target/ppc: implement cdtbcd

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>

1 files changed, 26 insertions, 0 deletions

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;