[Qemu-devel] [PATCH 2/6] target-ppc: Implement darn instruction

[Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>]

From: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>

darn: Deliver A Random Number

For both CRN and RRN, returning 64-bit random number.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
---
 target-ppc/helper.h     |  1 +
 target-ppc/int_helper.c | 14 ++++++++++++++
 target-ppc/translate.c  | 11 +++++++++++
 3 files changed, 26 insertions(+)

diff --git a/target-ppc/helper.h b/target-ppc/helper.h
index 8eada2f..257bfca 100644
--- a/target-ppc/helper.h
+++ b/target-ppc/helper.h
@@ -50,6 +50,7 @@ DEF_HELPER_FLAGS_1(cnttzd, TCG_CALL_NO_RWG_SE, tl, tl)
 DEF_HELPER_FLAGS_1(popcntd, TCG_CALL_NO_RWG_SE, tl, tl)
 DEF_HELPER_FLAGS_2(bpermd, TCG_CALL_NO_RWG_SE, i64, i64, i64)
 DEF_HELPER_3(srad, tl, env, tl, tl)
+DEF_HELPER_1(darn, tl, i32)
 #endif
 
 DEF_HELPER_FLAGS_1(cntlsw32, TCG_CALL_NO_RWG_SE, i32, i32)
diff --git a/target-ppc/int_helper.c b/target-ppc/int_helper.c
index 552b2e0..2b9fe13 100644
--- a/target-ppc/int_helper.c
+++ b/target-ppc/int_helper.c
@@ -182,6 +182,20 @@ target_ulong helper_cnttzd(target_ulong t)
 {
     return ctz64(t);
 }
+
+target_ulong helper_darn(uint32_t l)
+{
+    target_ulong r = UINT64_MAX;
+
+    if (l <= 2) {
+        do {
+            r = random() * random();
+            r &= l ? UINT64_MAX : UINT32_MAX;
+        } while (r == UINT64_MAX);
+    }
+
+    return r;
+}
 #endif
 
 #if defined(TARGET_PPC64)
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 2a87d1a..6a79fc1 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -526,6 +526,8 @@ EXTRACT_HELPER(FPW, 16, 1);
 
 /* addpcis */
 EXTRACT_HELPER_DXFORM(DX, 10, 6, 6, 5, 16, 1, 1, 0, 0)
+/* darn */
+EXTRACT_HELPER(L, 16, 2);
 
 /***                            Jump target decoding                       ***/
 /* Immediate address */
@@ -1893,6 +1895,14 @@ static void gen_cnttzd(DisasContext *ctx)
         gen_set_Rc0(ctx, cpu_gpr[rA(ctx->opcode)]);
     }
 }
+
+/* darn */
+static void gen_darn(DisasContext *ctx)
+{
+    TCGv_i32 l = tcg_const_i32(L(ctx->opcode));
+    gen_helper_darn(cpu_gpr[rD(ctx->opcode)], l);
+    tcg_temp_free_i32(l);
+}
 #endif
 
 /***                             Integer rotate                            ***/
@@ -6238,6 +6248,7 @@ GEN_HANDLER_E(prtyw, 0x1F, 0x1A, 0x04, 0x0000F801, PPC_NONE, PPC2_ISA205),
 GEN_HANDLER(popcntd, 0x1F, 0x1A, 0x0F, 0x0000F801, PPC_POPCNTWD),
 GEN_HANDLER(cntlzd, 0x1F, 0x1A, 0x01, 0x00000000, PPC_64B),
 GEN_HANDLER_E(cnttzd, 0x1F, 0x1A, 0x11, 0x00000000, PPC_NONE, PPC2_ISA300),
+GEN_HANDLER_E(darn, 0x1F, 0x13, 0x17, 0x001CF801, PPC_NONE, PPC2_ISA300),
 GEN_HANDLER_E(prtyd, 0x1F, 0x1A, 0x05, 0x0000F801, PPC_NONE, PPC2_ISA205),
 GEN_HANDLER_E(bpermd, 0x1F, 0x1C, 0x07, 0x00000001, PPC_NONE, PPC2_PERM_ISA206),
 #endif
-- 
2.7.4