[PULL 31/34] target/ppc: implement cdtbcd

[Daniel Henrique Barboza <danielhb413@gmail.com>]

From: Matheus Ferst <matheus.ferst@eldorado.org.br>

Implements the Convert Declets To Binary Coded Decimal instruction.
Since libdecnumber doesn't expose the methods for direct conversion
(decDigitsFromDPD, DPD2BCD, etc), a positive decimal32 with zero
exponent is used as an intermediate value to convert the declets.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Signed-off-by: Víctor Colombo <victor.colombo@eldorado.org.br>
Message-Id: <20220629162904.105060-12-victor.colombo@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 target/ppc/dfp_helper.c                    | 26 ++++++++++++++++++++++
 target/ppc/helper.h                        |  1 +
 target/ppc/insn32.decode                   |  1 +
 target/ppc/translate/fixedpoint-impl.c.inc |  7 ++++++
 4 files changed, 35 insertions(+)

diff --git a/target/ppc/dfp_helper.c b/target/ppc/dfp_helper.c
index db9e994c8c..5ba74b2124 100644
--- a/target/ppc/dfp_helper.c
+++ b/target/ppc/dfp_helper.c
@@ -1392,6 +1392,32 @@ DFP_HELPER_SHIFT(DSCLIQ, 128, 1)
 DFP_HELPER_SHIFT(DSCRI, 64, 0)
 DFP_HELPER_SHIFT(DSCRIQ, 128, 0)
 
+target_ulong helper_CDTBCD(target_ulong s)
+{
+    uint64_t res = 0;
+    uint32_t dec32, declets;
+    uint8_t bcd[6];
+    int i, w, sh;
+    decNumber a;
+
+    for (w = 1; w >= 0; w--) {
+        res <<= 32;
+        declets = extract64(s, 32 * w, 20);
+        if (declets) {
+            /* decimal32 with zero exponent and word "w" declets */
+            dec32 = (0x225ULL << 20) | declets;
+            decimal32ToNumber((decimal32 *)&dec32, &a);
+            decNumberGetBCD(&a, bcd);
+            for (i = 0; i < a.digits; i++) {
+                sh = 4 * (a.digits - 1 - i);
+                res |= (uint64_t)bcd[i] << sh;
+            }
+        }
+    }
+
+    return res;
+}
+
 target_ulong helper_CBCDTD(target_ulong s)
 {
     uint64_t res = 0;
diff --git a/target/ppc/helper.h b/target/ppc/helper.h
index 583c8dd0c2..ed0641a234 100644
--- a/target/ppc/helper.h
+++ b/target/ppc/helper.h
@@ -54,6 +54,7 @@ DEF_HELPER_3(sraw, tl, env, tl, tl)
 DEF_HELPER_FLAGS_2(CFUGED, TCG_CALL_NO_RWG_SE, i64, i64, i64)
 DEF_HELPER_FLAGS_2(PDEPD, TCG_CALL_NO_RWG_SE, i64, i64, i64)
 DEF_HELPER_FLAGS_2(PEXTD, TCG_CALL_NO_RWG_SE, i64, i64, i64)
+DEF_HELPER_FLAGS_1(CDTBCD, TCG_CALL_NO_RWG_SE, tl, tl)
 DEF_HELPER_FLAGS_1(CBCDTD, TCG_CALL_NO_RWG_SE, tl, tl)
 #if defined(TARGET_PPC64)
 DEF_HELPER_FLAGS_2(cmpeqb, TCG_CALL_NO_RWG_SE, i32, tl, tl)
diff --git a/target/ppc/insn32.decode b/target/ppc/insn32.decode
index 65bcaf657f..f7653ef9d5 100644
--- a/target/ppc/insn32.decode
+++ b/target/ppc/insn32.decode
@@ -317,6 +317,7 @@ PEXTD           011111 ..... ..... ..... 0010111100 -   @X
 ## BCD Assist
 
 ADDG6S          011111 ..... ..... ..... - 001001010 -  @X
+CDTBCD          011111 ..... ..... ----- 0100011010 -   @X_sa
 CBCDTD          011111 ..... ..... ----- 0100111010 -   @X_sa
 
 ### Float-Point Load Instructions
diff --git a/target/ppc/translate/fixedpoint-impl.c.inc b/target/ppc/translate/fixedpoint-impl.c.inc
index 892c9d2568..cb0097bedb 100644
--- a/target/ppc/translate/fixedpoint-impl.c.inc
+++ b/target/ppc/translate/fixedpoint-impl.c.inc
@@ -530,6 +530,13 @@ static bool trans_ADDG6S(DisasContext *ctx, arg_X *a)
     return true;
 }
 
+static bool trans_CDTBCD(DisasContext *ctx, arg_X_sa *a)
+{
+    REQUIRE_INSNS_FLAGS2(ctx, BCDA_ISA206);
+    gen_helper_CDTBCD(cpu_gpr[a->ra], cpu_gpr[a->rs]);
+    return true;
+}
+
 static bool trans_CBCDTD(DisasContext *ctx, arg_X_sa *a)
 {
     REQUIRE_INSNS_FLAGS2(ctx, BCDA_ISA206);
-- 
2.36.1