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Violators will be prosecuted for from ; Thu, 27 Oct 2016 18:09:05 -0200 Date: Thu, 27 Oct 2016 18:08:20 -0200 From: joserz@linux.vnet.ibm.com References: <1477487938-23921-1-git-send-email-joserz@linux.vnet.ibm.com> <1477487938-23921-5-git-send-email-joserz@linux.vnet.ibm.com> <20161027014734.GD19918@umbus.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20161027014734.GD19918@umbus.fritz.box> Message-Id: <20161027200820.GE19890@pacoca> Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH] 4/4] target-ppc: Implement bcdctz. instruction List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org, bharata@linux.vnet.ibm.com On Thu, Oct 27, 2016 at 12:47:34PM +1100, David Gibson wrote: > On Wed, Oct 26, 2016 at 11:18:58AM -0200, Jose Ricardo Ziviani wrote: > > bcdctz. converts from BCD to Zoned numeric format. Zoned format uses > > a byte to represent a digit where the most significant nibble is 0x3 > > or 0xf, depending on the preferred signal. > > > > Signed-off-by: Jose Ricardo Ziviani > > --- > > target-ppc/helper.h | 1 + > > target-ppc/int_helper.c | 54 +++++++++++++++++++++++++++++++++++++ > > target-ppc/translate/vmx-impl.inc.c | 7 +++-- > > 3 files changed, 60 insertions(+), 2 deletions(-) > > > > diff --git a/target-ppc/helper.h b/target-ppc/helper.h > > index f460635..3b928b8 100644 > > --- a/target-ppc/helper.h > > +++ b/target-ppc/helper.h > > @@ -372,6 +372,7 @@ DEF_HELPER_4(bcdsub, i32, avr, avr, avr, i32) > > DEF_HELPER_3(bcdcfn, i32, avr, avr, i32) > > DEF_HELPER_2(bcdctn, i32, avr, avr) > > DEF_HELPER_3(bcdcfz, i32, avr, avr, i32) > > +DEF_HELPER_3(bcdctz, 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 8cbbdfc..e0a84bb 100644 > > --- a/target-ppc/int_helper.c > > +++ b/target-ppc/int_helper.c > > @@ -2768,6 +2768,60 @@ uint32_t helper_bcdcfz(ppc_avr_t *r, ppc_avr_t *b, uint32_t ps) > > *r = ret; > > return cr; > > } > > + > > +uint32_t helper_bcdctz(ppc_avr_t *r, ppc_avr_t *b, uint32_t ps) > > +{ > > + int i; > > + int j; > > + int cr = 0; > > + int invalid = 0; > > + uint8_t digit = 0; > > + int sgnb = bcd_get_sgn(b); > > + int zone_lead = (ps) ? 0xF0 : 0x30; > > + ppc_avr_t ret = { .u64 = { 0, 0 } }; > > + > > + int eq_flag = (b->u64[HI_IDX] == 0) && ((b->u64[LO_IDX] >> 4) == 0); > > + int ox_flag = (b->u64[HI_IDX] != 0); > > This doesn't look right. The zoned format can accomodate 16 digits. > The low word of the packed format can accomodate 15 digits + sign. So > it should be possible to convert a packed for with a value in the low > nibble of the upper word. David, it seems that zoned format can accommodate 15 digits + sign at most. Suppose I have this 16 bytes zoned number: f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9xx. Converting it to packed bcd will give 999999999999999x. Do you agree? can I keep that ox_flag logic? > > > + for (i = 31, j = 16; i > 1; i -= 2, j--) { > > Again not seeing any point for the reverse order. > > > + digit = get_nibble(b, j); > > + ret.u8[BCD_DIG_BYTE(i)] = zone_lead + digit; > > + > > + if (unlikely(digit > 9)) { > > + invalid = 1; > > + } > > + } > > + > > + if (unlikely(!sgnb)) { > > + sgnb = (!get_nibble(b, 0)) ? 1 : -1; > > + } > > Doesn't bcd_get_sgn() returning 0 indicate a badly encoded sign > point. In which case you should set invalid, rather than making up a > sign according to this apparently arbitrary scheme. > > > + > > + if (ps) { > > + bcd_put_digit(&ret, (sgnb == 1) ? 0xC : 0xD, 1); > > + } else { > > + bcd_put_digit(&ret, (sgnb == 1) ? 0x3 : 0x7, 1); > > + } > > + bcd_put_digit(&ret, get_nibble(b, 1), 0); > > + > > + if (!eq_flag) { > > + cr = (sgnb == 1) ? 1 << CRF_GT : 1 << CRF_LT; > > + } else { > > + cr = 1 << CRF_EQ; > > + } > > + > > + if (ox_flag) { > > + cr |= 1 << CRF_SO; > > + } > > + > > + 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 9192f8f..62c44f0 100644 > > --- a/target-ppc/translate/vmx-impl.inc.c > > +++ b/target-ppc/translate/vmx-impl.inc.c > > @@ -918,6 +918,7 @@ GEN_BCD(bcdsub) > > GEN_BCD2(bcdcfn) > > GEN_BCD3(bcdctn) > > GEN_BCD2(bcdcfz) > > +GEN_BCD2(bcdctz) > > > > static void gen_xpnd04_1(DisasContext *ctx) > > { > > @@ -927,7 +928,8 @@ static void gen_xpnd04_1(DisasContext *ctx) > > case 2: > > break; /* bcdcfsq. */ > > case 4: > > - break; /* bcdctz. */ > > + gen_bcdctz(ctx); > > + break; > > case 5: > > gen_bcdctn(ctx); > > break; > > @@ -952,7 +954,8 @@ static void gen_xpnd04_2(DisasContext *ctx) > > case 2: > > break; /* bcdcfsq. */ > > case 4: > > - break; /* bcdctz. */ > > + gen_bcdctz(ctx); > > + break; > > case 6: > > gen_bcdcfz(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