Re: [Qemu-devel] [PATCH 20/40] Add vs{l,r} instructions.

[Aurelien Jarno]

On Tue, Dec 30, 2008 at 07:10:02PM -0800, Nathan Froyd wrote:
> 
> Signed-off-by: Nathan Froyd <address@hidden>
> ---
>  target-ppc/helper.h    |    2 ++
>  target-ppc/op_helper.c |   36 ++++++++++++++++++++++++++++++++++++
>  target-ppc/translate.c |    2 ++
>  3 files changed, 40 insertions(+), 0 deletions(-)
> 
> diff --git a/target-ppc/helper.h b/target-ppc/helper.h
> index cf2a655..5f94e9f 100644
> --- a/target-ppc/helper.h
> +++ b/target-ppc/helper.h
> @@ -176,6 +176,8 @@ DEF_HELPER_3(vsubuws, void, avr, avr, avr)
>  DEF_HELPER_3(vrlb, void, avr, avr, avr)
>  DEF_HELPER_3(vrlh, void, avr, avr, avr)
>  DEF_HELPER_3(vrlw, void, avr, avr, avr)
> +DEF_HELPER_3(vsl, void, avr, avr, avr)
> +DEF_HELPER_3(vsr, void, avr, avr, avr)
>  
>  DEF_HELPER_1(efscfsi, i32, i32)
>  DEF_HELPER_1(efscfui, i32, i32)
> diff --git a/target-ppc/op_helper.c b/target-ppc/op_helper.c
> index 15eee72..ce47ef1 100644
> --- a/target-ppc/op_helper.c
> +++ b/target-ppc/op_helper.c
> @@ -2210,6 +2210,42 @@ VROTATE(h, u16)
>  VROTATE(w, u32)
>  #undef VROTATE
>  
> +#if defined(WORDS_BIGENDIAN)
> +#define LEFT 0
> +#define RIGHT 1
> +#else
> +#define LEFT 1
> +#define RIGHT 0
> +#endif
> +#define VSHIFT(suffix, leftp)                                           \
> +    void helper_vs##suffix (ppc_avr_t *r, ppc_avr_t *a, ppc_avr_t *b)   \
> +    {                                                                   \
> +        int shift = b->u8[LO_IDX*0x15] & 0x7;                           \
> +        int doit = 1;                                                   \
> +        int i;                                                          \
> +        for (i = 0; i < ARRAY_SIZE(r->u8); i++) {                       \
> +            doit = doit && ((b->u8[i] & 0x7) == shift);                 \
> +        }                                                               \

According to the specification, the result is undefined in that case. I
think that always doing the computation is fine.

> +        if (doit) {                                                     \
> +            if (shift == 0) {                                           \
> +                *r = *a;                                                \
> +            } else if (leftp) {                                         \
> +                uint64_t carry = a->u64[LO_IDX] >> (64 - shift);        \
> +                r->u64[HI_IDX] = (a->u64[HI_IDX] << shift) | carry;     \
> +                r->u64[LO_IDX] = a->u64[LO_IDX] << shift;               \
> +            } else {                                                    \
> +                uint64_t carry = a->u64[HI_IDX] << (64 - shift);        \
> +                r->u64[LO_IDX] = (a->u64[LO_IDX] >> shift) | carry;     \
> +                r->u64[HI_IDX] = a->u64[HI_IDX] >> shift;               \
> +            }                                                           \
> +        }                                                               \
> +    }
> +VSHIFT(l, LEFT)
> +VSHIFT(r, RIGHT)
> +#undef VSHIFT
> +#undef LEFT
> +#undef RIGHT
> +
>  #define VSL(suffix, element)                                            \
>      void helper_vsl##suffix (ppc_avr_t *r, ppc_avr_t *a, ppc_avr_t *b)  \
>      {                                                                   \
> diff --git a/target-ppc/translate.c b/target-ppc/translate.c
> index a853683..b50aba3 100644
> --- a/target-ppc/translate.c
> +++ b/target-ppc/translate.c
> @@ -6316,6 +6316,8 @@ GEN_VXFORM(vsubsws, 0, 30);
>  GEN_VXFORM(vrlb, 2, 0);
>  GEN_VXFORM(vrlh, 2, 1);
>  GEN_VXFORM(vrlw, 2, 2);
> +GEN_VXFORM(vsl, 2, 7);
> +GEN_VXFORM(vsr, 2, 11);
>  
>  #define GEN_VXRFORM1(opname, name, str, opc2, opc3)                     \
>      GEN_HANDLER2(name, str, 0x4, opc2, opc3, 0x00000000, PPC_ALTIVEC)   \
> -- 
> 1.6.0.5
> 
> 
> 
> 

-- 
  .''`.  Aurelien Jarno             | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   address@hidden         | address@hidden
   `-    people.debian.org/~aurel32 | www.aurel32.net