target-ppc: Introduce DFP Extract Biased Exponent

Add emulation of the PowerPC Decimal Floating Point Extract
Biased Exponent instructions dxex[q][.].
Signed-off-by: NTom Musta <tommusta@gmail.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

target-ppc/dfp_helper.c

@@ -1121,3 +1121,34 @@ void helper_##op(CPUPPCState *env, uint64_t *t, uint64_t *b, uint32_t s)     \
 
 DFP_HELPER_ENBCD(denbcd, 64)
 DFP_HELPER_ENBCD(denbcdq, 128)
+
+#define DFP_HELPER_XEX(op, size)                               \
+void helper_##op(CPUPPCState *env, uint64_t *t, uint64_t *b)   \
+{                                                              \
+    struct PPC_DFP dfp;                                        \
+                                                               \
+    dfp_prepare_decimal##size(&dfp, 0, b, env);                \
+                                                               \
+    if (unlikely(decNumberIsSpecial(&dfp.b))) {                \
+        if (decNumberIsInfinite(&dfp.b)) {                     \
+            *t = -1;                                           \
+        } else if (decNumberIsSNaN(&dfp.b)) {                  \
+            *t = -3;                                           \
+        } else if (decNumberIsQNaN(&dfp.b)) {                  \
+            *t = -2;                                           \
+        } else {                                               \
+            assert(0);                                         \
+        }                                                      \
+    } else {                                                   \
+        if ((size) == 64) {                                    \
+            *t = dfp.b.exponent + 398;                         \
+        } else if ((size) == 128) {                            \
+            *t = dfp.b.exponent + 6176;                        \
+        } else {                                               \
+            assert(0);                                         \
+        }                                                      \
+    }                                                          \
+}
+
+DFP_HELPER_XEX(dxex, 64)
+DFP_HELPER_XEX(dxexq, 128)

target-ppc/helper.h

@@ -658,3 +658,5 @@ DEF_HELPER_4(ddedpd, void, env, fprp, fprp, i32)
 DEF_HELPER_4(ddedpdq, void, env, fprp, fprp, i32)
 DEF_HELPER_4(denbcd, void, env, fprp, fprp, i32)
 DEF_HELPER_4(denbcdq, void, env, fprp, fprp, i32)
+DEF_HELPER_3(dxex, void, env, fprp, fprp)
+DEF_HELPER_3(dxexq, void, env, fprp, fprp)

target-ppc/translate.c

@@ -8398,6 +8398,8 @@ GEN_DFP_T_FPR_I32_Rc(ddedpd, rB, SP)
 GEN_DFP_T_FPR_I32_Rc(ddedpdq, rB, SP)
 GEN_DFP_T_FPR_I32_Rc(denbcd, rB, SP)
 GEN_DFP_T_FPR_I32_Rc(denbcdq, rB, SP)
+GEN_DFP_T_B_Rc(dxex)
+GEN_DFP_T_B_Rc(dxexq)
 /***                           SPE extension                               ***/
 /* Register moves */
 
@@ -11367,6 +11369,8 @@ GEN_DFP_SP_T_B_Rc(ddedpd, 0x02, 0x0a),
 GEN_DFP_SP_Tp_Bp_Rc(ddedpdq, 0x02, 0x0a),
 GEN_DFP_S_T_B_Rc(denbcd, 0x02, 0x1a),
 GEN_DFP_S_Tp_Bp_Rc(denbcdq, 0x02, 0x1a),
+GEN_DFP_T_B_Rc(dxex, 0x02, 0x0b),
+GEN_DFP_T_Bp_Rc(dxexq, 0x02, 0x0b),
 #undef GEN_SPE
 #define GEN_SPE(name0, name1, opc2, opc3, inval0, inval1, type) \
     GEN_OPCODE_DUAL(name0##_##name1, 0x04, opc2, opc3, inval0, inval1, type, PPC_NONE)