Hello David,
Thank you for your review. I have just one question below, could you
help me to address it please?
Thank you!
Ziviani
On Thu, Nov 17, 2016 at 02:42:43PM +1100, David Gibson wrote:
> On Wed, Nov 16, 2016 at 06:07:27PM -0200, Jose Ricardo Ziviani wrote:
> > bcdcfsq.: Decimal convert from signed quadword. It is possible to
>
> I think there should be a "not" in there.
>
> > convert values less than 10^31-1 or greater than -10^31-1 to be
> > represented in packed decimal format.
> >
> > Signed-off-by: Jose Ricardo Ziviani <jos...@linux.vnet.ibm.com>
> > ---
> > target-ppc/helper.h | 1 +
> > target-ppc/int_helper.c | 48
> > +++++++++++++++++++++++++++++++++++++
> > target-ppc/translate/vmx-impl.inc.c | 7 ++++++
> > 3 files changed, 56 insertions(+)
> >
> > diff --git a/target-ppc/helper.h b/target-ppc/helper.h
> > index da00f0a..87f533c 100644
> > --- a/target-ppc/helper.h
> > +++ b/target-ppc/helper.h
> > @@ -382,6 +382,7 @@ DEF_HELPER_3(bcdcfn, i32, avr, avr, i32)
> > DEF_HELPER_3(bcdctn, i32, avr, avr, i32)
> > 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_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 9ac204a..db65a51 100644
> > --- a/target-ppc/int_helper.c
> > +++ b/target-ppc/int_helper.c
> > @@ -2874,6 +2874,54 @@ uint32_t helper_bcdctz(ppc_avr_t *r, ppc_avr_t *b,
> > uint32_t ps)
> > return cr;
> > }
> >
> > +uint32_t helper_bcdcfsq(ppc_avr_t *r, ppc_avr_t *b, uint32_t ps)
> > +{
> > + int i;
> > + int cr = 0;
> > + int ox_flag = 0;
> > + uint64_t digit = 0;
> > + uint64_t carry = 0;
> > + uint64_t lo_value = 0;
> > + uint64_t hi_value = 0;
>
> Most of the variables above don't need initializers.
>
> > + uint64_t max = ULLONG_MAX;
> > + ppc_avr_t ret = { .u64 = { 0, 0 } };
> > +
> > + if (b->s64[HI_IDX] < 0) {
> > + hi_value = -b->s64[HI_IDX];
> > + lo_value = b->s64[LO_IDX];
>
> I'm pretty sure this is wrong. Take for example 128-bit -1:
> ffffffff ffffffff ffffffff ffffffff
> Upper word is negative (64-bit -1), so
> hi_value = 00000000 00000001
> lo_value = ffffffff ffffffff
>
> 0x1 ffffffff ffffffff != +1
>
> > + bcd_put_digit(&ret, 0xD, 0);
> > + } else if (b->s64[HI_IDX] == 0 && b->s64[LO_IDX] < 0) {
> > + lo_value = -b->s64[LO_IDX];
> > + bcd_put_digit(&ret, 0xD, 0);
> > + } else {
> > + hi_value = b->s64[HI_IDX];
> > + lo_value = b->s64[LO_IDX];
> > + bcd_put_digit(&ret, bcd_preferred_sgn(0, ps), 0);
> > + }
> > +
> > + if (unlikely(hi_value > 0x7e37be2022)) {
>
> This doesn't look right. Unless by chance 10^31-1 is equal to (k*2^64
> - 1) you need to look at the lo_value as well.
>
> > + ox_flag = 1;
>
> You might as well just return 1<< CRF_SO here - no point actually
> computing a meaningless value.
>
> > + }
> > +
> > + carry = hi_value;
> > + for (i = 0; i < 32; i++, max /= 10, lo_value /= 10) {
>
> Looks like this loop has one too many iterations - there are 32
> iterations, but you only have 31 digits.
>
> > + digit = ((max % 10) * hi_value) + (lo_value % 10) + carry;
> > + carry = (digit > 9) ? digit / 10 : 0;
> > +
> > + bcd_put_digit(&ret, (carry) ? digit % 10 : digit, i + 1);
>
> Ugh, this is hard to follow. We're already using an Int128 library in
> the memory region code; wonder if we should just use that here as well.
>
today we have divu128 (host-utils.h) but it doesn't work for me because
it coerces the 128bits result in a 64bits variable:
__uint128_t result = dividend / divisor;
*plow = result; // -> plow is an uint64_t
So I wonder if you suggest me (like the idea) to implement div and mod
in Int128 lib. Something like:
static inline Int128 int128_div64(Int128 a, uint64_t b);
static inline Int128 int128_mod64(Int128 a, uint64_t b);
But, anyway, these functions would have to implement those hi/lo
multiplications for the case "!CONFIG_INT128".
> > + }
> > +
> > + cr = bcd_cmp_zero(&ret);
> > +
> > + if (unlikely(ox_flag)) {
> > + 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 7143eb3..36141e5 100644
> > --- a/target-ppc/translate/vmx-impl.inc.c
> > +++ b/target-ppc/translate/vmx-impl.inc.c
> > @@ -989,10 +989,14 @@ GEN_BCD2(bcdcfn)
> > GEN_BCD2(bcdctn)
> > GEN_BCD2(bcdcfz)
> > GEN_BCD2(bcdctz)
> > +GEN_BCD2(bcdcfsq)
> >
> > static void gen_xpnd04_1(DisasContext *ctx)
> > {
> > switch (opc4(ctx->opcode)) {
> > + case 2:
> > + gen_bcdcfsq(ctx);
> > + break;
> > case 4:
> > gen_bcdctz(ctx);
> > break;
> > @@ -1014,6 +1018,9 @@ static void gen_xpnd04_1(DisasContext *ctx)
> > static void gen_xpnd04_2(DisasContext *ctx)
> > {
> > switch (opc4(ctx->opcode)) {
> > + case 2:
> > + gen_bcdcfsq(ctx);
> > + break;
> > case 4:
> > gen_bcdctz(ctx);
> > break;
>
> --
> 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
