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Re: [Qemu-devel] [PATCH 3/4] target-ppc: Implement bcdcpsgn. instruction
From: |
David Gibson |
Subject: |
Re: [Qemu-devel] [PATCH 3/4] target-ppc: Implement bcdcpsgn. instruction |
Date: |
Thu, 17 Nov 2016 15:16:02 +1100 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
On Wed, Nov 16, 2016 at 06:07:29PM -0200, Jose Ricardo Ziviani wrote:
> bcdcpsgn.: Decimal copy sign. Given two registers vra and vrb, it
> copies the vra value with vrb sign to the result register vrt.
>
> Signed-off-by: Jose Ricardo Ziviani <address@hidden>
> ---
> target-ppc/helper.h | 1 +
> target-ppc/int_helper.c | 30 ++++++++++++++++++++++++++++++
> target-ppc/translate/vmx-impl.inc.c | 3 +++
> target-ppc/translate/vmx-ops.inc.c | 2 +-
> 4 files changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/target-ppc/helper.h b/target-ppc/helper.h
> index 503f257..dada48e 100644
> --- a/target-ppc/helper.h
> +++ b/target-ppc/helper.h
> @@ -384,6 +384,7 @@ DEF_HELPER_3(bcdcfz, i32, avr, avr, i32)
> DEF_HELPER_3(bcdctz, i32, avr, avr, i32)
> DEF_HELPER_3(bcdcfsq, i32, avr, avr, i32)
> DEF_HELPER_3(bcdctsq, i32, avr, avr, i32)
> +DEF_HELPER_4(bcdcpsgn, i32, avr, avr, avr, i32)
>
> DEF_HELPER_2(xsadddp, void, env, i32)
> DEF_HELPER_2(xssubdp, void, env, i32)
> diff --git a/target-ppc/int_helper.c b/target-ppc/int_helper.c
> index 1025438..a215bfe 100644
> --- a/target-ppc/int_helper.c
> +++ b/target-ppc/int_helper.c
> @@ -2961,6 +2961,36 @@ uint32_t helper_bcdctsq(ppc_avr_t *r, ppc_avr_t *b,
> uint32_t ps)
> return cr;
> }
>
> +uint32_t helper_bcdcpsgn(ppc_avr_t *r, ppc_avr_t *a, ppc_avr_t *b, uint32_t
> ps)
> +{
> + int i;
> + int cr = 0;
> + int sgna = bcd_get_sgn(a);
> + int sgnb = bcd_get_sgn(b);
> + int invalid = (sgna == 0) || (sgnb == 0);
> + ppc_avr_t ret = { .u64 = { 0, 0 } };
> +
> + for (i = 1; i < 32; i++) {
> + bcd_put_digit(&ret, bcd_get_digit(a, i, &invalid), i);
> + bcd_get_digit(b, i, &invalid);
This is a lot of bit fiddling to accomplish what you could pretty much
do just by copying the entire register. Checking for invalid input
makes it a bit more complex than that, of course, but you still don't
need to assemble every digit separately in the target.
> +
> + if (unlikely(invalid)) {
> + break;
> + }
> + }
> + bcd_put_digit(&ret, bcd_get_digit(b, 0, &invalid), 0);
This won't work. bcd_get_digit() will set invalid if digit 0 is an
invalid *digit*. But some valid sign indicators are not valid digits,
so this will erroneously set invalid in those cases.
> +
> + cr = bcd_cmp_zero(a);
> +
> + if (unlikely(invalid)) {
> + cr = 1 << CRF_SO;
> + }
> +
> + *r = ret;
> +
> + return cr;
> +}
> +
> void helper_vsbox(ppc_avr_t *r, ppc_avr_t *a)
> {
> int i;
> diff --git a/target-ppc/translate/vmx-impl.inc.c
> b/target-ppc/translate/vmx-impl.inc.c
> index 1579b58..c14b666 100644
> --- a/target-ppc/translate/vmx-impl.inc.c
> +++ b/target-ppc/translate/vmx-impl.inc.c
> @@ -991,6 +991,7 @@ GEN_BCD2(bcdcfz)
> GEN_BCD2(bcdctz)
> GEN_BCD2(bcdcfsq)
> GEN_BCD2(bcdctsq)
> +GEN_BCD(bcdcpsgn);
>
> static void gen_xpnd04_1(DisasContext *ctx)
> {
> @@ -1056,6 +1057,8 @@ GEN_VXFORM_DUAL(vsubuhm, PPC_ALTIVEC, PPC_NONE, \
> bcdsub, PPC_NONE, PPC2_ALTIVEC_207)
> GEN_VXFORM_DUAL(vsubuhs, PPC_ALTIVEC, PPC_NONE, \
> bcdsub, PPC_NONE, PPC2_ALTIVEC_207)
> +GEN_VXFORM_DUAL(vaddshs, PPC_ALTIVEC, PPC_NONE, \
> + bcdcpsgn, PPC_NONE, PPC2_ISA300)
>
> static void gen_vsbox(DisasContext *ctx)
> {
> diff --git a/target-ppc/translate/vmx-ops.inc.c
> b/target-ppc/translate/vmx-ops.inc.c
> index f02b3be..70d7d2b 100644
> --- a/target-ppc/translate/vmx-ops.inc.c
> +++ b/target-ppc/translate/vmx-ops.inc.c
> @@ -131,7 +131,7 @@ GEN_VXFORM_DUAL(vaddubs, vmul10uq, 0, 8, PPC_ALTIVEC,
> PPC_NONE),
> GEN_VXFORM_DUAL(vadduhs, vmul10euq, 0, 9, PPC_ALTIVEC, PPC_NONE),
> GEN_VXFORM(vadduws, 0, 10),
> GEN_VXFORM(vaddsbs, 0, 12),
> -GEN_VXFORM(vaddshs, 0, 13),
> +GEN_VXFORM_DUAL(vaddshs, bcdcpsgn, 0, 13, PPC_ALTIVEC, PPC_NONE),
> GEN_VXFORM(vaddsws, 0, 14),
> GEN_VXFORM_DUAL(vsububs, bcdadd, 0, 24, PPC_ALTIVEC, PPC_NONE),
> GEN_VXFORM_DUAL(vsubuhs, bcdsub, 0, 25, PPC_ALTIVEC, PPC_NONE),
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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