/ppc/cpu.h                    |  5 +++++
>  hw/intc/pnv_xive.c                  | 20 --------------------
>  hw/intc/pnv_xive2.c                 | 20 --------------------
>  hw/pci-host/pnv_phb4.c              | 16 ----------------
>  5 files changed, 5 insertions(+), 72 deletions(-)
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index 6d78078f379d..9a1f1e9999a3 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -47,6 +47,11 @@
>                                   PPC_BIT32(bs))
>  #define PPC_BITMASK8(bs, be)    ((PPC_BIT8(bs) - PPC_BIT8(be)) | PPC_BIT8(bs))
>
> +#define GETFIELD(mask, word)   \
> +    (((word) & (mask)) >> __builtin_ctzl(mask))
> +#define SETFIELD(mask, word, val)   \
> +    (((word) & ~(mask)) | (((uint64_t)(val) << __builtin_ctzl(mask)) & (mask)))

Can we retain the explanatory comment that says why we don't
use the standard QEMU mechanism for field extraction
(ie the FIELD_EX*/FIELD_DP* macros and the extract64()/deposit64()
functions) ?

> -/*
> - * QEMU version of the GETFIELD/SETFIELD macros
> - *
> - * TODO: It might be better to use the existing extract64() and
> - * deposit64() but this means that all the register definitions will
> - * change and become incompatible with the ones found in skiboot.
> - *
> - * Keep it as it is for now until we find a common ground.
> - */

thanks
-- PMM